C4 Tech/Performance L98 Corvette and LT1 Corvette Technical Info, Internal Engine, External Engine

TH350 in a C4?

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Old May 16, 2006 | 10:20 PM
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Default TH350 in a C4?

I gotta `87 vette with the 4+3 manual i wanna put a th350 in it what do I have to do to get it in there?
Old May 17, 2006 | 04:03 AM
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Make a custom bracket off the TH350 trans mount to take the C beam.
Find a VSS that will fit so the computer has a speed signal.
Old May 17, 2006 | 05:30 AM
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http://www.the-transmission-center.com/

I would talk to these guy's first.
They have all the parts to install the trans you want.
Old May 24, 2006 | 04:39 PM
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What about driveshaft?
Old May 24, 2006 | 04:46 PM
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Originally Posted by cemittar
I gotta `87 vette with the 4+3 manual i wanna put a th350 in it what do I have to do to get it in there?

The conversion is simple, I did it and it makes for changing trannies much easier since the t350 is MUCH smaller than the 700r4s. Not that this is a huge selling point, there are other reasons for that.

Call www.rosslertrans.net and tell him that Jesse Azzato sent you, and you want a conversion like I got to do the swap...he will hook you up. The piece you need is only about 80 dollars.

He can also build you a t350 that will be better than any other you can imagine getting. His racing reputation is second to none and guys all over the world run his stuff. Gotta see his car also....6.6 sec 57 chevy! THe tranny for that power level is only about 7k!

Charged me right around 1500 for a race built T350. Love it.
Old Jul 12, 2006 | 06:18 PM
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Some one one this forum had a modified C-beam fit for a Th350 for sale..any one know who it was?
Old Jul 13, 2006 | 12:07 AM
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Originally Posted by cemittar
Some one one this forum had a modified C-beam fit for a Th350 for sale..any one know who it was?
it was me i was selling the whole kit trans and all
Old Jul 13, 2006 | 11:21 AM
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A 700R4's tailhousing is the same bolt pattern as a TH350... Use a 9" tailhousing 350 with a spacer (I forgot who mfg's these) and a C4 700R tailhousing and voila...TH350...
-Jeb
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Old Jul 13, 2006 | 11:47 AM
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Barring speciific application, you'd be alot happier with a 700R4. Easier to swap, better street performance, better gas mileage, and better resale. And in my experience, better reliability.
Old Jul 13, 2006 | 11:58 AM
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Originally Posted by zr1fred
Barring speciific application, you'd be alot happier with a 700R4. Easier to swap, better street performance, better gas mileage, and better resale. And in my experience, better reliability.
BETTER RELIABILITY???? No sir... Not with any kind of power behind it. 700's start developing problems around 400 lb/ft of torque... Even the BEST built 700's die an agonizing death around 600 lb/ft. In contrast I've had a mid 8-second Nova with a built TH350 in it...
-Jeb
Old Jul 13, 2006 | 12:05 PM
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, But I'd consider that a specific application
Old Jul 13, 2006 | 05:32 PM
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i always thought the th 400 was better then the th350 why not go there? not trying to argue or contradict anyone ive always heard from guys around here ya cant beat a th 400 most i know junk th 350s lol
Old Jul 13, 2006 | 05:40 PM
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Originally Posted by scooter18155
i always thought the th 400 was better then the th350 why not go there? not trying to argue or contradict anyone ive always heard from guys around here ya cant beat a th 400 most i know junk th 350s lol

I run a T400 and love it!

Matt383
Old Jul 13, 2006 | 06:32 PM
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ok. same question how to install a th400?
Old Jul 13, 2006 | 06:44 PM
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Originally Posted by cemittar
ok. same question how to install a th400?
I did it the hard and expensive way.
Custom Tailshaft housing able to bolt right up to C beam like the 700R4 did.
I have heard that there is at least two companies out there that offer a T400 that bolts up to the C4 C beam.

I am sure someone will chime in on that.

Gear Vendors perhaps?

Matt383
Old Jul 13, 2006 | 07:32 PM
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i would have thought this thread was bigger
Old Jul 13, 2006 | 08:17 PM
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Originally Posted by scooter18155
i always thought the th 400 was better then the th350 why not go there? not trying to argue or contradict anyone ive always heard from guys around here ya cant beat a th 400 most i know junk th 350s lol
If you build the TH350 they can be as strong as "most" TH400's (all except the full-tilt $5k jobs like I have in my car). And for most applications they're better, here's why:
-Their gear split is better, unless you upgrade first and second in a 400 the split is too far apart and the 400's first gear to high at 2.48.
-The 350 is a smaller and lighter transmission and, in racing, ounces make pounds!
-The 350 is a MUCH more efficient transmission with less parasitic loss...As much as 12% less in some cases.
-For a C4 application the 350 is more practical and easier to install (just a simple spacer away with your supplied 700R tailhousing).

