Club 80-90 Forums

1990 1.9D

I am working my way slowly through the reasons my van failed her CVRT ,(Irish equivalent of MOT), and one of the reasons was the left front wheel and rear right wheels were 'Tight to turn' . Would i be right in guessing that maybe the callipers weren't functioning correctly or maybe its something to do with the bearings?

While carrying out another job on the front left wheel yesterday i ended up taking off the calliper and i noticed that one of the guide pins when i extended it would automatically go back to its rest position but the other pin would just stay wherever i extended it to. (forgot to get a picture). Also the same guide pin could easily be withdrawn completely from the rubber boot while the other one couldn't. They are the Girling type brakes and i'm just wondering does this mean i need to order a new calliper carrier or is there a way to just fix the guide pins? 

Any guidance as always is much appreciated

For clarity -(in my own mind).

The guide pin that stays wherever you position it,
Is that the one that can be withdrawn from the boot?

Or is it the one that returns to it's "rest position" that can easily be withdrawn?

If it is the first one, then that infers to me that the guide pin that returns to it's rest position is somehow bonded to it's boot.
Rusty flaky outer surface on the pin perhaps, gripping the inside of the boot.

Or it could be old grease that has gone hard.

If you are lucky, you may be able to clean the guide pin for your CVRT, but ideally I would replace the pin with a new clean one, and then smear some high-temperature grease on it's sliding surfaces to slow down the return of rust or corrosion.

It may be this sticky pin that is causing the brake to bind a little.

But my head says that if the guide pin is sticking due to corrosion, then the pads or piston may be too.

Whilst you are at it, check and clean the contact surfaces between the calliper and the disc pads.
To ensure that they too can move freely.

Thanks for the response.

Ya i changed the pads yesterday as they werent in the best shape and i gave the caliper a good clean with a wire brush. The piston was easy to move with a g-clamp as well and didnt look like it was in to bad a state.

Top pin - can withdraw fully, doesn't automatically return to its rest position and there is no sign of rust etc on the pin when it's pulled out.

Bottom pin - doesn't pull out, does return to a rest position after being extended.

In fairness I probably could pull the bottom pin out fully if I pulled it hard enough but I wasn't sure which pin is doing the right thing so i didnt want to break something else. In my head when I push the brakes the piston pushes the pads onto the disc and then when I release the brake, the pins would go back to their rest position allowing thr pad to relax and break contact with the disc. Which to me would mean the bottom pin is acting like it should, but then again if I knew what I was talking about I wouldn't be here

Should I be able to easily slide both pins out of the boot and should they automatically return to rest position after I manually extend them?

I am sure someone will confirm the correct information...

But the pins should allow the calliper to slide smoothly with no resistance or pull.
I suspect that the boot is there to keep the pins clean from debris and muck.
So they should not be physically touching each other, which means the boot should not restrict the pin movement.

Maybe not 100% technically correct, but...

The return springs in the brake pedal and the master-cylinder should allow the fluid pressure to be released from the pistons,
and so remove the braking force on the brake pads / calipers -
allowing the wheels to spin freely when the pedal is released.

The square profile of the piston seal in the calipers provides a very slight "spring" back to pull the pad off the disk.
When hydraulic pressure is applied they go slightly rhombus shaped, and when pressure is released completely they return to a square and this provides some slight clearance and overcomes stiction in the system. Or it should, anyway

Ok that all sounds good and makes sense, again thanks for the responses. I will just order new guide pins this evening and when I get a chance Monday week I will change them out and see what happens.

I haven't looked at the back wheel to see why it might be tight to turn, any guesses there? I have new shoes somewhere for the back brakes so I can change them I think.

Could be an over-adjusted shoe,
Or one of the "pull-off" springs may be snapped, weak or dislodged.

As with the fronts, a good clean and re-adjust should sort it.

Forgot to suggest - probably the most likely...
The shoe hold-down clip may have broken free from it's retaining cup.
this would allow the shoe to twist, causing it to bind or drag on the drum.

Was there uneven wear in your pads or corrosion on your disc? Often the worst corrosion is on the back side. The sliding pins should move freely. Pull them out and look for corrosion on the pins. They are a wear item and may need replaced. Clean out their locating bores as well and see if you can tell if they are corroded. When you removed the pads, was it easy to turn the wheel?

Cheers SyncroMatt, it was easy to turn when i removed the pads, but they were a bit crusty but they didn't look to uneven to me. At the same time it wasn't overly difficult to move with the pads on either. There was corrosion on the top edge of the disc and on the central part of it that sticks out, but i never checked the back now that you say it.  I have ordered new discs and bearings for both sides which i will get to Monday week. I ordered new guide pins as well earlier so that should sort the front issue. 

Cheers Robsey for those suggestions i will check all them Monday week as well.

Guide pins need to removed, cleaned up (wire wheel or wire brush), relubed, then they move freely.

Thanks Mioba, appreciate the response