Author Topic: Exchanging an automatic transmission for a new 4,5 or 6 spee  (Read 2225 times)

MB113

  • Full Member
  • Junior Level
  • USA, MO, Saint Louis MO
  • Posts: 3
Exchanging an automatic transmission for a new 4,5 or 6 spee
« on: February 12, 2023, 17:49:31 »
To whom would i address questions about exchanging a six speed manual  for the current automatic that is coming in my 1969 280SL?
we are beginning the full restoration and would appreciate any and all input.
Thank you

Peter (MB113)

rwmastel

  • Full Member
  • Platinum
  • ******
  • USA, OH, Canal Winchester
  • Posts: 4433
  • Pagoda SL Group: 20+ years and going strong!
Re: Exchanging an automatic transmission for a new 4,5 or 6 spee
« Reply #1 on: February 12, 2023, 23:54:49 »
I would start by posting in the Research and Development forum. As stated, that forum is for "Discuss, Research, and Development, including modifications that are not original or correct for the W113 series cars."

What have your searches of this site produced?  We've been online for 20 years, so maybe you'll find something.
Rodd

Did you search the forum before asking?
2017 C43 AMG
2006 Wrangler Rubicon
1966 230SL

Jack the Knife

  • Full Member
  • Senior
  • ***
  • USA, FL, Vero Beach
  • Posts: 239
Re: Exchanging an automatic transmission for a new 4,5 or 6 spee
« Reply #2 on: February 13, 2023, 00:04:45 »
A search on the forum will be exhausting, as there's been many dozens of threads on this subject that I've caught myself up on the last few months while I've researched this myself. Regrettably, no single thread has all the information. Also, the below just concerns the conversion of a manual car. For an automatic car, that is much more involved, but certainly not impossible. You'll need a different prop shaft, the manual flywheel, the pedal obviously, and probably some other stuff. That'll demand a bit of research on your part. There are some companies out there who do this kind of conversion, too, but I don't know their names or even if they're still in business -- just things I've seen from reading old threads.

There is a gearbox available from Siegfriend Thom over in Poland. I had it quoted delivered to me in Florida for about $7000. His kit should include everything you need. I believe it is adapted from a BMW 2-series gearbox, if I'm not mistaken. I didn't buy it because I don't actually want an overdrive gear.

You will regretfully not find any information about the conversion on this forum. However, Fantasy Junction has done it on a few of their cars. Here's an old article detailing exactly what they did: https://www.fantasyjunction.com/uploads/documents/file/017990-how-many-speeds.pdf

Note the cautionary bit at the end regarding lugging the engine. The overdrive gear, like that of the ZF, is great to use on the highway, but I wouldn't lug your engine just scooting around town. And by the way, here are the gear ratios:

1: 4.002
2: 2.108
3: 1.380
4: 1.000
5: 0.780
6: 0.645

Note that this is a double-overdrive box.

As for the five-speeds, there's a lot of information around here about using the Getrag 265 transmission from a BMW with a mechanical speedometer drive. These are getting harder/more expensive to find since the E9 owners have really consumed a lot of these, but they're still out there. If you look up "mkbull" or "Mark Bull" on this forum you should find some information about the kit he developed. It's unfortunately hard to find all of his posts since this forum did some sort of change to the accounts some time ago which made unpaid users show up as guests, so you can't just click on their name and find their posts. Anyway, doing the Getrag conversion is a bit more involved.

There's also the ZF 5-speed. A ludicrously expensive new unit was made available a few years ago. But I assume you're not willing to spend 20k for a finicky gearbox, or probably 6-8k for a good condition original one. I have learned from Benz Dr that the ZF 5-20 you see around must be from a Mercedes, not from the Maserati Mistral or the other two cars it was available with, as the tail stock and bellhousing are different.

I'd also advise you that depending on your needs, you may find a 3.27 rear axle to be more than satisfactory if your goal is just to reduce overall RPM. My understanding is they are cut down by like 500 in the 4th gear with that axle if you started with a 3.92 or a 4.08. I believe all 280SLs came with a 3.92. Dropping to a 3.27 should be comparable to using the overdrive gear from the ZF if you keep a 3.92 axle. Shameless plug, I have one for sale with an uncommon limited slip differential, a very nice thing to have. I bought it thinking I was going to add significantly more power to my 230SL but then my goals changed with my car so it has been mothballed.

Should you go with the Getrag option, you have two choices. Getrag 265/5 and Getrag 265/6. The former has the 1:1 final drive ratio. The latter has the overdrive gear. Here's a comparison of the two proven overdrive 5-speed options. Sidenote: I have heard about a Tremec conversion, but I haven't found much information. I believe it is heavier and is a larger unit that may not clear the tunnel.

