Pagoda SL Group
W113 Pagoda SL Group => Drive train, fuel, suspension, steering & brakes => Topic started by: awolff280sl on October 05, 2008, 19:28:03
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I have been doing some high speed driving with my recently installed 3.27 rear end. After the drives, I have noticed some hypoid leaking down from the diff vent. The rest of the diff is dry, and the vent is screwed down tight, so I think the oil is "perculating" up through the vent. I was careful not to overfill the diff with oil, having filled it with the rear wheels on the ground.
Has anyone else seen this? Given how hot the diff is to the touch after these drives, I wonder if it's not surprising to find some oil "boiling" out of the vent?
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Hi Andy,
I had a similar problem with my 3.46 axle which leaked quite badly from the breather on the top of the diff. When I first installed the axle I removed the large breather pipe and plugged the holes as many others had done but the only way I found to cure the leak was to have the left rear chassis modified and re fit the breather. I have now covered about 2,500 miles with no leaks at all.
Have a look at my post and photos from 21 June:-
http://index.php?topic=8490.46
David Brough
1969 280SL Auto with A/C & 3.46 Axle
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Hi David,
I have just got my car back after fitting the 3.46 diff and I notice that I have a small leak from the removed breather tube outlets. There is a pool of about 3" under the car after I took it for a drive of about 150 miles at the weekend. Am keeping an eye on it at this point and hoping that it will settle down. How much leaked did you get from your diff before you made the decision to re fit the breather.
Other than that the change is fantastic and really makes it a real pleasure to drive now.
Andy, I felt the Diff whilst under there looking at the leak after driving it mainly on open road at 60 mph + and it was not 'hot' at all.
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David,
Looks like I've got the same problem. Did you investigate altering the cooling tube itself rather than making a chassis mod?
Garry,
The several mechanics I've spoken with say that it's normal for the diff to be hot after high speed driving. I hope that's reliable information, though.
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I did look at some sort of modified breather and did try a flexible one first but there just wasn’t enough space and it rubbed on the chassis. I then thought of a smaller bore custom one but that would have been very convoluted to fit and I wasn’t sure if a much smaller bore would still work. What swung it for me was that our UK Pagoda specialists said they always modify the chassis and fit the breather with these axles and they did the mod quickly and cheaply and all is now well.
Mine only leaked when on the move and only from the breather on top of the diff, any leak from the breather plugs should just be a simple sealing issue. I found that only small drops of oil actually reached the floor as most was smeared all over the diff, axle, fuel tank and rear valance from leaks at speed which then dripped to the floor when stopped from just about everywhere at the back. It is surprising just how much mess a small amount of leaking oil will make as there was no real discernable drop in the diff oil level.
I do have to say though that this change makes such a difference and I can’t understand what the original engineers were thinking when they took out the 3.69 diff and replaced it with a 3.92 for the 280. Still, it was the same people that thought it would be a good idea to fit such an unusable first gear in the auto they then had to make it start in second and still had the audacity to call it a 4 speed.
David Brough
1969 280SL Auto with A/C & 3.46 Axle
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From what I'm learning, this diff vent leak issue is so variable among rear end conversions, some have it, some don't; and the reason for this variability is not known.
While I'm learning to live with it (and it's really not all that bad, mostly an affront to perfectionism), I've been playing around with small changes in the diff oil level and using synthetic hypoid oil.
I noticed that even when I filled the oil to the bottom edge of the fill hole with the diff cold and then drove the car, oil would still drip significantly from the fill hole when the plug was subsequently removed. I figure expansion of the oil volume from heat.
With the oil level filled cold to about 1-2cm below the bottom edge of the fill hole, I have no leak from the vent...yet. I would not expect this small difference in oil volume to leave the gears under-lubricated.
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Diff vent seepage eliminated. I installed an oil tolerant, large diameter/thick walled, flexible hose to substitute for the rigid "cooling" pipe. Had to come off the fixed axle side with a 45 degree adapter (indexed to point downward once fully tightened) to avoid hitting the chassis. No leaks along the hose nor at the diff vent. May be a solution for those with the diff vent leak problem that avoids cutting on the chassis.
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Andy.
