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Old 08-12-2009, 08:23 AM   #1
S/G 386N
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Default 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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Old 08-12-2009, 08:48 AM   #2
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Default 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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Old 08-12-2009, 04:48 PM   #3
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Default Re: Another transbrake thread, & tires

my question, how to shim the solenoid, between the trans case and solenoid or the plunger itself ? and how much shim? use washers, or is there a shim for this purpose?
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Old 08-13-2009, 05:02 AM   #4
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Default Re: Another transbrake thread, & tires

mine had 2 shims (washers), but brake wouldn't hold @ high rpm, unscrew solenoid and place shim or shims and screw back in.
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Old 08-13-2009, 08:55 AM   #5
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Default Re: Another transbrake thread, & tires

Keith, you shim between the solenoid and the case with a washer or washers.
You need to have the pan off and it is much easier to do with the trans on the work bench. Back out the solenoid to see when the reverse piston is engaged into the valve body .010 to .020 with the solenoid in the activated position. Then measure the distance between the case and the base of the solenoid and find a washer that is that distance thick or just a few thousands less and install that washer.
I have found transmissions that needed as much as .150 and some that needed nothing with the average being around .090.
I would guess and that is only a guess that if you needed a shim of .090 you should pick up about .020 of reaction time or maybe just a little more. There are lots of variables on this but it will help the reaction time for sure.
If you shim it out to far the trans brake will not hold or it will shudder the whole car and not hold so be careful if you are not sure what you are doing.
Just My 2 Cents
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Old 08-13-2009, 02:35 PM   #6
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Default Re: Another transbrake thread, & tires

What is there a ECHO around here ?
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Old 08-26-2009, 12:54 PM   #7
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Default Re: Another transbrake thread, & tires

Just an update. Moved the 4 link bars back to Don Davis' factory settings and picked up about .040 on my reaction time. Think I'll just keep them there and bracket race on the throttle stop. Unfortunately, had a lifter collapse and take out the camshaft as well. Looks like I'll be missing US Nationals now.
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Old 01-03-2014, 04:08 PM   #8
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Unhappy Re: Another transbrake thread, & tires

Quote:
Originally Posted by S/G 386N View Post
Just an update. Moved the 4 link bars back to Don Davis' factory settings and picked up about .040 on my reaction time. Think I'll just keep them there and bracket race on the throttle stop. Unfortunately, had a lifter collapse and take out the camshaft as well. Looks like I'll be missing US Nationals now.
I have a Don Davis 57 Corvette,
What are the factory 4 link settings?
I am having trouble on a Four O tree.
Thanks
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Old 09-09-2009, 10:09 PM   #9
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Default Re: Another transbrake thread, & tires

Quote:
Originally Posted by 63corvette View Post
Keith, you shim between the solenoid and the case with a washer or washers.
You need to have the pan off and it is much easier to do with the trans on the work bench. Back out the solenoid to see when the reverse piston is engaged into the valve body .010 to .020 with the solenoid in the activated position. Then measure the distance between the case and the base of the solenoid and find a washer that is that distance thick or just a few thousands less and install that washer.
I have found transmissions that needed as much as .150 and some that needed nothing with the average being around .090.
I would guess and that is only a guess that if you needed a shim of .090 you should pick up about .020 of reaction time or maybe just a little more. There are lots of variables on this but it will help the reaction time for sure.
If you shim it out to far the trans brake will not hold or it will shudder the whole car and not hold so be careful if you are not sure what you are doing.
Just My 2 Cents
63 Corvette

I build my own powerglides and have been using a (cast iron) Trans king pro-brake an I was interested when you describled shimming the solenoid to improve reaction times do you need to disassemble and install only part of the valve body so you can see when the valve uncovers the port that drops reverse?
I'm a little confused.

Bill Baer
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Old 09-17-2009, 01:27 PM   #10
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Default Re: Another transbrake thread, & tires

Quote:
Originally Posted by Bill Baer View Post
63 Corvette

I build my own powerglides and have been using a (cast iron) Trans king pro-brake an I was interested when you describled shimming the solenoid to improve reaction times do you need to disassemble and install only part of the valve body so you can see when the valve uncovers the port that drops reverse?
I'm a little confused.

Bill Baer
Just bumping this thread to see if anyone has any input. I want to do this on an old TCI trans brake, but not sure what I should be looking for. With just the pan off, can you see enough of the piston into the valve body to know how much to shim?

Thanks,
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