Everyone has always told me to go TH400, they never really gave me any reasons other than "It's stronger". But the deciding factor today was when they explained how much wider the clutch's are! I don't know how much more surface area there is, but I'm now convinced and I'm going to stick a TH400 in before race season. I've got a few questions: Will my TH350 converter work? Will my factory Nova coloumn shift linkage need changed? I've already got a custom driveline and I'm hoping I can just change the front yoke!? Is the TH400 any bigger/ longer? Will I need a different cross member? Thanks!
TH350 to TH400
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I went from Powerglide to T-350 then onto the T-400 thats in my car now. I put in an aftermarket shifter so cant answer that. But yes the crossmember is different and yes its slightly bigger( everything is tighter) and it required me to trim my driveshaft a tad and install the T-400 yoke on the Driveshaft. Yes the stall will interchange. Remember that while the T-400 is stronger it comes at a price in that its heavier and requires more parasitic horsepower to operate.
Shawn
Shawn
I've heard many times that a TH400 will rob more power, but I figure if I can't get the clutches to not slip in a TH350, I might actually gain HP w/ the TH400. I'm in the middle of installing a nitrous kit, and I wanna know that the trani. will take it. I remember someone on TC raced w/ a TH350, than stuck a TH400 in and didnt have any noticeable ET change.
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your shift linkage should work fine. As Shawn said your converter will still work. I know with chevelles, you can just slide the cross member back but I think Novas and Camaros use a TH400 cross member but you can try sliding it back and see what happens. If you have the 6" tailshaft now, you`ll probably have to shorten your drivershaft. I remember a buddy who had a 67 camaro told me that if you move the small block mounts forward to the big block mounts you could add the TH400 with the stock driveshaft. since the camaro and nova share the same front chassis I`m guessing it would work on a nova too.
Theres even a possible to shave a amount of metal off from the "clutchcases" and ad some extra clutch/disc combo, even "play" alithle with the distance on the clutch engagements and with a Th700 spragg in the Th350 a good shift kit and a transcoler You´ll bee fine upp in the 500Hp region even with your -72 chevelle..
Ad an extra inline filter from your trans to save your cooler IF you grenades the trans or converter.. You does´nt get debrise in your cooler and its easy to do a fast filter and oil change.. If you dont have get a trans temp gauge..
Allways keep your trans temp as equal as possible on every run cutting the race variables to a minimum...
Ad an extra inline filter from your trans to save your cooler IF you grenades the trans or converter.. You does´nt get debrise in your cooler and its easy to do a fast filter and oil change.. If you dont have get a trans temp gauge..
Allways keep your trans temp as equal as possible on every run cutting the race variables to a minimum...
G
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·OK,
What is the weight of the car and the total expected HP/Torque?
I've had good luck with Th350's up to and slightly over 600/lb ft in a 3500 lb car.
They don't need much, hardened sprag race, dual feed the directs, bump the pressure regulator spring up, double up the sun gear bushings, use a wide direct drum bushing (should do that on ANY Th350 build), install 5 direct clutches, tighten the endplay, make sure the pump body surfaces are flat to prevent crossleaks, use Teflon sealing rings, tack weld the outside snap rings on the direct drum/sprag race retainer and sun shell snap ring)
Open up the feed holes but retain all the checkballs, particularly the 2nd feed.
At steady rpm, a Th400 does not use any more power than a Th350. And unless you have a VERY fast revving motor, you will likely never see any difference between the two on an ET slip.
What is the weight of the car and the total expected HP/Torque?
I've had good luck with Th350's up to and slightly over 600/lb ft in a 3500 lb car.
They don't need much, hardened sprag race, dual feed the directs, bump the pressure regulator spring up, double up the sun gear bushings, use a wide direct drum bushing (should do that on ANY Th350 build), install 5 direct clutches, tighten the endplay, make sure the pump body surfaces are flat to prevent crossleaks, use Teflon sealing rings, tack weld the outside snap rings on the direct drum/sprag race retainer and sun shell snap ring)
Open up the feed holes but retain all the checkballs, particularly the 2nd feed.
At steady rpm, a Th400 does not use any more power than a Th350. And unless you have a VERY fast revving motor, you will likely never see any difference between the two on an ET slip.
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You are not going to be able to move the crossmember back on the nova, I tried that and you end up against the body mounts. Plus frame tubing is notched a bit so even if you could move the crossmember back you run out of meat to drill new holes. Plus you need to drill two big access holes for the bolt/nut on the bottom side of the tubing.
Tried a universal mount from TransAdapt and could have worked better if I had the time and tools to the necessary fabrication. But not worth the time and money if you cant do all the work yourself.
I would just get the Th400 crossmember from a 67-69 Camaro and get it over with.
Hope this helps.
Good Luck
Tried a universal mount from TransAdapt and could have worked better if I had the time and tools to the necessary fabrication. But not worth the time and money if you cant do all the work yourself.
I would just get the Th400 crossmember from a 67-69 Camaro and get it over with.
Hope this helps.
Good Luck
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The Turbo 400 is definately stronger but both the 350 and the 400 will still break the sprag if the burnout is done wrong. Neal Chance told a friend to do a water burnout in high gear and eliminate the hit on the sprag, making sure to shift back down into low before leaving the line. Never let it freewheel then hook up with your foot in the gas or you can kiss the sprag goodby. The Turbo 350 was eleven hundreths quicker and about one MPH faster than the Turbo 400 in my son's car behind the 481" and the 540" motors. You will have to do some driveshaft modifications as the Turbo 400 has a larger output shaft. You should also get a good chrome moly driveshaft with 1350 "U" joints for trouble free drag racing. If you wish to run a beefed up Turbo 350 tranny give ATI a call.19Nova72 said:
A crossmember for the TH400 is available from the various restoration houses. Around $60.
You will also need to shorten the driveshaft.
Make sure you don't have a TH400 from a 2wd truck, they used a bolt on yoke, and the standard yoke won't mate with the output shaft in the trans.
I discovered that in my car, after I had everything but the driveshat bolted in. I had to have the yoke modified by removing some of the splines in order to get it to work.
Ron
You will also need to shorten the driveshaft.
Make sure you don't have a TH400 from a 2wd truck, they used a bolt on yoke, and the standard yoke won't mate with the output shaft in the trans.
I discovered that in my car, after I had everything but the driveshat bolted in. I had to have the yoke modified by removing some of the splines in order to get it to work.
Ron
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Not if the burnout is done wrong. My son broke four of them. Two 350s (One stock and one beefed up) and two beefed up 400s. Came out of the burnout with his foot in the gas and let it chirp. He finally got tired of repairing and replacing the tranny and started to listen.bowtie455 said:
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The second gear burnout is where the most danger exists. If it ever grabs and you still have it under power you have a very good chance of breaking the sprag. I know one young man who likes to do dumb stuff that broke one going around a corner in his truck. Showing off and spinning the tires. It suddenly hooked up and took out the sprag.Bob West said:
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i don't know if this is rumor or truth but i have always heard that it takes 2 revs of engine to make one rev. in a t-400 tranny while it only takes 1.5 revs of the engine to make one rev. in a t-350. . . please correct if i am wrong. I have a t-350 with a shift kit in my 71 chevelle and it does fine behind a slightly built 305 SB
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