HELP!! Hydroboost and Master Cyl Replacement

[tandemfish]

I am in need to the hydroboost and master cylinder replacement. Could anyone tell me where I could get this inexpensively and could this be done be a do it yourselfer? Thanks a bunch!!!!

[Geophilist]

There are a number of posts on this subject. Do a search on hydroboost.

Steve

[GlenCoombe]

Also check www.millsupply.com and look in the StepVan catalog for lots of cheap P30 chassis parts.

[bobchevy89]

make sure it has the same numbers on it.got the wrong unit for mine brakes stayed locked up...

[swebster]

When you say hydroboost, do you mean the pup or the power units (bolted to the frame rail where the master cylinder connects)?

Both the MC and the pump can be purchased from AutoZone as rebuilts for about $50 each with lifetime warrantees. New replacement will cost quite a bit more.

The HB is expensive and available from online sources (Glen mentioned one) or a chevy truck dealer. Make sure you have your chassis VIN when you go in (or engine block VIN) as the P30 Motorhome Chassis is a little different.

I've replaced both the MC and the Hydroboost Pump but not the rest. It is a DIY project with time and patience. The MC is pretty easy but the pump is a real PITA.

Definately search this forum for hydroboost. Lot's of good info.

[tandemfish]

Thanks for the responses

SWebster_ your previous thread had great detail. I believe I need both the master cylinder and the hydroboost (this would be right beside the MC) Buddy that runs the Brake/Muffler shop next door said that the brake fluid was leaking from the master cylinder and the hydroboost appeared to be leaking power steering fluid (?) Does that seem possible. The power steering was squealing when I turned the steering wheel in a stopped position.

Regarding the parts; I went to AutoZone and it seems that in their system I could either have a JB7 or JB8 brake system. Does this appear correct and if so, which one. The "hydoboost" or what they call a Power Brake Booster runs about $175.00 while the master cylinder is about $50. Does this seem to be a fair price?

Thanks for all the responses!!!!!

[overlander63]

Originally Posted by tandemfish

The "hydoboost" or what they call a Power Brake Booster runs about $175.00 while the master cylinder is about $50. Does this seem to be a fair price?

Thanks for all the responses!!!!!

The master cylinder sounds about right, but the booster sounds too cheap. They are probably quoting you a price on a vacuum brake booster, not a hydroboost unit.

[tandemfish]

I looked at a photo of the unit and it does look similar. You have to also understand my limitatons with basic mechanics LOL. If the brake booster istoo cheap, what would I need to pay for it and where?

[overlander63]

It should look like this: Usually costs around $300, unless you get a really good deal.

[Chaplain Kent]

What symptoms are you having besides the leaking fluids? My brake pedal locked and would not return it had to be manually raised. Cause was the hydraulic boost. Mechanic found a crimped hose and cleaned the lines. If it had been replaced the cost would of been about $1500.00 parts and labor. Luckily I got by with just the repair and a rebuild of the back brakes, $1,000.00.

[swebster]

Terry is right..about $300. I hate to say this but with AZ or any of the big box stores it's always best to bring in the part. Sometimes AZ had rebuilds...I typically go with new whenever possible and this is one of the "spendy" items.

JB7 sounds right to me. It depends on your rear brakes (drums or discs). (Not sure which Airstream you have).

Buddy that runs the Brake/Muffler shop next door said that the brake fluid was leaking from the master cylinder and the hydroboost appeared to be leaking power steering fluid (?) Does that seem possible. The power steering was squealing when I turned the steering wheel in a stopped position.

One thing to check is a leaking high pressure line from the hydroboost pump to the hydroboost unit. These are inexpensive, leak and are easily replaced. Also, if your in there refreshing things this line is an obvious replacement. There is also another high pressure line to the power steering gear. Then a low pressure line back to the pump.

Yes, it is power steering fluid. Motorhomes rely on hydraulic pressure from the pump for steering and braking power. Just too big for vacuum assist alone.

[tandemfish]

Yes, the price of the hydroboost from AZ seemed a bit low given the fact that my friend from brake shop said his was about $300. His master cylinder was about $100, whereas at AZ it was about $50. I thought that maybe he was making a profit on the parts.

My MH is a 76 Argosy with disc in the front and drums in the back. They have been replaced as has the lines if I remember correctly. I have replaced so many things on her that I have lost count.

Parts will arrive on Wednesday and my other friend who is a mechanic and works on fire trucks and the like will be doing the work in the driveway so keep your fingers crossed

If in fact I have to replace the high pressure or/and low pressure lines, would they be available at AZ?

[swebster]

Yes they are available from AZ...a bit of advice...just replace them now. Easier and less expensive to do them now (in the driveway) alongside all of the other "newness" going in there. No additional labor from your friend and you'll know you have good, clean, strong hoses.

MC at $50 sound right (rebuilt)....consider replacing the HB pump too. This is a real pain to get to but again, it's about $50 from AZ with lifetime warrantee and you'll know everything has been replaced.

We're pretty good at spending money around here aren't we. Another member used to say we Classic owners make our "payments" at the parts counter instead of the bank.

You can also find things for the P30 at www.rockauto.com at good prices. I've had good luck with them but you can't exactly compare components on the counter with an online parts place.

[tandemfish]

Hey Steve,

Replacing the lines from the hydroboost is a smart move. Are they a special line that I would cut to length or are they standard for my rig. By the way, is the HB, the hydroboost? Or something else that I have not thought of>

[swebster]

They are specific to the chassis so you need to buy them for your motorhome. They have specific hardline sections with threaded fittings for the back of the pump and into the boost. There are two; one from the pump to the hydroboost power unit and one from the unit to the steering box. AZ sells both lines.

One note, the line from the pump is tricky. Since damaging the pump housing will void your warrentee I had the AZ guys install the line into the pump for me. No extra charge and it was ready to install when I picked up the pump. Typically the pump is a special order item and requires three - four days for AZ to get it in.

The low pressure line is essentially cut to length tubing with band clamps back to the pump for return fluid.

HB - Hydroboost.

[swebster]

tandemfish - well, how'd it go? Are you turning and stopping on a dime now?

[tandemfish]

Steven,

Thanks for asking. It turns out that the hydroboost was OK, it was just a HUGE amount of air in the brake lines. We bled them, first the rears and then the fronts with a power brake bleeder and the brakes are as good as new. That sure saved me a ton a $, now I get to return the hydroboost, master cylinder, hydro high pressure lines. We also replaced the valve cover gaskets because i was getting some leakage. All in all, it was a great day!

One question i have and i know a photo is worth a thousand words, but for the life of me i can't figure out what a certain toggle switch operates.
It is on the lower portion of the steering column. there are two red wires. One is ground and one goes to the solenoid in the engine compartment.
Then on the other side of the solenoid the red wire goes out to the refrig, where there is also a ground wire.

Now I have a small 110v refrig (purchased the coach this way). I am wondering if this was a switch that flipped the refrig over to 12v. My friend thinks it is. Any thoughts?

[swebster]

Good news on not needing any of the expensive parts for this repair.

Not sure about the switch...sounds like something the Previous Owners (PO) must have added. Does the solenoid look like a cube (used for driving light relay, etc.) or something larger?