I tried posting this in the Autocrossing and Roadracing section but got no responses. I’ve noticed a lot of hydroboost users in the C3 section so I thought I’d see if there are any opinions here.

I’m looking for someone who has experience using hydroboost in a competition setting. My car is a ’66 Corvette that gets autocrossed. I run 315 V710's all the way around so I do need some stopping power. I have to eliminate my vacuum booster because of its size and because I’m running low on vacuum with my new motor. The choice is a hydroboost system or going to manual brakes. My concern with a hydroboost is pedal feel, my concern with manual brakes is pedal effort slowing down braking reaction time.

Any thoughts from racers would be much appreciated,

Thanks, Cris

 

I can't speak to road racing but I can to pedal feel with manual brakes versus hydroboost. I had manual brakes in my car for quite some time before switching to a hydroboost unit. To me they feel about the same, I just stop alot better now.

 

I have not raced with my car so I cannot say with certainty, but I have some input.

First, the Hydro adds a bit of heat to the fluid so if you DO run with a Hydro, make sure you install a small frame mounted fluid cooler inline with the return line from the Hydro.

Also, pedal feel is actually quite good. You'll find you have complete control over the car's braking system with just your toe. If you like that kind of precision, then you'll like it. If you tend to shy away from sensitive brakes, then manual is probably better.

 

People seem to LoVe the hydroboost...

Me I race with manual brakes, granted they are 13" wilwoods, but they are manual.

And yes it's a road course, 3.5 miles 10 turns.

Keith

 

Guys, thanks for the inputs.

DB: Autocrossing usually involves WOT followed by full on brakes. Have you ever noticed your hydroboost unable to keep up with quickly-repeated, heavy-application of the brakes?

427V8: Road racing is a little more finesse than autocrossing. How are the manual brakes in full on panic stops?

Cris

 

I have been racing for several years. My 77 is a dedicated track car. When I got the car 4 years ago it had stock power brakes and was running 15" Hoosiers. I converted to 17" wheels and started running Kumho V700's then 710's when they came out. My wife and I both run the car (track and autocross) and a typical event weekend meand up to 20 runs for the car (this almost every weekend during the summer). Almost immediately after runnig the stickier tires I began having major braking problems. I would start having brake fade after 4 or 5 runs and have to bleed the brakes several times during an event weekend. This after rebuilding the calipers and running many types of brake fluid. After installing the hydroboost 2 years ago all my brake problems disappeared. No more bleeding brakes all weekend. I change the fluid twice a year and bleed the brakes before an event weekend. I have never had another incident of brake fade whether running multiple laps on a road course or autocrossing in 100 degree Texas heat. Other racers who have driven my car say they have never felt such powerful brakes (this from C4, C5 and C6 drivers). This was the single best investment I have made in the racecar and the unit has held up perfectly for 2 years. The only problem I had was last year I lost a power steering belt and thus lost the brakes. I had about 1 1/2 pumps from the accumulator on the hydroboost and that was it. Kind of strange. Took me a minute to figure out what was going on. BTW, this car was #1 in the Southwest region of NCCC last year and this was in no small part due to the hydroboost. This unit will bring a heavy C3 to a stop right now and do it all day. If you're going to AX or track your car this should be your first investment.

 

I'm not doubting 62C1's observations in any way, but wanted to mention that a well respected builder of Pro Touring style cars once told me that he wouldn't recommend hydroboost for a track car...that it is too touchy. He prefers manual brakes, either factory style for a car with OE calipers or the individual master cylinder style (Wilwood, Tilton, etc) for a car with fixed aftermarket calipers. I haven't run it before, so my mind isn't made up.

 

62C1 Paul there above, has it about correct.....I been driving for decades, and have NEVER had a set of brakes nearly as strong on any car ever, as this HB on my '72 vert .....that after fighting those brakes with marginal at BEST results for some allmost ten years....all I did was pull the large diameter truck master cyl forward leaving the lines connected...and install the HB ran the lines clear, let it set overnight to get all the bubbles out of the pump/lines/hydraulics.....then went for a test drive....pedal been GREAT for some 3 years now, not one thing rong, ask it to and Sharkey stands on his nose, and i'm into the steering wheel....i'ts THE way to go for brake boosters, toss them damn stupid vacuum boosters in the dumpster where they belong....

and this goes across the board for ALL cars Dodge, Ford, GM, Import, don't matter....

 

I have never found my Hydroboost brakes to fall behind. I have yet to put it through full on paces on twisties, but even when turning hard and braking I don't feel a difference at all.

 

I'm looking at putting Hydro Boost in my '82 in the next couple of months. It's just a Sunday driver with no plans to race it, but I don't want to run into any trouble at any point. Do you think a fluid cooler is still needed? And if so, any suggestions?

