[Kevin Moore]

Got a friend with a recently purchased 94 LT1 9C1. 138k but seller claimed that he discovered the trans was an SRTA with low miles. Anyway.

Symptoms are the 2-3 shift was becoming "weird," specifically it began to flare pretty noticeably. This happened for about 2 weeks leading up to the current symptoms. He was sitting in stopped traffic for about 10 minutes and when traffic cleared, he discovered that after 2nd gear the car felt like it was in neutral.

This evening I brought my laptop with Datamaster to check everything out. No codes. But I noticed something funny. The shift solenoid commands look normal. And the active gear readout looks normal. However, when it goes into 3rd and feels like neutral, we discovered it's actually in first with no overrun clutch. And when it commands 4th, it's actually in 2nd.

Trans temp was always good and I didn't feel any slipping.

I don't think it's a 2-3 solenoid issue. I suspect a valve body with a plugged circuit...maybe. What say you guys?

 

[sherlock9c1]

Try killing power to the transmission either by pulling the plug at the trans or by pulling the fuse (which kills some other things too but the car will still run). Does he get 3rd with manual 2nd available? If so, then the problem is electrical.

 

[SSleepingbeauty]

I'm gonna guess 3-4 clutches.......

 

[SStreet King]

having the same issue with my trans now.. and had it with the trans before this.. everyone tells me i blew the 3-4 clutches

 

[sherlock9c1]

It may be the 3-4 clutches, but you when you can spend 10 minutes diagnosing to make sure it's not something electrical, what have you got to lose?

 

[Kevin Moore]

Yeah I got out my 95 FSM and it looks like either the 3-4 clutches or something in the apply circuit isn't working. I'll have him try killing power to the trans but I suspect he'll get first gear just like before. Looking at the table (if the 3-4 clutches are shot) that makes sense.

But if it's really an SRTA trans, he has 3 years and 36k, 50k, or 100k depending on when it was done. Is there an easy way to ID these or do I need to get the VIN and find a friendly GM dealer to see what their system says?

 

[MikeOD]

Yeah I got out my 95 FSM and it looks like either the 3-4 clutches or something in the apply circuit isn't working. I'll have him try killing power to the trans but I suspect he'll get first gear just like before. Looking at the table (if the 3-4 clutches are shot) that makes sense.

But if it's really an SRTA trans, he has 3 years and 36k, 50k, or 100k depending on when it was done. Is there an easy way to ID these or do I need to get the VIN and find a friendly GM dealer to see what their system says?

Far as I know, SRTA warranties do not transfer ownership.

Last time I had an SRTA part, you could open the hood and look down at the top of the trans near the firewall, and see a GM sticker.

 

[Kevin Moore]

Current SRTA 3 yr/100k appears to be transferable.

http://www.goodwrench.com/_res/pdf/GMGoodwrenchEngineTransmissionWarranty.pdf

Perhaps the older ones were, too. Again I thought the seller said it had like 10k on it...or was it 30k. I forget. But I bet it's within the 3 years.

Gah. A local Chevy dealer says the VIN is too old to find any history.

 

[40767]

I add a vote for the 3-4 clutch stack. The factory rebuilds keep the return assist springs in place on the perimeter of the input shell. The factory rebuilds use a factory reaction shell (weaker). The factory rebuilds also use bonded piston seals. Those are examples of why factory rebuilds aren't always the best you can do.

Good luck on the warranty. I've found that with GM warranties if you are persistent and push hard enough you may get some action.

 

[SuperSport]

3-4 clutches... upgrade to BW HE clutches. I've used Alto RE clutches before. They last longer than OEM, but the BWs take a lot of abuse with longer life.

Good luck!

 

[Kevin Moore]

I actually don't think the clutches themselves are toast. I think it's something else, possibly something in the valve body. He said it shifted funny for only 2 weeks then, bam, no 3rd or 4th. I don't think clutches go out like that on stock 4L60-Es mated to stock LT1s. The fluid temp never went above 180 while we experimented, and the fluid itself looks and smells normal. So maybe some seal is leaking or an apply piston is cracked, or something along those lines.

Oh, and he tried the fuse pulling "trick." As I suspected, he got 1st gear (instead of 3rd) and did have manual 2nd. 2-4 band is fine...we know that I guess.