Brake shudder and grab Query

[Lorene and John]

Having an issue with all air brakes on 95 Vectra, Oshkosh chassis with 19.5 inch wheels. On first use following overnight park (park brake applied), brakes appear to bind and grab sharply causing a pronounced shudder in the front end. Short acceleration and application of brakes several times seems to wear them in and normal brake service then resumes.
I seem to remember a thread on brake burnishing but now cannot locate it. Can someone explain what this burnishing entails and is it likely to cure the problem? My chassis manual does not mention it.
Any advice would be most welcome.
Tks.

[Mike Canter]

There are certain types of brake pad compounds that will do that until they warm up. What you are doing by short application of the brakes after you start driving is to warm them up. Normally "brake burnishing" is done with newly intalled pads to seat them and should not be required on pads that have been used for a while. Is it a 100% air brake system or an air over hydraulic system? I believe that is an air over hydraulic system. Have the brakes been serviced at all in the last couple of years? That system needs to have the caliper slides greased with synthetic brake grease about every two years because the slides rust and the brakes will not release correctly when the pedal is released and can lock up when driving and you will see a lot of smoke coming from the brakes. The other thing that is required on a regular two year interval is to flush new brake fluid through the system. How many miles on the motorhome? Maybe just greasing the caliper slides and sanding off the pads may fix it but I would flush the system at the same time.

[Lorene and John]

Thanks Mike, that clears up the burnishing for me we just call that wearing them in or seating them, down under.
According to the Winnebago specs for the year and model (1995 XC-21RDX) the Oshkosh chassis was fitted with "Full air brakes" as standard. The Oshkosh manual under 'service' only mentions a fluid level check for the Hydraulic steering system. I was still unsure so crawled under and can't locate any hydraulic lines to the wheel assemblies.
The brakes have not been serviced since we bought the coach some eighteen months ago, although has passed the national road safety checks for brake systems twice in that time with no issues. Only 56K miles on it and runs well.
Will follow up on binding caliper slides as that would seem the next step.
Appreciate your post. Thanks.
Regards.