Coukd you post a picture of your new pipe, thanks
naj
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Here are pictures, broken up into 2 postings. Don't know if you can embed in postings?
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More pictures
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Automatically embeds a thumbnail, cool!
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Thanks, Andy. ;D
naj
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Hi Andy,
We'll be installing a 3.27 rear end in my 69 SL, and I'm going to follow your lead as regards the flexible cooling tube. As good fortune would have it, there is a shop within less than a mile from me here in Burbank that can measure the fittings from the old "U" pipe, incorporate the 45 degree angle fitting and recreate the complete hose for me.
My question - - about how long is your rubber cooling hose?
Cheers & thanks much,
Hank
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The hose is about the same length as the pipe. One of the problems to avoid is flattening of the hose where it loops back 180 degrees. The proper length will lessen this tendency, but I subsequently went back and slid on a Unicoil to keep the hose nice and round at the bend.
Check here: http://www.gates.com/europe/brochure.cfm?brochure=7718&location_id=11377
You can find them in most sizes in most auto parts stores.
I've also used a Unicoil under the PS reservoir b/o that short hose that tends to flatten.
They work great.
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;D
Well, there you have it !! The engineers @ MB figured they needed to have a cooling tube in that rear end - and Andy figured out how to make it all work in the W113. Of course, I'll include the Unicoil feature as well.
Thanks mate, Hank
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The so-called "cooling" pipe may in reality be a pressure equalizing device, ie it serves to reduce oil pressure within the diff by providing a shunt off to the axle tube.
That said, after a high speed drive my diff is very hot. and I wonder if it would be that hot if a metal "cooling" pipe was there instead.
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I wonder how hot it would be if you didn't have anything but plugs in place of the metal pipe. Honestly, I don't think any demons currently lurk in the 3.27 rear end of your car.
What the hey, yo - did this thread inspire you to go feeling around your car's rear end :):) after a spirited drive........... just for fun? But I like the fact that you're looking for perfection. My take, is that you've come up with a totally viable approach to this particular issue associated with a diff swap.
The company that will make my "diff hose", makes hoses for heavy industry. I will approach them regarding group pricing on this item.
Cheers, Hank
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The pipe is for cooling the rear axle lube in the heavier 4.5 The lighter 280SL shouldn't need this tube at all. A rubber hose won't provide much in the way of cooling compared to a metal one.
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Hi Dan,
Well, why then does this thread exist in the first place? Later today, I'll ask one of the techs at the hydraulics hose shop for their take on this subject, and I'll post their thoughts.
Cheers, Hank
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Could someone post a picture of the chasssis modification needed to fit the original tube ? The one a few posts above is not available anymore.
Another question : I have a 3,27 on my W111 Coupe with the cooling pipe fitted. I have slightly overfilled the rear end with three quarts instead of 2.5L (overfilled by 0.4L). I first had no problem but I then drove the car on the highway with a lot of weight in the trunk (temporarily) provoking a strong negative camber. When I reached home I noted the diff was all wet in oil, with a drip coming from up. I guess it's from the vent. Can the combination of overfill and negative camber (therefore sending all the oil that are in the tubes towards the diff) provoke a seapage, even with the cooling tube in place ?
Thanks !
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Yeah, it doesn't take much to overfill them; care must be taken to level the diff both ways as well as keep the camber close to zero. And somewhere in the older books I think there's a specified time to let it set after filling, with the fill-cap still removed, in order to allow any overfill to overcome the meniscus effect and drain out. [On reflection, that's probably from transaxles, not our diffs, but it is so German, n.v.? There's also a spec timing the rate of drips when draining engine oil during a change procedure, like when it slowed to no more than x number of drips in a minute you could consider it drained.] Probably best to underfill it very slightly if anything; if you "settle' the car a little after filling, the slight loss of camber should do it. It's one of those times to let things 'breathe' a bit in between. There's a filtered vent to atmosphere up near TDC and centerline.
