I have driven a good amount of manual transmissions, but only my 92 300ZX grinds gears when downshifting at a high speed.

Example: At about 70mph, in 5th gear, I downshift to 4th gear. With the clutch fully pressed, there is a grinding sensation like I'm trying to go into reverse. However, after about a second it will engage correctly and I can continue.

I asked a few people and one person recommended giving the car a little gas when pushing in the clutch to boost the RPMs by about 1k-- this should allow for grindless shifting. I tried this and it seemed to work a little.

Is this normal? Should I have this checked out by a mechanic? Thoughts? Suggestions?

Thanks.

~Steve

steve@woo****inghoo.com

 

It's normal for the Z32 to grind at times...some worse than others. The reason is because Nissan tried to be geniuses and used special synchronizers in the tranny that are of the double-coned variety instead of single-coned. Over time they tend to grind. A simple band-aid type fix is to use Redline MT90 or MTL in the tranny (and might as well put 75W-90 in the diffy while you're down there). This tends to lubricate much better and lessen the grinding. But if your tranny is to the point where it still grinds a lot, the only fix is to replace the synchros or get a new/rebuilt tranny altogether. Just make sure you use Redline always. It can be gotten at myoilshop.com. There's also a dealer code in the links section of twinturbo.net you can use to get 10% off. Hope this helps!