Front discs

My front discs are causing me a huge headache at the moment, the car has just been for its MOT and I knew they would come up as an issue, and sure enough they did. The problem is they are 'pitted and part worn' I don't know if there is enough of them there to get them skimmed and the only place I can find the original alcon ones are from pumabuild for £400. The problem I have with parting with that much cash at the moment is that the car isn't garaged and I dont want to be back in the same situation in a year or two (I know I need to drive it more but its a case of finding the time!) Are there any alternatives people would recommend?

Thanks Kev

The Bell and rotor system works well initial cost is similar to the Alcons (slightly cheaper) but you can then buy the outside rotor part for peanuts..

PM if you want a set posting..

Rgds
Chris

http://www.pumaspeed.co.uk/product-Repl ... ir_246.jsp

These will sort you out for the time being.
£169.99 a pair

Ive had the pumaspeed ones fitted for a year now and theyve been fine.

Any idea what those discs are from originally?

Assume they aren't directionally vented?

Here's the thread from last year http://www.rpoc.co.uk/viewtopic.php?f=6&t=3189 don't know what there from originally.

My memory is saying ST170 discs

yep I believe they are ST170.. 300x26mm from new (I think)...machined down to 295

Bit thin then as 26mm is the minimun to run Alcons too and these STs are at max 26mm.

Should be OK as long as you don't let the pads get too low. £67 pounds a pair on Ebay for ST170 discs.

Just need to machine a bit off in the lathe

I have two sets of Alcons spare, but if I need disks, I think I will go that route.

2 spare sets, and you'd opt to fit a bodge fit??! Fair enough

The Alcon items are not an option any longer in my eyes, think the Hi Spec units offer the greatest long term value.

If I need discs...

Oops, sorry I mis-read that

Either way... not sure these are the solution to the FRP's expensive brake consumables.

Watch this youtube video:-
Brake Performance by the Vehicle Operator Services Agency GOVUK
http://www.youtube.com/watch?v=xVpgCKz8oWs
All will become clear as regards the regulations.
1'50" to 3'40 particularly deals with disc condition & what is & is not structural.

Most of you will be horrified, but the guy talking is a VOSA Mot testing instructor, for & on behalf of .gov.uk. One of the guys that trains Mot testers.

No video link ..

Sorry just typed in 'Brake Performance' to youtube & came up with a VOSA instructional video.

Link is http://www.youtube.com/watch?v=xVpgCKz8oWs

Also the following quote:-
"Approximately 12 months ago VOSA changed the rules on pitting and scoring of brake discs, there is no longer a reason for rejection for discs excessively pitted or excessively scored.
However if the discs look bad enough that we’re unable to complete a brake test because the brakes may fail in use when testing on the brake test then that is a reason for failure, as we’d be unable to complete a brake test, thus the test should be aborted, I haven’t seen any that bad yet."
Source:- http://mottester.wordpress.com/2011/02/ ... scs-again/

To summarize, for Mot purposes, brakes are required to meet the following standard:-

1. Be structurally sound.
2. Have pad friction material of at least 1.5mm.
3. Meet or exceed a brake function & performance check by prescribed methods & equipment.

Another example from an Mot testers forum:-

"Heres an example.
I tested a Passat about 4 weeks or so ago, the OSR pads were so worn that they were both down to metal. As there was no actual danger I tested the brakes and of course the OSR failed.
The disc was in a right state and was rough enough to strike a match on and thinner than you would like (around 4mm [thinner] at a guess).
Metal millings were all over the wheel and the disc was obviously dead.
I failed the disc and pads (Ticked the Dangerous box) as well as brake effort and other stuff.
About 10 mins later in walked a VOSA Examiner (VE) to do a site assessment. He noticed that I had failed a disc and asked why.
I showed him the disc on the car, I was told in no uncertain terms by the VE that the disc was not a Reason For Refusal. I argued that if new pads were fitted and the brake was used in anger that the heat caused by the rough disc would cause the brakes to fade, and the disc may fail if friction material was involved.
I was told not to do it again.
The VE said in paraphrase "If you roller tested it and it didnt fall to pieces, how can it be dangerous"
I countered with " The rollers only go at 4KPH"
I was told to not to do it again, and to pass and advise next time.
I still disagree, but there you go.
And yes maybe I should have abandoned (VE said not).
So unless the disc has cracked, or the rotor vent webs are showing through the side of the disc, it seems we must pass and advise."
Source:- http://forums.motester.co.uk/forum3/1892.html

Now I'm not suggesting that people go to these extremes. But at £200 a chuck, I am suggesting that many a disc may well be unnecessarily junked on grounds of appearance rather than integrity/performance. A brake disc is specifically designed to do a very arduous job in the harshest of conditions. It is not designed to be pretty & will inevitably score with use, particularly when used with aggressive pads (which contain bronze scouring filaments). The bedding in process will score the disc as material is transfered back & forth.

The discs shown here:-
http://i583.photobucket.com/albums/ss27 ... 0_1288.jpg
Are fine, structurally sound & what is to be expected when bedded to more aggressive performance pads. It is possible, though unlikely at this stage that they may suffer from distortion &/or uneven wear, which is dealt with below.

Disc & pads perform best when bedded & left mated to their respective sides as a set. Ordinarily pads should simply be replaced when they reach their wear limit & bedded in to the disc as is. On this basis the disc should only be considered worn out & replaced where it measures less than the wear limit (26mm) by micrometer AT PAD REPLACEMENT.
Skimming a disc is not intended as a repair for a scored disc as such. It is intended as a solution to problems of distortion & uneven wear which appear as pulsing of the brake pedal & surging on the brake tester.
Tolerances are generally 0.1mm lateral (parallel to axis) & 0.025mm thickness
The focus of attention would be better spent on caliper maintenance in respect of regular cleaning of residue from piston & pad seats in order to avoid brake binding & piston seal damage due to the lack of dust seals.
(*****Chris (El Dude) used to do a good maintenance guide for about £8.00 or so. ****) WRONG !!!
Food for thought at least.

I don't do the '£8 guide'..thats our old friend wacko jacko...

I only do the full monty

Ah right, I bought a guide last year some time. Thought it was from you. A sort of 'Haynes Manual'. About 10-15 pages. Included part Nos. & photos n stuff. Must have been from Jacko then. How much is the full monty these days ?

It was Paul's (Jackos) guide

Ta Red !!

Now back to the original post by frp_024 (Kev)

"My front discs are causing me a huge headache at the moment, the car has just been for its MOT and I knew they would come up as an issue, and sure enough they did. The problem is they are 'pitted and part worn' I don't know if there is enough of them there to get them skimmed and the only place I can find the original alcon ones are from pumabuild for £400. The problem I have with parting with that much cash at the moment is that the car isn't garaged and I dont want to be back in the same situation in a year or two (I know I need to drive it more but its a case of finding the time!) Are there any alternatives people would recommend? Thanks Kev"

Reading between the lines, this vehicle will have received a pass & advise with respect to disc condition. This highlights a couple of issues.
1. The Mot at the point of service could be more subjective than VOSA would have liked; leading to the condemning, wrongly so, of many thousands of discs. (there are some 53,000 testers carrying out some 35 million tests per year. - Potentially resulting an enormous pile of 'borderline' discs.) A more scientific approach was needed to prevent waste & variation in standards within the industry.
............ More to follow...........