 

This beyond me! Braking is braking which = heat But if you say that H-boost cured the problem, it must have. different pads and using 600 degree brake fluid can help in short time brake use like Auto - X.

I have driven a road racing c-3 with Hydroboost. The only thing that I could see over my V.A. stock setup up was less petal pressure required.

If i was going to throw money at a car I would invest in 13 inch Wilwood rotors and super lite brakes on the front and run carbon metalic pads on SS sleeved O-ringed caliper and stock diameter rear rotors with wilwood 580 degree brake fluid. Then if you need help invest in H-boost.

 

For a daily driver it's not a necessary addition. It's a precautionary measure for heat build up. Street driving really won't generate too much heat but if you were going to race it where you were on your brakes aggressively then I would suggest the cooler.

 

Thanks to all for the comments.

62C1: Thanks for weighing in. You have the experience I was looking for. Its hard to describe to someone how hard a race-tired C2 or C3 gets driven in an autocross.

I am leaning toward the hydroboost, but would like your remarks on the pedal feel. Do you heel-toe the car? And, whose hydroboost system did you use? I am looking at Hydratech for a no fuss, no muss installation.

 

IMO - You can not heel and toe a stock petaled C-3. You have to have a bigger gas petal placed back towards the drivers seat or you are going to have to place the brake petal forward and away from the gas petal.

I've tried

 

Nice thing about HB is the pedal travel is about 1/3 of the distance, so you can lower the pedal and still stop the car fine....that damn vac booster takes about 12' of travel, and maybe the car stops with hte pedal on the floor, so it seemed....and I could allways force it to the floor on demand if I wanted...hardly the feeling of security....

no freeking WAY to do that with HB....and I even lowered the pedal allready long time ago for the extra room, ....

 

Mine is an auto so I don't need to heel and toe the car. I left foot brake entirely. I agree with the other posters that the hydroboost significantly changes the feel of the brakes. They are much firmer with a lot less pedal travel. It makes it much easier to lock the wheels up but after several events I eventually figured out how to threshold brake the car with it. I got my system from Hydratech. Everything bolted right up. Make sure that your MC is up to snuff. One thing that I think also helps me is I pressure bleed my brakes. This ensures all the air is out of the system. One reason I left foot brake is that my car corners better with trail braking and I use it a lot. I removed the stock combination valve and essentially isolated the front and rear brake systems and put a bias valve to the rears so I can dial in the amount of rear braking I need for a given track.

 

gkull: You're right, a stock pedaled C2/C3 is difficult to heel-toe. I have fabricated a new gas pedal that is a little wider and allows me to adjust the pedal postion relative to the brake. My "prototype" of this was a piece of wood that I taped to the stock gas pedal. I kept trimming it until I got it right. I actually raced with the wood piece in there. After I got the position sorted out, I fabricated the new pedal out of alumimum.

62CI: I am concerned with the hydroboosted brakes being a little too touchy. I don't want my feel to go away, that said, my vacuum booster was not exactly perfect. Three or four WOT stretches, followed by heavy braking, often left the pedal softer than normal.

I'll talk to Hydratech about adjusting the sensitivity. I'm sure master cylinder bore has a big impact.

Thanks again for all the inputs, Cris

 

62c1 what pads are you using?

With hawk blues and my hydraboost is real touchy

 

When I first started using the hydroboost I was running Hawk HP pads. My calipers were the dual pin design so I had limited options in pads. The Hawks wore pretty quickly and I found a shop in Dallas that would reline my pads a lot cheaper than buying new. I ran these for about a year. I'm not sure what the compound was they used but they seemed similar to the HP's. When it was time to rebuild my calipers i considered putting Wilwoods on the car (Corvette Engineering) especially since I could set the fronts up with a brake fluid recirculating system. I realized I prolly didn't need that since I wasn't boiling the fluid anymore and I had no problem stopping the car so I decided to go with a single pin stock C3 caliper so I had more options for pads. I used Hawk HP's again and they gave good performance but wore pretty quickly. I ran Performance Friction Z rated pads on my C4 when I raced it and really like the pads so this year I bought a set for the C3 and am going to try them out. I really don't notice my brakes as being touchy. They're more sensitive and took some getting used to but I really like the feel now. I have cracked some rotors from heat but I did that on the C4 with PF pads too. I will occasionally briefly lock a wheel especially when a tire becomes unloaded over a rough course but without ABS that's to be expected.With sticky tires and the bias set right it amazes me how deep into a corner I can drive the car before getting on the binders. What limits me now is not the brakes but the "see God" factor.

 

I'm not sure I understand why adding a Hydroboost would cure a problem with boiling fluid in the calipers. Maybe there's more to Hydroboost than I am familiar with, but I thought all it did was replace the vacuum booster?