123quattro

I finally got the EBay car on the road. It runs! Huge improvement over my other 928. Anyway, I've noticed that the gearbox grinds shifting into every gear unless the clutch is pushed completely to the floor and you wait maybe a half second before you shift. Doing that, it's fine, otherwise it will grind every gear on every shift. I also flushed the hydraulic system completely last night and made sure the clutch was bled. All the fluid was black, what a surprise... Is the grinding the best I can hope for on a 23 year old transmission, or is something funny happening with my clutch possibly that isn't letting it disengage fully?

Thanks,

AO

IIRC the bad syncro design (Porsche design) was from 82 through 84. Someone needs to confirm this. You can try some new gear lube which may help, but chances are if they're that bad - they will always be bad. Sorry.

But hey, at least it runs. No problem keeping up with my SCer!

Jim bailey - 928 International

The 78-84 Porsche syncros are not really BAD or a poor design it is just that the Borg Warner style hold up better for drag racing...All the 356s and 911s up to 1987 used exactly the same design and created the Porsche performance image. The problem was when a bunch of ham fisted Americans started power shifting and down shifting with no attempt to RPM match... just like they did with their Chevelles and Ford trucks.

nosnow

I believe your car has the double disck clutch setup. If you are grinding in all gears you may want to make sure that the clutch is not dragging, clutch shaft is smoot w/o burrs, and that your throwout bearing has not fatigued. Now that I read your signature I see you have an 80 so you should be familiar with the setup. With any luck this is the problem... it is a lot cheaper than a new tranny.

GregBBRD

Yes. If you can slow down the clutch operation and not slow down the shift, the problem is the clutch. Try it. Push in the clutch and wait. Then shift fast and see what happens. Easy way to tell which is which.

Change the gear oil, anyway. Use something thin. Kendall makes a great 75w/90 that works really good in these boxes.

layton108

I have this same problem in my 80. Is changing the gear oil a hard thing to do? I've never done it.

123quattro

Greg, I tried your slow clutch, fast shift suggestion. It appears the synchros are the issue. Damn. Thanks to everyone for the suggestions. I think I'll try the Redline 70W90NS that was suggested by Chuck.

Daniel Dudley

I would really be surprized if all your syncros were shot. Usually second gear goes first. Remember that there is a big long steel shaft between the clutch and the tranny. This shaft has a lot of inertia when spinning, and will spin the main shaft of the tranny at whatever speed it is spinning, until it slows down.

Changing to redline will no doubt be a good thing, but understand that there is a certain speed at which the gears like to be shifted, and this will vary slightly depending on RPMs, but in all cases there is a pause in neutral where you wait to offer up the next gear. I would just take the car out and drive it. You can and may wish to rebuild the tranny, buit in the end, you will still have to time your shifts to the car. BTW, i have totally shot second gear syncros, and I can still find second every time, with only occasional noise. It's on my list of things to do when I have money to burn.

Daniel Dudley

Just as an aside, I had the syncros replaced once already. A 928 ''friend'' was driving the car, and destroyed the syncros in less than a week. Learn the car.

WallyP

I would suggest adjusting the center plate on the clutch before doing anything else...

FlyingDog

It's the clutch.

First, make sure you are getting full travel out of the slave/release arm. Have somebody push the clutch pedal while you measure travel through the inspection hole. Check with both a slow push and a fast push of the pedal. If travel is good (14mm?, it's in the WSMs), then it's just not releasing the discs properly. Drop the clutch. Check the throwout bearing and pilot bearing for smoothness. Check the rings on the throwout bearing to make sure the haven't worn away reducing travel. Check the fingers on the pressure plate. Lastly check the infamous adjusters on the intermediate plate. They should require some force to move, and you should move them all the way rearward. Reassemble and let us know if it still doesn't work.

cdbtx

I would agree with Wally P on this one - if it's grinding in every gear then adjusting the center plate is the place to start. I'm not sure if Devek's website is still up, but they used to have the instructions there.

Charley B

It is so unusual for all synchros to be bad that it would be foolish to not do everything to eliminate the clutch system as the sulprit.

123quattro

Well, I haven't got a chance to adjust the intermediate disk yet. I did change the trans fluid out though. It came out blackish green. I put Redline back in and shifting is smoother. It's not night and day better, but it's a decent improvement. It took 4.75 quarts. Hopefully this weekend I'll get the time to adjust the clutch.