BHORT

What is the difference if any between the AP racing 4 pot brake conversion offered by GGR and that offered by scoobymania? I suppose that both would offer a big improvement compared to the standard UK 4 pots.

Mike Tuckwood

The kit sold by GGR has different calipers (I think) definately different discs & pads.

Our (Scooby Mania) kit was developed directly with AP Racing purely for Subaru Impreza Turbos.


HUGE improvement over 4 pots!


Mike.

BHORT

Makes things very confusing for the interested amateur.

BHORT

Craig H,

Which GGR kit did you have? and did you investigate the difference between the one supplied by GGR and the one supplied by Scoobymania. I think that one of the difficulties with this sort of thing is that if you buy Heinz beans form 5 different places you will get Heinz beans but with AP racing brakes that does not seem to be the case. Was the kit that you have purchased about the same cost as the Scoobymania kit, GGR does not publish prices on their web site. How did you find the service at GGR I would prefer to use them if possible as I do not live too far away, I may have my geometry changed to prodrive settings there as well.

Craig H

Just got the GGR kit - would've gone Scoobymania but had to go Visa. Sorry guys. Can't believe how much lighter the calipers are than the std 4 pots. Differences should be huge, just bedding them in. And they look the 8ollox.

Mike Tuckwood

Makes things very impressive for the 'enthusiastic' amateur.

Stef

Bhort.

Correct me if I'm wrong, but I believe the GGR kit also uses drilled discs, whereas the Scoobymania kit that I have utilises grooved ones.
AP seemed to think this was more suitable for the Impreza, which is good enough for me!!
I think the price is probablty pretty similar though, so it comes down to personal choice and which pads you get with it.
My advice (seeing as Craig would have if they took Visa!!!!) would be to get the AP 'developed for Impreza' Scoobymania one.

Stef.

Hermanator

Drilled discs are good aswell as grooved.

Mclaren F1, F1 GTR All quick porche, most GT cars etc.
Cost could be a factor in the drilled/grooved argument, it certainly is in the seperate bell situation.
Does anyone know which family of AP four pot is supplied by GGR and what size disc, is it a floating assembly ?

pnebbs

From what I have heard over the years drilled disks are slightly more effective at removing the dust and gas build up than grooves, but on tracks there is a higher risk of the disc cracking - on the road drilled discs will be fine

Paul

Craig H

My GGR kit has grooved not drilled disks for the same reason that Mikes given. What I was concerned about was that the calipers were the proper road ones. I can't fault the service. Ordered on tuesday, stock came in thursday, delivered friday. First choice would've been SM if they'd done Visa though. Tried em out first time last night and they're awesome.

Mike Tuckwood

We are unable to find any evidence that drilled discs are better, though the correct size/quantity of groove is important.

Drilled discs simply are not as strong as solid/grooved discs nor do they have the outright performance ability of a solid/grooved disc.

Total performance and reliability were pivotal in choosing to use grooved discs to the complete exclusion of drilled discs.

Mike Tuckwood

Drilled discs are not as strong, simple as that. <I>(Ask John Felstead if you don't believe me).</I>

Cost was not an issue in determining which discs to use when we planned our upgrade kits with AP Racing technical staff.

Floating Discs were ruled out very early in the planning stages, not through cost but for performance related reasons.

This advice came from AP Racing technical staff and another supplier's technical department were in agreement.


<I>Bl00dy Nat West, if only they had got their fingers out!.</I>

Mike.

johnfelstead

a bit of info on the drilled / slotted disk debate.

benefits of drilled disks: lower weight ,slightly less prone to green fade(fade caused by gasses escaping from the pad resins), looks racey.
benefits of groved disks:high strength,still good green fade charicteristics,lower pad wear than drilled, longer disk life.

disadvantages of drilled disks: high relative pad wear, lower lifespan of disk, risk of disk cracking due to "stress raisers" from each drilling(cracks spread quickly from the drilled hole when subjected to heat/cooling cycles)
disadvantages of groved disks: slightly higher weight, initial bite not as pronounced(talking milliseconds here),dont look as racey

IMHO drilled disks are an OK option for general fast road use, the cost difference between drilled and grooved is negligible.