ZF S5-20                       Getrag 265/6
1: 3.92                          1: 3.82
2: 2.215                        2: 2.20
3: 1.418                        3: 1.40
4: 1.000                        4: 1.000
5: 0.848                        5: 0.810

As you can see, the Getrag is basically the same as the ZF, and it's the no-brainer decision if you want the overdrive gear, if you're starting from scratch. Also, FYI, I believe the stock Mercedes 4-speed post-1965 has these ratios:
1: 4.05
2: 2.23
3: 1.40
4: 1.0

Good luck!
1964 230SL
2015 G550 """Professional"""

Peter van Es

  • Honorary Member
  • Platinum
  • ******
  • Netherlands, North Holland, Nederhorst Den Berg
  • Posts: 4027
Re: Exchanging an automatic transmission for a new 4,5 or 6 spee
« Reply #3 on: February 13, 2023, 12:13:57 »
If you look up "mkbull" or "Mark Bull" on this forum you should find some information about the kit he developed. It's unfortunately hard to find all of his posts since this forum did some sort of change to the accounts some time ago which made unpaid users show up as guests, so you can't just click on their name and find their posts.

Good point, however, it's one of the unfortunate side-effects of data protection regulations where we have te remove the account of members that have not accessed the forum in quite a while, and may have moved on, or passed away.

You can still find a lot of his posts though, by using the Search function from the menu, selecting a fairly common word (e.g. gear) and then adding his userid "mkbull" in the "By user" box.

Peter
1970 280SL. System Admin of the site. Please do not mail or PM me questions on Pagoda's... I'm not likely to know the answer.  Please post on the forum instead!

450sl

  • Full Member
  • Silver
  • ****
  • Netherlands, Gelderland, zelhem
  • Posts: 494
Re: Exchanging an automatic transmission for a new 4,5 or 6 spee
« Reply #4 on: February 13, 2023, 16:50:54 »
Peter, the six speed is a good choice ,but first find a manual Flywheel , a clutchpedalassembly (with mastercilinder and reservoir) and a gearstick assembly. the six speed kit , does not provide these items.

mark

teahead

  • Associate Member
  • Gold
  • *****
  • USA, WA, Des Moines
  • Posts: 781
  • aka "Rob"
Re: Exchanging an automatic transmission for a new 4,5 or 6 spee
« Reply #5 on: February 13, 2023, 19:46:23 »
https://www.ebay.com/itm/164237120959

$7k USD?

Where did you see that?
1970 280SL auto, AC - aka "Edelweiss"

gordon

  • Full Member
  • Senior
  • ***
  • United Kingdom, England, Burntwood
  • Posts: 184
Re: Exchanging an automatic transmission for a new 4,5 or 6 spee
« Reply #6 on: February 13, 2023, 19:57:24 »
I've got some rebuilt Getrag overdrive 5 speed gearboxes with mechanical speedo drives. Will ship anywhere at cost!

Jack the Knife

  • Full Member
  • Senior
  • ***
  • USA, FL, Vero Beach
  • Posts: 239
Re: Exchanging an automatic transmission for a new 4,5 or 6 spee
« Reply #7 on: February 13, 2023, 21:09:10 »
https://www.ebay.com/itm/164237120959

$7k USD?

Where did you see that?

If you email Siegfried directly at k-max@live.de, he will sell it to you. There are a few scalpers out there trying to resell the box.
1964 230SL
2015 G550 """Professional"""

Jack the Knife

  • Full Member
  • Senior
  • ***
  • USA, FL, Vero Beach
  • Posts: 239
Re: Exchanging an automatic transmission for a new 4,5 or 6 spee
« Reply #8 on: February 15, 2023, 16:29:20 »
It seems Mark Bull is no longer making those kits, but there is a German man who developed a really superb kit for the Getrag. His name is Wolfgang and he has been discussed here on this forum. His email is wolfgang@w113.eu. I believe the adapter kit is around $800. However, I just spoke to him via email this morning and he said his insurance does not allow shipping outside the EU still, as was discussed on this forum some years ago. He will sell it to anyone in the EU and they can forward it to the US. The work shown on his website is really top notch. I also did not know that AMG themselves offered a Getrag adapter kit back in the 1970s for these cars. Shocking that such an innovation hasn't been detailed here before. I'll likely be proceeding with one of these adapters myself.

Edit: Regarding Tremec conversions. Bud's Benz no longer does that conversion (nor much of anything beyond restorations... they won't even do a rear end swap anymore). But American Powertrains does. I just got off the phone with their salesman, Matthew. Check out the kit here: https://drivenman.com/product/mercedes-280sl-5-speed-conversion-kit/ I believe Raymond, club president, has this transmission kit or else one provided by Bud's in his car.

One thing to note is there are only two 5th gear ratio options now with this kit, both OD gears -- 0.63 and 0.73. I believe nice rebuilt Getrag boxes with an adaption kit and whatever else one needs will be around $4500-5000 by the time it is all at your door. Tire size plus rear end gearing is a consideration as well and you may need to budget having your speedometer reconfigured or using a Speedbox or something similar. Or just put up with the discrepancy, which with my 4.08 should be about 6mph. The Tremec kit, delivered to me, will be about $5950.

Another consideration is weight, by the way. It seems the T5, 265, and the ZF all weigh about the same at around 75lbs sans bell housing and fluid and all that other stuff. The 6-speed unit will be closer to 120-130lbs, if you care.
« Last Edit: February 15, 2023, 19:53:30 by Jack the Knife »
1964 230SL
2015 G550 """Professional"""