5 SPEED CONVERSION ?????

[colinwoodburn]

See duplicate message below

[Dash808]

Well, after a long and unsuccessful hunt I have eventually obtained a 3.46 axle for my 280 SL.  And was wondering if anyone has also fitted a 5 speed box into their Pagoda with this axle ratio  . I don't know which box would be required for the conversion but one easily obtained from a breakers yard not an original ZF item [Far to $$$] would be advantageous, perhaps from a 108?  Is this box a top or side rail/ rod change or a 5/6/7 BMW box instead?
  Regards Colin



Fixed it for ya  

[w113dude]

I have a 5-speed on my coupe w111 (same as w108) and it's side railed.

[Shvegel]

There are a couple of people here fitting a getrag 265 from a BMW. Really a good choice in terms of size, shafts etc.

[mkbull]

Hello Colin
I can help you with your plans regarding the 5 speed conversion if you really want to go that route.
However the 3.46 and 3.25 rear diffs kind of make your 4th gear similar to a 5th gear with a more standard ratio diff of 3.92.

Therefore I would not personally combine both of those changes. if you did and had a 5th gear of approx 0.8 like the zf or getrag then your potential top speed of 160mph at 6000rpm would need a well tuned engine and good brakes!!!!
I could email you a calculator spreadsheet I have done with all of this on it, you simply change your ratios and see what speed the pagoda will reach at given revs.

Regards
Mark

[DavidBrough]

I always thought that was the whole point of a 5 speed gearbox so you could cruise at 70mph with less than 3,000rpm. I have a 3.46 with an automatic which still revs a little high but because its only really a three speed I think the 3.27 would be a shade low but perfect for a 5 speed manual. If anyone knows of a proper 4 speed auto that will fit the Pagoda I would be the first to get my spanner out.

[georgem]

Guys,

An innocent question from a novice.

Our cars were designed and built with the engine/gearbox and diff rations to do the job for which it was intended. I assume torque curves/revs etc were carefully calculated by those very meticulous MB Auto Engineers  to match all the variables.  I guess they figured that the car would tour at high speed on the autobahns etc and knew what revs they engine would be sitting on for long periods.

What happens to those calculations if we now maintain those speeds but at lower revs - does it take it out of its torque curve, or maybe does it have to "push harder" to maintain the speed?  Does this "strain" the engine, what happens to fuel economy? I understand the noise level drops of course and this seems to be a major incentive  -  I will be the first to admit, when we first bought our car, on several occasions I changed out of 4th gear into an immaginary 5th gear because of the engine revs. Now I am used to it.

Don`t interpret this as a criticism - just something that has been nagging at the back of my head for a while.

Cheers

[DavidBrough]

Whilst I have no doubt that the engineering design team knew what they were talking about most of the time, they were also driven by fashion as they are now. In the 60’s performance was king over noise, economy, emissions and most everything else so you get 3.92 and even 4.08 final drives in a 280 which look good in the acceleration charts, keep the engine in the meat of the torque curve at cruise and just stop the engine over revving at full throttle in top gear.

Now I know that no one’s perfect and we all have different likes and dislikes but you do have to ask yourself just what were they smoking when they thought it would be a good idea to fit the automatic with a first gear so low they had to make it start in second. I can only assume that they had a three speed box and marketing said it needed to be four so they stuck the extra one at the bottom out of spite. Still, each to his own.

[mkbull]

No - I dont think the 3.27 would be perfect for a 5 speed manual.
I think you would only get to use the 5th gear downhill, and a steep one at that.

[DavidBrough]

I suppose it's all about personal preference at the end of the day and whether you're looking for best cruising or best responsive performance. A 3.27 axle should give 70mph at 3,000rpm for a 1:1 4th gear ratio and about 2,500rpm for an overdrive 5th which would make for nice cruising performance and also bring the manual low first gear more in line with modern vehicles. However, a slightly higher final ratio like a 3.46 should give better in gear response and better ultimate acceleration. All only opinion at the end of the day though as I have no actual experience in a manual 113.

