SSANDTA

iTrader: (1)

I have a reverse manual TH400 with Tbrake behind my Blown and nitrous injected 396. The Trans will not shift into 3 at WOT during a hard pass on the spray. The Trans works fine on a blower only pass but doesn't seem to like the extra 250 foot pounds of TQ the spray adds. Any ideas on what would cause a trans to work flawlessly on mid 9 blower passes but not work on the spray? One thing I thought of was the shifter cable binding with the extra TQ but I have pretty much ruled that out. Thanks

john kilgore

you need a pressure guage to find out what it is. it should be from 160-180. good luck

chris718

i agree with john.a gauge will be the starting point to finding the problem.if the pressure is within range then suspect that the friction elements are not able to control the load being transferred thru them.the direct clutch is very durable in a th400 as far as the direct clutch feed pressure and the multiplication of it when applied to the inner and outer areas of the piston such as with a tbrake set up however i have found most commercial type knockoffs to hurt third apply at high power levels because of the size of the passageways ported into the castings to produce the reversrse pattern brake type valve body. a simple evaluation of most designs immediately yields the fact that many never considered flow rates based on initial oil supply volume first introduced into the circuit and how it reacts with / to orifice size ,passage geometry ,length,width height etc.there are a few of us who payed attention to these principles and polished our apples accordingly,therefore they shine.i would also note that this application with 2 power adders certainly requires a well thought out converter design.if your putting the bottle on in 2nd gear i would also verify that your not driving thru the hydraulic coupling in the converter and you are in third but there is only a slight drop in engine rpm on a ratio change.

SSANDTA

iTrader: (1)

The Trans is an ATI so it has one of their valve bodies I always thought they made good stuff but maybe I'm just shocking in it in ways they haven't seen. I just changed my Converter it was an ATI I did suspect the converter they never could get that damn thing to work well. I replaced it with a very nice Pro Tourque converter that should be happy with alot more power than I make so I don't think thats it. I spray the car off the line and keep it on all the way down the track.

I have made passes where I only spray in third and it does hold it. The trans also holds third fine on the dyno. The problem is on the 2-3 shift at full power.

Thanks!