Changing brake discs by pair only

[zibizibi]

Hi everyone,

After servicing I've been told that one of the front brake discs is heavily rusty on the inner side, and one front coil spring is broken. I'm told that I must replaced both left and right front brake discs, not just the one that is problematic, and same with coil springs: I must replace both sides.

Why both sides? Is it absolutely necessary?

[Stewart(oily)]

So that the braking and suspension characteristics match.

[Chlorate]

Having uneven braking or spring rate either side of the vehicle would make for some very entertaining driving...

And to be honest if they've got to the point of corroding heavily it's probably about time for a new pair of brake discs anyway.

[Mandrake]

Agreed. Getting a good balance between left and right brakes can be hard enough without having a new disc on one side and an old one on the other! Balance of left and right front brakes is absolutely critical for safety if you want to be able to brake hard in a straight line...

[Northern_Mike]

Hi everyone,

After servicing I've been told that one of the front brake discs is heavily rusty on the inner side, and one front coil spring is broken. I'm told that I must replaced both left and right front brake discs, not just the one that is problematic, and same with coil springs: I must replace both sides.

Why both sides? Is it absolutely necessary?

The brakes - Yes. Definitely.

The springs - no. This is a myth perpetuated by garage owners and parts sellers to part you from your cash. A spring either works or it doesn't. The spring rates don't "deteriorate over time".

If it were a knackered damper, I'd say yes, change in pairs. Not springs though.

I changed one front spring with DickieG on my Berlingo last year. It's been perfectly ok with no change in driving characteristics at all.

[isisalar]

Rust on one side of one disc would indicate a sticky caliper which should be checked out and attended to before you start changing discs. They may or may not need changing but if the cause of the lack of wear isn't attended to you will have the same problem in a matter of weeks or months. I would suggest you have them looked at by someone with no financial interest in the job before you proceed.
Check out the price of a pair of discs from a local motor factor, the mark up some garages put on parts can be eyewatering, likewise the spring.
I don't know what car you have but for my HDI Xantia a pair of new front discs are £60-£90 depending on quality, from GSF.
Cheers
Paul

[Dommo]

I think the issue with springs is that they may end up being different lengths if one has been used and compressed a billion times, compared to one that hasn't been used at all yet. I'm not certain so I'd gladly be wrong on that one.

[Peter.N.]

Changing both discs is the ideal - but I have several odd discs in my garage

[zibizibi]

Thanks guys for the input.

[qprdude]

Brake discs yes.

Springs? debatable. Interesting tgat a garage will recommend changing both springs if one is broken, but only if you're paying!! If the job is under warranty, they wil seldom offer to change a perfectly good spring.
Springs of course, will never shorten, even if they are on the car for a hundred years. It's also a moot point about the good spring needing to be replaced because it has the same wear as the broken one. For one thing, unless you have had the car from new, how do you know when springs have been changed, and secondly nearside and offside springs will almost certainly never be subject to the same stresses and loads. They are under limited working stress during a 400 mile motorway trip, and each side is under totally different stress during urban driving. There is no reason therefore, to discard a perfectly good spring, other than to line the pockets of manufacturers and fitters. Spring steel has a tremendous lifespan, unless subjected to extreme heat.

[Xaccers]

Or replace your springs with a car with proper suspension