Brake disc rust channels

[ggoodwin]

I was checking underneath my 1991 GTi 8v over the weekend and I noticed that both the front discs had a build up of rust on the inner surfaces which had gone into grooves in line with the drilled holes.



The outer surface was ok.



I'm obviously going to change the discs and pads but I just wondered why it had gone like this and why only on the inner surface?

The pads themselves have got plenty of wear left on them.

Also what is the latest thinking on replacement discs, is there any benefit to be had in fitting grooved/drilled discs on an 8v GTi?

Graham


ps Apologies for not having got my head around the image thing here  :embarassed:

pps I'll stop trying random bits of html as I think I'm just making it worse!

[Thom89]

Get a Photobucket account, upload pics, copy IMG code, paste into thread, dead simple

I'm not an aficionado on Discs brands, but I'm sure you'll get an expert soon

Thom

[ggoodwin]

Thank you, Thom!

Much appreciated 

Graham

[Mr Blue]

Look normal. I would worry if they dont work 

[X4MGS]

Gone like this due to the fact that only one side of the piston moves...

Hence why you have a thinner inner & thicker outer disc.

If they were like porsche calipers with 4 moving pistons you would have a disc with the same thickness on each side...

Good idea to change them though looking at them...

[Thom89]

Look pretty normal to me... working, but not at their best, just give the sliders a little TLC when replacing the disc's and pads.

Thom

[ggoodwin]

Thanks for the feedback/comments guys.  I guess it seems to stop when needed and it passed its MOT fairly recently so they can't be too bad but, having seen them now, they just don't seem to look like a model of efficient braking  .  As the grooves seemed to line up with the drilled holes, I wasn't sure if the drilled discs were adding to the issue or improving it. 

I like the look of drilled and grooved discs but that's not necessarily a good reason to get them!  Are they a good idea again if I decide to change these?

Look pretty normal to me... working, but not at their best, just give the sliders a little TLC when replacing the disc's and pads.

Do you mean clean/lubricate the caliper piston?

Graham

[rob.043]

General opinion in the past has suggested that there is no performance benefit for 'regular' driving. But if you like the look sufficienly, go for it!

[Diamond Hell]

Do you mean clean/lubricate the caliper piston?

No - the sliders need cleaning and greasing to ensure they move freely.

These look like 239mm brakes, they're rubbish.  Grooved and vented discs will only make a marginal difference.

[Thom89]

Thanks for the feedback/comments guys.  I guess it seems to stop when needed and it passed its MOT fairly recently so they can't be too bad but, having seen them now, they just don't seem to look like a model of efficient braking  .  As the grooves seemed to line up with the drilled holes, I wasn't sure if the drilled discs were adding to the issue or improving it. 

I like the look of drilled and grooved discs but that's not necessarily a good reason to get them!  Are they a good idea again if I decide to change these?

Look pretty normal to me... working, but not at their best, just give the sliders a little TLC when replacing the disc's and pads.

Do you mean clean/lubricate the caliper piston?

Graham

No, the sliders are what hold the 2 halves of the Caliper together, and they should be able to move freely... this says it all
http://www.youtube.com/watch?v=LTllR-nOo28

Thom