5th Gear grind after maintenance
 

Hi All,

I recently had my flywheel, clutch, CSC and Master cylinder replaced all at once.
Switched to the JWT lightweight flywheel and clutch, as well as the CMAK csc replacement.

After doing so, with zero hard driving, I'm grinding in 5th gear, up and down shift.

Flywheel chatter is also very noticeable when in 5th gear.

Taking it back in to the shop, but they're already saying it's likely that my syncros are screwed.

My question is, can doing these replacements cause the issue, or is it not likely something that's wrong?

Thanks.

I'm no transmission expert, but they are separated from the rest of the work you had done, so I dont see a relation. The synchros in the Z are known to have issues.

Does this happen all the time, or only under certain circumstances? My 6th gear synchro grinds if I try and power in to the gear. If I press the clutch, wait a second and then shift, it works fine.

about 70-80% of the time. I've been messing with how I shift to get rid of it.

Probably the syncros and probably unrelated to the clutch work unless you are having physical trouble getting into gear.

My 5th gear started doing the same thing around 20K miles. Just be a little patient with it and it won't grind. It hasn't gotten any worse and I'm over 100K miles now. I can still shift into 5th without any noise as long as I take it easy. I don't ever have a need to power shift into 5th on the street anyway.

Although my Z is an 09, it only has around 25,000 miles on it. This 6th gear grinding issue started at approximately 13,000 miles, but it was already out of warranty. Its obviously not my daily driver. From all accounts, its not worth replacing the synchros. The cost of labor would exceed the cost of a new transmission and the labor to install it. For now I'm living with it, but I plan to replace it in the not to distant future.

Do you due diligence though and have the shop check their work before you jump to any conclusions of your own.

Thanks everyone. Looks like making it to 76k and having it start has been a blessing.

Agreed. A brand new 370Z OEM transmission is too cheap to bother rebuilding syncros in a used one.

My understanding is Chris Carver Motorsports in Houston has experience building these transmissions. I am considering reaching out to him when I finally decide to address the problem. No point in putting stock syncros back in if I have it rebuilt.

I got a quote from MA Motorsports in Baltimore for the following work:
1. New Trans
2. Install Z1 Clutch, flywheel, CSC elim kit, transmission mount, RJM clutch pedal and master cylinder for $3,412.00

Really not a bad price at all.

I had 5th grinding from time to time from day one when I try to quick shift into fifth, but with time started to shift easier to fifth, without issues, until recently, fifth started to grind all the time I try to shift to it, I thought it was syncros but didn't bother to change them until now, I would be more interesting in getting an upgrade to them if it is available instead of getting a new trans that will have same issue with track time. My car has around 25k miles and lots of track days.


Jar, what is the options available?

If I do a quick downshift from 6th to 5th. It will grind a little. If I take my time, no noise what so ever.

Be prepared to change out the CSC slave cylinder from Z1 a few times. Hopefully they fixed the issues with them.

Sounds like your shifter is out of adjustment. It needs to be adjusted properly for 5th gear to work properly. It will grind.

I'm not entirely sure. I have yet to reach out. His name is CCarver on the forum IIRC.

What was wrong with it? I've actually been considering selling it and getting a CMAK.

For some reason. They don't hold the adjustment, and can be a bitch to bleed. Think Jar went through a couple of them. The CMAK is a better option. That's the one I would go with.

I won the CSM Elim kit at the 2017 Z Nationals, so I figured I would just stick with it, but I wasn't aware of any issues. Thanks for the info. I'll have ot look it to it a little more.

I was an early adopter of the Z1 CSCEK. I went through 4 cylinders in about 50K miles. Had external plastic shell leak as well as internal seals leak. Z1 only replaced the first one at their expense. The last three I paid for out of pocket. I purchased the ZSpeed CMAK a few months back to replace it.

This can be clutch related, Do you have issues getting into any other gears? 1st/Reverse?
Is you shiter hard to move into gear sitting still?

JWT disk is sorta heavy which adds centrifugal weight to the disk, which in turn leads to the syncros having a harder time slowing down to shift.

Yea, actually I do have issues getting into reverse sometimes

Do you have to force the shifter into 1st gear sitting still? Does it grind going to reverse?

Have had to force into reverse a couple of times. Never any grinding though.
Have had an issue going into 1st maybe once. Didn't try to force it in, just went into a couple of other gears first, and it went in just fine after that.

If you have to force it... that's a bad sign. Check the guide plate. Super easy to do. And super easy for a shop to screw up. Best of luck :driving:

They may have replaced gear box oil to a different viscosity.

Changing gear box oil is usually done when clutch is replaced.

On the JWT clutch you need to ensure that the fingers of the pressure plate are not hitting the center of the clutch disk at full stroke (pedal on floor) I have seen quite few of the JWT have interference issues when new. If the pressure plate fingers hit the disk when you have the pedal to the floor it can cause shifting issues and cause gear grinds.

You can normally tell this is happening at idle as well, if you push the pedal all the way to floor you can normally hear it scrape a little and can also cause it to be hard to get into gear. if you let up a little it will go right into gear.

Thanks for the info, Joe. I'll try and check it out tomorrow and see what the issue is. I really appreciate your input.

Hey joe,

This finger contact to the clutch disc is what you mean about clutch overstroke im guessing? I emailed you yesterday about a similar symptom. Mine also can be hard to get into first/reverse at a stop, i can remedy this by shifting into 2nd then back into first.

Beau

Your issue sounds more like a disk is not sliding smoothly on the input shaft upon release or there is possibly some material transfer from one of disk, Could also be a trans issue causing that. The overstroke could happen with the OS giken if you do not have a pedal stop and the fingers may hit the top disk. Most twins triples will require a pedal stop to prevent this.
They way to set up a twin is to find the point at which the clutch is fully released on the down stroke, at this point make a pedal stop that will limit any further travel so you do not over stroke it.