MOT time

AdrianC

Unless the pads can be seen without removing the wheel, there is no check on thickness in the test - the tester doesn't remove the wheel. The only thing checked is how well they work.

ElkyElky

I have one of those trolley jacks, 5t if I remember correctly. It has been valuable with having 3 4x4s in the drive. Caliper rewind tool I can get from my uncle, he does his own servicing and such.

Never done it before myself but plenty of videos on YouTube demonstrating it and one or two specific videos for my car although I haven't watched them yet. Brakes certainly feel and act fine though, and the discs from a quick glance look in good condition (no scratches or deep lines).

arcon5

Bleeding the brakes and removing fluid cap = not necessary for simple brake pad replacement.

RMS2

arcon5 wrote: »

Bleeding the brakes and removing fluid cap = not necessary for simple brake pad replacement.

What do you think will happen to the fluid cap when you wind the callipers right back in?


I don't mean a complete bleed, but a partial bleed to get the crud out of the system and stop the brakes being spongy. Mind you, for the time it takes and having the wheel already off, clipping a self bleed bottle on is no great shakes.

AdrianC

"Crud" doesn't cause spongy brakes. Air in the fluid causes spongy brakes, and is what gets bled out.

Air only gets in if the hydraulic circuit's been broken into somewhere down the line, if the master's been run very low on fluid, or if the fluid changes have been so badly neglected that the fluid's become very "wet" (brake fluid is hygroscopic) and has then boiled.

Unless the fluid's been topped up since the pads were last changed, then the level will merely rise back to where it was. The surface area of the master reservoir is much greater than the piston surface area, so the level rise will be less than the thickness difference between old and new pads. And the cap has an air breather hole to stop pressurising/sucking a partial vacuum as the level rises and drops in normal use anyway.

JustinR1979

RMS2 wrote: »

What do you think will happen to the fluid cap when you wind the callipers right back in?

Undo the bleed nipples, you've no worry of flipping the seal, spilling fluid all over the place, and you get fresher fluid to the calipers.

[Deleted User]

Iceweasel wrote: »

I'm afraid it is true and your tester is wrong, Lee.

Here is the wording from the tester's manual:

Reason for Rejection.

1. a. One tyre is of a different nominal size or aspect ratio to any other on the same axle

So Joe H is correct - the tyres on opposite sides of the same axle must be of the same dimensional data and construction type.

I took that as different brand and/or tread pattern, not size. OP didn't state about size of tyre.

Iceweasel

JustinR1979 wrote: »

Undo the bleed nipples, you've no worry of flipping the seal, spilling fluid all over the place, and you get fresher fluid to the calipers.

Very true - but that is a typical example of the type of thing that you find rusty/stiff and may shear off in your hands.

JustinR1979

Deleted_User wrote: »

I took that as different brand and/or tread pattern, not size. OP didn't state about size of tyre.

You quoted this: "same sizes fitted across each axle" but didn't realise it meant size?

Iceweasel

AdrianC wrote: »

Unless the pads can be seen without removing the wheel, there is no check on thickness in the test - the tester doesn't remove the wheel. The only thing checked is how well they work.

True the tester will not remove a wheel or dismantle anything at all.

But he will likely shine a torch in at angle from underneath when the car is up on the hoist.

He can't test/fail what he can't see - which is why we are all getting these advisories about under-trays and engine-covers.