Skim or new discs?

[elenitro]

I'm getting quite bad vibrations from the front when braking from more than 60-70mph so had a look at the pads/discs but can't really tell if there is anything wrong with them. The pads look hardly worn and there is a tiny lip around the edge of the discs. The discs were a bit caked in black so i've cleaned the cross drill holes and the inside of the discs but that's seemed to make it worse.
I've been quoted £380+vat for new discs and pads on the front from the dealer. Is it worth getting new ones or going somewhere that will skimm them for me?

Leon

[RobP]

I'd check the run-out on the hubs first. Almost undoubtably where the problem stems from. With new hubs, you'll still need to get your disks skimmed to take out any high spots.
If you don't do the hubs - skimming/replacing is a very short term solution.

[elenitro]

wouldn't the hubs make the wheel wobble all the time?

I borrowed a little tool that measures the movement in the disc and the front passenger side has a slight variation (10 points on the scale whatever that is) in it which makes it catch slightly on the pads whereas the other 3 spin quite freely.

Could this still be the hub? If so how do I check?

Leon

[Richie350]

10 thousands of an inch, remove the rotor and measure the run-out on the hub face.

[Richie350]

Remember the absolute max run-out on the hub face should be 2 thou. Richie350

[F.C.]

There has been past problems with the mounting bells as well.
F.C.

[elenitro]

OK thanks.

I've just done another check on the center of the wheel (see pic) and I'm getting the same 9-10 variation on that. I'm assuming that this means the wheel hub is duff and I just need to order a new one? If so is the dealer the only source?

Cheers

Leon

Edited by elenitro on Tuesday 27th May 18:09

[Biggriff]

I seem to remember someone on NobleForums had improved ones made. Check out the search facility on that site.

[Richie350]

That is not the best place to check run-out as that is just a securing washer/plate and simply cannot get a correct reading here. Remove the disc and repeat the check with the DTI gauge directly in the hub face - where the rotor sits. Richie350

[Adrian W]

not sure about that method of measuring, measure the disc runnout about an 10mm from the outside edge, take the disc off, clean up the hub face, and measure just outside the studs, when i did this i used a hight guage standind on the floor with the clock strapped to it, this method was accurate and repeatable.

[Adrian W]

Richie350 said:

That is not the best place to check run-out as that is just a securing washer/plate and simply cannot get a correct reading here. Remove the disc and repeat the check with the DTI gauge directly in the hub face - where the rotor sits. Richie350

snap

[mr.man]

Remove the disk.
Remove any rust on the face on the hub where the disc touches.(this is the only surface that matters)
Mount the DTI securely and rotate the hub slowly to determine the maximum run out.
You are using a metric DTI so "two thou" will show as five little marks.
Apply leverage to the hub at maximum run out to check for worn bearings.
If more than five marks total movement replace hub.
If five marks or less get you disks skimmed by your local precision engineering machine shop.

[Richie350]

On the car skiming

[elenitro]

OK so time to remove the discs.

Do I need to undo all the little bolts around the inside of the disc and/or the big nut in the centre?

Leon

[Adrian W]

elenitro said:

OK so time to remove the discs.

Do I need to undo all the little bolts around the inside of the disc and/or the big nut in the centre?

Leon

Neither, undo two socket head bolts holding calliper on, pull calliper off (dont let it hang on the flexible hose) disc should fall off, if not give it a tap from behind with a mallet or bit of wood.

[elenitro]

Adrian W said:

elenitro said:

OK so time to remove the discs.

Do I need to undo all the little bolts around the inside of the disc and/or the big nut in the centre?

Leon

Neither, undo two socket head bolts holding calliper on, pull calliper off (dont let it hang on the flexible hose) disc should fall off, if not give it a tap from behind with a mallet or bit of wood.

That implies that the disc is in no way secured to the wheel hub other than by the caliper!?!?

[Twerlie]

elenitro said:

Adrian W said:

elenitro said:

OK so time to remove the discs.

Do I need to undo all the little bolts around the inside of the disc and/or the big nut in the centre?

Leon

Neither, undo two socket head bolts holding calliper on, pull calliper off (dont let it hang on the flexible hose) disc should fall off, if not give it a tap from behind with a mallet or bit of wood.

That implies that the disc is in no way secured to the wheel hub other than by the caliper!?!?

The 4 bolts that hold the wheel on also hold the disc in place!

[elenitro]

Good point!

I just need to find something to help take the bolts holding the calipers on now. My 9mm allen key and my arm/hammer isn't working!

[Adrian W]

elenitro said:

Good point!

I just need to find something to help take the bolts holding the calipers on now. My 9mm allen key and my arm/hammer isn't working!

Try using an 8mm allen key

[elenitro]

Adrian W said:

elenitro said:

Good point!

I just need to find something to help take the bolts holding the calipers on now. My 9mm allen key and my arm/hammer isn't working!

Try using an 8mm allen key

I did use an 8mm but that was too small?! It fitted the 4 bolts holding the caliper together though!?