Tranny swap
 

Found out today that my tranny pump isn't keeping a good pressure at all times. My mech said the pump is on the way out, so I'm looking right now at a new or used transmission. Used installed would be $1000 with a short warranty (30 days to 6 months) and new would be $2900 with a 3 year 36,000 mile warranty. Thinking the new, but it depends on WHEN it goes and what the wallet sasys at that time

I know I have the 4T45 transmission, and I also know that the GAGT Tranny has a 3.29 FDR and the Cobalt, Ion, G6 base, etc have the 3.63 FDR

Two questions:

1 Which would be the better FDR for my car? I googled FDR's and found that the calc's aren't that far off using 3.05 FDR, with a 25 inch tire at 70 MPH I came up with 2009 RPM's which is pretty damn close if not dead on. I like the 3.29 but thinking the quickeness of a 3.63 would be just simply :awesome:

2 If I did the 3.63 FDR, all those trannies are mated to 4 bangers. Are the clutch packs, tranny pump, gears, etc able to handle a V6 motor, or did GM used weaker items to save money?
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Keep in mind I'm going to be doing an engine build with a WOT-TECH Street/Strip cam

Specs of cam:

i know this is of topic but have you thought of swaping in the 4T65e-HD from the grand prix.

Just as a comparison Ken, my trans has a 3.42FDR and the motor is turning ~2000rpm @ 60mph. 70mph is ~2300rpm.

^^ Hmmmm, I'm guessing that a 3.63 might be a little too high for my cruising tastes. 2300 @ 70 would be good.


What car had a 3.42 FDR? I'm not going to be doing a rebuild, just a swap ;)


After the problems Bdyman had, no way

what problems did he have?

Bdyman also had an LS4....a bit more power in a much heavier car.

I had my transmission rebuilt with different drive/driven gears. The LD9/4T40-E Alero came with this gearset.

How good are those gears/clutches/etc in stock form in the 4T40.

It's the same case, right :awesome:

I know he blew 2 transmissions, maybe 3 or 4, with normal driving and in was a common problem for that car

Not really looking at the fab work, IDK, it all depends on when this trany goes, I just like to have options ;)

I couldn't say......when I had the gears replaced, I did a new chain, Blue Plate clutches, new steels, and billet accumulator pistons.

What did that run?

I'm pretty much looking for something that will also match my new cam which I have listed above. Matt the heads I bought off you will work nicely with that cam, but I also want to get the proper gearing and convertor for it. The convertor can be replaced at the engine build

If you are looking to do it on the cheap, find a low mileage 4t45e out of a 03-05 Grand Am GT (3.29 ratio). I picked up a used 4t45e out of a 04 gagt in MI that had 25K miles for $150 a few months ago. It was missing the torque converter, but I had one in the garage so I was good to go.

I actually took a peek at car-part.com and found one not too far away out of a 05 GAGT with only 3,385 miles on it :eek: Somehow I doubt that mileage

Seen others on there fairly inexpensive ;)

what are the advantages of grabing a gagt tranny instead of a alero one?
the alero being a 6 cyl

I don't know about Alero's, but on my 1995 Ford Escort the transmission's oil pump is externally mounted and actually pretty easy to get to once you have removed a wheel and a splash shield. It would not be much of a problem to replace just the transmission oil pump on that car. It's that rusty thing pictured here:

Ever think about going with a higher stall converter? Maybe one from like a 2200 J-Body?

Well I'm going to need a high stall convertor anyway.

What's the stock convertor stall anyway

Not sure what it is, but the "73CW" is the highest stall factory converter you can get with the woven carbon lining....

I like this thread....cause my tranny is starting to poop the bed and i want to rebuild it but make it able to handle the abuse i want to put on it in the future :P I will be keeping a CLOSE eye on this thread ;)

Isn't there a way you can make the existing transmission oil pump increase the oil pressure by putting in a stronger spring? I've seen threads about it (not here) and for my Escort there is a TSB on it with a revised valve and spring.