Changing one brake disc - Fine according to dealer???

[Petrolhead_Rich]

Put my car in for MOT yesterday at a main dealer (no names), it's been stood for a while and I've just completed a load of work on it (new Turbo, DPF, Bearings, Pads, Ball Joints, couple of sensors, good clean of the intake manifold and new oil, coolant etc.

They failed it because the rear brake was "pulsing" because of a warped disc, I know the disc's were not great and was happy for them to sort this, but they then said the most bizzare thing:

"for one brake disc is £x fitted and hopefully that should fix it as the other side seems ok", now I know both rear brake discs are pretty knackered and have never had anyone suggest you only change one, least of all a main dealer!

Is this normal/safe, with the wear on the other disc I'm almost certain it would lead to uneven braking!

Your comments/thoughts?

[sunbeam alpine]

I'm not an engineer, but I think it would depend on the car and its use.

I've always replaced in pairs on any of our sportier cars. I've recently replaced just one side on my old Disco II as it spends most of its time on small country lanes and rarely gets above 60 mph.

[Davi]

the pads, pistons, seals, bores, slides etc will all be in a different condition one calliper to the other, it's never going to be identical side to side, if the pad is bedded correctly and there is enough meat on the disk to be within manufacturers tolerances, then I really do not understand the hangup requiring all things to be paired.

[Turbodiesel1690]

Do both at the same time

[kambites]

I don't see why the age of the disc would affect braking performance, so I don't see why it would be a problem as long as the new disc is of the same design and hence offers the same coefficient of friction.

[julian64]

Davi said:

the pads, pistons, seals, bores, slides etc will all be in a different condition one calliper to the other, it's never going to be identical side to side, if the pad is bedded correctly and there is enough meat on the disk to be within manufacturers tolerances, then I really do not understand the hangup requiring all things to be paired.

Read this. On Pistoheads there is probably only one really sensible post per day, and today was this threads lucky day.

[Petrolhead_Rich]

doogz said:

Are they re-using the old pads?

They were brand new, so yes!

[Ean218]

I am an Engineer and I wouldn't have a problem with that.

[Petrolhead_Rich]

Fair enough!

IMO it needed new discs all round but I ran out of cash so hoped it would be fine, shows what my standards are like compared to a main dealer!

Thanks for the advice, must admit i thought it was odd, but apparently not...