Loading suspension & launching

[Larry]

I am running a 400 trans with Rosslers Transbrake. I was told by my transmission builder that I need to load the suspension before releasing the transbrake. I understand the theory, but- How do I load the suspension with the foot brake and bring it up and launch with the transbrake at the same time . Im having a time just getting used to the transbrake, let alone working the foot brake also. He warned if I launch without loading the suspension - that I could damage the transmission or the rear end. Thanks for any thoughts on this ... Larry

 

[TurboTR]

Yes if you let go of it with no driveline preload you get an impact load <whack>, which is much more severe than otherwise. This is how at least one of the old "stage right" brake cars would launch around here (lol). Totally unloaded drivetrain; then big boost against the brake and WHACK, let go- Ugh. I doubt it lasted long. The thing to do is bring it up against some load on the footbrake 1st, then engage the brake. Most people spool up at least some prior to getting into the 2nd beam anyway, no? Then "bump" their way into the 2nd beam on some boost, or while it is still coming up before engaging the brake.

TurboTR

 

[BAGN]

Yes if you let go of it with no driveline preload you get an impact load <whack>, which is much more severe than otherwise. This is how at least one of the old "stage right" brake cars would launch around here (lol). Totally unloaded drivetrain; then big boost against the brake and WHACK, let go- Ugh. I doubt it lasted long. The thing to do is bring it up against some load on the footbrake 1st, then engage the brake. Most people spool up at least some prior to getting into the 2nd beam anyway, no? Then "bump" their way into the 2nd beam on some boost, or while it is still coming up before engaging the brake.

TurboTR

I agree. Bring the car up into some boost in the pre-stage light. Then bump in until the stage light comes on, Then press the trans brake button. That will stage the car with the suspension pre-loaded. Then let go and hang on Have fun & good luck.

 

[turbodave231]

I have been doing this for a long time. I have my linelock and the T-brake wired to the transbrake button. I can stage the car and "bump" into the second beam by brake torquing against the footbrake. I engage the T-brake (and linelock) before I let off the footbrake. Suspension stays loaded.

This configuration needs a diode between the linelock and the T-brake so that you don't engage the T-brake solenoid when you use the linelock button on the burnout.

This same arrangement can be used with the Stageright T-brake, but you need a microswitch on the Shifter that engages only when the shifter is in 1st gear (no need for a diode).

DR

 

[TurboTR]

Hmm good points, thanks!

TurboTR

 

[slamming 6]

The only way that will work is if you have the linelock hooked to the back brake's dave.As soon as you let your foot off the brake the suspension will unload.You dont need any preload on the suspension. The hydraulic process of the converter takes most of the hit.When the tranny brake is engaged the tranny is in first&reverse from the drive shaft back has no load on it at all.Hope this helps, BTW both my nova and firebird have a tranny brake on them and have not had any problem's to date with eighter the transmission's or rearend's.Take Care,AL.

 

[Larry]

Now its getting complicated I can see how the trans would be loaded, but not the rear suspension as Slamming explained. Then TurboDaves process sounds logical - but Im taking this out tommarrow ( I have had limited time this summer) and I do not have time to work that sys into my car.
SO- If I get this correct- I can power brake it "just enough" to load the car- bump it in to the 2nd bulb and then hit the transbrake? That sounds good, but- It seems I would need to hold the foot brake and release that at the same time I release the button? That sounds like a "timing" issue that will take some practice. Am I correct on that? Thanks guys - interesting suff. I will say- before putting in the transbrake - watching cars lauch using a brake looked very simple from the Grand Stands - Im finding very quickly - it takes some seat time to get it all cordinated. Its alot more fun though. Larry

 

[turbodave231]

Al,

My linelock, when engaged, holds pressure on the front brake and releases the rear wheels to spin.

I'm braketorquing to start building boost as I bump the car into the lights. This loads the entire car slightly (rear tires are pushing the car forward). Engaging the T-brake and line lock at the same time locks front brakes and then holds trans output. Both the t-brake and front brakes hold the car in a slightly preloaded position.

I've been running my T-brakes for years this way and haven't had a major problem with parts durability. My 60' times might suffer a little because the suspension is not completely at rest when I release the brake, but 1.47's ain't all bad.

Dave

 

[turbodave231]

Have you ever watched someone braketorque into the beams building boost, Hit the T-brake button and then car relaxes and rolls forward slightly after the brake is engaged? Locking the front brakes at the same time as the T-brake avoids this unloading (and deeper stage position).

That's what I was trying to say in the post above.

 

[JCotton]

Like putting combos together, we all have our own way of launching...... I guess I might add mine, it just recently changed, after Salem, BPG event. Up to that point, it was simple, when not running the pro tree, with a competitor in the other lane, I roll into the second beam, depress the button, then step on the gas, when the tree comes down, let the button go and hang on.......... of course, with a sportsman tree, boost can get a little out of hand with that much time, resulting in launches that require a parachute for a soft landing...
For a pro tree, I will now engage the trans brake on the first bulb, bring up the RPM to about 3500, bump the trans button and hit the second lite, once again, matting the gas pedal and releasing the button when the tree lites up. Of course hanging on for dear life after that.
As for loading the suspension, haven't seen that since I was foot braking a 200r4 and using air bags.

Good luck Larry, give me a call and let me know what up.

 

[slamming 6]

Jack please dont use the tranny brake to bump into the beams that will lead to alot of unnecessary heat in the transmission.Not to mention inconsistensy in reaction time & 60' times.Dave I dont think you will ever have the problem of your car rolling foward as your stuff is to nice.most of if not all of the time the car moves their is too much slop in the driveline.Hope everyone A Safe BlastOff.Take Care.AL