A610 Binding/Dragging/Overheating rear caliper - again!

.I have had this issue with my GTA. I'm not sure if the calipers are exactly the same.

Paul ..... just FYI .... the rear calipers on the 610 are quite different to the GTA's rear ones ..

Hi John

I thought they would be, thanks.

[pgoldsmith]

I'd disconnect handbrake cables and try winding the pistons back in again. It can only be the piston not being square on the pad or piston / piston housing pitted.
Do the brakes work initially for a short run or do they get very hot immediately ?

Hi All,

Thank you so much for your continuing contributions to this saga!

Embarrassingly, I didn't follow the proper instructions for the location of the vent hole and the brake pad pin thing that corresponds with the slots in the piston. The instructions in the A610 workshop manual are much less clear than those in the GTA manual. In the A610 manual it says the vent hole should be "opposite" the bleed screw, but there's no picture of that. Does it mean the other side of the caliper, or nearest the bleed screw? Not clear. The GTA shows exactly where it should be, so I followed that instruction.

I think BiggRed did fit new pistons. I can check with them!

Brake discs are brand-new Brembo. 24mm thick, 300mm diameter.

I have now rectified my silly mistake of fitting the calipers wrongly. However, the binding brakes issue remains, but it does seem a little bit better.

I also checked that the calipers are free to slide on the sliding pins. They don't seem to bind at all.

I wonder, however, if I've used the wrong type of grease on them? Copper grease was supplied with the pads so I used some of that - the instructions said to use it sparingly on the pins. I did that. I wonder if it's heating and becoming "sticky"? I would have thought it would have got more liquid with heat and thus slide more easily?

I am using DOT 5.1 brake fluid. My reservoir says "DOT 5 only" which has always been a mystery to me... I have flushed the brakes several times recently.

Maybe I need to drive until the brakes get hot, then see if the sliding pins are binding?

Any more thoughts are most welcome.

Oh and on initial driving, the brakes are fine. If I drive fast without using the brakes they are fine too. However, if I use them in town and then drive on the open road, where I don't use them much, they get very hot.

Andrew

Oh and once installed afresh, brake applied a few times to extend the pistons correctly, the brakes feel like they are binding very slightly. It still feels like they are "on" a little.

Andrew

Yep. New pistons fitted by BiggRed. Just contacting them now to enquire as to what I should do next.

Andrew

Have I caused damage somewhere by overheating them? Caused by my incorrect installation in the first place?

Andrew

Don't use copper slip on slider pins.It damages rubber and will get sticky.You want silicon or red stuff ........Take it all off,clean and the use correct stuff.
I always use high temp DOT4 .The Dot 5 sticker is just a French joke for the Ross Bifs ......Also check with Bigg what seals they used .I've had rebuilt calipers for GTA with Cit seals and they stick like the proverbial to a blanket ...They weren't from Bigg Red tho .

The instructions in the A610 workshop manual are much less clear than those in the GTA manual. In the A610 manual it says the vent hole should be "opposite" the bleed screw, but there's no picture of that.

Andrew ..... if you go to my previous pic of page 33-6 of the manual and click on the picture, you will get a zoomed up pic ..... now move the magnifying + icon over pic 94418, and you will get a super zoomed up pic giving very good detail of where the vent hole should be in relationship with the bleed nipple.
Basically you must end up with your 10mm square section tool at right angles to the caliper bracket at the same time having the vent hole under the end of the tool as per pic 94418.1 page 33-4, and 94418 page 33-6.
Unfortunately The pic I posted up as an attachment is not detailed enough unless you zoom it up.

Brake discs are brand-new Brembo. 24mm thick, 300mm diameter.

Can I take it the height is the same as the originals ?

However, the binding brakes issue remains, but it does seem a little bit better.

Oh and once installed afresh, brake applied a few times to extend the pistons correctly, the brakes feel like they are binding very slightly. It still feels like they are "on" a little.

There will always be a very slight drag as the pads do stay in contact with the discs even when the brakes are not on .... this is normal as there is nothing pulling the pads off the disc ........ the only thing stopping the pad from staying tight to the disc is the distortion of the piston seal when the pedal is depressed ........ when the pedal pressure is removed, the piston seal returns to its original shape removing the "full on" pressure of the pads, hence the pads do not actually leave the discs.

Maybe I need to drive until the brakes get hot, then see if the sliding pins are binding?

Once you check all the above and are satisfied the your work ........ making sure the discs will turn ... with slight resistance ... it may be worth going for a run and seeing if things have improved.
I hope all of this makes sense to you.

John

Thanks guys!

Lee - I think you may have it. I was very surprised at how difficult the pistons were to wind back in. I had to extend the handle of my caliper piston rewind tool in order to put enough leverage on it.

I suspect they have used Citroen seals. Wrong fluid. Sticky seals!

That would explain why they worked perfectly to begin with then got steadily worse. It's now so bad that I can't drive the car at all. A few stops and they just start dragging. Then drag harder and harder and harder.

BiggRed have offered to take them back.

Thanks John - I managed to study things and I'm pretty sure I got it right this time. I did as you said and zoomed in!

Andrew

[phildini]

BTW Andrew, when the car was in my possession I used 5.1 fluid.

Thanks Filippo - that's what I am using too.

Andrew

Update - got the calipers back from Bigg Red. Unfortunately they weren't able to identify the problem. They have replaced the piston seals. I still think that may have been the problem but I will have no way of checking until I refit the calipers.

Another unfortunate - I won't be able to test them for a while. Decided to do the gearbox oil in the meantime - it's been leaking and I wanted to make sure there was enough oil. However, the driveshaft seals are leaking, so I decided to replace those after draining the oil, which has turned out to be more of a mission than I thought!

My thoughts are: if I replace the calipers and find that they are fine to begin with and then get worse, it suggests that the wrong seals are still being used. In which case, I will need to find a source of the correct seals!

No time to work on the car this weekend...

Andrew

Brakes international used to list the seals, they fit a few other models and were abou 20an axel when I got some.
On the drive shafts, on my red 610,they were leaking but it turned out to be badly sealed roll pins. Paul Sage sorted it for me.
Draining gearbox oil on a 610 is easy, getting it back in needs an oil syringe, a long pipe and a shower afterwards to remove the gear box oil from your body and hair ( not so much hair in in my case).
The gear change rods, water and ac pipes seemed to have been routed in a way to make refilling the gearbox a messy to impossible job.
Have fun...I have learned that Alpine Work needs at lest a weeks gap afterwards for unexpected rectification before you plan to use the car or to buy unexpected extra tools.
Lee

Right - an update!

Biggred replaced the seals and returned the calipers. However, they couldn't tell me definitively whether the correct seals had been fitted this time round.

So, it was with some trepidation that I refitted them. For a couple of months everything appeared perfect. Then yesterday, they started sticking on!

It seems to take a couple of months for the sticking issue to manifest itself. I strongly suspect that the wrong seals have been fitted again. I'm a bit fed up with taking the calipers off and redoing everything so I have asked Biggred if they will pay for the calipers to be taken off and sent to them. Whether I will have any success in that endeavour or not, I don't know. I don't feel that I should have to "pay" for their mistake, but maybe they already have terms and conditions that exclude labour for remedial work for when there are problems with their reconditioning service.

Argh.

Andrew