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08-11-2009, 08:05 PM | #1 |
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Another transbrake thread, & tires
Trying to pick up my reaction time so I can get a bit more delay in the box to play with. Was thinking about going to a Hipster or Grinder transbrake. Anyone with experience on either one? Any feedback to reliability and consistancy?
Also thinking about going to a 23" front tire compared to the current 24". Wondering how much time this might pick up.
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JJ Nance '06 Don Davis C5 Corvette |
08-12-2009, 05:21 AM | #2 |
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Re: Another transbrake thread, & tires
Had .a alum. Hipster and didn't care for it .
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08-12-2009, 07:05 AM | #3 |
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Re: Another transbrake thread, & tires
I have also heard that the Hipster aluminum ones are not as good, but I have a steel one and with a shimmed soleniod it was worth about .025 over a TCI pro-brake...
Not sure about the tires, but it ought to give you a little... My experiences have shown me that other than the brake all the real gains I ever saw were from working on the suspension, and leave rpm's....getting the chassis to react faster....
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Dave Steltz 135G SG/SP/SST BIAECH Racing Team |
08-12-2009, 07:07 AM | #4 |
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Re: Another transbrake thread, & tires
I would be curious to know which brake is the fastest, and how much RT you picked up with it. I'm running a TCI brake from the mid-1980's, so I imagine there is some room for improvement.
As far as tires, IIRC when I swapped from 25" front tires to 23" (which actually measured around 22.6"), I gained between 0.015 and 0.020 in RT. I've got the 25's back on the car right now for no-electronics bracket racing, but will probably switch back if I can't redlight with them when I run S/G in a few weeks. Regards,
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Michael Pliska 643 S/G |
08-12-2009, 07:58 AM | #5 |
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Re: Another transbrake thread, & tires
JJ, you want to stay away from the aluminum valve bodies in my opinion.
I build race transmissions and that has been my experience. Ten or fifteen years ago I worked with B&M on their development on their alum. valve body for a powerglide. Those just did not work out very well at that time. My personal feeling is that the pistons and valve parts are steel and with the body being alum the growth rates being different the clearances changed as the transmission heated up. That in turn affected the consistantcies and another problem was if the pump pressure ever fell below 150 to 170 at idle when you applied the brake the car would back up a short distance. That issue was a major one as you stage the car. I first thought it was a clearance issue with the band for first gear or the reverse pack but found it was with the body. Just my opinion is that you stay away from the alum bodies. Most of the GM bodies that have been converted to a brake are all done the same. The major difference on all the manufacturers is whether they use a spring on the reverse apply piston in the body. Most all the major manufacturers will work the same if the brake solenoid is shimmed. The torque converter also has an affect on how fast the car leaves and if it matches the cam torque band. JJ, with a Davis car you should be able to go red anywhere. I can with mine which is an 07 model. Good Luck at the races. My 2 Cents Rick |
08-12-2009, 08:23 AM | #6 |
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Re: Another transbrake thread, & tires
Thanks for the responses. I think the problem I'm having is we changed the suspension so I can bracket race the car and run it flat out. Moved the instant center quite a bit forward, and can actually pull a 1.15 60', launching at 3400 rpms, riding the bar the whole time. Have had the car down to 7.99 flat out, which I'm told is not possible in a Davis car. Any higher launch RPM, and it just rides the bar forever. Thinking about taking the suspension back to the way it was, and just bracket race on the throttle stop and see what happens, but would like to explore other options first.
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JJ Nance '06 Don Davis C5 Corvette |
08-12-2009, 08:48 AM | #7 |
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Re: Another transbrake thread, & tires
Have the same problem off the stop....wants to go on the bumper and carries the hoops clear through the 60', best to date was at Immokalee: 1.13 60' & 5.13 @ 136mph in 95* very high humidity and 3500+ air. I don't bracket race much, mainly Quick 32 stuff and just use the stop, don't want to touch my .90 setup, works too good.
I'm using a "BTE" Pro Brake and it's quick, just my .02
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Rick Blake 2395 SG, SC, SP |
08-13-2009, 10:38 PM | #8 | |
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Re: Another transbrake thread, & tires
Quote:
We have ran Hipster modified stock pro valve bodys and their Aluminum Pro ones for some years and on the aluminium ones they have a totally seperate steel screw in pressure control that also has an adjustment for setting the line pressure as you wish, Ray. |
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08-14-2009, 09:53 AM | #9 |
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Re: Another transbrake thread, & tires
Ray, the B&M had the same pressure adjustment you describe. The issue was with the pressure falling off (just a short blip) as you apply the brake. That was a pump pressure/volume issue with the passage size. To make the brake react quickly the volume is reduced in the passages to dump quickly for quick reaction but you have the same issue on the apply side. Applying takes longer that dumping with the port size. You could remedy that issue by going to an after market pump with the larger gear set or using a stock pump/gear set and setting the engine rpm no lower than 1200 to 1400 in low gear as you stage the car. It was just an issue that could bite you at the wrong time as you go rounds and I decided not to build those problems into a transmission I was using or selling a customer.
I build them and I race them so I don't want any possible issue I can get away from. I also do not want a customer with any of those issues either. Everyone has his or her own way to do things and their opinions but for me I stay away from the aluminum bodies from all the manufacturers if at all possible. All the major transmission people still have the cast body model and that is what I always use. Some of the people I build for want a specific brand of brake. I believe most are all about equal so I give the customer the choice of what they want. My 2 Cents |
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