Benz aficionados,

I'm contemplating retrofitting an automatic tranny to my W116 280SE
Euro. The car currently has the original 4-speed manual gearbox.
Used transmissions in my local Benz yard are in abundance and I
should have no trouble finding a good used gearbox from an M110-engined W116 or W126.

Questions:-

What parts (apart from the new tranny) are needed for the retrofit?
Will it be a straightforward bolt-on job or does it entail more
elaborate modifications (driveshaft, engine parts, etc.)?

Was the original auto tranny on the stock W116 280SE a 3- or 4-speeder?

Will an auto gearbox from a W126 (identical M110 engine) be suitable for this transplant?

Any other thoughts/advise welcomed.



Hisham
Kuala Lumpur
1978 W116 280SE Euro "BlauPanzer"
1995 E36 BMW 325is "BahnScreamer"
1984 Volvo 240GLM "SmorgasBox"
plus a few wheelbarrows and a lawnmower

Well fellas?

Has anyone here done the procedure or has any thoughts?
Thanks again

Hisham

There appears to be a "cone of silence" (Get Smart tv show from the 1960's) about any Mercedes Benz parts swapping especially transmissions and such. It aint like Chevy engines and transmissions that will bolt up to almost anything. I had a brainstorm about possibly swapping an automatic transmission from a 2.3 8v engine or possibly just the torque converter to possibly get some better acceleration from a 190e 2.6., Just like the old Chevy Vega torque converter swap on cars equiped with a small block Chevy engines and turbo 350 trans.
When I find out I will be sure to let everyone know.
Sorry I could help you but I'll ask around.

__________________
1990 190E 2.6
1996 Grand Voyager 3.3
1985 Mustang GT 5.0 5 SPD
1982 Suzuki GS 750T

Armed with the following from a junk yard...

- An automatic transmission from the same motor type.
If possible, the same model year
- The torque converter
- The drive shaft (from same body type w/motor-type)
- The rear transmission support
- Flex plate and ring gear
- Brake pedal assembly
- All the old bolts (Torque cvtr to flywheel & tranny to motor)
- The shift linkage, including the gear selector
- Any/all wires that connect the tranny to the rest of the car.

With the TDM, ETM, chassis & engine manuals for your car at your finger tips. The job isn't too difficult.

1. Take your old tranny out (remove starter & drive shaft too).
2. Remove the old flywheel and ring gear & pilot bearing.
3. Have A/T starting ring gear balanced to the old flywheel.
4. Attach starting ring gear to your motor.
5. Attach the new tranny.
6. Bolt torque converter to the motor.
7. Attach linkages.
8. Attach drive shaft.
9. Wire in the electrical connections.
10. Put back the starter & the exhaust.
11. Switch over the brake pedal assembly.

The big pitfalls, are steps 3, 5, 8 & 9.

- The engine was balanced as a unit. A good shop should be able to maintain the balance. The whole engine may need balancing again.

- To attach the new tranny, you are levitating a 100 pound block of alloy steel over your head. This is not a driveway operation.

- The drive shaft lengths vary. Cross your fingers that this will go fine. If not, you will have to have the shaft lengthened or shortened and then balanced.

- The neutral saftey switch wiring is critical. Also it controls your backup lights. If you're real lucky, it's the same wire connection harness as the one in your car now. I doubt you'll be that lucky.

BTW, how is the clutch cylinder fed fluid?

While you're doing this, lots of parts can/should be replaced.

- New bolts for the flex-plate. You MUST not reuse the old ones.
- Check the starter's pinion & the new ring gear. Are they worn? Should they be replaced?
- Have the transmission resealed. If it's a junkyard unit, have it pressure tested too.
- Replace the shift linkage bushings. They're cheap.
- Consider a new torque converter rather than a high milage junkyard one. Ask a tranny specialist.

Above all else, research the job. Read the service books. The Technical data book has all sorts of tables that compare things. Find something that doesn't match between your donor car(s) and your own.

Test fit as many components as possible as soon as possible. If you can swap out the shifter before removing the transmission, do so. It just helps verify that you've got the right part.

Two last words of wisdom. Most likely, you are going to want to swap out the differential too. The gear ratio will be wrong. Also, watch your speedometer and odometer. Either they will be fine with the tranny swap or they will only be fine when you swap the tranny & the rear. Have the junkyard one be made available.

-CTH

PS. All of the parts removed from your car should be put aside so that you can sell somebody (like me) an auto-manual swap kit.

Very well covered CTH. The only thing I would add is that the original cranks for manual trans aplications have a different number than those intended for automatics. The most obvious difference would be the area where a pilot bearing sits on the manual trans or the torque converter nose is supported on automatics.

I would say the risk should be equal, through engines of that era (since they use similar pilot bearings and torque converters) and I know that I have done this on Diesels with no machining. I am not sure we supported the torque converter properly; but I know of no subsequent problems.

I have also worried about the balance, especially due to the vast difference in weight between manual and auto flywheel assemblies. Since the ones we did exhibited no problems I have to assume that even though the crank assy is balanced as a unit the individual parts most be close to balance. Balance could be more important on high revings gas motors.

The original chassis 116.02x auto trannies were 722.1 with 4 spds.

__________________
Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician

The M110 had two possible cranks? That's good to know. I hadn't noticed that in the M110 euro fiche.

In the check and replace department, I forgot to mention the engine shocks, engine mounts and rubber flex disks on the drive shaft and the support bearing.

-CTH

__________________
- cth350@gmail.com
http://www.111lakeside.com/

I was really only guessing that the 110 would exhibit the same differences that the Diesels did. Your question made me curious so I had to come to the shop and verify.

Sure enough the manual trans crank is 110 030 69 01 and the auto trans crank is 110 030 48 01.

__________________
Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician

CTH350 and Stevebfl,

Thanks for the valuable feedbacks.

Well, I can see that the key aspect of this not-so-simple procedure is to meticulously itemize and source all the required parts/assemblies before even the first bolt is touched. I can also see that a significant number of new parts are necessary to ensure a top-notch transplant. The nature of the work would also necessitate a proper garage set-up with professional expertise. It is really not the kind of job that could be effectively accomplished with a weekend mobilization of buddies inspired by generous supplies of distilled/fermented spirits. Yup CTH, I certainly do not relish the prospect of "levitating a 100 pound block of alloy steel" over my head in my driveway.

A grand excursion to the junkyard(s) is in order and we’ll see what parts could be extracted from the disemboweled W116s.


Hisham

remember, While you're looking for parts, if you find a 5-speed or a v8 w/a stanard, I'm first on line for some parts.

I have everything I need to convert a 107 body from automatic to a standard, except of course, for the 107 body. So, I'm going to use the tranny to convert a 250se/c instead. The other parts will just sit around until somebody needs them.

I've already done the research for my swap. You got the distilled essense of it.

-CTH

__________________
- cth350@gmail.com
http://www.111lakeside.com/