Manual Transmission - Grinding 1965 230 SL

[rjmarco]

I just bought a 65 230 SL with a manual transmission.  Has 52k miles.  There is a lot of grinding/crunching shifting between gears.  2nd and 3rd gears are most noticeable.  Anyone have any experience with transmission rebuilds or exchanges?

Regards,

Rich

[georgem]

Before I started rebuilding the gearbox, I`d check that the clutch is ok. With the engine running and the park brake on, push the clutch all the way to the floor and after a slight pause, run through all the gears inc reverse. If you get any sort of feeling that the car is starting/trying to move, it means the clutch isn`t dissengauging properly; the input shaft is still turning and the synchros are engauging.

If it fails this test, all is not lost as it might be a clutch adjustment issue rather than a crook clutch. Fingers crossed that it is as there is plenty of info in the Tech Manual re adjusting the clutch

Cheers

[Miloslav Maun]

I had a similar problem. I tired to replace all synchros, all sorts of bearings, some of which were pretty expensive, etc. nothing helped. I used the right AT fluid instead of oil. Eventually I've bought a used transmission on eBay which cost very little, installed it and it worked beautifully. I only regret I did not swap the transmission in the beginning and spend the time on cleaning and preparing the new one.

[glenn]

FWIW   A MB friend rebuilt a manual tranny years ago.  Said it was a pretty simple job, just time and being clean and careful.  MB manuals are pretty detailed, also.

[rjmarco]

To all:  Great comments.  I can tell you that I already did the swap out of gear oil that was in the transmission for AT fluid.  This didn't help.  Will try the clutch test next.  Thanks so much for the comments.  I'm new to the forum and this is great info. 

Rich

[ja17]

If your speedometer bounces around during acceleration and de-acceleration, you may have a loose slotted flange nut on the transmission / drive shaft flange. This can cause the gear cluster in the transmission to loosen up and and cause all sorts of shifting problems. Not that uncommon an issue. Is a bit of work to check, since you have to unbolt the driveshaft at the transmission to see if the nut is loose.

The problem can be diagnosed often times by watching the speedometer when you drive. During acceleration the speedometer needle   may actually drop before it rises. Also when letting off the accelerator pedal, the speedometer needle may actually, bounce upward before it falls.

[rjmarco]

Here's an update.  I gave the clutch test a try.  With the clutch pedal fully depressed, there is no tendency for the car to move in any of the gears. 

My local MBZ dealer has a few people who worked on these transmissions 20 years ago.  We're going to drop the tranny and take a look.  Will keep y'all informed.

[Benz Dr.]

I don't think that's a valid test. Try this instead:

If there's a return spring on your slave cylinder, remove it.
There will be a small pin coming out of the slave cylinder that sits in a detent on the clutch fork. Move the clutch fork towards the pin and see how much movement you have. It's about right when you have just a little bit of free play at maybe 2 - 3 mm. This should corrispond to about 19mm of free play on the clutch pedal before you feel any resistance. The clutch should start to engage about half way to about 1/3 of the way up from the floor.
If you have to push the pedal in almost to the floor and it doesn't engage until it's almost at the top of its travel, you have too much free play. Once you have it set, the clutch will automaticaly adjust as the plate wears so it never needs any more adjustment.

[rjmarco]

I had my car at the dealership and had an experienced tech drop the transmission.  Need to replace two synchronizers and a helical gear.  Took a couple of attempts to get the right parts to match the production of my 1965 230 SL.  In the end, the job was a success.  The transmission now shifts smoothly.  Successful project but was expensive and took several weeks.