Situation: Transbrake (new) does not hold above 3500rpms. The overhauled and upgraded C4 transmission has less than 100 miles on it and only a few T-brake launches. I want to launch at WOT but had to put a 3k pill in my 2-step to keep the car from launching with the button held down. The bands were tightened 1 turn (each) to no avail. The VB is the <edit: uncertain> How many turns do you back off the adjustment screw on the bands? Would being low on tranny fluid cause this? Any other hints as to why it's not holding? Thanks.
C4, right? when you say not holding...which way is it going? Backing up or driving forward? The way you describe it, it almost sounds like the direct clutch is slipping a little. That'll usually let them drive forward a little under power. Of course, there is also low fluid level, bad solenoid (usually bad solenoids just work intermittently...but occasionally they'll stick a little)...TB valve sticking in it's bore, filter issues, and of course clutch packs. All that doesn't count a possible valve body leak.
C4 It's moving forward. I'd been puzzled by my inconsistant 60 foots last weekend. My 1st pass was a 1.5x 60 foot. Subsequent ones were 1.8 and 1.9. I thought, at the time, that the tires were spinning but now I'm not so sure. All the launches felt great. The last two certainly didn't feel like 1.8 or 1.9 launches. Since I wasn't concerned about cutting a good light, only to Test and Tune (1st 'real' time out in the car), I'd let the tree go greeen, push the button, put my foot to the floor and then release the brake. I now suspect that as I'm holding the brake, my car is inched forward and my tires broke the beams THEN I let go of the button. That would explain the SLOW 60's and 7.4x runs (it should run at least a 7.0 I think). I'll add some fluid 1st to see if that takes care of the problem. I 'really' hate to have to pull the tranny. Thanks for the advice.
Friend of mine had the same problem....started like yours at first, then kept creeping forward at lower and lower RPM....after a tranny rebuild, still did it. Replace the $20 button and problem was solved.
Certainly checking the button voltage is one idea. My PA unit wouldn't hold either unless it had a full 12 volts. Also, did you set this transmission up or did someone else do so? Band adjustment from TCI's instructions state...... Also, low fluid level will do this. A Kevlar band will also not hold well until it's "seasoned". You might also call TCI and ask them.
Good info. Thanks. I'll check the fluid, torque the adjusting screw, make sure I have 12V and give her another go. edit: the builder set up the tranny bands adjustments.
what did tci say? if fluid not an issue, sounds like a valve body problem. maybe button, but the rpm relationship sounds like you nrrd some pressure/are bleeding pressure where you shouldnt.
Rick, it couldn't be a voltage problem...your car NEVER has electrical issues Hope you figure it out and it is something simple and CHEAP
Local racing tranny mechanic with excellent reputation. I haven't spoken to them yet. I want to check the fluid level, adjust the bands, and check the voltage before calling them. Scott, wanna trade alternators?
Did you ever figure out if that jumper was a problem, or hooked to the wrong terminal? I left mine alone since I am charging and you had to jump yours at the dyno, so I figure even if I am charging at 12.5-13v, at least I am not killing the battery. New alternator was only $50 or so...
I haven't touched the car since I got it back from running at HMP. Been busy at work and 'tarred' when I get home. I'll check it again this weekend.
