TH400 tranny for drag racing?

ben99

ben99

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Jul 22, 2008
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Anybody running one? I know these are a lot cheaper to build than my 47rh, does anybody build them to run behind a cummins? I'm just looking to save some money in my build. And I know the th400 can handle a lot of power if built right the only downfall being lack of an od. But I would think with all the torque of a diesel you could make up for it with a taller tire or higher gears in the reared. Any thoughts or opinions are greatly appreciated!:Cheer:
 
The lack of a lockup converter would be the biggest issue I see. Also I would think it would take a really tall gear unless you race 1/8th mile.
 
A 727TF from 89-91 NON IC Cummins will be cheaper to build because you won't have to buy an adapter plate...
 
True but id rather buy an adapter plate and be able to run a transbrake. If I went that route id wanna get a 518 so I would have overdrive. How much lower do you think times could be with a 47rh vs a th400 or 518?
 
Ryan with the black truck ran one, and went through about 20 different converters, IIRC he was pretty much out of RPM just past the 1/8th with a tall slick. I do not remember what rear ratio he was running.
 
Billysgoat said:
Ryan with the black truck ran one, and went through about 20 different converters, IIRC he was pretty much out of RPM just past the 1/8th with a tall slick. I do not remember what rear ratio he was running.
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It was the glide in the truck I had so much trouble with, any good convertor shop could build a nice unit for the 400. Keep in mind though for anyone serious about going the th400 route; if you wack the bellhousing off to go with a nice sfi aftermarket bell, you will be right back in the same position you;d be in if you had a glide; limited once again to the little 11" convertor. I ran the factory case/bell TH400 in both the truck and Altered, just had to run a tranny blanket around it and a FP shield for legal reasons and safety.

2 speed power glide in a 1st gen? - Competition Diesel.Com - Bringing The BEST Together
 
So if I go with a th400 or a 518 which would be the better choice? Which is more durable, cheaper, ect. The overdrive would be nice but this is going to be a drag truck that is somewhat streetable (my definition of streetable is pretty crazy lol) and I figure being so light I can run a pretty tall rear end to keep my top end speed and not suffer down low.
Anybody have any prices on these trannys, or know about what they cost built to hold about 700hp?
 
J.W.Performance Transmissions

Finally, as of this past month at the PRI show they released the first ever aftermarket TH400 case. It says to will only house up to a GM 12" convertor, thats a shame if thats the case but at least it's another inch more than would fit in the previous bells made for both the 400 and glide. I believe a 'built' 400 would be quite a bit stonger than a built 727 or 518a, lots of good aftermarket support for the 400 since its been used for hard core racing for so many years. Look up Rossler or RTI and read some on what they offer for the 400, also Art Carr. I had all 3 aftermarket shafts in mine, alum. drums, more clutch capacity, straight cut planets, Pro Mod style 36 element sprag, rollerized rear bearing housing, improved pump, full manual VB/Pro Tree Trans Brake, etc.... it's a tough tranny for sure. I ran a really tall ratio Pro Gear and a set of 36" Hossiers but was still gearbound in the 1/4 at 152 mph, it layed over at prob. 1200'; but I built both of my rides to race mostly in the 1/8th. For strickly 1/4 mile racing a even taller gear could be ran for more top end speed though, Chad R. ran a 2.50 ratio, they make so many choices for the 9" however. A 2.50, 2.70, 2.90, 3.00, 3.10, 3.40, 3.50, 3.70 would all be good choices to run with a non O/D 400 depending just on HP available and mph expected; oh and you better have a good efficent convertor to pull a tall final drive, or you will just run right through it.

Ryan
 
Ben, from my quick google research, the TH400 and TF727 are ALMOST equal. The TH400 is harder to rebuild but stupid proof. The 727 is easy to rebuild but if the kick-down (TV) cable isn't adjusted right you can smoke the tranny in short order.

In the world of tranny's, the TF727 is the Duramax. Easily built up but upgrades needed sooner and has 1 less support bearing (2). The TH400 is like the Cummins. Less upgrades needed now but stouter with 3 support bearings. The 727 has less parasitic loss but the TH400 is built a bit more heavily. So which would you have? The Duramax or the Cummins?
 
ben99 said:
So if I go with a th400 or a 518 which would be the better choice? Which is more durable, cheaper, ect. The overdrive would be nice but this is going to be a drag truck that is somewhat streetable (my definition of streetable is pretty crazy lol) and I figure being so light I can run a pretty tall rear end to keep my top end speed and not suffer down low.
Anybody have any prices on these trannys, or know about what they cost built to hold about 700hp?
Click to expand...

It's not the 700 horse you need to be concerned with, its the 1400 ft. lbs of torque which will be more equal to pricing a tranny for a 12/1400 HP gasser. Keep that in mind.

