Hi all you tech talk people. I'm hoping someone out there can answer my questions.

We have a 1988 33' Regal with the 454 Chev and a tag axle (not sure if that's important or not).

We (I say we but really it's my hubby who does the driving) finds the braking takes a lot of force to stop the unit. My son is an auto mechanic, who has worked in a shop where they worked on the smaller town trucks. He has had a look at the brake system and asked me to ask you knowledgeable people.

He is wondering if the problem could be a failed brake booster? Also, would you know if there is a vacuum booster? He says there is a vacuum booster underneath, but he thinks it's in a strange location. It has a hose and line, but doesn't seem to be attached to the brake booster. Also, does anyone know if it can be upgraded?

As an aside, the front brakes have all been checked and are in very good condition. We haven't been able to do a complete check of the rear brakes on the inside dual because until this weekend we lacked a jack that would lift the unit enough. He will be able to get into the back brakes now, but is thinking the problem lies with the booster.

Thanks in advance!!

Tish (and Bob).

Your rig has what is called "Hydroboost". There is no vacuum to your brake system. The brakes are powered by the power steering pump. That is a hydraulic pump which supplies power to both the steering and brakes systems.

If there seems to be brake power problems, the first think to check should be the belts driving the power steering pump.

The picture is from the P30 Chassis manual and it is available on this site.

Happy Motoring!
Matt

The main wheel brakes are part of the so called Hydroboost system. This system uses hydraulic pressure from the power steering system applied to the brake master cylinder for boost.

The tag axle brakes are drum brakes. They have a separate braking system. There is a master cylinder and vacuum booster under the coach. The tag axle brake cylinder uses engine vacuum for boost. It is connected to a tee in the main rear brake line and receives signal pressure from there.

When the normal brakes are applied, the pressure in the rear lines drives the tag axle master cylinder to apply the tag axle brakes.

Be sure the vacuum source is good, the master cylinder is full, the brakes are bled and adjusted. They should work.

You likely have a TA-5 tag axle like I did on my 33ft 86. We. have no info for that axle but there is general info on the similar TA-3 unit here:

http://truckroadservice.com/ba...aintenance_Files.pdf

There are a couple pages on the braking layout.

Thanks for all this information! I will print it off and give it to my son. I'm sure it will make a lot more sense to him than to me. I'm really hoping this solves the issue because we haven't yet gone more than 45 minutes from home with it, and we don't travel anywhere with sizable hills, just in case. I'd like to travel a bit further afield. I envy all you guys who travel long distances with your rigs.

T & B!

Your son will find much of the information here....

Bill NY, the man, the legend, compiled a collections of manuals and documents....
https://www.barthmobile.com/eve...31087061/m/145102933

Steve VW posted the P-30 Service Manual.
https://www.barthmobile.com/eve...1087061/m/4893991167

The "P30 Chassis Manual" seems to have gone away, so I posted it here just now.
https://www.barthmobile.com/eve...1087061/m/8693999597

There is some good reading in those links!!!!!
Matt

quote:

Originally posted by BarthBluesmobile:
T & B!

Your son will find much of the information here....

Bill NY, the man, the legend, compiled a collections of manuals and documents....
https://www.barthmobile.com/eve...31087061/m/145102933

Steve VW posted the P-30 Service Manual.
https://www.barthmobile.com/eve...1087061/m/4893991167

The "P30 Chassis Manual" seems to have gone away, so I posted it here just now.
https://www.barthmobile.com/eve...1087061/m/8693999597

There is some good reading in those links!!!!!
Matt

Thanks for this! I have some serious reading to do