Brake disc skimming

[Ian C]

I've always wondered about this procedure. I would have thought that, once warped, the whole disc structure is shot so even made flat again the hub part isn't quite right. Also, I have no idea what it'd cost, although a new pair of UK fronts is not much change from £300 so I doubt it'd be that expensive.

 

Reason I ask is because my fronts are warped and now the Supra isn't my only vehicle for the first time in about 7 years, I can actually have it sat up on jacks in the garage while waiting for bits. But I have 3 concerns:

 

1) The above - is it a valid fix or is it a bodge?

2) Would it make me a pikey for not just getting new fronts?

3) Can I get the calipers off in the garage with the limited manouvering room? It's a mission normally when on the driveway...

 

-Ian

[SBDJ]

Perfectly valid fix (as long as the discs have enough meat left on them to make it economical), I've seen places offering an on-car skim as well to try and get it as perfect as possible catering for hub runout.

 

Plenty of information on warping here:

 

http://en.wikipedia.org/wiki/Disc_brake#Disc_damage_modes

Edited October 16, 2008 by SBDJ (see edit history)

[Ian C]

Well the disks have done about 10k miles so they darned well should have plenty left on them I'll check the runout when I'm off shift and see.

[Scott]

One of the guys in here asked me to do his. I took the tinyest of skims off the front face of the hub then did the back face of the disc as well as a tiny skim off the rear hub face. I then turned it over and did the other side of the disc. Like yourself, i was a bit worried about warping of the whole disc. I'm pretty sure its not as bad as you think though as it was nowhere near as bad as i thought. I think i took less than 5 thou off each side of the hub and it was reasonable. The discs themselves took a bit more though lol.

[Ian C]

Well the printout from the brake testing machine was quite amusing as the braking force fluctuated wildly each time the bent bit of the disk came around. It certainly feels unpleasant on braking as well... What sort of place can do brake disk skimming then?

[rick001]

Mr Toyota does on car skimming but is not worth the money as there hourly rate over inflates the cost so better to buy new imo

[Burna]

Also, I have no idea what it'd cost, although a new pair of UK fronts is not much change from £300 so I doubt it'd be that expensive.

 

I know it was couple of years ago but I only paid £116 for a pair Ian http://www.mkivsupra.net/vbb/showpost.php?p=763818&postcount=12

 

Maybe worth just checking the price and going with new ones.

[marc_p]

I just had my disc's scimmed for the MOT today(mine had a large lip on the edge) and it cost me £30, not bad really, they look and feel like brand new discs aswell

[4packet]

Search for 'Pro Cut'. I found a garage local to me that had the equipment and it worked OK. They leave the discs on the car and the machine spins the hub whilst cutting on both sides of the friction surface. This means that it will compensate for any hub irregularities. Cost me £20 per disc. The alternative is to use harsh track day pads on the road. This has also worked for me but these pads can be a bit harsh on your paintwork.

 

BTW I thought a front set of UK's were only about £130ish from Steve?

[Dnk]

Ive recently bought new uk discs and they were £77 each

[garethr]

Search for 'Pro Cut'. I found a garage local to me that had the equipment...

Found a list

http://www.skimmydiscs.co.uk

 

http://www.procuteurope.eu

[snake]

Well the printout from the brake testing machine was quite amusing as the braking force fluctuated wildly each time the bent bit of the disk came around. It certainly feels unpleasant on braking as well... What sort of place can do brake disk skimming then?

 

if you can find an engineering firm with a ring grinder it will not take long to grind them.They can be done on a lathe but it will

take longer to do.

[Tricky-Ricky]

Should be done by grinding, but the majority of engineering places do it by skimming on a lathe, look at it this way, if they are going to charge more than £35 for skimming then you will probably find some new disc's for under £100.

[paul mac]

out of interest how exactly did you manage to warp them Ian

[UltraFlynn]

I had my disks skimmed. Cost £30 per disk and gave me plenty of extra miles on a set of disks. If money had not been a factor then I would have just bought new disks.

[VIL]

can you skim drilled/grooved discs? I had a set on the front of the Supra that warped but as they had loads of life in them I did not chuck them. They are sat in my garage and I have always wondered if I can bring them back to life.

[4packet]

I had my disks skimmed. Cost £30 per disk and gave me plenty of extra miles on a set of disks. If money had not been a factor then I would have just bought new disks.

 

I believe there is an argument to suggest that a set of discs that have gone through a heat cycle and warped, then skimmed are more robust to future abuse. My limited experience follows this trend. I replaced my discs because they had warped, only to warp the new ones within a week or so. I had these skimmed and they seem to have held up better.

 

You can procut drilled/grooved dics but was told it takes longer.

[bignum]

I believe there is an argument to suggest that a set of discs that have gone through a heat cycle and warped, then skimmed are more robust to future abuse. My limited experience follows this trend. I replaced my discs because they had warped, only to warp the new ones within a week or so. I had these skimmed and they seem to have held up better.

 

You can procut drilled/grooved dics but was told it takes longer.

 

Thats exactly my experience too, had 2 sets done now using the procut machine, the 1st set i had done were grooved aswell, they had to do each face seperately.

[4packet]

Thats exactly my experience too, had 2 sets done now using the procut machine, the 1st set i had done were grooved aswell, they had to do each face seperately.

 

That's right I remember now. The groove causes the cutter to skip so would affect the backside cut if done at the same time.

 

On a side note I remember you said at the Ring you ran the PF97's all the time. Do you not find the dust a bit troublesome? It baked onto the rims and left a rust surface down the side of the car if I used them in the wet (despite cleaning once a week). Not sure if the 'rust' is from the pad or the disc.

[TRD DAN]

perfectly fine fix at 10k we do them all the time at work as the toyota's seem to suffer pretty bad with surface corrosion

[bignum]

That's right I remember now. The groove causes the cutter to skip so would affect the backside cut if done at the same time.

 

On a side note I remember you said at the Ring you ran the PF97's all the time. Do you not find the dust a bit troublesome? It baked onto the rims and left a rust surface down the side of the car if I used them in the wet (despite cleaning once a week). Not sure if the 'rust' is from the pad or the disc.

 

Yes mate the dust is a nightmare, its wrecked my bbs lm`s, i tried scrubbing with acid once and as the dust started to break down so did the lacquer,

[Ian C]

out of interest how exactly did you manage to warp them Ian

 

I don't know Can't honestly say I was doing anything out of the ordinary. I must have done a fairly heavy stop off a motorway or summat and parked up for a while I guess. Nothing heroic alas.

 

Sounds like I'm paying too much for disks! I use Blueprint ones from Partco, are Toyota seriously half the price?! A set of rears rushed me near £300, they are more expensive than fronts but I round up to the nearest £100 - good practice when budgetting for these cars

 

Thanks for all the info and reassurances I won't be a pikey I'll have a root around some places, failing that I'll give Mr Manley a call (sorry Nic but postage from HK would probably make it unviable)

 

-Ian