Mine seemed to hold anything I threw at it which was ~900/2k on fuel and maybe 1300/???+ on the hose; which I really never got to use. It held it at the line right off the trans brake the few times I tried though.
 
I guess ill call a couple places and see what they reccomend, do those places you mentioned build converts for a diesel to?
Thanks for your guys help. I've spent too much money on 47re trannys and would like to find a cheaper more durable option.
 
stock600 said:
It was the glide in the truck I had so much trouble with, any good convertor shop could build a nice unit for the 400. Keep in mind though for anyone serious about going the th400 route; if you wack the bellhousing off to go with a nice sfi aftermarket bell, you will be right back in the same position you;d be in if you had a glide; limited once again to the little 11" convertor. I ran the factory case/bell TH400 in both the truck and Altered, just had to run a tranny blanket around it and a FP shield for legal reasons and safety.

2 speed power glide in a 1st gen? - Competition Diesel.Com - Bringing The BEST Together
Click to expand...

Thanks for correcting me, CRS kicking in again LOL
 
My 727 handles c.500 at the wheels and all it has is a shift kit, clutches, and a good converter.
 
is a manual 4l80/85 an option? aren't they sorta the OD version of a th400??? My understanding is that the OD part (sprag rings a bell but please forgive me fumbling through this, I've never dabbled in this stuff) is the WEAK LINK in the 4l80/85 BUT some people are working on making them live and in a light vehicle (a la dmax mustang and grand national) they are living. The mustang is making similar power to what you're stating and never had an OD problem. They also have lockup convertors. Not sure on price to build one with all the best gadgets but a couple years ago when I was looking into it, they were cheaper than building a similar allison which is cheaper than most 47/48 builds from my understanding.
 
JQmile said:
My 727 handles c.500 at the wheels and all it has is a shift kit, clutches, and a good converter.
Click to expand...

And Los Hermonos has great beef tacos. Whats that 500hp minus 2 stages at .125 each leave?

Theres not a ton of diff. in the 727, 518a, 47rh, 47re, 48re...... just gets more complicated due to computer control. If your sticking with a dodge unit it'd prob. be hard to beat a well built 518 with all the trimings...If you've ever built any of them; they all look about the same and most all parts interchange. Thread was about the 400, I dont know of but 3 of us that run it, so not a lot of feedback and info present. Toolman, Chad's roadster, and myself. The later 2 have taken our rides in the 8.20's and 8.30's, and Aarons little truck is knocking on 9's door step, all 3 are light weight race only rigs, but thats all were talking about here anyhow.

Ryan
 
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Im running a th400 in mine. No times yet but in a half ton truck with a full manual vb its a riot to drive.
 
stock600 said:
J.W.Performance Transmissions

Finally, as of this past month at the PRI show they released the first ever aftermarket TH400 case. It says to will only house up to a GM 12" convertor, thats a shame if thats the case but at least it's another inch more than would fit in the previous bells made for both the 400 and glide. I believe a 'built' 400 would be quite a bit stonger than a built 727 or 518a, lots of good aftermarket support for the 400 since its been used for hard core racing for so many years. Look up Rossler or RTI and read some on what they offer for the 400, also Art Carr. I had all 3 aftermarket shafts in mine, alum. drums, more clutch capacity, straight cut planets, Pro Mod style 36 element sprag, rollerized rear bearing housing, improved pump, full manual VB/Pro Tree Trans Brake, etc.... it's a tough tranny for sure. I ran a really tall ratio Pro Gear and a set of 36" Hossiers but was still gearbound in the 1/4 at 152 mph, it layed over at prob. 1200'; but I built both of my rides to race mostly in the 1/8th. For strickly 1/4 mile racing a even taller gear could be ran for more top end speed though, Chad R. ran a 2.50 ratio, they make so many choices for the 9" however. A 2.50, 2.70, 2.90, 3.00, 3.10, 3.40, 3.50, 3.70 would all be good choices to run with a non O/D 400 depending just on HP available and mph expected; oh and you better have a good efficent convertor to pull a tall final drive, or you will just run right through it.

Ryan
Click to expand...

Ryan, did you run a 1" shaft in your 400 too?
 
DIESEL_POWER said:
Ryan, did you run a 1" shaft in your 400 too?
Click to expand...

Not at first, I did break a Vasco and 300M input and twards the end had to go to the big areospace shaft and drum, the shaft had a greenish look to it. I also broke a set of hylical planets but no more failure after going to the straight cuts, I stayed with the 2.41, 1.41, ratio's. What have you decided to run, just curious....
 
If you're thinking of running a non-lockup, rpm and turbo sizing are key. No trying to spool a 80mm single and hoping the trans will stay effective. Also, more rpm = less slip...so spin that sucker!
 
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