3,27 axle checkout, reseal, repair & install

[Naj ✝︎]

Jeff,
Is there any noticable difference between the left and right drive axle shafts (on this side of the pond we refer to them as 1/2 shafts)?  :?:

naj

68 280SL

[jeffc280sl]

Naj,

The right half axle as a small C clip about 1/4 from the top of the spline end.  Further down the axle shaft you can notice in the pic a raised section on the right shaft which is not present on the left side. Please keep in mind these are from a 280SE(L)4.5 and may be different on an SL.

Download Attachment: half axle.jpg
30.86 KB

Jeff C.
1970 280SL 4-speed

[Naj ✝︎]

Thanks Jeff

naj

68 280SL

[jeffc280sl]

Just about finished with the axle rebuild.  Diff case has been reunited with axle tubes.  Axles are in place and emergency brakes are installed.  

Need to finish the caliper rebuild and then I'm ready to install.  A time consumming yet very satisfying project.  

Received the second axle.  It is in good shape overall but it is not a LSD.  I intend to repair and replace all neccessary components and then offer it for sale.  I plan to document the repairs with pictures for those interested in buying it.  In this way you have some idea of what you are getting.

Jeff C.
1970 280SL 4-speed

[jeffc280sl]

Had 3 hours to spare today so I thought I'd get started on removing the 3,92 rear axle from my 280SL.  Things have gone smoothly so far and here is where I stand.

1) Removed exhaust system  ( job much easier because I have a 6 month old stainless steel system.  Just needed to loosen some clamps and presto)
2) Disconnect emergency brake cable
3) Remove compensating spring ( much easier second time for this, I installed an Olson spring set 3years ago)
4)Loosen, two turns, slip nut on drive shaft mid section. (made a 46mm wrench as per BBB, made this job a snap)
5) Disconnect rear drive shaft to axle connection.
6) Disconnect trailing arm to body and remove L&R coil springs. (see note above for comp spring)


This week I expect to complete the following steps and remove the old axle.

1) Disconnect hydraulic brake lines
2) Disconnect cross strut bolts 7&9
3) Loosen lower shock bolts
4) Raise and support rear axle and remove hex bolt in trunk disconnect shock bolts and lower axle.


Jeff C.
1970 280SL 4-speed

[jeffc280sl]

Old axle is out and will do some cleaning of road grime under the car today.  Lowering the axle from under the car went well.

Jeff C.
1970 280SL 4-speed

[jeffc280sl]

Mounted the new axle yeasterday,  Secured the cross strut (did not remove it or change adjustments) and main trunk carrier. Connected the drive shaft and shocks.   Caliper rebuild kit came yesterday.  Worked on those in anticipation of needing them soon. Having a little trouble with the dirt guards on the calipers.  I'll figure it out.  Need to finish the brakes and connect lines, hookup emergency brake ( W108 cables are too short, dangit) Need to install springs and trailing arms and tighten the mid universal drive shaft nut.  Then check rear geometry using Arthur's tool.  I'm expecting it to be as good as before.  We shall see later this weekend.

Jeff C.
1970 280SL 4-speed

[jeffc280sl]

The axle is securly installed as are the springs and trailing arms.  The mid section drive shaft nut has been tightened and I've checked the geometry using Arthur's tool.  I'm happy to say no adjustments were needed as hoped.  I did not remove the cross strut and was very careful to align and adjust the carrier arm so it went as planned.  Tomorrow I'll hook up the emergency brake cables, install the calipers and bleed the brakes.  I have this feeliong I've forgotten something.  Should finish tomorrow and will go through a check list  before taking it for a spin.  All in all it's been a fun project.  Can't wait to take it out.

Jeff C.
1970 280SL 4-speed

[jeffc280sl]

Completed the project last night and took the SL out for a spin.    For those that have a manual transmission, as I do, I think you will like the change very much.  With the old axle I felt first gear was way too low and there was a fairly urgent need to shift into second.  Now take off from start feels like a modern manual transmission car.  Highway driving was very smooth with less vibration from the engine. I figure about a 20% reduction in rpms.  Now I need to have the speedo adjusted.  I highly recommend the gear change for those with a manual transmission.

Jeff C.
1970 280SL 4-speed

[lurtch]

Hello Jeff - - I am one of the fortunate few other Pagoda guys who have a 3.27 rear end in my car.  However I have not , as yet ,  had the speedo re-calibration done. Could you post  the details when you have successfully completed that?

Regards and thanks for the photos,
Larry in CA

[jeffc280sl]

Will do Larry.  I'm glad you like the upgrade.  How many tickets do you have because of the speedo?

Jeff C.
1970 280SL 4-speed

[TheEngineer]

Replaced my 4.08 axle several years ago with a 3.27 and I have an automatic. It made the car much nicer to drive. It was one of those modifications that was well worth the effort. The speedo reads low and I just multiply the indicated speed by 1.25 like 40 is really 50, 60 is really 75. I take a quarter of the indicated speed and add it. I have gotten so used to it that it's automatic. I have never received an answer why MB put a 4.08 axle into those cars. It makes no sense. The acceleration of my car is very satisfactory, it just stays in a lower gear longer. I can out accelerate most cars on the road and on the freeway.

