MeanWS6

Since a footbraked th400 does not launch nearly as hard as the 4L60e (learning stuff every day), I was all ready to pull the trigger on a TH400 with t-brake but how hard is it on the car? Will the rear end (moser) be able to handle it? Is it hard on the motor in anyway? How high of an RPM do you t-brake at?

DERTY

I sprayed 300 on my 382 with a Moser 12 bolt and 30 splines. It held up just fine. I wouldn't worry about it at all. It's not that hard on the motor either. Just make sure you have a good cooler for the trans.

97ssmokem

I have TH400 with a trans brake and you can not drive the car for more than a few miles because you get rid of the modulator and the fluid runs like it was at WOT. If you were to drive on it would start popping seals. Also, the heat created with a brake is incredible. My tranny normally runs around 160 after launching on the brake the temperature is around 220 and that’s with an inline cooler only. Change the fluid regularly.

I also run straight slicks on a Moser 33 spline 12 bolt with a custom steel drive shaft with dana splicer yokes. The tranny, driveshaft and rearend can handle up to 1200 HP.


Last time I launched it pulled the front wheels about a 1' in the air.

theblur98ss

iTrader: (71)

I drive my t400 with a brake on the street. It's not a daily driver but it goes on trips here and there. I did have to go down to a 3.50 gear to make it livable. Tranny runs about 180* and seems to be holding up fine.

97ssmokem

What brake are running? The guy who built my tranny told me that I couldn't drive the car for more than a few miles. This is fine because it was a trailor queen before. You haven't had any problems blowing seals? What would be the furthest you have driven with the brake installed?

Thanks

MeanWS6

So with a t-brake you cant drive it on the street, only for track use???

I thought you could set the t-brake at the track, tach up, and let her rip . . .
So how does it work then?

DERTY

Guys, that's a rediculous load of crap. I drive mine on the street with the brake. Even put 300 miles on it in a day just fine. It doesn't cause any issues. If I would have blown a seal it would have been a long time ago. If your builder doesn't have any confidence in them, then that's a different issue. Rossler knew I would drive it on the street and never mentioned anything about the transbrake and seals being an issue. Sure, you might get a small drop of oil on it every now and then. But that's normal even if you just trailer queen it to the track.

97ssmokem

Wow, I didn't mean to ruffle any feathers. What I know is what the tranny builder told me, he is a great tranny builder and knows his stuff. I have been told by other performance shops that since you get rid of the modulator valve that the tranny will not last if you run it on the street for a long period of time. If this is not true and you have been doing this for a long time now with no problems then either you have been lucky or I have been miss informed by many knowledgeable people. I am not trying to be rude but this is what has been told to me. Good luck with the tranny.

Colonel

I never had any trouble driving my transbraked TH-350 on the street. I've never had a braked TH-400 though.

Back to the original question...

I would tend to think that the brake is somewhat like dropping the clutch at high RPMs with a manual, as far as all of the drivetrain behind the tranny is concerned. However, the engine doesn't care. The tranny doesn't really care much but you do need to keep it cool no matter what it takes to do it. I recommend a pillar mounted temp gage.

97ssmokem

The transbrake replaces the modulator valve, at least that is how mine is, the modulator valve controls the fluid pressure in the tranny via vacuum. You remove this and put in a transbrake the pressure runs through the tranny as if you were at wide open throttle. This causes great stress on the seals and will cause them to leak. If you have a different way of setting it up please let me know so I can change mine so I can drive it more than 5 miles, anymore than that and the temp goes up to about 210. Granted I only have one inline cooler and 6an lines running from the tranny to cooler, from the cooler to the external filter and back to the tranny.

MeanWS6

cool - and I thought I was making "progress" in learning about the TH400 swap until I read his post)
thanks for setting things straight