13 replies to this topic

[Geofff]

We have a 1993 mini sprite that we restored over last winter and are now using to attend events etc.

We have however noticed a braking issue that I don't think has been considered in the forum. I have looked.

 

The nearside front disc is doing most of the braking. It's bright and shiny after use but the offside disc is shows that rusty look as if the car has been standing for a week.

During the work over winter I have fitted a new master cylinder and all new rear brakes.

The disc brakes had new pads fitted at the same time.

Seems to me that the brake fluid pressure is not getting to the offside but the car does not pull to the left under braking.

Could it be that I have a problem with the pressure reducing valve.

Many thanks

[stuart bowes]

whats the condition of the calipers?  new? .. refurbed recently?  .. original and untouched?

 

they can start sticking and might need work

 

other possibilities are possible

[Lplus]

We have a 1993 mini sprite that we restored over last winter and are now using to attend events etc.

We have however noticed a braking issue that I don't think has been considered in the forum. I have looked.

 

The nearside front disc is doing most of the braking. It's bright and shiny after use but the offside disc is shows that rusty look as if the car has been standing for a week.

During the work over winter I have fitted a new master cylinder and all new rear brakes.

The disc brakes had new pads fitted at the same time.

Seems to me that the brake fluid pressure is not getting to the offside but the car does not pull to the left under braking.

Could it be that I have a problem with the pressure reducing valve.

Many thanks

Odd that it should not pull if one caliper isn't working/getting pressure.  Some cars had the brakes split diagonally rather than split front/rear possibly to reduce pulling to one side if a circuit goes out.  If you have  a diagonal split system it might be worth checking if the nearside rear brake is doing any work..

[sonscar]

The front brakes are teed at the subframe so the fluid pressure has to be the same in both lines.There could be a blockage(damage,flexy deterioration,dirt etc)reducing the flow to the poorly side.I a suspect that if you brake hard the steering will pull out of your hands as it is now.You could have a brake roller test done to see if there actually is any imbalance.Goes without saying that driving it like this may be inadvisable,Steve..

[sonikk4]

We have a 1993 mini sprite that we restored over last winter and are now using to attend events etc.
We have however noticed a braking issue that I don't think has been considered in the forum. I have looked.

The nearside front disc is doing most of the braking. It's bright and shiny after use but the offside disc is shows that rusty look as if the car has been standing for a week.
During the work over winter I have fitted a new master cylinder and all new rear brakes.
The disc brakes had new pads fitted at the same time.
Seems to me that the brake fluid pressure is not getting to the offside but the car does not pull to the left under braking.
Could it be that I have a problem with the pressure reducing valve.
Many thanks

So when you hit the brakes is the car pulling to one side, if so plus with what you have seen with regards to wear i would not be driving the car.

So have you attempted to bleed the brakes at all. If so a simple measure of how much fluid comes out from each side after say five pumps should give you an indication of a potential issue within the system.

[Geofff]

Wow that was quick.

All good advice. I will take the caliper off and do the inspection suggested and check the oil flow.

I refurbished the calipers last winter could be clumsy fingers.

Many thanks for the reply's.

G

[timmy850]

Before you remove the caliper from the hub, try jiggling the pads to see if they are loose or have a very slight preload against the disc. Then try again with someone pressing on the pedal. Compare this to the known working side

You can check for fluid by bleeding the caliper and checking that it comes through when the pedal is pressed

[andyapanel]

Jack the front up before you do anything, apply pressure to the brake pedal and see if you can turn the offending wheel
My money is on rusty calliper cylinders
Good luck

[Geofff]

Thanks everybody.

Took your advise andyapanel and jacked the car up again with both front wheels clear of the floor.

Wife in the car applying the footbrake ... nearside brake effective but offside brake has pads on the disk and rubbing but I can turn the wheel by hand.

Wife returned to the house!

Fluid flow through the bleed nipple is as I would expect.

The discs are 30 years old so maybe the offside is glazed and the pad will not cut through the surface glazing.

I take the point that the car should not be driven in this condition.

So more business for Minispares me thinks ... new discs, pads, and new bearings whilst I am at it.

Thanks for taking the time to reply.

G

[sonikk4]

Thanks everybody.

Took your advise andyapanel and jacked the car up again with both front wheels clear of the floor.

Wife in the car applying the footbrake ... nearside brake effective but offside brake has pads on the disk and rubbing but I can turn the wheel by hand.

Wife returned to the house!

Fluid flow through the bleed nipple is as I would expect.

The discs are 30 years old so maybe the offside is glazed and the pad will not cut through the surface glazing.

I take the point that the car should not be driven in this condition.

So more business for Minispares me thinks ... new discs, pads, and new bearings whilst I am at it.

Thanks for taking the time to reply.

G

 

Better to be safe than sorry.

[mini13]

I would pump the pistons out part way and check them for corrosion or galling.

 

also Ive had flexi pipes that would bleed ok, but then cause issues under pressure

[gazza82]

Scrub the pad surface on some coarse wet&dry and take any glazing off ..

Edited by gazza82, 10 August 2022 - 10:39 AM.

[andyapanel]

If it was me, I would splash out on new pads to complement the new discs and a set of retaining pins

A few years ago, Minispares were selling callipers for hardly more than a pair of stainless steel cylinders; I don't know their price these days, but its worth looking into.

Good luck

[sonscar]

Even shiny pads and shiny discs you should not be able to turn the wheel(unless you are the Hulk)There may be other problems,do the pads move freely?push the pistons back and check they are not rusted in place.Pump the pistons back out,are they both free?Costs nothing,Steve..