That said, when I changed my axle overall performance didn't seem to change much except that the kick down to third in normal overtaking conditions was much improved and now feels more meaty and useable with the higher speed range and, of course, the car is significantly quieter when cruising. I do accept that the manual ratios for 2nd and 3rd are higher than the auto though and the only proof is in the driving experience.

The ratio details I have are as follows:-

         
K4A 025 Auto      G74 Manual 4      ZF S5-20 Manual 5

1st       3.98         4.05         3.920
2nd       2.52         2.23         2.215
3rd       1.58         1.40         1.418
4th       1.00         1.00         1.000
5th       ---         ---         0.848

[colinwoodburn]

Thanks for posting up the different gear ratios in the 3 boxes. I have obtained the ratios from Metric Mechanic for the Getrag 265 which are nearly identical to the ZF box
               ZF BOX                       GETRAG
    1        3.92                            3.82
    2        2.215                          2.20
    3        1.418                          1.40
    4        1.000                          1.000
    5         0.848                         0.810
So ............... The next question has to be. What diff ratio was fitted in the axle of a ZF car ? Don't suppose it would have been a 3;46 by a any chance ?Oh btw its proving harder to obtain a box than it was in finding an axle but hey it all adds to the 'fun'
Regards Colin

[Garry]

Hi Cilin
My car came out of the factory with a 5 speed zf and a 4.08 rear.  the 5 speed has been changed to a 4 by a PO and I have fitted a 3.46 rear now.  Gave up on finding a reasonably priced zf 5 speed that was in going condition for two reasons.

a. most have been installed on other cars as a non standard mod, and
b. the repair costs to a ZF are beyond a reasonable level if needed and they are not a user friendly box to start with.

I have looked at converting to a Getrag and I believe Alfred (66andBlue) had some info on a conversion kit that was being developed in Germany but the German end appears to have gone quiet at this point.
Cheers
Garry

[Khurram Darugar]

Garry,
        If you have a choice try and get a 265 box with the speedo drive, you will need to get the box opened to add this later on.
Briefly you will need the following:-
Getrag 265 with speedo drive.
Adapter b/t transmission and bellhousing
Early clutch release bearing (You may not need this if youre existing one fits)
Modified shifter linkage.
New speedo cable.
Shortened and rebalanced driveshaft with the BMW flange on one end.
BMW donut
Transmission mount adapter to mate you're getrag to the sl mounting plate.
Getrag mounts.

Based on some of the other frankly astonishing projects, technically speaking this is not that far out, although I take my hat off to those who have taken the effort to crunch the numbers and get it right!  However you need to get youre old diff back to make this worth while.

Considerably more challenging is finding a M130 manual flywheel, for the auto to manual conversion.  

Kay

[Garry]

Thanks for that info Kay.
I have kept my old axle just in case and will keep my eyes open for some of those parts mentioned in the wreckers if I can pick them up cheaply as time goes by.
Was that Getrag 265 fitted to the 5 series BMW?

[colinwoodburn]

Hi Garry/Kay
 Yes, You are quite correct. The Getrag 265 was fitted to the E28 2.8i around 81,82or 83 and some 635 735 BMWs around 86,87. But be carefull as you don't want the identical looking box with the 'dog leg' 1st gear as 5th on this box is 1;1 ratio and not an overdive gear which you require. Actually ones a 265/5 and the others a 265/6. Sorry can't remember which ones which
   I have tried many breakers yards all over Scotland but no luck tracking one down yet
    Regards Colin         

[mkbull]

Hi Colin/Garry
I can supply you with all the parts you would need including M130 flywheels.
Ed Mander from London (member ejm) has several of the correct gearboxes Getrag 265 5 speed "overdrive". Some have been refurbed with the speedo drives fitted others are as he found them.

Regards
Mark

[Garry]

Thanks for that info Mark, I will put it in the car file for future reference if I can find a 265 with o/drive

I will have a hunt around in the new year and see if I can find a 5 speed.  
It will be fairly rare in Australia as probably 99% of BMW's sold here were and are still sold in auto.

