PONTIAC MUSCLE

I just lost 3rd and 4th gear in my transmission, it will shift into but not hold when I give throttle. I have a 1998 Pontiac Trans Am with the 4 speed automatic 4L60E GU5 for the LS1. Does anyone know the best solution for this or know of anyone parting out their A4 LS1 Firebird/Trans Am/Camaro with the GU5 Transmission? Any help is greatly appreciated, thank you.

mrvedit

You already asked this question in this thread:
https://ls1tech.com/forums/automatic...-4th-gear.html

I answered it there:
Nope different problem; your 3/4 clutch is worn out, the most common problem reported here.

You either need a rebuild or a replacement trans. You don't need a specific "GU5" (whatever that is), any '98 to '06 300mm input shaft 4L60E or 4L65E will work perfectly.

4L60Eshredder

Im new here, but pretty sure GU5 is a GM rear axle option code.. and good luck with a 4spd auto. Ive had many, they all turned into junk with very few miles and no fluid loss or provocation. Spent thousands on rebuilds from different builders, and few miles later junk junk junk. Waste of time or I have terrible luck. Wish all GM vehicle were T56 or muncies..

PONTIAC MUSCLE

Thanks, it did'nt notify me of your reply. GU5 is 3.23:1 gears and GU2 is 2.73:1. I hate autos but I got a very good deal on the car. mrvedit thank you brother, i'm still learning how to use this thread thing.

PONTIAC MUSCLE

I found a 4L60E on Craigslist for $250, it came out of a 1999 Chevy K1500 5.0/Vortec 5000 4X4. Will that be fine?

mrvedit

No, it will have a different output shaft for the 4x4 transfer case.
Also I don't think the Vortec 5000 is a LS engine and therefore will not have the correct input shaft. Changing the output or input shaft requires a complete rebuild.

If you want to PM me links to CL, that will be fine; I get email notifications of PMs and therefore will respond quickly.

PONTIAC MUSCLE

Okay, thanks.

lsxstudebaker

needs more v tec

PONTIAC MUSCLE

Lol! Hell no dude!

projectX

iTrader: (51)

Had that problem too, upgraded and now it rocks, GL

mrvedit

Please detail what you upgraded. The entire trans, specific parts, etc?

projectX

iTrader: (51)

They make stage 1/2/3 kits for rebuild - I bought a stage 2. Transco shift kit, high performance boost valve (sonnax), corvette servo, 11 plate ( 3-4 clutch pak ), clutches Kevlar, hi energy band (2-4 band) beast shell, etc.