Love what you're doing with those cars,
Denny
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Thanks, Andy; your fix has a lot going for it. In a lot of searching nationwide over a week or two I could find only one hose product with a diameter suitable for fitting over the existing tube (to be cut off near its fittings) for a solution similar to yours, and that hose was rated for milk. Getting hydraulic fittings made up to the heavy-duty high pressure hose and then welded to our metric fittings was going to run two or three hundred dollars in our market, so I took Walter's advice and just bent it out of the way, pretty much the way your hose goes. ["Just" bent it isn't really accurate; it's challenging in the cramped areas upside-down and underneath, and took a goodly portion of my levers and tweakers and odd-shaped wrenches.] Not pretty but after several re-tightenings of the threaded fittings, no leaks or rubbing in the ensuing few thousand miles. 'Twere more neatly and easily done prior to installing the axle -- and with a torch to smooth things -- but then it's hard to know just where it needs to move to and how much. [Though two or three swaps ought to teach that.]
It's a much cleaner and more elegant swap with the external circulating tube removed and the holes plugged neatly with M-B oil drain plugs. And for, let's say, 80% of these swaps that is the way it's done: viola! Mine looked all nice like that when it left Joe's shop. By the time I arrived home a day's drive later, at least 75% of the nice new lube was gone, except for what was all over the rear - - underside sopping and outside slick. So what determines the difference between those of our swaps that blow out their contents and those that don't? Where's the variable?
I'd much rather we proactively find and fix it - control the situation at its source - than have to mess around coming up with improvised reactions to unpredictable crisis.
I'm not at all pleased that I haven't been up to the challenge myself. I've asked some of the most experienced and respected 113 pros about it with little result. In Britain they carve off a bit of the understructure to clear the tube.
Here's a fairly major failure that occurs, apparently randomly, in 20% (?) of one of our largest and most favorite improvements, and we haven't figured it out -- yet.
Yours in motoring happiness,
Denny ;~)
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I think the reason for it to happen is that the oil is drawn up by the gear and hits a perpendicular surface where the plug is. Then I guess depending on the oil's properties, it emulsifies more or less and ends up overflowing through the vent. The difference between the lucky and the unlucky ones may be due to oil properties and how fast and how long the car is driven on the highway.
The best solution is to reshape the tube so that it clears the chassis. We should document this as indeed it's easier to do it when the rear end is not in yet.
Love what you're doing with those cars
Thanks ! We're not far from each other. We could meet one day so that I can see on your car what's involved to clear the chassis with thatt tube, and you could have a drive in my 5.0L coupe and tell me what you think.
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Hi Dan,
Well, why then does this thread exist in the first place? Later today, I'll ask one of the techs at the hydraulics hose shop for their take on this subject, and I'll post their thoughts.
Cheers, Hank
Why? Because we can.
Rubber insulates. Try placing your hand on the rubber hose near your IP thermostat and then place it on the thermostat housing with the engine fully warmed. Your hand won't stay there very long. In most cases involving gear oil or hydraulic fluids, a rubber hose usually goes to a metal one that goes to a tank or oil cooler. In this case, the oil cooler is the metal tube. The crown gear throws oil off as it spins and some of this oil hits the opening for the tube and runs down until it gets picked up by the crown gear and the cylcle is repeated over again. The crown gear and differential carrier are capable of moving the oil around inside of the axle to the extent that it will keep everything well lubed. The problem withn the 4.5 was the gear oil would get too hot without a cooler.
If you fit a rubber hose so the gear lube can circulate it won't be about cooling. The 4.5 and 280SL have similar power to weight ratios at 16 and 15 to 1 respectively. The 280 engine has more than enough power to push the car down the road with the 3.27 axle so maybe this problem has a different source.
Overfilling is probably 90% of it yet I've seen 3.92 axles that were somewhat overfilled and they didn't really leak out very much. The problem could be something as simple as the 3.27 gear ratio. Lower gearing spins the pinion gear faster but seems to produce less heat because it requires less torque to turn the gears.
I've seen this on tractors. As long as I was running in a low enough gear the fluids inside the transmission and rear axle would run cool. When I tried to run in a higher gear the oil would over heat and I had to stop and let everything cool down. Oil lvel also played a key roll as too low would make it over heat just as quickly as too much fluid. I was running a 155 HP 2WD with a 22 foot cultivator behind me. Conditions were less than ideal so it was pulling hard. This system had an oil cooler in front of the rad.
