TH400 Common Upgrades?
TH400 Common Upgrades? 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"
After clutches.......what would you have done to one of these to make it more "better"
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.
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.
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 $$ do these usually run?
I plan on having 550 rwhp and 550-600 rwtq in the near future...and just want to be sure this next tranny adventure i am looking at will handle what i want to throw at it!
He did mention the upgradable 34 sprag.....how much $$ 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!
Originally Posted by Spl170s
He did mention the upgradable 34 sprag.....how much $$ do these usually run?
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.
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Originally Posted by Spl170s
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"
After clutches.......what would you have done to one of these to make it more "better"
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Originally Posted by Spl170s
What would be the gains of going this? Not being sarcastic.....really would like to know? Would this make the tranny stronger?
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Originally Posted by Spl170s
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..........
Originally Posted by 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.
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Originally Posted by 12secSS
But all you would need is 3.90 gears (I am using 4.33s) to offset the difference.
trans brake? 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. 
