HOME FORUM RULES SPONSORS CONTACT
     
   
   
Go Back   CLASS RACER FORUM > Class Racer Forums > .90 Heads Up Class Racing Tech

Reply
 
Thread Tools Display Modes
Old 09-15-2020, 12:57 PM   #1
J518
Junior Member
 
Join Date: Feb 2015
Posts: 14
Likes: 0
Liked 0 Times in 0 Posts
Default Transbrake or Electrical issue?

Hey Guys looking for some guidance here...
The issue I am having is my transbrake will not hold when I bring the rpms up to the two step. Not all the time but of course the last two divisionals in second round it decides not to. I run super street with a powerglide and sbc setup. When I stage the car I set the transbrake and let my foot off the actual brakes, car holds fine then, when I mash the gas its like I never had the transbrake on. It has tried to engage before about 3ft out and sent me into the steering wheel before I was able to release the button.
I had the same issue at the end of last year when running at Great Bend so over the winter I put a total different transmission in. Happen at topeka this year so I thought my steering wheel button was the issue, on my third button this year with same result. I've checked every wire connection I could think of. Also another side note is I run top and bottom bulb races in between divisionals with no issues. Put 24 passes on at Onawa two weeks ago without an issue. Last week at Earlville, 2 out of 4 passes it happened. I put a camera inside the car to make sure I wasn't flinching of some sort and its clear I am not.

Leads me to think of 3 scenarios:
1. My delay box has an issue(Elite 500) when I only run around .030 of delay in it but I would think it wouldn't hold the car in the first place then??
2. Voltage issue -The only difference in the car from when I run top/mod vs SST is the added electric throttle stop. I run a 40 amp alternator but is the added load of the throttle stop putting me where there is not enough juice to hold the transbrake but if it holds at idle shouldn't it hold at higher rpms? or is fluid pressure higher and overcoming it.
3.Grounding issues- This wouldn't explain why it only happens in SST form but the car is Chrom Moly, is there a rule of thumb when grounding to chrom moly chassis?
Sorry for the long post but pulling my hair out on this one...
J518 is offline   Reply With Quote
Old 09-15-2020, 11:24 PM   #2
voltdr
Senior Member
 
Join Date: Jan 2008
Location: Texas
Posts: 648
Likes: 60
Liked 47 Times in 25 Posts
Default Re: Transbrake or Electrical issue?

Not sure of a lot of details about your car. Motor plate? Is it powder coated? Do you run a separate ground wire from the battery to the engine block? Do you just ground the battery to the frame? Do you ground the TB to the transmission?

Good rules to follow when wiring a race car.

1. Chrome moly does not make a good ground.
2. NEVER ground the TB to the transmission.
3. There is a lot of vibration on wire connections in a race car.
4. Use “star” type lock washers on all ground connections.
5. Poor grounding connections are the most common and the most difficult problem to diagnose.
Dan
__________________
Dan Foley
SC 4698
voltdr is offline   Reply With Quote
Liked
Old 09-16-2020, 06:55 AM   #3
J518
Junior Member
 
Join Date: Feb 2015
Posts: 14
Likes: 0
Liked 0 Times in 0 Posts
Default Re: Transbrake or Electrical issue?

Quote:
Originally Posted by voltdr View Post
Not sure of a lot of details about your car. Motor plate? Is it powder coated? Do you run a separate ground wire from the battery to the engine block? Do you just ground the battery to the frame? Do you ground the TB to the transmission?

Good rules to follow when wiring a race car.

1. Chrome moly does not make a good ground.
2. NEVER ground the TB to the transmission.
3. There is a lot of vibration on wire connections in a race car.
4. Use “star” type lock washers on all ground connections.
5. Poor grounding connections are the most common and the most difficult problem to diagnose.
Dan
Dan,
We run a front and mid plate. The batteries are grounded to the main 2x3 frame rails which now that I think of it are actually mild steel and all round tubing are chromoly. At the mid-plate which is also mounted to the main rails I run an 8 Guage ground wire to a distribution block inside the car. From there I run indivisual grounds to the transbrake and tb button. Delay box is npn, if you are wondering about the ground to the tb button.

Is my theory of not enough voltage for the transbrake and that when I apply gas the higher fluid pressures over come the transbrake out of the question? Not much of a transmission guy....
J518 is offline   Reply With Quote
Old 09-16-2020, 11:24 AM   #4
Lenny5160
Senior Member
 
Lenny5160's Avatar
 
Join Date: Nov 2015
Location: Inver Grove Heights, MN
Posts: 688
Likes: 328
Liked 211 Times in 119 Posts
Default Re: Transbrake or Electrical issue?

I had a friend with a very similar issue years ago, and it was the transbrake ground having intermittent contact when the car started shaking on the chip.
__________________
Tony Leonard
S/ST 5160
S/C 5160
Lenny5160 is offline   Reply With Quote
Old 09-16-2020, 12:11 PM   #5
James Sessoms
Junior Member
 
Join Date: Oct 2010
Location: Suffolk, VA
Posts: 14
Likes: 0
Liked 0 Times in 0 Posts
Default Re: Transbrake or Electrical issue?

I had a similar problem with a mega 450. The problem was the driver in the delay box. I called and talked to Digital Delay. When I described the problem they said to send it to them. The driver was fixed at no charge and sent back to me.
__________________
James Sessoms 2444 S/G
James Sessoms is offline   Reply With Quote
Old 09-16-2020, 07:47 PM   #6
sgasman
Junior Member
 
Join Date: Jun 2014
Posts: 18
Likes: 2
Liked 7 Times in 3 Posts
Default Re: Transbrake or Electrical issue?

Do you switch from Full tree to Pro tree?
sgasman is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -5. The time now is 02:54 PM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2020, vBulletin Solutions Inc.
Copyright © Class Racer.com. All Rights Reserved. Designated trademarks and brands are the property of their respective owners.Ad Management plugin by RedTyger