Garry

[Raymond]

If you go to the latest edition of the Pagoda World magazine you will find my article on installing a Tremec 5-speed.  I have to tell you the results are fantastic!  The gear ratios are very comparable to the Mercedes G72 that came in the cars. Fifth gear is a great .72 which results in 70 mph at 2,775 RPM.  The T-5s are very common, easy to find, not terribly expensive, tough as nails, and there are thousands of shops in the US that have parts for them on their shelves. 

You can choose a variety of gear sets.  Mine are: 3.76 - 2.18 - 1.42 - 1.00 - 0.72

I had to fabricate an adapter plate, (for which I still have the template) a drive shaft, and cut the transmission mount.  There is a company that makes a box to convert electronic speed pick up to mechanical drive.  This way, you can dial in the accuracy of your speedometer with a few dipswitches.

I converted my '89 BMW 325i automatic to the Getrag 265 dogleg and it's okay.  If I had to do it again, I'd go with a Tremec T-5.

[Leah]

WOW, this sounds very good Raymond,

How much does the Tremec T-5 all cost. please ?

I could get very excited if the price is right; as I drive long distance, here in Australia.

The fuel costs is the killer; down here. 70 mph at 2,775 rpm is dreamy.

The Lower Diff Ratio in 4th gear give you nearly the same result as the ZF in 5th. The DIFF is fairly simple to do.

LEAH

 

[Raymond]

Leah,

I did all my experimenting on a bench before taking the car apart.  I bought an extra bell housing and rear driveshaft coupling to play with and had to have my transmission shop help fabricate the prototype adapter.  I used a new throwout bearing and clutch disc, had a new driveshaft fabricated and bought an Abbot Cable-X box and made a custom length speedo cable.  I spent about $3,900 total.  I could do it again now for about $2,600. 

If you want to, you can get the T-5 with a .63 fifth gear.  I just think that you'd never be able to use it below 50 mph because the engine would be turning so slowly it would labor.  However at 100 mph, you'd probably hear more wind noise than engine .

[mdsalemi]

Leah--if fuel costs are really an issue, a W113 isn't a car to be fooling with...(N.B. my wife's new Taurus SHO is AWD; 365 HP, 350 ft-lb of torque; 0-100km in 5.2 secs...oh yes, 25 mpg on the highway, 22 around town actual on any octane fuel you can locally purchase)...I rarely get more than 16.5 mpg in my W113, and may G*d help the fool driving my car who fails to put in the highest octane fuel he/she can find!  If you really want performance and fuel economy, can you spell L-O-T-U-S??  We all love the Pagoda, but a miser in the fuel department isn't one of its attributes!

Ray--Leah makes an interesting point.  I know your are pretty astute and methodical in your work, but did you ever do a before/after comparison on MPG with the new 5-speed?  You didn't do it to save fuel, but that's one benefit (aside from noise) of the reduced RPM's.  Just a curiosity point.

[Raymond]

Michael,
Yes, I did do a comparison of Highway mileage.  I haven't compared city driving yet.  I have been traveling by air so much lately that the Pagoda has done about 100 miles since Blacklick.  The highway mileage is based on my records from the trip to and from the PUB in 2007, vs. the mileage to and from the PUB in 2009.  I don't have the numbers in front of me here, but I do recall being skeptical, and then pleasantly surprised at the 25% improvement.  I'm trying to remember, but I think my highway mileage was a bit less than 17 and improved to almost 22 mpg.

[mdsalemi]

That's great Ray!  And as I recall, you were not 100% done with the conversion when you came to Blacklick in 09, right?

[Raymond]

Correct. Unfortunately, I haven't had a lot of time to get back to it.  I did install a better transmission mount and I have just pulled out the mechanical speedo cable, (I broke it) and replaced it with the Cable-X box.  I haven't had to get to connect it in yet.  When I get that done, I'll do an update for Pagoda World.