Hey guys, I am wondering how much torque a TH325-4L can take that has been modified for a reverse mount engine? Basically flip the diff upside down and it spins in reverse, then flip the engine so the belts are backwards. This would work great in a Fiero, but this old 4 speed might have too little torque rating. so, anyone know how much this little trannie can hold?

quote Originally posted by Racing_Master: Hey guys, I am wondering how much torque a TH325-4L can take that has been modified for a reverse mount engine? Basically flip the diff upside down and it spins in reverse, then flip the engine so the belts are backwards. This would work great in a Fiero, but this old 4 speed might have too little torque rating. so, anyone know how much this little trannie can hold?

The 325-4L is basically a 2004r in transverse form. the internals are almost identical, the gears on the planets are cut the opposite way and the sprag and rollers rotate in the opposite way also. So pretty much the upgrades you can do to a 2004r you can do to a 325-4L. The turbo buick guys are running the 2004r behind some pretty stout engines, so i can imagine with a few upgrades the 325-4L should do just fine with some higher torque numbers.

I think this transaxle was a step up from the 440t4. The 325-4L was used in big boat cars like 80's Cadillacs, buicks and oldsmobiles. I also believe they had v8's in front of them, although that isnt saying much being from the 80's and all.

[This message has been edited by MonteC (edited 02-02-2008).]

quote Originally posted by MonteC: The 325-4L is basically a 2004r in transverse form. the internals are almost identical, the gears on the planets are cut the opposite way and the sprag and rollers rotate in the opposite way also. So pretty much the upgrades you can do to a 2004r you can do to a 325-4L. The turbo buick guys are running the 2004r behind some pretty stout engines, so i can imagine with a few upgrades the 325-4L should do just fine with some higher torque numbers. I think this transaxle was a step up from the 440t4. The 325-4L was used in big boat cars like 80's Cadillacs, buicks and oldsmobiles. I also believe they had v8's in front of them, although that isnt saying much being from the 80's and all.

Supposidly these have been used in the Oldsmobile Tornado, which produced 400ft/lbs of torque. BUT that was back before they started doing net HP. Which would be around 300ft/lbs by our standards. the 425 was used on the Olds Tornado, I am guessing the 325 holds more being newer, but it could hold less. I am a fan of Longitudnally mounted engines, and would be better for weight if the trannie was mounted backwards in a reverse mount engine, put more weight over the front axle, and with a shorter engine could possibly save the trunk, or at least most of it :P

quote Originally posted by Racing_Master: Supposidly these have been used in the Oldsmobile Tornado, which produced 400ft/lbs of torque. BUT that was back before they started doing net HP. Which would be around 300ft/lbs by our standards. the 425 was used on the Olds Tornado, I am guessing the 325 holds more being newer, but it could hold less. I am a fan of Longitudnally mounted engines, and would be better for weight if the trannie was mounted backwards in a reverse mount engine, put more weight over the front axle, and with a shorter engine could possibly save the trunk, or at least most of it :P

the 425 would hold more. Higher number. but the 425 is only a three speed, as is the 325. Only the 325-4l is a 4 speed.

the 325 is about the same as a 200, and the 325-4l is about the same as a 2004r, and the 425 is about the same as a 350 or a 400 cant remember which.

So if you want overdrive and a longitudinally mounted engine, go with the 325-4l.

I'm running an LT1/thm325...and I have a thm425 setting around for some reason.

It's allways been my understanding that the 325-4L was the weakest of the three.

PM sent.

David Breeze

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Pantera Rebody Kits

[This message has been edited by opm2000 (edited 02-03-2008).]

I would rather the 4 speed for higher top speeds, and better fuel economy at speed. if I mate a TH325-4L to a 3.8SC Series III with an adapter plate, it could be quite the intresting combo. though if I am gonna do that, might as well rebuild the trannie with beefed up parts :P

quote Originally posted by MonteC: So if you want overdrive and a longitudinally mounted engine, go with the 325-4l.

How responsive is the shifting?

quote Originally posted by AP2k: How responsive is the shifting?

it is a TH-350 with the output and input shaft on the same side. So I would guess the same as a 350!

quote Originally posted by Racing_Master: it is a TH-350 with the output and input shaft on the same side. So I would guess the same as a 350!

The 325-4l is the same as the 2004r not the th350.