Frustrating brake issue after fitting new parts

[Maki65.]

This is a bit of a saga but:

My Triumph Tr7 V8 had a slight pull to the right when braking and some judder. eventually I found a dragging not stuck left front caliper. I purchased a pair of reconditoned Ford M16 Capri 2.8i calipers which is the conversion on the car. I put these on and found the left on had a leak, but the car now pulled to the left when warmed up!

I sent the calipers back and got them replaced, put the new ones on and it felt great, until they got warmed up and then it still pulled to the left when braking.

At this point I thought new pads and discs, which I duly bought. The pads are EBC Yellowstuff, which have always been great on this set up. I fitted all these taking great care as always. Went for a drive and now it pulls to the right when braking!

In all the above, the car brakes great for a few miles but then from nowhere starts the pulling, which is quite aggresive and will lock the wheel up and takes some degree of effort to keep the car straight.

To recap, New/Refurbed calipers, Yellowstuff pads and new discs. Bled to death as you might expect and the car has braided hoses which are not kinked or damaged.

I feel like I have tried everything, but I am very frustrated. I have owned the car 39 years and done this work before without issue. I am thinking that the calipers are not right in some way and one has a slight weep I now notice. The wheels spin freely with no binding but the left caliper may not be applying as much pressure as it should, I don't know!

Any help/advice would be great

Edited by Maki65. on Saturday 11th April 19:18

[paul_c123]

Kink in the brake line somewhere?

[E-bmw]

Just for clarity notes added.

Maki65. said:

I put the new ones on and it felt great, until they got warmed up and then it still pulled to the left when braking.

Obviously pulling to the left when braking implies the right calliper is "lazy" in some way.

[quote=Maki65.At this point I thought new pads and discs, which I duly bought. Went for a drive and now it pulls to the right when braking!

Obviously pulling to the right when braking implies the left calliper is now "lazy" in some way

[quote=Maki65.In all the above, the car brakes great for a few miles but then from nowhere starts the pulling, which is quite aggresive and will lock the wheel up and takes some degree of effort to keep the car straight.

I am assuming it is locking the wheel that brakes harder/pulls towards?

For the side that is pulling to change it makes me think that you may have inadvertently done something different from one side to the other.

Most likely would possibly be:-

Sliders not free, pads not seated correctly, calliper not sitting true/straight in the mounts.

Best bet for me would be start again, take everything off, clean/check/grease everything that should be, bleed the hell out of the system and see where that leaves you.

[Maki65.]

E-bmw said:

I am assuming it is locking the wheel that brakes harder/pulls towards?

For the side that is pulling to change it makes me think that you may have inadvertently done something different from one side to the other.

Most likely would possibly be:-

Sliders not free, pads not seated correctly, calliper not sitting true/straight in the mounts.

Best bet for me would be start again, take everything off, clean/check/grease everything that should be, bleed the hell out of the system and see where that leaves you.

Yes, that's pretty much where I am. I did as always take my time and be methodical. However, anything is possible. I take your points about the sliders and misaligned caliper, but why ony when hot? To me everything looks spot on. I am wary over the calipers as I did have to send one back initially with a piston leak.

[stevieturbo]

So is the pulling actually down to a single brake sticking on ? Have you tested this when stopped ? Temperature of the disc ? Rotation by hand ?

When stuck, have you tried anything to release the "stick" ? ie undo a bleed nipple ?

Some say old flexi hoses can deteriorate inside and cause a lock of pressure. I haven't had it myself, but seen a few people have that problem.

[E-bmw]

Maki65. said:

E-bmw said:

I am assuming it is locking the wheel that brakes harder/pulls towards?

For the side that is pulling to change it makes me think that you may have inadvertently done something different from one side to the other.

Most likely would possibly be:-

Sliders not free, pads not seated correctly, calliper not sitting true/straight in the mounts.

Best bet for me would be start again, take everything off, clean/check/grease everything that should be, bleed the hell out of the system and see where that leaves you.

Yes, that's pretty much where I am. I did as always take my time and be methodical. However, anything is possible. I take your points about the sliders and misaligned caliper, but why ony when hot? To me everything looks spot on. I am wary over the calipers as I did have to send one back initially with a piston leak.

Sorry, my quote didn't seem to have happened correctly, you didn't answer this.

"I am assuming it is locking the wheel that brakes harder/pulls towards?"

I don't think the issue is "when hot", I think it is "after braking something settles in" which is what I am pushing you towards.

[Panamax]

After a short drive in conditions where the car is pulling to the right under braking get out and feel the temperature of the brake discs. If they're both the same temperature you might not have a brake problem. A sticking calliper will often result in either a cooler disc or a hotter disc, depending where it's sticking.

I'm wondering if the issue is knackered suspension bushes or something along those lines.

If you reverse and brake firmly what happens? Any clunks? Then drive forwards and brake firmly. Any clunks? Any pulling one way?

FWIW what AI says is, "A car pulling to the right due to suspension bushes is typically caused by worn, cracked, or failed lower control arm bushings on the right side, which allow the wheel to shift position under load. This creates improper camber or toe angles, forcing the vehicle to drift or pull to that side."

[Maki65.]

The right wheel is the one that locks up which is the way it is pulling. Only if you push hard enough, if only light pressure it still pulls but not as aggresively

I did a test after my last drive, the wheels felt roughly equal temperature, hand only. I jacked the car up and both wheels span freely. The suspension feels fine, no clunks. The bushes are all poly bushes, although been on a few years they are in perfect condition and don't do many miles , 1-2 thousand per year.

