Help - My MK1A brakes are driving me nuts

[Tiger Tim]

These brakes are cracking me up. I fitted new copper pipes, flexi hoses & brake callipers all round to my MK1a. Sailed thru’ the test with no problems. First 100 miles were no problem then occasionally the front left calliper would stick the pads to the disk & it would get red hot. Sometimes after 10 miles, sometimes 20 or sometimes I could drive 100 without a problem. Checked the front left caliper & sliders working perfectly. Put it back together & worked for a while but started sticking again.

I have a good set of MK1A callipers so I gave it to my mechanic who firstly changed the front left. Went for a 25 mile spin & found the front left was cold but now the front right wheel was quite hot & I couldn’t touch the disk. The problem seemed to have partially transferred to the right. I got him to change the right caliper last Friday. Car is driving & braking perfectly but the right wheel is still getting very hot. What could it be. Its really annoying. Can’t depend on it to go for any long spin.

Could the unit (equaliser? that sits in the frunk in front of the master cylinder) that the 4 copper pipes go back to be at fault or the master cylinder. The brakes are good but lack real bite like I remember Toyota brakes on previous Corolla’s I have owned.

Hope someone can help,

Thanks,

Tim

[System-G]

Pull the calipers off and strip them down. get rid of all the copper grease from anywhere and clean them up thoroughly.

Get new seal kits either from Toyota or Brakes International and rebuild them using either the Budweg brake lubricant or the Mintex equivalent.

Get decent pads on them too - nothing less than EBC Redstuff (greenstuff, Ferrodos (DS2500 & 3000), Halfords own etc... IMO are utter pants on a 1a).

Don't use copper grease anywhere near brake components - it reacts with heat and the brake dust causing seizing.

You want the slides and the pistons to be totally/freely moving.

I do a full service as above on my brakes every 3 months or so (whenever I do a pad change) as the car is used heavily on track and I can't afford my brakes to be anything less than perfect. I can now do a full stripdown and rebuild on all 4 callipers easily in an afternoon

[Tiger Tim]

Thanks,

I've replaced both calipers so I guess I've ruled out the calipers. Both sides were free moving with the previous refurbed calipers & are free moving with the set I have now installed.

Thanks,

Tim

[LimeyMk1]

In addition to what Garrick's posted make sure the pads move easily in the carriers as well, so some new pad retaining clips may be required. I've seen pads that have needed a hammer to remove them from the carriers. Rust and dust builds up behind the retaining clips holding them tighter and tighter.

[ligertigon]

I recently fitted motor factor pads to my bro's mk1a, they simply would not fit into the carriers

I had to take a hand file and take off 1-2 mm then fit them. Otherwise they would have been wedged in

[System-G]

Been thinking about this a little more...

There is a bias valve just under the master cylinder. It should work front to rear. If the brake pipes have been replaced, are you sure they have been done properly - i.e. front pipe to the front exits of the bias valve and rears to the rear exits?

The top three connections are for the front and the bottom two for the rear. For the top 3 the one closest to the brake pedal is the inlet and the top and front are the outlets. For the rear the inlet is also closest to the brake pedal and the outlet to the front of the car.

Make sure these are connected properly.

If you're getting fluid out each calliper when bleeding and the pedal pumps up fine, then everything should be working OK.

I'll try get some pics up later of how the system should be.

Also another consideration is wheel bearings. I have had one collapse before which casued a lot of heat to transfer through the wheel.

[DNOS808]

I had a problem on my MK2 that was like this. I changed the disks, pads and caliper and it still had the problem!!!! In the end changing the stainless steel clip things that go between the pad and the cast brake pad mounting cured the problem. I assume that the pad was not able to move freely due to the rough surface of the worn clips.

[Tiger Tim]

Thanks for all the replies.

WIll check again but I think the pads are OK in the carriers.

System-G - I suspect the bias valve but not too sure what's inside. Will check that the pipes are connected the right way. All 4 corners bleed fine.

It seems strange that after changing & bleeding one corner. the other side is giving trouble. Are there seals inside the bias valve that might be faulty. Its not sticking like the front left but the wheel is getting quite hot.

Thanks,

Tim

[MartG]

The bias valve only affects the pressure to the rear calipers - if the pipework is correctly connected the front calipers get full pressure direct from the master cylinder.

[System-G]

As far as I can remember the bias valve only has a spring inside to control the amount of pressure going to the rear. If one of the fronts is connected then it will be getting less pressure than the other and the rears will be getting full pressure with the other front.

I don't remember seeing any seals in the bias valve. Only the master cylinder and if one of them went, you'd know fairly rapidly that the car just doesn't slow as it should (experienced this not long ago on track )