I think that gear ratio and load ( weight ) play a factor. I'm thinking they placed a cooling tube on the axle because of the gear ratio and the extra heat it would produce. Since the 280SL is almost 1,000 pounds lighter than a 4.5 you really shouldn't need the tube at all. Lower the oil volume slightly in the axle and use a good quality synthetic.
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WOW - thanks Dan,
"OVERFILL", don't go there !!! Your post was greatly appreciated - at least a full day's worth in the lecture room !!
Cheers mate,
Hank
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Hey Dan, while the rubber diff hose I installed did eliminate my vent seepage, my diff does run hot, too hot to touch after some drives. I think I need to get around to taking its temperature. So far I've driven a few thousand high speed highway miles without a problem, but maybe I've been lucky.
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WOW - thanks Dan,
"OVERFILL", don't go there !!! Your post was greatly appreciated - at least a full day's worth in the lecture room !!
Cheers mate,
Hank
Thanks Hank.
It's really only an educated guess at best but close ovservation over the years around all sorts of equipment helps a bit.
I'm doing a 4.5 axle for a guy right now and I plan on removing the cooling tube. I wouldn't, under any circumstances, alter the frame of the car just to fit the tube.
One thing to note: the 4.5 vent is placed differently than on 113 cars. The ones with a vent on the left axle tube never give trouble and axle only starts to leak if the seals are worn or the vent tube is plugged.
If the axle is running really hot then there's something wrong with it. I'm no expert on rear axles but they normally get warm much like a standard trans. If anything, I wold expect the trans to be even warmer than the axle but never be '' burn your hands '' hot simply because of proximity to the engine. The rear axle is not near any other heat source and should be fairly warm to the touch.
With the car on a hoist and the axles hanging down, I use my littler finger to feel the oil level. You should be just able to touch the oil using this method. If oil comes out of the axle any time you remove the fill plug it's way too full.
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Okay, so at this point I’m really confused. About 15 years ago, I installed my 3.27 rear end in my 1970 113. I read up on doing the conversion at that time, it recommended plugging the metal vent pipe with an early oil pan drain plug. (Of which I did). I have never had any problems with leaks, and I don’t believe the rear end gets too hot. I have put about 70k miles on the car in this configuration, and now after reading this thread I’m a little concerned about not having the vent at all. I plan on doing a long road trip in the near future, Should I attach a rubber vent set up or not? What sort of filter is on the end of the tube?
Michael
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I think you are confusing two things : the cooling pipe that can be plugged with oil pan drain plugs, and the vent, which is on the top right of the center housing, and which is too small to be plugged by an oil pan plug. So I doublt you did that and I think you're fine if you're not blowing oil through the vent and if your oil level is OK.
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I'm happy to see serious consideration given to this topic; it's made me a little crazy for some time, and we may not get to the bottom of it for awhile yet. Thanks for sharing your experience and acuity.
Particulars in my bout with the disease are that several members and I disassembled, cleaned and inspected a very decent 3.46 axle after PUB 09. The diff assembly per se looked to be 100% and Joe and I left it alone - - see Benz Dr.'s weigh-in on that one in a post above. Wear of any kind was hard to find anywhere, though somehow there was a parts bill of several hundred dollars all up, mostly for gaskets, seals and external fitments. I left for home and other issues. Joe assembled it -- without the external Tube -- over time as his schedule permitted, even to the inspection paint codes. He filled it with Valvoline synthetic lube, and I doubt very much that he overfilled it: how many has he filled in the last quarter-to half century? I drove it home at Interstate speeds, savoring the 3.46 ratio. At the end of the ~300 mile trip, the rear 15-20% of the car was a slimy mess, under and above. Lube definitely did still remain inside, but little and only discernable in the axle tubes. The differential housing was just comfortably warm and has not made any noises at all, ever, so apparently it was caught in time. I subsequently re-installed The Tube, modifying it to fit, drained and refilled the lube. [Drained fluid was filtered thru coffee filters and yielded zero sediments of any sort to the naked eye.] Beyond a few sessions re-tightening the poor threaded fittings -- tested mightily by the alteration process but proving quite stout -- it has been fine ever since.