Now, having said that I choose to run a 400 that's a full race piece: it has 300M input and output shafts, billet pump, drum, and planetary as well as upgraded ratios in first and second. It will also hold 2500 hp and while I only make between 1250 and 1500 (depending on how big a pill I put in it) I believe in overkill when it comes to a full-on race tranny. However in a C4 application they're a bitch to install if you wanna do it REALLY right. You can build a tailhousing adapter and attach to the c-beam but that's really not the method I choose in a full-on race application. Since there's no real crossmember you put the load on the pinion nose of the diff case. When you hit the tires the tailhousing tries to move upwards the just like the pinion climbing the ring gear. As stout as that c-beam looks, when you're capable of REALLY hitting the tires it will MOVE. You ought to see the buckles in the one out of my car from 5500 rpm stick launches!!! If there's any slack whatsover, that exacerbates the problem and with the diff nose in a bind, it BREAKS! The secret to racing a SERIOUS C4 with the IAS, I'm totally convinced hinges on two things:
1) An automatic transmission, even one with a huge stall and a t-brake doesn't shock as hard as a manual.
2) A REAL transmission crossmember to take the load off of the diff.

Now, that may have seemed like it got off subject, but my feeling is with a Turbo 400 the best way to use it in a C4 is by fabbing a real tranny crossmember and that involves cutting the floors right in front of your seats...Just a slot, but still the floor is cut with a nice 1.5" piece of chromoly tubing "just" poking up through the floor. It is my opinion that most people that want to can the 700 (or whatever else) and don't want to cut up their cars and aren't deep 9 second cars would be better of with a Turbo 350 due to the better availability of the adaptor and the fact that you can use your stock tailhousing and the stock c-beam.

I've actually built a tubular c-beam to adapt the 400 to the C4 but my prototype doesn't allow easy removal cuz I'm a dipsh!t and wasn't thinking about in car removal! I've since revised it and solved that problem but I still think with the 400 (and honestly, the 350 if you plan on going in the 9's pretty deeply) should have a crossmember. I'm actually in the midst of triangulating mine even further with the addition OF a torque arm with the crossmember...But instead of being attached to the tailhousing it will attach to the crossmember; that way you have a nice "spine."
-Jeb

Last edited by jburnett; Jul 13, 2006 at 08:19 PM.

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Old Jul 13, 2006 | 09:07 PM
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I run an all out 4l80e in my 93. now this is the way to go. I control everything the trans will do with its computer.
Regards
Old Jul 13, 2006 | 09:26 PM
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i went with a built 700R...i know it's gonna die...

the TH350 solution with spacer seems like easiest option, i like easy...

but jburnett is right...the TH400 is the only way to go for al ALL out drag car. and the only real way to keep the driveline in one piece is to take as much load off of it as possible.

my C-beam is sandwiched (top & bottom) in 1/4" thick steel, and i'll be adding some sort of crossmember eventually when the 700R dies. hell i might as well do it now since the car is in the air. tie it into the frame, and use a traditional trans mount. a diff brace wouldn't be a bad idea as well...but then again i'm just begging for a solid axle as is, and i'd be better served to wait till it goes in before i do any of the above mentioned work. but should by some grace of god the D36 lives, i will be going TH350 with a spacer...or TH400 if the deal is good enough
Old Jul 14, 2006 | 03:30 PM
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Originally Posted by jburnett
Now, that may have seemed like it got off subject, but my feeling is with a Turbo 400 the best way to use it in a C4 is by fabbing a real tranny crossmember and that involves cutting the floors right in front of your seats...Just a slot, but still the floor is cut with a nice 1.5" piece of chromoly tubing "just" poking up through the floor. It is my opinion that most people that want to can the 700 (or whatever else) and don't want to cut up their cars and aren't deep 9 second cars would be better of with a Turbo 350 due to the better availability of the adaptor and the fact that you can use your stock tailhousing and the stock c-beam.

I've actually built a tubular c-beam to adapt the 400 to the C4 but my prototype doesn't allow easy removal cuz I'm a dipsh!t and wasn't thinking about in car removal! I've since revised it and solved that problem but I still think with the 400 (and honestly, the 350 if you plan on going in the 9's pretty deeply) should have a crossmember. I'm actually in the midst of triangulating mine even further with the addition OF a torque arm with the crossmember...But instead of being attached to the tailhousing it will attach to the crossmember; that way you have a nice "spine."
-Jeb
Thats more along the lines of what I was think`n



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