: Grinding into 3rd under hard acceleration

09-12-11, 10:49 AM
This week I've started to notice that high RPM shifting from 2 to 3 is grinding. Normal to moderately spirited driving it shifts fine, but it's happening almost every time I wind her out at WOT. Trans fluid was changed last summer and clutch fluid was changed and bled last fall. One thing I've been meaning to do that I haven't got around to is installing my CS transmission mount. I'm hoping that might remedy the problem, as the OEM mount is definitely allowing movement that's messing with my shifting a bit.
What do you guys think? Any trouble shooting suggestions?

09-12-11, 11:52 AM
1. Flush the fluid again. 2. Install the trans mount. If those don't cure it, I'm betting your pressure plate is going bad. That was the first symptom of mine going bad. Try running out third gear and shifting into 4th. Usually a fluid flush will fix it though.

09-12-11, 12:06 PM
1. Flush the fluid again. 2. Install the trans mount. If those don't cure it, I'm betting your pressure plate is going bad. That was the first symptom of mine going bad. Try running out third gear and shifting into 4th. Usually a fluid flush will fix it though.

Thanks for the suggestion Brian. I'm going to assume you're referring to the clutch fluid, right?
I have wound it out all the way from 1st to 4th a few times and the 2-3 seems to be the only shift I'm getting any grinding. Hopefully that rules out synchro issues.

09-12-11, 02:03 PM
I would say it makes synchro issues more likely...

But, as was said, change the transmission fluid.

09-12-11, 04:32 PM
Right, flush the clutch fluid and see if it helps. Then install the new mount and replace the transmission fluid as mstrjon32 suggested. If those don't cure it, I agree with him, sounds like the 3rd gear synchro.

09-12-11, 06:09 PM
If it makes you feel any better, the synchro in the Aisin AX15 in my old Cherokee on 2nd was pretty much shot when I bought it with 155K miles. It would grind every time without a double-clutch. I replaced the fluid twice and bled the clutch, and it was working much better. Not buttery smooth, but no grinding and very drivable. When I sold it with 218K miles, you wouldn't have thought it was so rough some 70K miles earlier...

09-12-11, 10:14 PM
Sawdust. Saw it on a 1963 episode of the Andy Griffith Show when Barney Fife bought a used car and the tranny went bad. It had been filled with sawdust to make it buttery smooth if only for a few days. http://www.youtube.com/watch?v=pU8TxB2h7eI

j/k Do the fluid change. Just remember, when you remove that plug that sucker comes shooting out like a fire hose. Be prepared.

09-13-11, 01:19 AM
Also make sure when you shift into 3rd, that your foot is pressed on the clutch


09-13-11, 01:35 PM
If sawdust is cool with Barney Fife, then it's cool wit me. lol

I agree with the clutch fluid bleed. If that doesn't help, I would lean towards synchros.

mstrjon32: I have that same trans in my YJ. Those trans aren't even smooth shifters brand new! lol

09-14-11, 10:49 AM
I was just about to post the same question!

I also have noticed grinding when shifting into 2nd and 3rd lately.
I also still have to install my CS trans mount and Im going to change the fluid.
I hope that this helps. It sucks because I have less than 30K on the car.....I really hope its not the synchros. Dammit.

09-14-11, 11:22 AM
I use Amsoil Synchromesh ATF in mine. It shifts like a dream, when the clutch fluid is clean.

09-14-11, 12:07 PM
I use Amsoil Synchromesh ATF in mine. It shifts like a dream, when the clutch fluid is clean.

That's what I put in it last year when I changed all the fluids. Would hate to drain and refill the stuff already if its not for good reason. I'll do the mount first, see what happens. I can see that the clutch fluid reservoir is already filthy, so I'll probably change that stuff again too. Might leave the trans fluid though, unless none of the above solves anything.

09-14-11, 12:29 PM
Mine felt pretty clunky driving home from work today. I filled it with Amsoil ATF earlier this year...I think I'm overdue for a clutch fluid change myself.

09-14-11, 05:40 PM
It shifts like a dream, when the clutch fluid is clean.

