Bruno drive brake still won't hold

I've been fighting the brake in my bruno behind a blown promod. It failed at 4100rpm on a air throttle. After tearing the unit apart and finding no issues we raised the C02 pressure to 250 and put it on a 2 step at 3500rpm. It held good for one pass and then got flakey so we dropped the rpm to 2500.It held in the pits but pushed through at the starting line.
I know there are some mods for the fluid system in these but never really hear of many problems with the brake. We will put a line lock on it if we have to.
Any ideas? Thanks Mike

 

Bruno Brake

Line lock is fine, but you are not fixing the problem. Find out what is causing it.
How else will you learn. Good luck

 

good luck with the linelock idea ,thats up to you but... I have heard of a lot of guys doing that and knocking off a break rotor!

 

Mike, Has the drum been turned down if so that could be your problem, Also check the band to see if it is adjusted or if it is burnt, Hope this helps ,
Jerry

 

bruno

i would think twice about adding a line lock. i have seen the disaster with the bruno releasing quicker than the line lock resulting in a broken brake rotor - not pretty. find and fix the true problem - the band aid of a tranny brake has a down side with brakeage. check the adjustment of the tranny brake cylinder - it screws in and out externally - i have used this small adjustment to refine the holding power. i have recently heard of synthetic oil being too slick causing not enough friction on the clutches to hold the tranny brake. andy b.

 

bruno

To make matters worse the problem is intermittent. I took all the air piston and solenoids apart and found nothing wrong.We fired the car and hit the brake 3 times at 3500rpm on the 2 step. It was rock solid. I even tried to push the car and it would barely rock.

 

Ive heard some guys say they change the band twice a year cause they stretch.

 

we have run this same combo like your running for years never really any troubles that weren't self inflicted. was this a new or used unit? some of the first units would not hold as well but you can update them, its just different sizes cylinder , the only other thing could be the drum as with any type of band and drum you may not be able to just take a quick look at it and see that its bad look for it to be smooth and that the band hasn't wore any grooves in it. we had to replace a drum after 5 seasons, yes we replace the band twice a year just because there cheep and we don't want to take a chance of a problem over 30 min and $25. Bruno is not a people person but call him and I am sure he can help you
my 2 cents you cant turn the drum and it work properly , its to hard,
the fluid has nothing to do with it holding , the other thing would be how tight is your converter?

 

Just a thought guys. When I first used my Bruno , it was intermitant , it turned out to be the transbrake button couldnt handle the ampage of both solenoids , so we added a relay. Problem solved

 

bruno

We inspected the drum and band closely. The drum still has the factory machined finish on it. The car creeps slowly. So slow that it won't redlight if the tree is quick. It moves the same speed with a lot of rpm or a little so I don't think it's a solenoid. We've checked numerous times for co2 leaks in the pits with the car shutoff.

 

bruno slip

Did you ever solve the problem?

 

brt

Not fixed, we lost another round because of it. Put a line lock on the front brakes and a 9qt oil pan for ADRL Topeka this weekend.

 

Pardon me, but wouldn't it be wiser to fix the problem before going to another race? If the transbrake should release before the line lock?!?!?!

 

brt

I've been completely through this slushbox 3 times and can't find a thing wrong. Not a scratch on the drum or band and btw they don't stretch. The apply piston has huge travel so it self adjusts.
The bruno setup will not keep the car from rolling due to the sprags in the lenco.After watching a bunch of video we think the car is rolling fwd when the handbrake is released.The problem has been intermittent and its done it at 2100rpm to 4100.
When I ran a clutch car I used to put a little brake pressure on it and use the line loc to hold it. I thought it was commonplace.
I'm sure I launched before with front the brakes locked and it was no big deal.
We're going to hit it hard in the driveway with the lineloc and without and hopefully duplicate the problem. The BRT is simple and rugged but this has been painful.

Thanks for the ideas,
Mike

 

i dont see how a line lock on the front is going to give you any problems as most cars frontend is hanging the 1st second or so anyway so as long as the line lock would release within that time but i've never had a line lock take that long to release. we just bought a car with a lencodrive and he has linelocks on front and rear and has over 200passes like that with no problems and i'm told most turbo cars put linelocks on both front and rear. not saying a problem couldnt happen, but alot of guys are doing it...keep us updated please!!!

 

fixed BRT

Tested at shop at 4500 rpm and 4 hits at topeka at 4000. Holds solid and the worst light was .024.
Big Wolfe oil pan kept temps below 200 deg also.

 

What was the problem ? Iam interested as I use a Bruno too.

 

It needed a line lock on the front and more oil/deeper pan for our cooling program. We just put a blower on the unit between rounds.