Modified Minors

Installed the new Ford kit last week, and I'm having some trouble sorting it out. There is a noise and some vibration that pops up after a few miles of driving.

The noise comes and goes somewhat, but has been persistent after about the first 15 miles I drove. It's a constant pitch with somewhat varying pulsing, a woowoowoowoowoowoowoo sort of thing with a bit of a ring to the sound.

I've also noticed that there seems to be quite a bit of drag on the brake disc from the pads (nothing else is hitting the disc or hub as far as I can see). Both sides

I'm wondering if the pads or caliper is vibrating once things heat up a bit and expand. Are the pads not retracting far enough?

I also just noticed that there is a step in the instructions about removing a rubber seal from inside the master cylinder. I had disc brakes on this car before (Spridget) and figured the master cylinder was already setup for discs, but maybe I was wrong.

Any thoughts? I'm leaving in a week for a long trip with this car and need to get this sorted out.

How much pressure you got at the bleed nipple
when nobody's pressing the brake pedal please Drew?



Edited 1 time(s). Last edit at 2018-05-19 01:42 AM by 0123.

Just sent you an email Drew.

The instructions given with the kit are there to ensure correct fitting, unfortunately if these are ignored then you will run the definite risk of the pads staying on as the fluid will not be released back into the m/c. In turn you will over heat the discs and pads, something one should never do with new components. Sorry if this sounds like a telling off, but instructions are there to avoid such issues.

If the residual valve is still in the master cylinder, it may be difficult to determine externally. Perhaps you'll see a bit of fluid out of a bleeder, but at 10psi or so it won't be much. On the other hand 10 psi on the area of the piston will be significant. Try taking the pad out in front of the caliper piston and reposition it so you can slip it out easily. Apply the brakes and release and pull out the pad while noticing the force required to move it. Now try to push the piston back into the caliper. Get a feel for the amount of force required to move it and keep it moving. If the piston is almost all the way in with new pads, then use something thinner than the pad like a piece of wood or just be careful and only push the pedal enough to move the piston out a bit. With the diameter of the piston you can calculate the force to move the piston back if it's lower than that number, the cup is out of the master cylinder.

`Once the 'top hat ' valve is removed all will be good, Leave the callipers alone until this is done, then re bleed and see what you are then presented with.

I pulled the master cylinder last night, and the top hat seal *was* already removed as I had thought it might be (this is why I didn't pull the MC before). The master came from Gerard and was already modified for disc brakes (I was running Spridget discs before this).

The only other "non standard" part of my brake system are a couple valves that I put in when I redid the master cylinder. Now I'm wondering if I need to pull the 2PSI one on the front line, if that's causing problems somehow. It's not been an issue in the last 2 years, but maybe it's conflicting with the different calipers.

This is a quote from the drum-to-disc thread on this forum.

I realise that everyone has their own opinion and experiences with fitting a disc kit. We have never fitted any bias valve or restrictors into our set ups and the brakes work perfectly. Even with rear discs or large rear Ford drums. IMO the original system with the top hat valve removed and a disc kit preferably with a servo works extremely well.

Is the master cylinder reservoir above caliper height in your vehicles please John?



Edited 1 time(s). Last edit at 2018-05-19 08:48 AM by 0123.

I suggest you check the pressure at a caliper bleed nipple Drew.
You wouldn't be the first person whose been supplied an incorrect part.

I'm certainly no expert (obviously). The question now is could that 2psi valve be causing the pads to drag? I can remove it, just means I would have to make up a new hard line.

Otherwise, what else could be causing the pads to drag?

If your master cylinder is higher than your caliper then I see no point in fitting a residual pressure valve.

If your reservoir is below the floor I think an RPV is a good idea.

If you don't fit an RPV when you have a lower reservoir, gravity will pull your brake fluid back towards your reservoir.
Air will then try to get past your piston seals.
I see that as bad practice.

Incorrect part , what do you mean by this comment ?

First off, thank you all for your help in diagnosing this issue. I'm no Minor expert, and it is always difficult to do this all via typing in the best of circumstances.

So here's the update as of now:

Master Cylinder is correctly modified as per the instructions. This was in place before the conversion started, and was just verified by dissassembly so this is not the root cause. Something ruled out at least.

Even with no fluid in the system (so no pressure) the pads drag on the disc. Even with a wheel installed it doesn't seem to spin as freely as I would expect. Both sides.

My next step is to pull one of the calipers and make sure I didn't do something incorrectly in the install. I will also triple check the hub install, but I'm pretty confident those are ok.

To test with out the 2 psi valve, you don't have to make a new hard line. The valves come with adapters from 1/8 pipe to 3/16 flare fittings. You can just use ordinary 1/8" plumbing parts. If removing the valve cures it, THEN you can make a new hard line.

Any possibility that the Ford calipers have built in residual valves?