Spl170s

iTrader: (8)

I am getting ready to have a TH400 built for my 98 Trans Am. I am curious as what the most common upgrades to these tranny are to be considered a "built" tranny though. I guess you coudl say what is the most common failure part on one of these?

After clutches.......what would you have done to one of these to make it more "better"

Spl170s

iTrader: (8)

Hello?

TTT

James B.

iTrader: (1)

My experience is with the 4L80E, but some of the same tricks work...

Replace the intermediate sprag with a 34-element HD sprag. I believe th stock piece has only 16. Use a kevlar front band. Install a TransGo shift kit and bolt on a finned aluminum pan. Somebody makes a kit that converts the thrust washers on theoutput shaft to torrington bearings. The thrust washer in that location wears out faster than the other parts do.

I haven't seen a Transgo kit for a TH400. If it doesn't come with a new Boost valve get one separately from Sonnax.

TH400 doesn't need the myriad of hard parts that a 4L60E needs to be strong - it already is.

Spl170s

iTrader: (8)

That is what my tranny guy is telling me. That it is already a strong tranny and should handle what i want to put at it..... But, to me it sounds like just rebuilding and putting in the reverse manual valve body i want jsut isn't enough to do. I know he has his tricks he does as well to make it shift harder and what not...similar to a shift kit. he does not like to use trans go and says he can do all the same without buying the kit to do it.

He did mention the upgradable 34 sprag.....how much $$ do these usually run?

I plan on having 550 rwhp and 550-600 rwtq in the near future...and just want to be sure this next tranny adventure i am looking at will handle what i want to throw at it!

James B.

iTrader: (1)

I can't rememebr exactly how much I spent on it, I think it was about $50 locally. Every trans shop carries these.

One thing I forgot is a rear bushing the Sonnax came out with that solves the problem of the rear bushing walking out of the case.

john kilgore

have you given any thought it differant ratios?

Spl170s

iTrader: (8)

What would be the gains of going this? Not being sarcastic.....really would like to know? Would this make the tranny stronger?

john kilgore

if your removing a 4L60 and installing a 400 the ratios in the 60 are 3.06-1.62. the 400 ratios are 2.48-1.48 a natural bog off the line. that is 29% less low gear.

Spl170s

iTrader: (8)

So, it would be really noticable then off the line. So, most people are swapping out the gear then who do this swap? Guess i hadn't heard of people doing this..........

john kilgore

l do.

12secSS

iTrader: (30)

But all you would need is 3.90 gears (I am using 4.33s) to offset the difference.

john kilgore

to make the ratios the same you would need a 5.63 rear end. l'm in sun valley and l would like to talk to you. jk

KRAZY K 2000 TA

iTrader: (5)

i Know u did not mention if u are going for a trans brake or not,if so and it is a good investment i have had very good luck with TCI trans brakes on my firebird and my 70 chevelle"540 big block, merlin heads,brodix intake,1090 cfm king demon,etc" Never had a problem with turbo 400,s strong trans.