Since I bought the car I have had some minor grinding when shifting to 3&4. It's only a split second when I'm throwing it in place and only for the first few shifts, until the Trans warms up. This weekend I replaced my transmission fluid with redline mt-90, because I heard it was good for Grinding gears. Could this be something else? I already suspected that the flywheel has something wrong with it so I have plans on putting in a new clutch, flywheel and TOB. Will this solve it or should I just look for a new transmission?

 

Bad synchros in the trans.

 

Good.

 

I agree with flash its typically the most common problem because of the NLS feature.

But I am curious if you have an aftermarket shifter or not? and if so is it aligned properly?

I had a similar issue on my old ss/sc with a hurst shifter when i first bought it and it just needed some minor adjustments. Here is the thread i found and used when i had my grinding issue. https://www.cobaltss.net/forums/08-1...inding-187224/

 

It's mt 80 OE spec? Pretty sure it's recommended to use OEM fluid. Like ACDelco. Anything else causes problems.

 

I thought MT-90 was for the F35. If it's an LE5 then it has an F23 transmission which uses GM#88861800.

 

It was Grinding before the mt+90, so that is irrelevant. Stock shifter, haven't picked a short throw yet. I used the mt-90 because it is supposed to have better lubrication properties that reduce grinding.

 

The grinding only lasts until the tranny has warmed up.

 

So, wait until the car warms up before driving. lol. I have the same problem with my eclipse grinding. If I take it easy it doesn't grind between shifts. Synchros going out are a common thing. Not sure how handy you are but if you have access to some tools like a press, a feeler gauges, torque wrench, sockets & ratchet... you could probably replace the synchros yourself. Or buy a used trans or have yours rebuilt.

 

I would like to find a used Trans and rebuild the current one but I can't seem to find any rebuild kits for the F23.