I have to say it is pretty perplexing, particularly as it was the opposite way around prior to new pads and discs. I am going to have another look tomorrow weather depending. I want to just run over that everything is as it should look. I am pretty sure it is but...

Thank you everyone trying to help it is great!

[Panamax]

Is the car so old it doesn't need an MOT? If so, I'd stick it through a test anyway and see what they come up with. Could be £50 well spent.

[5s Alive]

You seem to have covered all the bases but still have less force going through the left caliper. Front rear split on these (I think), not diagonal, so probably no master cylinder issue there either. Assuming no physical interference/binding, that leaves air somewhere between the master cylinder and caliper pistons as the most likely culprit. Some systems seem to be near impossible to bleed effectively.

[Smint]

Left field suggestions.

Are the rear brakes doing their part, ok they don't contribute much but if they're barely working at all then the fronts will overheat very quickly.
Is there a load or pressure proportioning valve for the rears.

I don't know the presume upgrade of brakes you've completed but decades past experience of improving front brakes (simply fitting Ferodo pads to a mk 2 Diesel Golf) very quickly resulted in me having to fit the same brand of rear shoes to the car to rebalance braking, just doing this rendered the rears effectively redundan, that lesson never forgotten, maybe your rear brakes need overhauling or even uprating to re-balance things too.

Rear suspension wear, anyone who experienced rear void bush wear on mk 3 and 4 Cortina will recall how unsettling that can be.

I'll get me coat

[E-bmw]

Maki65. said:

The right wheel is the one that locks up which is the way it is pulling. Only if you push hard enough, if only light pressure it still pulls but not as aggresively

Try these.

Bleed the hell out of the full system.

Try to see if the sliders are free on the left calliper, it could be that only one of the left pads is coming into contact with the disc, this may be evident on the pad/disc surface.

As above, check the rears are also actually doing their job.

[Maki65.]

E-bmw said:

Try these.

Bleed the hell out of the full system.

Try to see if the sliders are free on the left calliper, it could be that only one of the left pads is coming into contact with the disc, this may be evident on the pad/disc surface.

As above, check the rears are also actually doing their job.

Off outside to have a look see now.

To be fair I have bleed 1.5L of fluid through up to now.

Because this is not a floating caliper, ie, sliders it is the old style pins, through the pads. They are clean and free, no grease as all this does is clog up and bind with dust, especially Yellowstuff. They do move freely.

The rears are cylinders and that will be the first thing to look at. They usually leak when they fail, but one could be stuck in its piston bore.

[stevieturbo]

Maki65. said:

Because this is not a floating caliper, ie, sliders it is the old style pins, through the pads. They are clean and free, no grease as all this does is clog up and bind with dust, especially Yellowstuff. They do move freely.

But does each piston move freely.

Again, get into this scenario where the problem is bad and then investigate.

[ssray]

Have you replaced the brake hose? How old is it? Could be breaking down internally if it's a oe spec hose

[Maki65.]

stevieturbo said:

But does each piston move freely.

Again, get into this scenario where the problem is bad and then investigate.

the pistons can be pushed in with finger pressure, however, what is happening when the caliper is hot is another thing. I stripped it down again this morning and made sure all the pads move freely on the pins and even swapped pads from one side to the other, no difference.

The brake hose is a goodridge hose and looks to be in perfect condition. If that was bad I would suspect it to be a problem from the off, but it is not. In fact the first few miles the car is perfect, only after around 4-5 miles or so does the issue appear. Then if you do not brake for a while it calams down, only to reappear after braking again.

I am begininng to suspect the recon calipers I bought are not as good as they should be. I have had issues with leaks initially, which is an aside in this case. But I am wondering if the left caliper when hot loses efficiency and does not apply enough pressure.

After the drive this morning I checked the temperatures of the discs, the one that locks up was getting on for 20 degrees hotter than the other side, as you might expect as it was doing more of the work. This makes me think the other caliper is defective in some way.

[stevieturbo]

If the pistons move freely....the caliper doesn't really need to do much else other than not leak.

But again, try an get this problem to happen, then investigate before it is gone again

[Smint]

The pistons might be moving freely, at least they are cold when you check them, but unlubed slide pins can jam against the pad backing plates, again you can't really check for this when the brakes are really hot.

Are the rear brakes correspondingly hot both sides.

I used a laser thermometer to check for brake sticking on my trucks sometimes, they're cheap enough with many other uses.

[Maki65.]

stevieturbo said:

If the pistons move freely....the caliper doesn't really need to do much else other than not leak.

But again, try an get this problem to happen, then investigate before it is gone again

So, I took the car out and whilst the brakes were still hot I took the pads out and tried to push the pistons back in. In this instance they felt stiffer than before and could not be moved by fingers alone, as before. I am now ondering if the braided lines are at fault. They look good but are old. After reading a bity they can look good but still crack inside creating a one way valve.

[TriumphStag3.0V8]

Maki65. said:

stevieturbo said:

If the pistons move freely....the caliper doesn't really need to do much else other than not leak.

But again, try an get this problem to happen, then investigate before it is gone again

So, I took the car out and whilst the brakes were still hot I took the pads out and tried to push the pistons back in. In this instance they felt stiffer than before and could not be moved by fingers alone, as before. I am now ondering if the braided lines are at fault. They look good but are old. After reading a bity they can look good but still crack inside creating a one way valve.

I would definitely replace the flexi hoses (all of them). Even braded lines can deteriorate internally. I have had weird braking issues in the past that turned out to be the flexis.