To make a long story short... i have a 93' with a 3 speed th350 tranny conversion. Drove AMAZING!!!! for awhile, transbrake iand ratchet shifting s def a new experience... recently the car began to shake like crazy. AFter taking it to KDR i found out the bell housing is cracked damaged fairly bad. Basically Im planning on buying a new tranny that should bolt up to the same adapter plate thats on there right now. I was told its a B.O.P. (Buick, olds. pontiac) th350.

Problem is I want to see if I can find one that has an overdrive gear, because im not trying to use it for only drag racing and besides the short gearing its a very streetable car. I wanna bring the rpms down when driving highway sppeds. currently it tops out at125mph... when im doing 70mph im almost at 4000rpms. The only reason im not looking into getting a diff auto tranny is because I would need to modify the drive shaft and pay out the *** to get a new adapter plate installed
few questions...

- Does anybody know if you can buy a b.o.p. th350 with an overdrive gear? and if so would it be the same length, bolt pattern etc.

- Could I take the internals of my current tranny( which is supposely built up already) and have a shop swap them into a new bell housing to keep the cost down?

- Keeping in mind that im not trying to drop a lot of money into the car after buying it for 20k a few months ago, does anybody have suggestions or comments to the direction I should take with the car.?

-Does anyone have a wealth of knowledge about this conversion and these trannys?

I want to get my car back ASAP!! so any help would be greatly appreciated!!




SUSPENSION
R1 Front Strut Tower Bar
Tokico Shocks (5-way Adjustable)
H&R Springs
RaceShop Roll Bar
Toe Links (not installed yet)
Trailing Arms (not installed yet)
RX7.com Diff Bushings
Diff. Brace
KAAZ 1.5 LSD

DRIVETRAIN
TH350 Transmission (fully built, w/ Trans Brake)
5500 Racing Torque Convertor (Edge Racing)
B&M Pro Ratchet

ENGINE

SS Downpipe
SS Midpipe
Racing Beat Catback
Pettit AST
Race/Street Port (HUGE)
88 High Compression Rotors
Racing Seals
180 Thermostat
Silicone Hose Replacement
XS Engineering T04E Single Turbo (Garrett)
Cast Ductile Iron Exhaust Manifold
HKS Racing Wastegate with 50mm valve
A'PEXi Twin Chamber Blow of Valve
K&N Air Filter
M2 Large (Racing) intercooler

FUEL SYSTEM
1600cc Secondary Injectors
KRD Fuel Rail
Supra TT Fuel Pump
Aeromotive FPR

 

Im thinking that if you want a 4 speed, you need to go 700R4 or 4L80E. Theres few more 4 speed GM slushboxes, but I cant remeber them.

 

A BUILT 700r4 or 200r4 is what you need. Either one is light and if built right, will take anything you throw at it.

 

700r4 my man! will do just what you want out of it.

 

who sells the conversion kit, if you don't mind me asking? anyone know what it takes to do this conversion?

 

a 700r4 will have a different bellhousing than a th350 out of a pontiac, buick, or olds.

 

then why not get one of those push button over drive units they sell for hot rods and muscle cars.. where it attaches on the end of the tail shaft and cuts the engine rpm by half or 60 percent i forget.. i seen it in a umm mopar muscle mag like 3 years ago.. i cant even think of the name.

 

so a 700r4 out of a firebird is different bellhousing? i know the converter is different but i thought bellhousing was the same make to make.. also a 200r4 out of a buick GN would be a nice tranny too!!

 

My God, you have ripped the soul out of your RX-7!!!

You should have swapped in a T56...

 

He's not asking which transmission to go with, he's already swapped in a TH350.

Insomniac21772, this is the last place you should be asking advice. Try posting on LS1Tech or just call a transmission shop. http://www.gearvendors.com/ sells the aftermarket overdrive to add to your TH350.

habu2, you don't have any idea what you're talking about.

 

Im leaning torward maybe dropping a 700r4 in. I just dont know where i could get an adapter plate for that, and god knows how much money i'd have to spend to get it installed. the person who had the car before me dropped like 3-4k just in labor to get that 350 to work. I think I may be able to save if I get an over drive unit, just not to familiar with them.

 

Why don't you just change the gears and throw another bellhousing on. A bellhousing is only like $20. I would ask Dave that, it sounds like something wasn't aligned right. Something Dave should take care of.

Seriously, no point in throwing the TH350 swap in the trash and starting over again.

 

have to agree with viking but isnt 3.90 the highest gear u can get for the rx7? and that wont help out highway too much.. id still be looking at that push button overdrive unit that those muscle car guys buy when they run stout rear ends with 3 speed trannys. just wish i could remember the name of that darn thing..

 

for all u tranny guru s out there is it possible to have a turbo 350 tranny rebuilt with different gears? not talking about changing the rear gear.

 

you have allot more options than what are mentioned here such as:

TH-2004R


http://www.phoenixtrans.com/html/gmtrans.html

 

I like the th-2004r idea, has the extra gear and is about the same size. According to the info from that site the th200 is 1/8th inch longer then my current tranny. Is this going to work? the splines are the same and it says it does come with BOP bolt pattern, so imguessing it would bolt up to my current adapter plate.

TH-2004r
Overall length 27 3/4”, Face to mount distance 26 7/8”, Ratios: 1st 2.74, 2nd 1.57, 3rd 1.00, 4th .67

Th-350
Overall Length 27 5/8” Face to mount distance 20 3/8”, Ratios: 1st 2.52, 2nd 1.52, 3rd 1.00

 

can anyone answer this for me? ^^^

 

you can put in a first gearset from a 700r4, it is lower though...i have one done on my rock crawler...

you can also just swap you internals...i just got done doing this....allbeit not in an FD....new housing cost me $150 took about 4 hours to swap....with adding a new art carr full reverse manual VB with compressinon braking.....

 

Insomniac21772,

whats the max rpm you see when on the transbrake?

 

If I drop it any higher then about 3k it will just spin on the streets with 275's. Never really took it any higher then that. Im excited to see how much better it would hook at the track. Im not sure how far its possible to rev up before hitting the trans brake.

 

I know this is old post but who else has done this? Fpr a street fd