Front hyrdo brake?

Wuero370z

Has anyone ever hooked up a hydro brake to the front wheels?
My goal here is to preload on the launch similar to Cleetus’ Leroy.

Was wondering if it’d be best to run a separate caliper or how people traditionally do it?


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Rusty

Line Lock. 2 solenoids, one on each front brake line. Controlled by a button. Press the brake pedal and hold the button. Release the brake pedal. When you want to go. Release the button. They make kits for this.

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Wuero370z

That was my original plan but then the only control I have is in the rpm and clutch. If I could modulate both the brakes/clutch and rpm at the same time I feel like I could get a better launch than just line locks.

Just playing with the idea. I already have the hurst line locks and a switch, just need some custom lines and I could go that route.


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SeeThruHead

wouldn't you want to use a two step rev limiter, so you'd actually not be modulating rpm?
if your line lock circuit could engage the brake switch when enabled you could use ecutek launch control.
would probably be ideal to be able to bump up and down the launch revs via + - buttons somewhere. not sure if that's possible with ecutek. so you could adapt to different traction situations

I have read of people putting the solenoid onto the rear break lines and then closes the valves when the brake is not pressed.
Causing the break pedal to only actuate the front brakes.

Also read of someone putting in pressure gauge in the dash for brake pressure. so they can see what brake pressure they are locking at. assuming you want to lock it at less than full pressure.

related:

https://www.corvetteforum.com/forums...eo-inside.html
https://youtu.be/Ct7Qel3nNUU?t=436

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Wuero370z

Yep you’re right. I typically launch on the two step but I’ve seen some people launch without it so figured it’d be worth considering/testing.
Ideally, when I launch I want to be as far in the clutch engagement process as possible without the car moving forward. If I was to increase rpm and slip the clutch a bit “extra” whilst applying a bit more handbrake pressure at that very moment that would be more forgiving on my clutch than a line lock launch where I have to set the rpm and brake line pressure

I was thinking of something along the lines of a proportion valve also so they’re not totally locked, I could “bump in” and whatnot.


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SeeThruHead

so from what i can tell cleetus uses a hydraulic handbrake on the rear. his two step is automatically enabled when the ecu detects no wheels speed.

to bump in he's using pressure on the hydro brake and letting the clutch out. he may or may not have a linelock on the front, i kind of doubt it but could be wrong.
you could create a bump button the same way that transbrake cars have if you had the time and inclination.

basically the button would disengage linelock/rear brake for a very short time. you'd have to be slipping the clutch while you press it.

EDIT: I dont actually understand the physics of why you'd want a linelock except to heat up your tires (or for bumping in for staging like cleetus does)
for brakeboosting it makes sense because revving the engine with the clutch in will reduce your roll speed.
for starting from a dig. if you engage linelock you'd have to slip your clutch to "load" the rear wheels while still having enough engine speed to build boost. also i remember from high school physics class that once something is slipping it's coefficient of friction is different. static vs kinetic coefficient. that might also apply to slipping the clutch not sure sure.
in an ideal world i think you'd want to engage the clutch instantly at the perfect rpm for the surface you're on. and never slip the clutch. But I have no practical experience with this stuff just keyboard jockying so could be completely off base

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sirnixalot

You will need to have a dual master cylinder hand brake if you wanted to retain ABS. Something like this
https://www.compbrake.com/product/tw...le-2-cylinder/

I opted for the line lock route myself. Used 2 of the solenoids below with the required fittings and hoses. Think I used 6" from the OEM hardline to the solenoid and then 18" from the solenoid to the caliper
https://www.summitracing.com/parts/sum-760002

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SeeThruHead

I would personally put a hydro in the rear anyway! So many options for it since 370z is such common drift car. Seems to work fine for cleetus and side benefit you can drift your car around for fun. Can do it with dual caliper bracket. A bump button on your line lock would be pretty fancy tho. i think too hard to do for it's purpose tho. since you'd need to relieve and then reapply pressure to the front brakes, vs letting off the hydro a little while slipping your clutch.

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Wuero370z

Did you use a relay? I’ve seen mixed things on if they’re needed for line lock


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Wuero370z

Might give soho a ring and see what they’re doing. That 9 second pass had a very weird bump in. Never seen anything like it


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SeeThruHead

take a look at the power draw of the solenoid vs the switch/wire you want to use. i don't think solenoids usually draw enough power to require a relay tho.

you may want to use a combination of toggle switch and momentary switch.
Toggle switch disconnects the circuit so pressing the momentary switch by accident doesn't disable/lock your brakes.

i would switch on the positive side as you don't have the possibility of a short disabling your brakes that way. also grounding to the chassis by the solenoid is fine.

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SeeThruHead

that's exactly what a bump button on a transbrake looks like tho.
not saying it is that but that's what it looks like to me
You can see the same thing in the real street performance videos they explain it in one of them as well but i forget which video it is.

edit: this kind of thing is interesting https://www.nxtshiftinnovations.com/
or:


edit:
bump button explained at 1:19 https://youtu.be/mFdMYaZNL7Q?t=79

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