Transmissions and Drivetrain Need help with your trans? Problems with your axle?

700R4 vs TH350

Old 04-19-2012, 10:02 PM
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Car: 1986 camaro Sports Coupe
Engine: L31 350
Transmission: 89 700R4
Axle/Gears: 3.42 gov lock
700R4 vs TH350

im putting a 5.7 vortec into my car and i need to decide what to do for a trans, im hoping for atleast 400 RHP and i really only drive in town so i dont have to worry about the highways unless i really need too but what would be the easier install and handle the power im wanting to have? can the 700 even take the abuse the 350 can? advice? tips? help?
Old 04-19-2012, 10:33 PM
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Car: 84 Z28, '15 Colorado
Engine: L69
Transmission: A4
Axle/Gears: 3.73
Re: 700R4 vs TH350

There isn't much of a reason to put the TH350 in when you 700R will work just fine, plus it will have an overdrive for those times you do go on the highway.

Pro-Built Automatics and Bowtie Overdrives both sell 700s that can withstand well over 400 horse power. In fact, I'm driving to California to pick up my new stage 2 tomorrow.

Also, with keeping the 700R you don't have to buy a new cross member or driveshaft. Win - Win if you ask me.
Old 04-20-2012, 10:58 AM
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Car: 87 camaro
Engine: 350
Transmission: th350
Axle/Gears: auburn 4.10
Re: 700R4 vs TH350

400 rwhp. so about 450 flywheel hp. I don't think your stock 700 will last very long. you can build them up to handle it but it'll be salty. a built 700 is about as strong a stock th350. I had my th350 rebuilt stonger and warrantied up to 500 hp for 650$. my tranny guy said he could do the same to a 700r4 but it will be around 1400$.

Theres is just a ton of stuff you have to do to make the th350 swap work right. torque arm, crossmember, speedo gears, driveshaft, tranny lines, high rear end gear ratios are a problem also cause 700s have a low 1st gear unlike th350. with a 3.23 like yours u might be ok. Im lookin to put 4.10s in mine because 2.73 ratio and th350 sucks.

Last edited by krisner89; 04-20-2012 at 11:05 AM.
Old 04-20-2012, 01:21 PM
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Car: 1988 IROC-Z
Engine: L98 - full intake & exhaust boltons
Transmission: Bowtie 700r4, 2400 rpm stall
Axle/Gears: Borg-Warner 9bolt, 3.45 gears, posi
Re: 700R4 vs TH350

Our cars are already set up for 700r4's. Like others have said, in stock form it won't last to long with your set up. Modified 700r4's are more than able to handle the level of power you put out.

If you were just drag racing, I could see and argument for the th350. Its higher 1st and 2nd gear ratios (2.52 and 1.52 respectively) would cause less tire spin off the line. There is no overdrive gear though. Some of the lateer th350's don't even have lockup converters. As a result your engine will be screaming down the highway.

The 700r4 has lower 1st and 2nd gear ratios (3.06 and 1.62 respectively) which will help out acceleration overall, not just with respect to getting off the line. 3rd gear is the same in both transmissions, 1.00 You also get the 30% (0.70 gear ratio) overdrive gear and a lockup converter. If you do any kind of street driving you are going to want an overdrive gear. Less wear and tear on the drive train and better fuel economy. Just drive your car around in 'D' for a while and don't use overdrive. That will give you and idea of what a th350 will be like in your car.

I know we don't view our cars in the same way as a honda civic in terms of fuel economy. But these cars return very good numbers for what they are especially with the overdrive gear. Our cars also have excellent aerodynamics which also lends a hand in fuel efficiency.
Old 04-20-2012, 01:46 PM
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Car: '82 z28
Engine: L83 5.7
Transmission: 700r4-1985
Axle/Gears: 3.42 posi
Re: 700R4 vs TH350

i have had bot th350 and 700r4 in my car over the years
liked the 350's 1-2 ratio spread better than the 700r4s,
but installed the 700r4 when i got the AC working and
didn't want the compressor turning 3500+rpm on the
highway i think car was a little faster with the 350...
I think the 700r4 is tougher than often given credit for
(and the strength of the th350 might be exaggerated
some...also i think the 700r4 may have a stronger
bellhousing than the kinda weak looking one on the
350)i have done some very nasty things to my 700r4
over the years-some on accident-and no problems at all.
I am only running about 240-250 hp though.
last time i looked,th350 had a better selection of
torque converters avalible for it.
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