The car and our relationship being what it is, actual mileage accrued over the intervening year and a half hasn't amounted to more than a few thousand miles, but did include several hundred- and two-hundred mile outings plus another round trip to Ohio for PUB, which entails two 250+ mile runs at speeds over 80mph in some states.
Michael - Yes, the vent is separate from the U-tube. It's located up high on the central differential case, smallish and hard to see and reach after the whole shebang is installed underneath the car. The Tube, absent in your case, is for circulation of the lube and doesn't directly involve venting of anything. It's purpose may have been for cooling the lube in it's more demanding original duty under much heavier sedans. Ours shouldn't need it, it gets in the way, and it works out fine in most cases to just leave it off.
However, for some unfortunate wretches among us..... Oh, let me put it another way: you live right, don't you? Well, I liked to think I did, too. And then this. I tell you; it just shakes your faith in the fairness of things. As for you and all the others like you, go Tubeless and enjoy, lucky so-and-so's! : )
Denny
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This may be totally obvious, but I seem to recall that it's important to check/set the diff oil level with the car flat on the ground. It had to do with oil running out and down into the axle tubes resulting in false readings when the car is jacked up or on a lift and the tubes are sloped downward. Could the oil spewing problem be as simple this, i.e. we check oil level on a lift, then as soon as we lower the car all the oil out in the tubes pours back in creating an over-full situation?
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You recall correctly, Peter and yes, it is important to not get fooled into overfilling by axles that are not level/horizontal when filling/checking axle fluid level. It's a touchy proposition; a little bit off makes more difference than you might think. The car should even be level fore-and-aft as well, though it's not nearly as important as it is to eliminate any and all axle 'droop'. [An inexpensive magnetic-mounting caster/camber gauge works well for this on both the axle and the door sills.] More is not better here: just a little low will work fine. And it is hard to doubt that some of the lesser outflows have been caused by overfilling. But as I mentioned in my post just above, surely someone such as Ja17, who has been servicing and refurbishing this type of axle for decades, would assemble and fill one properly. I have no doubt mine was.
Further, it seems reasonable that outflow caused by overfilling would be self-correcting. That is, when enough loss occurs to lower the fluid to the correct level, hasn't the cause been eliminated and so the outflow should cease? But when I looked into my situation I could find fluid remaining inside of the axle only by removing the plug from the U-tube mount location down on the axle tube, where I could reach a fluid level with my finger. That's a heckuva lot lower than the proper level. Something else is going on.
Denny
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I think I may have come up with a viable solution for this problem.
The vent on the 4.5 axle is different than on the regular six cylinder cars. The 4.5 axle is designed to be stronger due to the heavier car and there are several places where they used larger fixing screws and heavy duty parts.
The vent on the 4.5 is placed at the top of the diff housing facing away from gear rotation. If you remove the vent you will be able to see that the internal diameter is considerably larger than the vent that's placed on a car where it's on the axle tube. The threaded hole on the 4.5 unit is probably 14 mm whereas the earlier axle vent is a 10mm thread. Inside any vent tube you should be able to find a felt wick which is supposed to prevent oil from making its way up and out of the vent. The vent on the 4.5 has a lot of oil splashing around right near the opening in the casting and I think this is where the problem starts. It's also possible that the wick fell out so that's something to check.
My cure for this is to go back to the original set up found on earlier axles. On the left axle tube, you will find a protusion in the casting on the 4.5 axle where the vent would normally be found at the top of the axle, right next to the difff housing. We drilled and tapped a hole in this casting to accept the smaller vent found on earlier axles. There is little to no oil splashing around in this area as it's well behind the main carrier bearing on that side of the gear set.
Since we had the whole axle apart ( except for the pinion shaft ) is was fairly easy to drill a hole in the casting. We placed a tap in the drill press so that it would start perfectly into the hole and then carefully turned the drill press by hand. It's not possible to be able to use a regular tapping handle due to the diff housing being in the way.
Since regular diff vents on six cylinders cars usually don't have any gear lube spewing out of them, I'm thinking this will work the same way on the modified 4.5 axle. If it doesn't, we'll use a modified return hose or pipe but I have a feeling it will work just fine.