'69 280SL,Signal Red,113044-12-007537,tired engineer, West-Seattle,WA

[jeffc280sl]

Thanks for the input on auto tran SLs.  I was reluctant to recommend the change because I have the manual.

Have you looked into buying a ratio converter box?  I'm just starting to look into them.  They would go in-line somewhere with the speedo cable to compensate for the rear change.  Seems like a good way to go as it would take care of the odometer also.  

I've found lots of info on odometer gear changes but very little on the speedo itself.  I suppose this is because of the magnetic nature of it.

Jeff C.
1970 280SL 4-speed

[DavidBrough]

I have been following this thread very closely as it is something I keep thinking about doing but can’t quite pluck up the courage, or the cash for that matter.

However, I would be interested to learn from Peter and those who have carried out the change to auto cars how they behave when starting from rest in second gear. Is this OK and on what sort of incline do you have to force the use of first gear.

Great thread Jeff thanks.


David Brough
1969 280SL

[rwmastel]

David,

One member here had Gernold at SL Tech instsall a first gear start system on an automatic transmission 280SL.  I don't know if this was done in conjunction with a lower axle ratio, but it would make sense.  I have no idea what the cost would be for this modification.

Rodd
Powell, Ohio, USA
1966 230SL, Euro, Auto, Leather, both  tops
1994 E420

[DavidBrough]

Thanks Rodd, that would seem to make a lot of sense when done in conjunction with a diff change to make the auto a proper 4 speed. I don't suppose anyone knows how it works do they?


David Brough
1969 280SL

[hands_aus]

quote:Originally posted by DavidBrough

Thanks Rodd, that would seem to make a lot of sense when done in conjunction with a diff change to make the auto a proper 4 speed. I don't suppose anyone knows how it works do they?


David Brough
1969 280SL

A Dalton ( whatever happened to him anybody know? ) devised a method and mentioned it on here but I can't find it.
Maybe someone has the item numer.

This is one of those IMPORTANT topics that should be included in the WORKSHOP MANUAL??? but it has been swallowed up in the topic list and not easily found by the 'search' because you have to know exactly what words were used in the discussion.

Bob Smith (Brisbane,Australia)
RHD,1967 early 250 SL, auto

[66andBlue]

If anyone wants to repeat this here is a 3.27 on eBay:
http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&ih=007&sspagename=STRK%3AMEWA%3AIT&viewitem=&item=170080500993&rd=1

Alfred
1966 blue 230SL automatic

[Shvegel]

It would seem that you could use some sort of rpm sensor controling the kick down solenoid. Below 900 rpm and the kickdown would be active which would give you first gear. Maybe one of the later RPM emission relays depending on the range of the relay.

[al_lieffring]

quote:Originally posted by 66andBlue

If anyone wants to repeat this here is a 3.27 on eBay:
http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&ih=007&sspagename=STRK%3AMEWA%3AIT&viewitem=&item=170080500993&rd=1

Alfred
1966 blue 230SL automatic

The axle in the foreground of the picture in the Ebay auction is for a 300SEL with air suspension. It's most likely is just the axle that was closest to the door when they went to take the photo. 300's had rear calipers that floated on the axle and had radius arms that held them to the chassis.
300's also had a rear anti-sway bar. Now that would make a cool addition. Has anyone tried to modify one to fit a pagoda??

Al

66 230sl
113-042-10-014715
904/396 blue, Ivory Tex
condition: not-as-rusty-as-before-bucket

[France]

Hi Guys,

Well thanks to Joe A., Carling has a brand new (OK, you know what I mean--thoroughly reconditioned) 3.27 diff, installed without a hitch by Steve our friendly resident race car mechanic!  What a difference.  

May have to consider the kick-down switch, because she's a little slow off the mark now, but highway driving (in fact all driving) is soooo much more enjoyable.  We put in a new exhaust while we were at it, and her underside looks positively new.

Now for that stumbling ignition; Pertronix to the rescue, to be installed next week.  Many thanks to all on this forum for the great advice; there is not a time I take Carling out for a spin that someone doesn't look admiringly or say how lovely she is!

Trice
1968 280SL US, signal red/bl leather, auto, kinder seat
Sarasota FL; Alsace France; Switzerland
You only need 2 tools in life: WD40 to make things go, and duct tape to make them stop.

[jeffc280sl]

Just returned from my first long trip with the 3.27 axle.  It was over 300 miles at an average speed of 70mph.  24.2 mpg was the fuel consumption rate.  I thought that was very good.  Comments?

Jeff C.
1970 280SL 4-speed

[Dick M]

Joe Alexander made the following video on the 3.27 rear axle conversion.
http://video.google.com/videoplay?docid=6365474313884505435&hl=en

Down load video for best quality....

[BABAK]

I just got my 3.27 from pick a part yay.I guess i have a new project

[jeffc280sl]

Babak,

Let me know if you have any questions.  I'll be happy to answer what I can.

Jeff C.
1970 280SL 4-speed