Daniel DK

Hi Guys,

My 92 now have a ZF-6 !

It's a lot of fun to drive, especially ripping through the gears at WOT. :driving: It is however kinda rough when just cruising around town.

Since i have never been in a manual c4, I could really use some input from you guys on the issues I'm having - i simply do not know if this is to be expected or if stuff is broken

• Gearbox is noisy, all gears have a whining noise like, even when in neutral and clutch out. Driving along sounds like a whining diff. I see some threads regarding this..
• Shifting is clunky, depressing the clutch all the way to the floor during shifts helps somewhat.
• Clutch is super heavy. Daily driver clutch now feels like it is broken/not there
• Got some vibration at 3000-4000 RPM - all gears and at standstill, clutch in or out.. I'm guessing flywheel which is a used dual-mass may be broken - thoughts?,

Btw: let me know if you have any questions regarding the swap, it is all fresh in memory right now

Thanks Guys


Daniel

Beater12

Don't have a whining noise in mine, just some gear noise in first.
Yes I do find shifting to be clunky and yes I need to push the clutch into the carpet.
My clutch is very heavy to push as well. I have a bad left ankle and it is aggravating how hard it is to push.
No vibration.
That's how my transmission performs but I'm not sure if has issues as well? I do know I've got something going on with reverse as it will barely engage and takes a good yank to get it in.

KSA Aaron

A couple of questions and comments....

Did you change rear gears when you did the ZF swap?
The ZF gearbox is a bit clunky and does tend to be noisy. The DMFW helps to alleviate some (most) of the noise and whine.
You should not have a vibration unless there is a bad u-joint in the driveline or some other reason for imbalance.
I never recall the OEM clutch assembly to have a heavy pedal feel.

It sounds like most of your issues originate with the clutch assembly. Be careful driving the car with clutch issues, as this is how transmission syncros get destroyed. ZF repairs are expensive.

RWDsmoke

I did a ZF-6 swap about 10 years ago. Now it is fun and it drives like a new car but it wasn't that way just after the swap. It was very noisy, especially idling in neutral. After a conversation with zfdoc about how critical transmission alignment is I pulled it back out and checked the bell housing surfaces. Not flat, warped a little between bolt holes. I used a large flat file to take off the high spots, It took out about 95% of the noise. If I had it to do over I would have sent the bell housing to the machine shop to get the surfaces flat and parallel. I also used new aluminum spacers on both sides of the bell housing. Second issue, hard shifting unless pedal is hard into the carpet and hard to get into reverse, I fixed by machining down the spacer behind the master cylinder. Now I have about an inch of play at the carpet and the clutch is very smooth, it's easy to shift and easy to get into reverse. I also use Redline MTL in my transmission but there are several other good quality synthetic synchromesh fluids which make a big difference in shifting.

Daniel DK

Thank you KSA Aaron

I see threads regarding balancing a new flywheel to match the one it is replacing. Since i only have the flex plate i'm gonna call some machine shops and ask if they can somehow match the imbalance of my flexplate to the used DMFW i'm using.

Daniel DK

Hi RWDsmoke,

Thank you - searching for zf-6 alignment produced a lot of info.
I actually machined my own MC spacer with a larger footprint because the firewall was messed up. Now i'm gonna go back to see if i got the thickness correct/test with a thinner bracket.

I'm running bmw engine oil in teh gearbox, gonna do some experimenting with other MTFs

thanks again

RWDsmoke

[QUOTE=Daniel DK;1603328177]Hi RWDsmoke,

Thank you - searching for zf-6 alignment produced a lot of info.
I actually machined my own MC spacer with a larger footprint because the firewall was messed up. Now i'm gonna go back to see if i got the thickness correct/test with a thinner bracket.

I'm running bmw engine oil in teh gearbox, gonna do some experimenting with other MTFs

thanks again [/QUOTE


If the clutch pedal is lower than the brake pedal at rest, it may hit the carpet and the master cylinder may not have enough stroke. A thinner spacer will raise the clutch pedal at rest height and allow more travel before hitting the carpet. A slightly dragging clutch is not good for the syncros and requires more effort to shift.
I know the BMW oil is "recommended" by some but a good synthetic synchromesh oil makes a world of difference.