Drivetrain Downshifting from 3rd to 2nd issue

Scott_S · Apr 23, 2026

Down shifting issue. Give me your best virtual diagnosis.
My punch list is getting smaller and all the easy stuff is almost done. The biggest issue I'm having for drivability is when downshifting from 3rd to 2nd.
Shifting UP through the gears is fine. But, when coming DOWN from 3rd to 2nd, it's nearly impossible to get it into 2nd gear. I have to slow almost to the point of just choosing 1st gear instead.
It never grinds, doesn't pop out of gear, etc.
I tried adjusting the clutch at the firewall. The car is in the shop right now for some fluid changes and I've asked them to do a proper clutch adjustment while it's on the lift.
In your experience, do I have a clutch issue, or a transmission issue? I would think that if it's bad synchros or something, it would grind. What should I prepare myself for here?

AeroCoupe · Apr 23, 2026

I am going to guess either synchros, input shaft end play (doubtful but always good to check), or the clutch is engaging too quickly off of the floor.

limp · Apr 23, 2026

My experience with manual transmissions is that 2nd gear gets the biggest workout of all the gears.... Banging 2nd gear the most often and downshifting into 2nd for a slow down so its the gear that gets used the most " in my experience" ... Back in my day, when we would go to a Wrecking yard and pull a 4 speed out of a wrecked car for $100, the 2nd gear usually ground into gear and sometimes popped out....
Just a guess here....

AeroCoupe · Apr 23, 2026

Also, how many miles are on the transmission? For that matter what year car are we dealing with? What brand and series of clutch is it and how many miles are on it? Has the transmission ever been gone through? Stock or aftermarket shifter and if aftermarket which one?

Scott_S · Apr 23, 2026

Car is a 1989. I think that it was originally an automatic and has been swapped.
Unfortunately, I don't have any history on the car. I don't know what heads or cam are on it. I don't know how many miles are on the transmission.

AeroCoupe · Apr 23, 2026

Any other issues with the transmission at all? I would be curious to see what the fluid looks like. If it’s a Borg Warner unit (Tremec bought them in 1995 maybe 1996) and you do not know the condition then it may time for an overhaul. See how things come out after the service you are having done. If you still have problems then you need to pull it and do an inspection. The longer you let it go the more it will cost.

Service manual is here (you have to click on “download”:

Resource icon

T5 Rebuild Manual

Oct 2, 2013

T5 Rebuild Manual

Really good videos on going through a T5:

Part 1

View: https://youtu.be/XREsRG9Y1mU?si=2mRJORjUp0UHUvAE

Part 2

View: https://youtu.be/mR8LetFQSoc?si=OQqJoHQ4zVf-dnJH

Part 3

View: https://youtu.be/BhbI4c6UFiQ?si=F_JF3xJteCOsSi9Z

Paul is a wealth of knowledge and Eric is pretty entertaining.

Scott_S · Apr 23, 2026

No other issues with the transmission. Shifts smooth other than that 3-2 downshift. Never grinds. Never pops out of gear, etc.

AeroCoupe · Apr 23, 2026

Most likely clutch adjustment (hopefully) or synchros. If the clutch adjustment doesn’t get it then I’d plan on pulling it and doing some looking.

Mindseye007 · Apr 25, 2026

limp said:
My experience with manual transmissions is that 2nd gear gets the biggest workout of all the gears.... Banging 2nd gear the most often and downshifting into 2nd for a slow down so its the gear that gets used the most " in my experience" ... Back in my day, when we would go to a Wrecking yard and pull a 4 speed out of a wrecked car for $100, the 2nd gear usually ground into gear and sometimes popped out....
Just a guess here....

I just throw it in to neutral when slowing down.
To save synchros from getting fried .

Scott_S · May 2, 2026

Clutch adjustment helped, but only a tiny bit.

My mechanic (who doesn't do transmission work) suspects 2nd gear synchro. There's a highly reputable transmission shop in town that's been here forever.
Other than the synchros, educate me on what to expect. Are there other wear items that would be dumb to not replace? And while I don't suspect any clutch issues, is this one of those "while you're in there" situations?

I'm not looking to cheap out, but I'm also not looking for a reason to spend money. What's the smart, logical approach to a transmission repair?

AeroCoupe · May 2, 2026

Save your money and put either a Z spec T5 or a Tremec TKX in it. Rebuild kits are damn near $500 and don’t come with all the bearings anymore. Then you still need synchros and who knows what else when you open it up. While you are in there you should put a billet cluster shaft support in it which are $65. So call it $700 in parts plus the labor. You would be damn close to the cost of a new Z Spec T5 that would just drop in and it’s something g you can do yourself.

