4t60-e talk

[Jonathan_C]

So the transmission in my 1993 z34 lq1/4t60e went out. Completely, no chance at an affordable rebuild.

 

Due to financial concerns my only recourse was to locate a replacement. I did a search on some site that looked through junkyard databases and bought what I was led to believe a transmission from a 1993 lq1 powered lumina.

 

Upon my arrival at home, which is 3 hrs from the boneyard, I look at the invoice and it said in comments, 3.1 red lumina. I called the boneyard to ask exactly which car the trans came from, but they havent responded yet, and I am not certain they ever will be able to ascertain the origins of the transmission.

 

It is my best knowledge the 3.1 4t60e from 1993 had 3.33 final drive and I believe the z34 came with a 3.06? I'm not positive on this, if I'm wrong - feel free to correct me.

 

So... short of pulling the trans apart to identify it, is there anyway to determine the final drive by the coding on the tag? Also, what's best and worst case scenario for the install if the gearing is a little low - or high, whatever the case is. I know it WILL bolt up to the lq1, but will it play nice?

 

If I can identify the transmission final drive then perhaps I can get some sort of refund. If it will work 99% good being out of a 3.1 I might do that as well.

 

I figure you guys are smarter than me, so what should I do?

[Crazy K]

ON THE REAR OF THE CASE IS A TAG AND A STAMPED NUMBER. THE TAG IS TOWARDS THE RIGHT SIDE. THE STAMPED NUMBER IS ON A FLANGE RIGHT ABOVE THE PAN. GET BOTH AND POST ASAP.

 

 

3.4= 3.43 FDR

3.1= 3.33 FDR

 

 

FYI You CAN use that transmission in your car(since you are OBD 1), but you'd overdrive the engine around 5% = more efficient, slower starts... basically:

 

3.4 w 3.43 fdr = 2000 RPM at 58mph

3.4 w 3.33 fdr = 2000 RPM at 62mph

 

(approximation)

[slick]

You'll get better gas mileage, if you are concerned about it.

 

Otherwise, swap up to the 3.73 gears and call it a day.

[AL]

If your set on getting the original gearing, I have a tranny in my shed from a 93 3.4 GP, Ill give it to you for 50 bucks but I am not sure how close you are to NE

[Jonathan_C]

ON THE REAR OF THE CASE IS A TAG AND A STAMPED NUMBER. THE TAG IS TOWARDS THE RIGHT SIDE. THE STAMPED NUMBER IS ON A FLANGE RIGHT ABOVE THE PAN. GET BOTH AND POST ASAP.

 

 

3.4= 3.43 FDR

3.1= 3.33 FDR

 

 

FYI You CAN use that transmission in your car(since you are OBD 1), but you'd overdrive the engine around 5% = more efficient, slower starts... basically:

 

3.4 w 3.43 fdr = 2000 RPM at 58mph

3.4 w 3.33 fdr = 2000 RPM at 62mph

 

(approximation)

 

Thanks, I - forwarded your information to my mechanic who double-checked and agrees with your conclusion. Decoding of the tag says it's 3.33 gears, which is fine by me -

I don't really beat on the car anyway - I already have a ton of personal wrench time in the car including an engine swap.

 

I'll eventually get some help and rebuild the original powertrain and swap it back in, but for now I'll settle for running and moving.

[alec_b]

Even though it's OBD-1 isn't the computer going to be upset about the FDR change since it's a 4T60-e? If the PCM is looking for certain parameters from the 3.43 FDR one would think switching to a 3.33 would make it act goofy. But maybe it's just the OBD2 cars that are picky about that.

[AL]

Yah I agree with Alec... but did you see my previous post?

[RobertISaar]

Even though it's OBD-1 isn't the computer going to be upset about the FDR change since it's a 4T60-e? If the PCM is looking for certain parameters from the 3.43 FDR one would think switching to a 3.33 would make it act goofy. But maybe it's just the OBD2 cars that are picky about that.

 

the difference between 3.43 and 3.33 is so minimal, the PCM really wouldn't care or possibly notice.

[Crazy K]

Even though it's OBD-1 isn't the computer going to be upset about the FDR change since it's a 4T60-e? If the PCM is looking for certain parameters from the 3.43 FDR one would think switching to a 3.33 would make it act goofy. But maybe it's just the OBD2 cars that are picky about that.

OBD 2 is picky. Obd 1 doesn't care.

[RobertISaar]

OBD 2 is picky. Obd 1 doesn't care.

 

truth... you'd probably set TCC/tranny slip codes with OBD2.

[alec_b]

Man OBD1 is nice, I'm glad I have it

 

I just wondered because the newer GM's will set incorrect ratio codes with the wrong FDR. That's what the N* guys have trouble with when they swap the 275 horse for the 300 horse engine sometimes. You have to switch the trans to the 3.71 or re-burn the PCM.

[RobertISaar]

only the VERY late OBD1 PCMs check for that type of thing, but N* going from what, 3.11 to 3.71, yeah, that's quite a difference, 19.3% compared to the 3% difference of a 3.43 to 3.33.

[Jonathan_C]

Yah I agree with Alec... but did you see my previous post?

I saw it and appreciate the offer, but I'm in west Michigan and I barely had even resources to pick up the trans from 200 miles away - that's why I decided to go ahead and start the install: I can't afford another 400 mile round trip right now and the 8 hrs driving that it entails.

[AWeb80]

rebuilding a trans isn't hard. i did mine. just take your time, have a parts washer, an ASTG manual, take your time, some normal tools, and take your time and It's simple.