The Mustang Forum for Track & Racing Enthusiasts

Taking your Mustang to an open track/HPDE event for the first time? Do you race competitively? This forum is for you! Log in to remove most ads.

  • Welcome to the Ford Mustang forum built for owners of the Mustang GT350, BOSS 302, GT500, and all other S550, S197, SN95, Fox Body and older Mustangs set up for open track days, road racing, and/or autocross. Join our forum, interact with others, share your build, and help us strengthen this community!

4th gear grind at high RPMs MT-82

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

So I was at the track this weekend and ran into a transmission issue.

At high RPMs, anything over roughly 5k, it grinds going into 4th, at 7k it won't go. MGW shifter but factory clutch etc. It's only 4th gear this happens in.

My initial thought is bad synchro as I've never had this issue before on track and yes the transmission was hot when this happened, thought it would fix with a cool off but no luck.

Shifts fine in street driving situations. I'm going to pull it apart soon, just wanted to see if anyone else had a similar issue.

Thanks in advance.
 

Mad Hatter

Gotta go Faster
5,206
4,191
Santiago, Chile
Many many many times before.... By many many people. I went through so many lost count, brings tears to my eyes thinking about it.. huge amount of info and opinions available here on TMO though...

If you track the car a lot, look to a tremex XL or a calimer MT82 (Stage 3 ideally)... try to get the syncros fixed ASAP, and you will probably find some damage done to the gears already (have a bucket full of second, third and fifth gears in the garage). 5th gear was the worst. Went to a 3.31 rear to avoid using 5th for a while.

A clutch upgrade should also be on your list!

Sounds extreme I know, but lots of people here on TMO have gone through more then 2 tranny rebuilds.
 

JDee

Ancient Racer
1,782
1,980
Exp. Type
W2W Racing
Exp. Level
20+ Years
5 miles from Mosport
+1 to what Mad said.
Stock clutch is junk, it starts all these problems. You're also likely going to need a trans rebuild.
Strongly suggest at the same time to put a good racing clutch in, that really solves the problem. I had my trans rebuilt with the Syncrotech carbon kit and also put an Exedy HyperSingle in.
The clutch really starts the problem and replacing it solved the issue.
 
+1 to what Mad said.
Stock clutch is junk, it starts all these problems. You're also likely going to need a trans rebuild.
Strongly suggest at the same time to put a good racing clutch in, that really solves the problem. I had my trans rebuilt with the Syncrotech carbon kit and also put an Exedy HyperSingle in.
The clutch really starts the problem and replacing it solved the issue.

Yeah, I have the Hypersingle already, just haven't put it in. (Oops) Going to add a cooler while I'm there, I just wasn't sure if a synchro would only grind at high RPM and not at low rpm.

The Synchroteck parts have been doing well so far?
 

JDee

Ancient Racer
1,782
1,980
Exp. Type
W2W Racing
Exp. Level
20+ Years
5 miles from Mosport
Yes they are, though TBH it's only had 2 track days on the rebuilt tranny. For sure put a cooler in, it's a bit of work sourcing out all the parts but I believe it is well worth the effort. Syncros grind hot or cold if they're bad enough, at least with the MT82 they do. Especially 1st gear cold.
 

Bill Pemberton

0ld Ford Automotive Racing Terror
8,372
8,241
Exp. Type
Time Attack
Exp. Level
20+ Years
Blair, Nebraska
As noted it is the bizarre mystery of the M-80 tranny ( a proper nickname in my estimation) . My first Boss 302 ( purchased used ) began to grind going into 5th. Fifth gear having a problem seemed super strange as who shifts quickly into that gear , but found out it was quite common. Not problems from then on with my next Boss, but I am overly anal about changing transmission fluid. I would change after every two race weekends and was often told I was nuts, but I never had a problem with my 2012 or 2013 doing that. A beefier clutch is also a help for many ( I only had the stock clutch in my cars ). You are welcome to the Club of M-80 Issues, there are new members joining every week. Ford got smart and switched to the Tremec in the GT 350s and Mach 1s, and the advice of Madhatter is likely your best avenue as you are well out of your warranty phase.
 
Yes they are, though TBH it's only had 2 track days on the rebuilt tranny. For sure put a cooler in, it's a bit of work sourcing out all the parts but I believe it is well worth the effort. Syncros grind hot or cold if they're bad enough, at least with the MT82 they do. Especially 1st gear cold.

A cooler was in the plans anyways but this just accelerates it. 4th only grinds on high RPM shifts, 5k+, but it's the only gear that does it.
 

JDee

Ancient Racer
1,782
1,980
Exp. Type
W2W Racing
Exp. Level
20+ Years
5 miles from Mosport
A cooler was in the plans anyways but this just accelerates it. 4th only grinds on high RPM shifts, 5k+, but it's the only gear that does it.

High rpm upshifts to 4th were mostly the problem with mine, but both my 2nd and 3rd gears were junked and had to be replaced. Even though you sometimes can't hear the grind it's still there. It really is a crap gearbox, not even all that good on the street. 2nd being bad was weird since I rarely use it on track.
 
501
550
Exp. Type
W2W Racing
Exp. Level
20+ Years
Snowy North
Change out the OE clutch, go to a highest quality DCT-type gearbox oil and re-assess objectively. The OE clutch is the root cause (along with extended high temp/rpm ops) of the majority of MT82 ills.
 
1,071
1,066
Exp. Type
HPDE
Exp. Level
5-10 Years
Lenoir City TN
I just joined the MT82 club. Mine finally started giving me trouble at Barber Saturday morning. I went to downshift from 4 to 3 and it wouldn't go into any gear. The clutch only came half way up. I pulled off to the edge and turned the car off and shift in and out of gear, then restarted the car and drive around to the pits. I got under the car and couldn't see anything leaking. I drove the car a few miles down the road and it shifted fine. I went back out for another run and after 3 or 4 laps it started started shifting harder and the clutch pedal felt funny. It looks like the clutch fluid level is down a little. I can't complain too much my car has 94k on the original MT82, clutch, and slave cylinder and I started tracking it about 6 years ago. I consider myself lucky and know I was on borrowed time. I already had a clutch on order and was planning on doing it in the off season.
 

TMO Supporting Vendors

Buy TMO Apparel

Buy TMO Apparel
Top