Due to the extra heat produced in the axle by the 4.5 sedan, the set up they used was the perfect answer. The circulation tube and a larger vent placed high up on the axle to bleed off any excess heat was the answer. Since this set up requires some modification for the 113 I think this is the extra part of this mod that could be the answer. It's also easily reversed if you decide you want it the other way. You will need two diffrent sized plugs to close either hole depending on which vent you end up using and where it's placed.
Of course, you need to do this before you install the axle. We removed all of the screws that hold the left axle tube to the diff carrier mostly so we could clean it up better. While we had it apart the idea came to me but I had been thinking about how to fix this problem over the weekend.
The hole drilled through the casting enters inside the axle tube just behind the outer race for the main carrier bearing, right where the casting is at about a 45 degree angle. This can't be seen unless the axle tube is removed but there's no chance of hitting anything important. If you decide to try this idea without taking the axle apart, use some grease on your drill to prevent any chips from falling into the axle tube.
We will monitor the axle temps and see how it works.
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So Dan, how did it go?
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I did it on my Pagoda and it works perfectly. The other option is to fit the left wheel tube of later Pagodas rear axle (yes it fits) which already has that vent and block the vent on the center housing. This option may require checking the adjustment of the left differential bearing outer race, which is done by adding or taking out shims behind it.
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I am wondering if any (all) of you who have made the with to the 3.27 rears, have replaced the entire rear end, or do you keep any of the old parts? Also, have you been breaking down the replacement rear end and cleaning and re-painting? What has your process been?
Best,
Roland
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So Dan, how did it go?
I am unable to say because we sold the axle. No complaints though.
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I'm happy to see serious consideration given to this topic; it's made me a little crazy for some time, and we may not get to the bottom of it for awhile yet. Thanks for sharing your experience and acuity.
Particulars in my bout with the disease are that several members and I disassembled, cleaned and inspected a very decent 3.46 axle after PUB 09. The diff assembly per se looked to be 100% and Joe and I left it alone - - see Benz Dr.'s weigh-in on that one in a post above. Wear of any kind was hard to find anywhere, though somehow there was a parts bill of several hundred dollars all up, mostly for gaskets, seals and external fitments. I left for home and other issues. Joe assembled it -- without the external Tube -- over time as his schedule permitted, even to the inspection paint codes. He filled it with Valvoline synthetic lube, and I doubt very much that he overfilled it: how many has he filled in the last quarter-to half century? I drove it home at Interstate speeds, savoring the 3.46 ratio. At the end of the ~300 mile trip, the rear 15-20% of the car was a slimy mess, under and above. Lube definitely did still remain inside, but little and only discernable in the axle tubes. The differential housing was just comfortably warm and has not made any noises at all, ever, so apparently it was caught in time. I subsequently re-installed The Tube, modifying it to fit, drained and refilled the lube. [Drained fluid was filtered thru coffee filters and yielded zero sediments of any sort to the naked eye.] Beyond a few sessions re-tightening the poor threaded fittings -- tested mightily by the alteration process but proving quite stout -- it has been fine ever since.
The car and our relationship being what it is, actual mileage accrued over the intervening year and a half hasn't amounted to more than a few thousand miles, but did include several hundred- and two-hundred mile outings plus another round trip to Ohio for PUB, which entails two 250+ mile runs at speeds over 80mph in some states.
Michael - Yes, the vent is separate from the U-tube. It's located up high on the central differential case, smallish and hard to see and reach after the whole shebang is installed underneath the car. The Tube, absent in your case, is for circulation of the lube and doesn't directly involve venting of anything. It's purpose may have been for cooling the lube in it's more demanding original duty under much heavier sedans. Ours shouldn't need it, it gets in the way, and it works out fine in most cases to just leave it off.
However, for some unfortunate wretches among us..... Oh, let me put it another way: you live right, don't you? Well, I liked to think I did, too. And then this. I tell you; it just shakes your faith in the fairness of things. As for you and all the others like you, go Tubeless and enjoy, lucky so-and-so's! : )
Denny
This remains a viable axle ratio and I wonder why there is so little interest in it. This ratio is very close to what a 5 speed trans will give you in high gear and should not be over looked.
