S2 Exige - Are my front brake discs on the wrong way ?

a4drk · Post by **a4drk** » Sun Apr 26, 2015 5:04 pm

I think they are ........

David

Post by **campbell** » Sun Apr 26, 2015 5:12 pm

Without understanding the physics, I think it may be alleged that it doesn't matter.

Mike Scib · Post by **Mike Scib** » Sun Apr 26, 2015 5:15 pm

It's more to do with the veins on the inside of the discs rather than the groves on the outside.

BigD · Post by **BigD** » Sun Apr 26, 2015 6:12 pm

Mike Scib wrote:It's more to do with the veins on the inside of the discs rather than the groves on the outside.

Agree but I always get confused with which way is the right way.

Don't think the groove direction matters. I've had discs that the grooves run the opposite way from different manufacturers.

http://www.zeckhausen.com/images/Rotors/how_to2.jpg

Mike Scib · Post by **Mike Scib** » Sun Apr 26, 2015 8:12 pm

Is it not to let the heat out rather than to catch/scoop cold air.

Most discs veins are straight anyway.

BigD · Post by **BigD** » Sun Apr 26, 2015 9:14 pm

I've never seen straight vanes.

Ferg · Post by **Ferg** » Sun Apr 26, 2015 10:40 pm

Standard disks must be straight vanes, if they're directional then it can't matter as they are not handed...are they?

BigD · Post by **BigD** » Mon Apr 27, 2015 7:44 am

Ferg wrote:Standard disks must be straight vanes, if they're directional then it can't matter as they are not handed...are they?

Just replaced the discs on the Elise and the originals were handed as curved vanes and each side went in the opposite direction. The new ones I put on, standard blank discs, have curved vanes and are handed too.

All the discs I've ever had on any car have been sided with curved vanes. I've never seen straight vanes and I tend to do the discs and pads on all my cars.

robin · Post by **robin** » Mon Apr 27, 2015 8:04 am

The curves should trail the direction of rotation, i.e. the other way around to those in David's picture.

I doubt it makes much difference in reality. I don't like grooved discs - they just make the pads rattle

Post by **campbell** » Mon Apr 27, 2015 8:31 am

BigD wrote:
All the discs I've ever had on any car have been sided with curved vanes. I've never seen straight vanes and I tend to do the discs and pads on all my cars.

Fascinating. I've changed a lot of discs too - one of the few things I'm capable of! - but never been aware of any handing.

Oops.

:shock

Corranga · Post by **Corranga** » Mon Apr 27, 2015 8:58 am

A quick google image search as I was convinced I'd seen straight vanes, and I found a link with straight vanes and an arrow pointing to the front

http://brakedepot.co.uk/Fitting-Guide.html

a4drk · Post by **a4drk** » Mon Apr 27, 2015 9:02 am

Thanks guys
Good link that - " the grooves lean towards the rear"
In other words - my discs are on the wrong way round
I'm going to replace them soon anyway

Thanks

David

Sent from my iPhone using Tapatalk

BigD · Post by **BigD** » Mon Apr 27, 2015 11:03 am

campbell wrote:
BigD wrote:
All the discs I've ever had on any car have been sided with curved vanes. I've never seen straight vanes and I tend to do the discs and pads on all my cars.
Fascinating. I've changed a lot of discs too - one of the few things I'm capable of! - but never been aware of any handing.

Oops.

:shock

When I ordered new discs for the Elise there was 2 part numbers for the left and right. I ordered a full set and the front and rear are exactly the same so the 2 different part numbers were for siding. I checked the box and disc for an 'L' and an 'R' as that's what my previous discs have had, just a little sticker to tell you what side. Anyway there were none so I had to check the invoice and the description on left and right and which part number matched which side. At that point I drew a big 'L' and 'R' on the corresponding boxes to make sure I didn't mix them up. Easy done when you have all 4 discs to change.

Anyway the point I made earlier is that I've had discs from different manufacturers that had 'grooves' running in opposite direction but the 'vanes' for cooling have always been the right way as per the pic above.

Grooves and vanes are two distinctly different things. I didn't bother with grooves on my replacements either as like Robin I don't see that they make that much of a difference.

All that said it does look like the vanes in David's discs are the wrong way from what I can tell from the photo. I usually stick a screwdriver in the disc to determine easily which way the vanes run. On the K sport discs I had the vanes and grooves ran in opposite directions which made me question which way was correct everytime I changed them.

David you can just swap them over if there's plenty of life in them, 10 minute job.

BigD · Post by **BigD** » Mon Apr 27, 2015 11:09 am

Here's a pic of the ksport with vanes and groves going in opposite directions.

You can see the vanes curve rearwards but the groves curve forwards.

Sanjøy · Post by **Sanjøy** » Mon Apr 27, 2015 11:36 am

Wait a minute is the caliper on the right way? It should be on the LHS.

Scottish Elises