700-r4 swap

Daniel Jost

Squirtin six
Oct 11, 2003
I have a 85 GN with a well built motor on 20PSI of boost. Its backed by a 200-r4 which has gone through 3 input shafts, and am now burning the clutches out of it, and im starting to get sick of these S***y trans. My uncle builds trans for side jobs, and is very good at building 700-r4 trans, he has offered to build one for me and gave me an emty case whitch bolted right up to the motor, but not the cross brace no big deal just mount the brace forward more, i've read all over on this site they are not supposed to but a 2WD 700-r4 trans fits perfectly behind my motor, what is this adapter plate that i read is needed about? I was wondering how 700-r4 setups have worked for anyone else that may have used one is. Any help would be apreciated.


I thought 700-r4 were specific to chevrolet bolt patterns. I was looking to put a 700r4 behind a pontiac 400motor (see sig) and realized I would need an adapter plate which I found at a reasonable price, but never found a core to build. Make sure U have a 700r4 case, I would bet that its not---also consider that 460le or whatever those newer transmissions are called found in the Chevy Pick ups--Ive heard there supposed to be as strong as a 400 turbo. I found a few on ebay for 25 bucks---"Trans adapter plates" no idea how good they are.
the trans fits perfectly, the problem becomes holding it to the motor. The bolt-pattern is different. If its not, then its either a one-off 700 or its not one at all. I would recommend against it anyways, the 700's lower first gear might be amusing at first, but the large skip into 2nd makes it slower than a 200-4r also consider that the 700r4 has a .7 OD whereas the 200-4r has .67 not a huge amount but gas is expensive enough... The work and fab required probably don't make up for the marginable strength upgrade. just my .$02
PS: the 4l60e is an electronicaslly controlled 700r4, the 4l80e is much stronger and is basically a th400 with an overdrive, and electronically controlled. both having chevy bolt paterns.
Something is wrong, How much power are you putting through your 200? There are better input shafts available.
To be correct it is a 4L60E that i was bolting up which is the same as a 700-r4, i'm running just a tad over 20 PSI, and have had multiple problems with my trans, and we have put a 700-r4 behind a built small block 350 we have and it is very durable, and still havent had any problems. Thanks for all the help, any opinions/information is appreciated.

Thanks, Dan
You got the rarest of the rarest then...Like 1 out of 100 million.

There is NO WAY it will bolt up correctly.
I will say it again...NO WAY!!!

Before you run it, and do major damage to something, ck your facts again.
I think I have Some kind of input into this.
And for a little bit of money , you could have a billet input shaft that if you broke with a hot air car, I would pay for.

But I am telling you, NO WAY will a 700r4 bolt up to a 3.8 block correctly.