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I agree, but it is quite rare on the US/Canada side. And even the 3.27 is getting quite rare today.
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I'm just in the process of fitting the 3.46 to a customer's car and have opted to cut a relief into the chassis. it seems the easiest and most reliable option to me.
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Did you live a hole there? Or you reshaped some metal to close the hole?
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We'll be fabricating a repair panel to weld in and return the strength.
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Did you already cut the relief? If not, and as metal work is involved anyway, you may consider modifying the tube instead. With 2 of them you may be able to fabricate one that clears.
Otherwise, I crossed the US twice round trip with my V8 Pagoda and drive it hard regularly. I don't have that pipe and I've had no issues so far.
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I don't like to experiment with customer's cars; I prefer an option that guarantees results. If it was my car I would certainly experiment with other options.
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I was talking of the cooling tube in my previous message, not the wheel tube.
If your client is ok with cutting the relief, then it is certainly the most elegant solution technically speaking.
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I have run a 3.27 axle for years! It is wonderful! Dan - I so love your insight with mechanical things! You are very talented!
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Well gee, thanks! Coming from you that's a compliment I'll always cherish. I guess mechanics always came easily to me and carpentry not so much. Being interested by mechanical things, I always wanted to know how something worked because you can't fix much if you don't know how it works.
Some of you may find it hard to believe, but I'm entirely self taught and it was through talking to other mechanics, machinists, body men, and guys who love old cars that I was able to put it all together. Depending on how you look at it, this may be my last year in the restoration biz as I've been at it for 40 years and I don't have the help, energy, or real desire to continue on. I'll finish those projects that we are working on right now and then I have a couple of my own because I want to do them before I'm unable. I will still do general repairs and tune ups for as long as I can but full restorations might be a thing of the past.
I often wonder what I could have done with formal schooling and training............
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I am pretty much with Dan straight down the line as far s the rubber hose being an insulator and all. I am wondering if perhaps there is any sort of "Slinger" on the center section that causes more oil to be thrown up to the top of the rear axle on the 3.27 rear axle as opposed to the higher (Numerical) ratios?
I am also wondering if the people doing the conversions are moving the vent to the boss on top of the left housing??? Without the cooling tube in place the location of the vent on the 3.27 might be more prone to oil splash being forced out the vent and the rubber hose is just giving some of the oil a path and cutting down on splash through the vent.
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For those of you who might be interested: my 3.27 differential started leaking. I found some oil on the garage floor. One small leak was from the drain plug. I unscrewed it about 3/8 inches only because I did not want to drain the oil and wrapped it with Teflon sealing tape. Then tightened it. It has stopped leaking. The other leak came from the vent pipe on top of the differential housing. I wedged a napkin underneath and found that it leaks only after a prolonged drive. I unscrewed the vent pipe. it was loose. Attached is a picture. There are two seals: an o-ring and a flat seal like a garden hose seal. I put some Permatex tread sealer on and we shall see.
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I use a sealer that comes in a tube which I believe is also Teflon. This stuff stays soft and will seal up just about anything that's threaded.
I thought about why some 3.27 axles run hot or spew oil out everywhere, and why some are near prefect, and can really only come to one conclusion. Something is different inside the axle. My best guess is that some are in good shape and some aren't, or are worn in some way.
Before I even think about installing any axle I check for gear play at the crown and pinion as well as the internal gears inside the carrier. By holding the pinion flange and turning either wheel it is possible to get a rough idea of what's going on inside the axle. Moving the pinion flange only enough to feel any play should give you a basic back lash reading. Not very scientific but generally you should just be able to move the pinion flange a very small amount. If I find anything more than just a nominal amount I usually pass on using that unit. I can't really say how to do this exactly. It's sort of a feel thing but if you do feel something that seems like a lot of play I would advise not installing that axle.
Maybe those who are having running problems could do a little checking and see if in fact they have wear problems. Something is causing this - guessing isn't good enough and there is a reason for it. I suspect wear of some sort. These are used pieces and there's no telling how the car was driven or cared for.