Braking options to build boost

slow94

Active member
Some may know my truck is turbo and obviously foot braked. Now I just got a new A1 trans with 3500 stall so I'm good there but I do want to discuss break pressure while staging to help load converter harder to build boost on the 2 step. 2 options I'm thinking about are either switch to hydro boost which will probably cost over $1000 but be permanent and full time. The other thing is to install a electric vacuum pump on a switch and only use when at the drag strip. Was thinking the pumps made by Hella which are basically the same pump in some volvos and perhaps Porsche's. It can pull near 30 inches in some applications. Any of you turbo guys do anything to the brakes to be able to leave harder on boost only? I am not scared in any way to spray it out the hole but just want the option to not to if I can leave hard enough on boost.

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Raymond_B

Administrator
I Support the NLOC
Are you pushing through the brakes? Just trying to understand what hydroboost will fix
 

bobwhite

Member
i think the OEM power brake booster has a regulating feature built into it to limit the maximum vacuum it will hold to 12 inHg. i'm going by memory which is sometimes sketchy. i believe i can remember reading this in an old manual when i was diagnosing my booster with a hand-operated vacuum pump and 12 inHg is as high as they are designed to hold. my vacuum test with the hand-operated pump verified it. however, you would need to verify that my memory is correct. i realize this is sketchy info, but maybe it will help somehow
 

slow94

Active member
Are you pushing through the brakes? Just trying to understand what hydroboost will fix
Well I am when in my driveway. Now track is obviously stickier but I would like to get all the way up on converter without worrying about rolling through the beams

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slow94

Active member
i think the OEM power brake booster has a regulating feature built into it to limit the maximum vacuum it will hold to 12 inHg. i'm going by memory which is sometimes sketchy. i believe i can remember reading this in an old manual when i was diagnosing my booster with a hand-operated vacuum pump and 12 inHg is as high as they are designed to hold. my vacuum test with the hand-operated pump verified it. however, you would need to verify that my memory is correct. i realize this is sketchy info, but maybe it will help somehow
If that's the case then hydroboost may be only option.

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Raymond_B

Administrator
I Support the NLOC
Well I am when in my driveway. Now track is obviously stickier but I would like to get all the way up on converter without worrying about rolling through the beams

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I know I could easily stall mine up to 3K maybe higher I’ll check my datalogs. we’ll see with the new TCE front brakes if it goes higher.
 

oilwell1415

Active member
You could install a separate brake on the driveshaft. T into the rear brakes and install a linelock on the driveshaft brake. This would also stop the suspension from getting a bunch of preload in it at the line.
 

slow94

Active member
What about rear disc brakes with double calipers?
Well I just put new drums and shoes on. I also run 15" race wheels and want everything to fit. Plus from what I understand drum brakes have higher cold holding capacity than discs. Maybe not dual calipers though.

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slow94

Active member
I know I could easily stall mine up to 3K maybe higher I’ll check my datalogs. we’ll see with the new TCE front brakes if it goes higher.
I can get to 3k as well but I would like to get to 3500 on stock motor. Got a motor being built that I'm sure will get to 3500+ but that won't be for quite some time. Trying to get into the 1.4x 60' on boost if possible.

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slow94

Active member
You could install a separate brake on the driveshaft. T into the rear brakes and install a linelock on the driveshaft brake. This would also stop the suspension from getting a bunch of preload in it at the line.
This may be a good idea. I have heard of shaft brakes before.

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lightn95

Active member
Your only going to hold as much as your front tires can if your trying to push with the rears....the drive shaft brake is as close to a t brake as you'll get, but I'd imagine it's going to be hell on the trans....
 

slow94

Active member
Your only going to hold as much as your front tires can if your trying to push with the rears....the drive shaft brake is as close to a t brake as you'll get, but I'd imagine it's going to be hell on the trans....
Well the trans is the best I can buy. Stage 3 A1 with his new converter. Would hope it would hold up. Shouldn't be any worse than people with trans brakes I'm assuming. Really want a fool proof method of getting all the way up on the stall quickly with foot braking so I can build boost. Thinking I need to leave on close to 10lbs to get it to leave hard. My first thought was to maybe tie a rear line lock and an extra vacuum pump for the booster to my momentary switch I use for the 2 step. That way it's only engaged when I'm staged.

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oilwell1415

Active member
Well the trans is the best I can buy. Stage 3 A1 with his new converter. Would hope it would hold up. Shouldn't be any worse than people with trans brakes I'm assuming. Really want a fool proof method of getting all the way up on the stall quickly with foot braking so I can build boost. Thinking I need to leave on close to 10lbs to get it to leave hard. My first thought was to maybe tie a rear line lock and an extra vacuum pump for the booster to my momentary switch I use for the 2 step. That way it's only engaged when I'm staged.

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If you use a line lock on the brakes the vacuum you've got available shouldn't matter. A line lock holds the hydraulic pressure in the brake lines, so once that pressure is there it won't go away with the vacuum. Maybe just get the brakes set with the line lock and then spool it up?
 

slow94

Active member
If you use a line lock on the brakes the vacuum you've got available shouldn't matter. A line lock holds the hydraulic pressure in the brake lines, so once that pressure is there it won't go away with the vacuum. Maybe just get the brakes set with the line lock and then spool it up?
You are right. My only thought was a vacuum pump would increase pressure initially until line lock holds it. However that may be overthinking it.

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lightn95

Active member
If you use a line lock on the brakes the vacuum you've got available shouldn't matter. A line lock holds the hydraulic pressure in the brake lines, so once that pressure is there it won't go away with the vacuum. Maybe just get the brakes set with the line lock and then spool it up?

The front tires are only going to hold so much until the rears turn the skinnys into ski's and they slide through the beams. Did you try it with a wider tire to get a bigger contact patch?
 

Briansshop

Missing My Lightning!
How about holding the trans in 3rd gear while staging? Allows the brakes to easily hold without the torque X of first gear.
 

slow94

Active member
How about holding the trans in 3rd gear while staging? Allows the brakes to easily hold without the torque X of first gear.
Well I did think about trying 2nd gear but not sure how the logistics of that would work after the launch. Especially with how sloppy my shifter already is.

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oilwell1415

Active member
The front tires are only going to hold so much until the rears turn the skinnys into ski's and they slide through the beams. Did you try it with a wider tire to get a bigger contact patch?

If the rear tires aren't turning they won't push the fronts through the beams.
 
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