Truer words never spoken. I am amazed at how often you should bleed your clutch fluid if you want butter smooth shifting! At least every 3k for me but I have a Motive and remote bleeder so its no biggie.

09-14-11, 06:31 PM
I had to flush mine every 1000-1200 miles until I switched from Motul RBF600 to Castrol SRF. Way more expensive, but it lasts about 3 times as long.

09-16-11, 08:41 AM
I have Mobil 1 ATF in mine. Just like Brian says......shifts like a dream after the clutch fluid gets changed out.

Don't be expecting much if you are only doing the turkey baster trick and only changing out the reservoir fluid. The slave needs bled for real. Hooray for my remote line!

09-17-11, 08:02 AM
I have a motive bleeder that I bought for last year's clutch and brake bleed, so I'll be using that again. I can't believe how dirty this stuff gets in such a short time. I wish I had the remote bleeder, but instead I have this really fancy 8mm wrench that I cut down to 2 inches long so it would fit to loosen/tighten the stupid bleed valve. Ugh.

10-19-11, 11:31 AM
Bled the clutch fluid a few weeks ago. The stuff that came out was less than a year old, but looked TERRIBLE already (see pic). Unfortunately the new fluid didn't stop the occasional WOT 2-3 grinding. BUT...

2 nights ago I FINALLY installed my CS transmission mount, and WOW! What a difference! No more grinding, no more binding when coasting with clutch disengaged, no more being blocked out of gear. This is by FAR the best my car had shifted since I've had it. I'm now feeling the full benefits of the PISNUOFF shifter too. It's like driving a different car! Oh, and also of note is that the oh-so-famous 2,200 rpm vibrations are significantly decreased too. They're still there, but less prominent.



10-19-11, 12:07 PM
glad to hear this..

One thing I have not done in all my efforts is replace my trans mount, and I too have the 2000-2500 rpm issue. Dealer replaced my flywheel and the overall vibes reduced greatly, but the specific rpm vibes continued. I read about the guy who shimmed his mount to fix vibes, which gave me the idea that it could be the trans mount since i noticed it sagged so bad when I removed it.

In an attempt to verify it wasnt the fw or trans, I removed the driveshaft, trans, clutch, and fw...

I looked all over locally- people who build engines for nascar, speed shops, etc..and no one could balance the dm flywheel, they said it should be done 'on the car'... or just couldn't. They also said it should be pretty good from the GM factory.

I also called RPM to see if I could ship them my trans for diagnosis. They said yes, but all they could do is tear it apart, not run it up to 2000 rpm and check it.. They also said it was a 99% chance it was not my trans. The trans is either bad, or its not. I don't have the 6th gear vibes, or any other issues. The cost to check was about 400. I'll just have them rebuild before I spend that to check it..

So, I have decided to throw all that stock stuff back in before I spend a dime on upgrades. I have a new stock fw, disk, and clutch that will be going in.

I noticed my trans mount went back to level stock height when the weight was removed, at least 1/2 to 3/4 inches.. so temporarily I have filled the void with 3m window weld, which is a nice firm durometer but not rock hard. If this form of "shim" helps, I'll invest in a new mount.

If the vibes persist, I'll just deal with it.

Long term I'll invest in the LS7 kit and install next summer since I know my way around down there now...

10-19-11, 01:44 PM
since I know my way around down there now...

not married, eh? JK

The LS7 clutch and a lightened FW is on my wish list too. I've read a lot of reports saying that this setup caused increased vibrations though, which scares me off a bit. That, and the cost of having a mechanic install it because I don't have the time or patience for a job that big...

10-19-11, 08:59 PM
not married, eh? JK

Yes, which explains why my V has been on jackstands for 3 months.

Doesn't the LS7 'kit' from Lindsay come with a lw flywheel?

10-19-11, 09:49 PM
It's been a while since I've read up on this stuff, but let me see if I remember correctly. The LS7 fw isn't all that much lighter than our v fw. You still save significant weight savings with the rest of the LS7 clutch, but for the V you're better off to go with a lighter aftermarket fw. IE the scoggins dicky LS7 kit for the V which comes with the 18(?)Lb RAM fw.

10-19-11, 11:19 PM
I think it's 27 lbs vs stock 45 lbs..