Scott_S · May 9, 2026

Well, after the clutch adjustment, the problem got even worse. It got hard to find 1st OR 2nd at a stop, and reverse would grind a little in the driveway. It didn't do that before.
I had it hauled to a local, well respected transmission shop. Their initial diagnosis: They're 95% sure it's all clutch related and that the transmission is fine. I ordered a clutch master kit, throw out bearing, rear main seal, etc. Fingers crossed that's all it is!

Scott_S · Jun 12, 2026

I updated my Project post, but wanted to update here, too.

After replacing the clutch, flywheel, etc., it helped and shifted smooth .... until it got hot. Even the transmission shop was stumped; they were willing to bet a clutch would have fixed it.

Long story short, they got behind, lost a tech, etc., and the car was just today being pulled back into the bay. After talking to them about parts availability, etc., I did what I should have done two weeks ago and ordered a new T-5 from LMR.

Fingers crossed that I can get it back by the end of the month.

Mindseye007 · Jun 12, 2026

Scott_S said:
I updated my Project post, but wanted to update here, too.

After replacing the clutch, flywheel, etc., it helped and shifted smooth .... until it got hot. Even the transmission shop was stumped; they were willing to bet a clutch would have fixed it.

Long story short, they got behind, lost a tech, etc., and the car was just today being pulled back into the bay. After talking to them about parts availability, etc., I did what I should have done two weeks ago and ordered a new T-5 from LMR.

Fingers crossed that I can get it back by the end of the month.

Is it the Z-Spec T5 from lmr?

Mindseye007 · Jun 12, 2026

Mindseye007 said:
Is it the Z-Spec T5 from lmr? That is what I have 2.95 first gear and it's so awesome with my 4.10 gears.

Scott_S · Jun 13, 2026

Yes, I believe so. It's this one: https://lmr.com/item/LRS-7003A/mustang-t5-transmission-79-93

That's good to hear, because I also have 4.10's!

AeroCoupe · Jun 13, 2026

I believe it also has a 0.63 fifth gear vs the 0.68 fifth gear in the OEM one. Not much but with 4.10’s take what you can get.

Mustang5L5 · Jun 13, 2026

Generally speaking, one good way to see if things a clutch engagement issue vs trans is if you push the clutch in and just wait 10-15 seconds or so and then try to into gear or reverse. If the clutch fully disengages it should allow enough time for the trans to spin down and for the gear shift to be seamless.

If the clutch is dragging, it usually keeps the input gear spinning which spins the counter gear and speed gears and you’ll get grinding even after the delay.

Reverse gear is not synchronized. 92-later cars do have a “brake” so don’t put too much weight into it if you grind reverse easily.

Mindseye007 · Jun 13, 2026

Scott_S said:
Yes, I believe so. It's this one: https://lmr.com/item/LRS-7003A/mustang-t5-transmission-79-93

That's good to hear, because I also have 4.10's!

You will love the pull you get while in 3rd gear it's amazing. Feels like I picked up 50 horses to the rear with my 4.10's. For passing or merging onto the freeway leave it in 3rd gear put the pedal to the floor and feel the pull so awesome.....my shift light is set with a 5200 rpm pill then i shift into 4th.

limp · Jun 13, 2026

Mindseye007 said:
You will love the pull you get while in 3rd gear it's amazing. Feels like I picked up 50 horses to the rear with my 4.10's. For passing or merging onto the freeway leave it in 3rd gear put the pedal to the floor and feel the pull so awesome.....my shift light is set with a 5200 rpm pill then i shift into 4th.

The freeway with 4:10's??

Drivetrain Downshifting from 3rd to 2nd issue

Scott_S

Active Member

AeroCoupe

lube between the nut and the face. I know my lubes

limp

wrap a little cheese around it and its a done

AeroCoupe

lube between the nut and the face. I know my lubes

Scott_S

Active Member

AeroCoupe

lube between the nut and the face. I know my lubes

T5 Rebuild Manual

Scott_S

Active Member

AeroCoupe

lube between the nut and the face. I know my lubes

Mindseye007

Scott_S

Active Member

AeroCoupe

lube between the nut and the face. I know my lubes

Scott_S

Active Member

Scott_S

Active Member

Mindseye007

Mindseye007

Scott_S

Active Member

AeroCoupe

lube between the nut and the face. I know my lubes

Mustang5L5

That is…until I whipped out my Bissell

Mindseye007

limp

wrap a little cheese around it and its a done

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Drivetrain Downshifting from 3rd to 2nd issue

Active Member

lube between the nut and the face. I know my lubes

wrap a little cheese around it and its a done

lube between the nut and the face. I know my lubes

Active Member

lube between the nut and the face. I know my lubes

Active Member

lube between the nut and the face. I know my lubes

Active Member

lube between the nut and the face. I know my lubes

Active Member

Active Member

Active Member

lube between the nut and the face. I know my lubes

That is…until I whipped out my Bissell

wrap a little cheese around it and its a done

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