Grinding when shifting quickly

[BrianZ32]

Hello forum,


I am having an issue where i grind going into 4th gear quickly or downshifting to 4th quickly. I just learned how to drive stick shift a few weeks ago and at first i thought that was the issue, but now that i have been driving stick for about a month, i dont think that is the issue. During the first couple weeks, there was a certain smell which i believe was the clutch. It smelled like my brakes when i would drive a lot, but a bit sweeter. I still can smell it under the hood but just not as strong. I am throwing it in here just in case it helps discover what could be my issue. 4th gear is the only gear that grinds. Dont know whether it can be my clutch going out. I noticed that in the morning, when first using my car, that is when i experience the best driving experience oddly. I can shift so easily in the mornings and getting into and out of first. I also just replaced my shifter because the old one was trash.


Let me know what you guys think on what i can do.

Thanks Nico

[NolimitZ32]

Sweet smell is usually coolant. As for the 4th gear grind, sadly you have the same problem that pretty much everyone with a Z32 runs into, the synchros on these cars are a known weak point and yours is very likely been beaten because people just love to slam 4th. Only fix is a rebuild or a new transmission.

[BrianZ32]

Hello forum,


I am having an issue where i grind going into 4th gear quickly or downshifting to 4th quickly. I just learned how to drive stick shift a few weeks ago and at first i thought that was the issue, but now that i have been driving stick for about a month, i dont think that is the issue. During the first couple weeks, there was a certain smell which i believe was the clutch. It smelled like my brakes when i would drive a lot, but a bit sweeter. I still can smell it under the hood but just not as strong. I am throwing it in here just in case it helps discover what could be my issue. 4th gear is the only gear that grinds. Dont know whether it can be my clutch going out. I noticed that in the morning, when first using my car, that is when i experience the best driving experience oddly. I can shift so easily in the mornings and getting into and out of first. I also just replaced my shifter because the old one was trash.


Let me know what you guys think on what i can do.

Thanks Nico

Edit: I also have noticed when in 1st and releasing the clutch slowly without much gas, the car starts to rattle and making this flapping-type sound, or knock sound. I've experienced this particularly in drive thru's

[NolimitZ32]

Clutch chatter maybe? your clutch disk could be cracked, I've done that before.

[brian300zx]

Knock sound could also be your transmission mount. Quick fix and part isn't too expensive as I just replaced mine!

[DCaff300ZX]

Yep, check both especially the trans mount.

[brian300zx]

Could also be your diff bushings as I have just realized mine are gone.

[BrianZ32]

Sweet smell is usually coolant. As for the 4th gear grind, sadly you have the same problem that pretty much everyone with a Z32 runs into, the synchros on these cars are a known weak point and yours is very likely been beaten because people just love to slam 4th. Only fix is a rebuild or a new transmission.

I just replaced the slave cylinder and master cylinder because it leaked and had no pressure on clutch. Once that was out of the way, i tried experimenting with 4th gear and now realized that it tend to grind when the car is warm and i shift quickly such as on the freeway, if i give it a split second going from 3rd to 4th, it wont grind. But if its a straight shot from 3rd go 4th, it will grind
Could this still be the same issue with the weak synchro?

[NolimitZ32]

Could be your clutch adjustment is not correct and its not disengaging all the way but likely the 4th gear synchro is damaged, not gone but beat up.

[itsa300zx]

What trans fluid is in there now? MAybe try some MT90, some including myself have had good luck with new fluid.

[BrianZ32]

Could be your clutch adjustment is not correct and its not disengaging all the way but likely the 4th gear synchro is damaged, not gone but beat up.

I took it to a Z specialty shop and the guy did a clutch adjustment as well with the same idea hoping that it could be that, it helped because it doesnt grind as much, but i still get the grind every now and then. I just dont like knowing that i have to replace my transmission eventually. Im not in a position to just drop over 1k for a transmission );

[BrianZ32]

What trans fluid is in there now? MAybe try some MT90, some including myself have had good luck with new fluid.

Honestly, im not too sure. That would be my last resort and best hope that it is not a damaged synchro

[DCaff300ZX]

Unfortunately, the 2nd and 4th synchros in Z32's are pretty notorious for having been damaged by speed shifting at some point, or even just normal wear in higher mileage Z32's. The earlier year the manual trans, the weaker the synchros, also...the "93b" manual trans is supposed to have the best synchros, and the one I bought for my swap from A/T shifted perfectly and still does.
The MT-90 fluid has been known to help, probably the only solution besides replacement.

[BrianZ32]

Unfortunately, the 2nd and 4th synchros in Z32's are pretty notorious for having been damaged by speed shifting at some point, or even just normal wear in higher mileage Z32's. The earlier year the manual trans, the weaker the synchros, also...the "93b" manual trans is supposed to have the best synchros, and the one I bought for my swap from A/T shifted perfectly and still does.
The MT-90 fluid has been known to help, probably the only solution besides replacement.

With that being said, how many quarts of Redline will i need? Is it a transmission flush i need to do and refill with this? I will be ordering 3 quarts soon from Z1

[NolimitZ32]

I can't think of a reason to do a flush unless what comes out looks like crude oil and feels like molasses, just a drain and fill is all anyone needs 99.9% of the time.