Tranny syncro set replacement ?. Winfred/Bill/Don pls advise.

[emw525E34]

Gents,

My 95 Touring has 55K miles (mostly city driving though) and I had just put in a new sach clutch (pressure plate/throwout bearing, disc and new seals), also a new slave clutch cylinder, new fluids. After 3 weeks, I am having trouble shifting from 2nd to 3rd gear. Now only after a few miles when the engine is warm and car driven moderately hard. Who drives a manual gently these days!?. From cold, there is no problem.

My indy told me the clutch sychronizer set needs replacement. I check the ETK parts and see that there is a front set and a rear set. Pretty pricey. Just wanted your take on whether this will completely eliminate my shifting problem.

Note: I have missed shifted into 1st twice before (while looking for 3rd). But was not pulling serious revs. Its real stiff getting into the 3rd gear slot. 1,2 and 5th was easy enough though. Pls advise.
:(

[winfred]

i've not had the need to go into one of those trannys so i don't know how much trouble it is to replace, it's kinda odd that syncros would go out with that few miles, i would be looking at the recent work done for some problem there, like a bad component or wrong fluid, the wrong type of fluid in the tranny can cause shifting problems, and some fluids can improve shifting over the factory specified, like my 90 325ism, it's 2nd gear syncro was getting slow about 50k miles ago i put in red line mtl and it shifts great with almost 200k miles on it now. i've seen on some cars a dragging clutch cause problems (not on a bimmer but it's possible)

[gale]

Could have been a fluid problem. Synthetic oil/fluids are great for almost all other components for lubrication, but syncro's need a certain amount of friction to work properly and some synthetics can be too slippery, causing the syncro's to wear prematurely. Most modern manual transmissions call for ATF, usually Dexron. Somewhere in the early-mid 90's, Dexron II was superseded by Dexron III which is a synthetic blend and could cause syncro problems in theory(?).

If it had gear oil in it and was not a GL-4 spec fluid, the syncro's could have corroded, GL-5 gear oil will attack bronze, unless specifically formulated with anti-corrosion additives.

I tried many types of fluids in mine. I started out with full synthetic ATF but it didn't feel right in warm weather. Then I switched to GL-4 80W90 synthetic. Then I tried Swepco 70W80 petroleum GL-5 with anti-corrosion additives. It worked great until it got cold so I switched to Pennzoil Syncromesh until finding out after the fact it wasn't good for the Getrag, even tho it worked well. I finally ended up with Redline MTL and it works great so I will stick with it. Pennzoil Syncromesh is formulated for problematic syncros in Mitsubishi manual transmissions & if you can determine it is compatible with your ZF trans, you might give it a try.

All of the indies in town recommend against rebuilding a Getrag 260/6 due to needing special tools and set-up fixtures and lots of experience, they can have a high failure rate after being worked on. When it goes, I'll just replace it with another used trans. Yours likely has a ZF trans. I'm not sure what's involved in replacing syncro's in it but certainly different than doing a Getrag. Before resorting to having it worked on, try running Redline MTL in it. Give it a few dozen miles to work itself in.

[emw525E34]

Don and Winfred,

Many thanks on your comments regarding the syncho oil. My tranny is S5D310Z , I suspect is the Getrag and is exactly the SAME as the 95US M3 3.0 tranny. I saw the part number in a picture I had of the US 95 M3. I would expect this to be a pretty strong tranny for the M50TU engine which pushes up 192HP and 180 ft lb of torque. It appears that touring torque is flatter so maybe a different ECU programming.

I am begining to suspect that the syncho set changes are not necessary considering the car had only 55K miles in it and does not seem abused. Fluid used has been and still is BMW ATF fluid. I shall get the shop to change to RedLine MTL as I know where to get it. My clutch slave cylinder was changed twice in a year!. Don't know why but the Indy said my clutch was thin, so I replaced that with a new clutch. Was going to do that soon anyway. Now, it seems problems shifting into 3rd is causing more concern.