Drilled disks are a disaster as soon as you start to use a car harder in conditions of very fast road(lots of scooby's) or track / race aplications. They have a tendency to eat brake pads at a mind boggleing rate, they need regular checking for the development of cracks from the drill holes.

You will not find any serious race or rally car using cross drilled disks, they are not reliable, they wear quicker, they reduce pad life, when used in applications with carbon metalic pads they actually reduce the effective braking as the carbon pads rely on the carbon deposited on the disk surface to grip against, cross drills reduce this surface area.

Whilst i was playing with different brake setups myself on my 350BHP cossie, i tried a set of cross drilled disks at donnington to see how they coped (curious),after about 80 miles of hard driving the result was one front and one rear disk split from outer edge to the hub, the front had 3 full width cracks, another 5 miles or so and a chunk of aprox one third of the disk would have been torn from the disk, i get shivers thinking about that.

Dont use drilled disks if you plan track days, IMHO they are dangerous, none of the race teams bother with them for this reason mainly.

strong

John,

Since you make it sound like drilled discs are dangerous for any car that goes fast, how come the latest Porsche 911 Turbo and the Ferrari 360 both use drilled discs?

Paul

Blow Dog

Because a majority of their drivers are posers =)

johnfelstead

strong, read my statement's again.

I know's what i am talking about, honest

peterhe

Porsche uses cast-in holes in their "drilled" discs. Supposedly reduces the risk of cracking substantially.
- peter

Ian Cook

and also adds another zero onto the price of a replacement disk ???

strong

John,

I know you know what you're talking about, but I expect so do Porsche and Ferrari, so I had to ask the question!

It was the "Drilled disks are a disaster as soon as you start to use a car harder in conditions of very fast road(lots of scooby's)" statement that got me -- Porsches and Ferrari's are used in this way and your comments just sounded a bit alarmest.

Paul

strong

So I take it that unless the kit description says they are using cast holes (do any aftermarket kits do this?) then they are using strength sapping drilling?

Stef

Yes, but those discs aren't really 'drilled' are they, as they are cast with the holes already in as Peter said.
They can't then really be put in the same category as standard drilled discs.

Stef.

johnfelstead

strong, none of the aftermarket disks use cast holes, it is just too expensive.

The reason drilled disks suffer from cracks is mainly due to tiny tears in the metal on the side of the drilled hole, these are unavoidable on a drilled hole.

These tears act as a stress raiser and expand and contract with the heat changes untill a crack starts to develop.

Once the crack sets in it will spread very quickly on a brake disk, most people will not spot this until it has reached a very dangerous point.

I worked in Non Destructive Testing for 5 years working with Ultrasonic, Xray and Eddy current test systems used to detect and monitor crack propogation, mainly in the aerospace and nuclear industries. This is a huge issue for them. One of the most time consuming tasks that an aircraft goes through during maintanence is crack detection using mainly eddy current testing techniques.

The point i am trying to put accross is that if you plan to do track day driving and fast road, why take the risk, the gains in using drilled disks on your road car are non existent.

Try this little experiment for a graphic ilustration of how cracks spread from a tear/cut.

get a thin piece of metal, steel or alloy, about 6" long and 3" wide. At half its length put a small knick in one side with some tin snips or a small cut with a hack saw.

start to bend the metal plate up and down in fairly fast but relatively small movements.

Watch how a crack will start to apear on the side with the knick but nothing on the other side and how quickly it spreads accross the plate.

Now think again about what disks you fancy stopping you from 150MPH

Hermanator

All good points, but i think we must all agree that any of the good quality aftermarket brake conversions (AP, Brembo, ALcon etc) drilled or grooved will be a significant improvement over the standard sti style brake setup.

Stef

Agreed Hermanator, but that wasn't the original question!

Stef.

[This message has been edited by Stef (edited 18-03-2000).]