Hi Guys,
Super odd one this, hopefully having many minds on this may get me closer to the answer as to what went on the other night. On Tuesday I took my '79 Clubby Estate for an MOT at a classic specialist near work. They tweaked the rear brake adjusters and gave a quick check over then, MOT'd with no problems/advisories (Thanks to DomCr250 for the wheel hubs!, which cured the play in the front offside wheel). On collecting the car I noted the brake pedal felt fantastic! about 1/4" movement in pedal before brakes applied, and they felt the best they have ever felt (original twin leading shoe drum setup). However that evening when driving home after about 3 miles, I suddenly felt the car pull/ hold back, I pulled over after a few hundred yards. The rear nearside wheel was red hot! with smoke pouring from it. I jacked the rear and the wheel was locked up completely! The offside also had a fair bind on it when checked, I backed the adjusters right off and proceeded home with caution.
The following day I re-adjusted all adjusters and got the pedal back to the way I have had it for my 3 years of ownership - about 1 1/2" of pedal travel before brakes applied. Not having ever driven another drum braked car I figured this was normal, the car has always braked adequately. After speaking with the classic specialist he listed a number of parts that could have caused this issues - Master Cylinder, Rear Hoses, FAM7821 valve. The Master was changed in 2006 (converted to GMC227) by the previous owner/Have bill from Garage that carried out the work - £450! the rear hoses were fitted by myself in 2016. This afternoon I checked FAM7821 and I could feel slight dampness. After operating the pedal a number of times I could definitely detect brake fluid appearing from the end of the valve nearest the wing, the corrosion on the subframe turret suggests this may have been leaking for some time! The classic specialist told me that 'FAM7821 can release the brakes slowly when sticking and then the drum gets hot its expansion then grips the shoes'
So I will be replacing FAM7821 valve, but the question is, does this sound correct can this valve being faulty cause the rear wheels to lock completely up (after being adjusted correctly with slight shoe rub), Im sure this leak could be the cause of my long pedal travel, though!
Ideally I would like to replace the pipe and unions feeding from the valve to the front brake banjo union - Part HMK006 and HMV009 as mine look a little rough, however these appear to be obsolete/ No longer available, any ideas were I can get these?
I have attached a couple of pictures of the offending valve.
Thanks in advance,
Olie