Hydra-boost brake install issues in C3 vette

[tektrans]

great write up. Nice work! I have hydroboost and havent had any issues yet but then again I havent driven the car much either. Now I'm prepared if I do have problem-thanks!

[496BBC]

One other thing that the tech mentioned was that the type of power steering fluid can also help. He indicated that there are a few that he has seen help with the foaming and groaning issues and they were Lubegard from NAPA (Lubegard makes an additive and a power steering fluid) and synthetics are also a good option to help with foaming and pump groaning.

I read in another article that GM power steering fluid was also a good fluid for a noise pump while using the Hydra-boost system.

He strongly recommends that you do not use transmission fluid in the power steering system.

Neal

[TimAT]

Originally Posted by 496BBC

He strongly recommends that you do not use transmission fluid in the power steering system.

Jim Shea can tell you about that one too. Way back when I was playing dealer mechanic the Tech Center guys were all over that one too. It's been done for years, but it's not the best for anything in the system.

[496BBC]

Well I got the pump inlet hose installed and started the car up to hear the same noise from the brakes and steering, bled the system a couple times, brought the system up to temp and let it cool off a couple times and the brakes are a lot better now. The brake peddle feels more like my Denali which has Hydro-boost brakes and its not noisy anymore but the steering is another issue.

The fluid has metal flakes in it so I started trouble shooting. With the steering wheels off the ground there are hard spots in the rack and pinion. I put the car on the lift and disconnected the tie rods and gave it another try, still have the hard spots while turning the steering wheel with the engine off. It sounds as if the fluid is going through an orifice than it quits and does it again. I’ve ordered a replacement unit so I’ll have to wait on it to take a test drive.

Right now I’ll say that the brakes are much improved but the real test will be once I have the car back on the road and take it for a test drive.

Most installation guides for the Hydro-boost say to give the system up to 500 miles to allow all the micro bubbles to escape. I noticed the accumulator acting funny until all the air was out. Whit air in the accumulator it causes the peddle to kick back when you apply the brakes. I think this is due to the accumulator trying to pressure up with brake fluid but due to the air it can’t.

The accumulator pressures up when the peddle is pressed when the car is started, it diverts pressurized fluid into the accumulator and a check valve prevents it from escaping. If there’s air in it or if the check valve leaks, the peddle when pressed will travel down and than kick back once the accumulator is pressured up, then the brakes will apply. It'll give you an uneasy feeling when this happens while driving the car.

I’m going to do a good flush of the system to try and get all the metal flakes out of the steering system and hope the pump and Hydro-boost system is not damaged.

Neal

[010752]

All hydraulic systems should have strong magnets and decent filters.

[496BBC]

010752, I agree with the magnet but am not sure how much affect it would have on a system that is 95% aluminum.

Neal

[496BBC]

Well I got the replacement rack and have it installed; there was a small piece of metal stuck in the inlet to the rack. Something I didn’t notice before is there is a check valve in the inlet to the rack and the piece of metal had lodged in the check valve. I’m not sure if this was the issue with the rack but it more than likely added to the issues. When I took the rack off I turned it by hand and it had hard spots in the travel so it appears there where internal issues also. The new rack is smooth and operates as it should when turned lock to lock.

I had to install a fine mesh around the return fitting in the reservoir to keep the returning fluid from creating a vortex at the outlet of the reservoir and feeding air to the pump, it also helps with removing air from the fluid.

I’ve flushed the system a couple times and the fluid is clean now so hopefully I’ve gotten all the contaminants out.

The Hydro-boost feels more like my Denali now and is not making any noise like before. I’m a little concerned about the backup reservoir on the Hydro-boost right now as it feels as if it works some times and not others. I may replace the Hydro-boost at a latter date to see if I can resolve the peddle kick back that happens every so often. The cause could be air remaining in the back up reservoir so I’ll give it a little time to bleed out before I replace the Hydro-boost.

I had a failed front brake caliper so I have to replace it before I can take a test drive. The steering is quiet now and has a smooth feel so I’m confident I have resolved the two main issues.

I’m really interested in seeing how the reduced flow has affected the road feel of the rack.

I’ll post back when I get the car back on the road and complete the test drive.

Neal