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Brakes Locked on..

8K views 16 replies 6 participants last post by  guyslp 
#1 ·
Hello Gents,


Just to jacked her up and attempted to turn the wheels, and they were locked up..

Started her and did the same thing and they spun freely :nerd


Is that normal for them to be locked on when she isn't running?


H
 
#2 ·
The front wheels should turn freely, once the gearshift is in neutral and the handbrake is off you should be able to turn the rear wheels with slightly more effort. The rear wheels would be a little more sluggish because of the connection of their hubs to the drive shafts. I suspect that your problem turning the rear wheels may have to do with the gear selector having been in park, I think it won't de-select from park unless the ignition is switched on to activate the gear selector inhibit switch.
 
#4 ·
Even with the transmission in park, I was able to turn the rear wheels on SRH33576. If you turn one clockwise, the other will rotate counterclockwise. This is without the emergency brake on.


It makes sense that however that little trick is accomplished it would keep the car in place.
 
#5 ·
Brian,


You are absolutely correct providing both rear wheels are in the air.


I am not a diff expert but even a LSD would transfer the movement from one wheel to the other going in the opposite direction. However if the other wheel is on the floor the movement would have to go down the propshaft and the interlock would not allow the wheel to turn. However you might get a slight movement from backlash but that is all.


All the best


Steve
 
#9 ·
Hi Henry,


Well the idea of the engine running is to create the pressure.


Pump the brake pedal ....engine off .....ignition on..... until both red brake warning lights show then try again.


Alternatively crack the bleed nipples at all four calipers and then try again.


Best I can suggest in my current state of diminished cells...........they will wake up in the morning though...........but given the time difference hopefully someone across the pond will chip in overnight here in UK.


All the best (hic)


Steve
 
#11 ·
Hi Henry,


Check your warning lights............not sure you have a switch like earlier cars or it is when ignition is on depends on year.


Also do the test ......release of calliper nipples too...... and just confirm it is trapped pressure..........not uncommon on old pipes to have collapsed but I can't say why it should release when engine runs.


Steve
 
#12 ·
In a good system in can take more than 60 presses of the brake pedal before the warning lights will illuminate, I've recorded closer to 90 pumps on occasions. Your pressure switches might be stuck closed but that would be a separate issue that wouldn't cause the front brakes to lock.
I've heard of brake pressure travelling from the rear suspension to the front when there's a blockage in the return pipes from the rear. If you can raise the rear to take the weight off the rear suspension and then find that your front wheels will turn more freely it would indicate that this might be the problem but this wouldn't be a definitive test.
There's also the possibility that you have sticking pistons in your front callipers, with the engine running the pump pressure might shift the calliper pistons which might cause them to temporarily release but they could stick again once the pump pressure is released on switching off the engine.
It appears to me that all the flexi hoses will need to be changed, the restrictor valves on the rear crossmember will need to be cleaned out and resealed and the pressure switches will need to be cleaned and resealed, the brake callipers will need to be cleaned out and resealed and then the whole system will need to be flushed. You can use regular DOT3 or DOT4 brake fluid for the flush to save on the expense of wasting more expensive Castrol RR363.
What would concern me is that other components e.g., accumulator control valves, distribution valves, height control solenoid valve, height control valves etc could be contaminated with crud or rust too, especially if the system hasn't had a fluid flush and change for many years but you might be lucky enough to get away with a flexi hose change, a calliper and restrictor valve clean & reseal and a good flush & bleed.
You really need to get yourself a hydraulic pressure test gauge that you can screw into the various hydraulic components to find out what is working properly and what isn't, that could save you a lot of unnecessary expense and work as you would be able to pinpoint where the problem/s lie. Kelly Opfar at Britishtoolworks in the USA supplies a good quality pressure gauge and fittings at a very reasonable price. Good luck.
 
#14 ·
Which brakes/wheels are locked? When was the brake fluid changed? Brake hoses as well? This is important to know because if the answer is I don't know or never, There is a good chance debris has dislodged within the system and has now been pushed into the brake distribution valves, causing either the front, rear, or both to lock up.
Once this has been established, you can plan your next cause of action.
 
#15 ·
Thank you for your knowledge. I only just purchase the car a few months ago and the former owner was not someone who took care of the car. The only thing good about the car is the body as it has no rust. We just rebuilt the calipers. All went well and had to replace a few of the pistons. The wheels somehow have freed themselves up! I have been running brake fluid through it to clean out the system. I think that my next plan of action is to replace all of the hoses. I will let you know how it goes. I am a Senior and this is a hobby for me. I am getting the RR363 from GRM Distributing. They also sell the hoses. Here is their contact info.
Phone: 480-940-8219
E-Mail: info@grmdistributing.com
PO Box 59027Phoenix, Arizona 85076
They sell the RR363 for 225.00 for a case of 10 and that seemed pretty reasonable.
I will order the hoses today and see if that helps out.

Thank for all of your input. Bill in Canada
 
#16 ·
Wait on the RR363. Use the GRM for the final fill after the caliper hoses have been replaced. There are more hoses other than the brake caliper hoses that are to be replaced. Any old hose in the system will degrade internally and pollute the system. Remove the brake reservoir lid, remove the internal flat plate and then unscrew the 2 filters on the bottom with the 1" hex top. They must not be ripped or clogged. Once the entire system is overhauled, bleed with DOT3 and when completed, introduce the GRM into the system.
 
#17 ·
If this car has been neglected then the best thing you can do for yourself is a replacement of all hoses (these days I would replace all of them only with new ones with PTFE carrier "lining" - it increases service life drastically and prevents the kind of internal hose breakdown that causes the vast majority of the fouling problems in the system).

As @Wraithman has already indicated, it's essential to pull your reservoir cover and make sure that everything is assiduously clean in there as the very first step. If your reservoir filters have collapsed and developed holes, replacements are available with better designs that do not allow for collapse. I also agree that until you are ready to put the car back on the road, use either straight DOT3 or YAK363 (search the forums) as your working fluid as it all ends up being pushed out and disposed of as part of the purging/bleeding process.

SY Brakes & Hydraulics - Diagnostics and Maintenance
 
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