Ap Strap Drive

[LotusGTR]

OK, Roy and all the usual-braking-expert suspects, let's have it on this topic.

I can go to a number of places and buy AP brake kits. Common to all of them are CP5555 6 pot calipers. What differs are the rotor options. You can get PWR, AP Strap Drive, and one mob make their own (I'll be seeing these this afternoon). They range from 32-34mm thick (the caliper is spaced for the thicker rotor) and 355 to 365mm in diameter.

There is a fair bit of difference in the price from one kit to another. $1,400 from the most expensive to the least, with the most expensive having the AP Strap Drive system.

So I understand SD is AP's take on a fully floating rotor and the benefits are the usual ones of a floating rotor (minimal pad knock off, allowance for thermal expansion etc) but they are not noisy and prone to wear as per the conventional bobbin systems.

I've yet to check out the other rotors in question, but they have been described as semi floating (which seems to be what StopTech offer), so the question is.........

How important is it to have a fully floating rotor?

How much difference do semi flaoting rotors make?

Is it worth an extra $1,400 for SD!?

Does anyone have experience of the AP Strap Drive system and or floating versus non?

The gtr.co.uk site has little if any info on this.

Thanks.

[jonn]

Try pm'ing JustinFox. I know he has, or had the sd setup.

[Roy]

The other big thing to consider is the cost of replacement rotors. Nothing worse then when it comes time to replace the rotors and you are looking at $710 each

[Sydneykid]

OK, Roy and all the usual-braking-expert suspects, let's have it on this topic.

I can go to a number of places and buy AP brake kits. Common to all of them are CP5555 6 pot calipers. What differs are the rotor options. You can get PWR, AP Strap Drive, and one mob make their own (I'll be seeing these this afternoon). They range from 32-34mm thick (the caliper is spaced for the thicker rotor) and 355 to 365mm in diameter.

There is a fair bit of difference in the price from one kit to another. $1,400 from the most expensive to the least, with the most expensive having the AP Strap Drive system.

So I understand SD is AP's take on a fully floating rotor and the benefits are the usual ones of a floating rotor (minimal pad knock off, allowance for thermal expansion etc) but they are not noisy and prone to wear as per the conventional bobbin systems.

I've yet to check out the other rotors in question, but they have been described as semi floating (which seems to be what StopTech offer), so the question is.........

How important is it to have a fully floating rotor?

How much difference do semi flaoting rotors make?

Is it worth an extra $1,400 for SD!?

Does anyone have experience of the AP Strap Drive system and or floating versus non?

The gtr.co.uk site has little if any info on this.

Thanks.

What do you use the car for? What tyres are you using (street , "R" type, Slicks)? Ducting? What wheels? If racing, the length of the races? This is important to know, because the main advantages of 2 piece fully floating rotors is heat related. If you are doing only street driving then you won't get the rotors surfaces hot enough to need low heat transfer rates or reduce the heat differential.

The big advantage of a fully floating rotor is that it allows the rotor to move to the centre of the pads. This is important when one of the pads (usually the inner) wears out faster than the other. This is caused by heat differential, the outer pads gets cooled a bit more as the wheel rotates. If there is a lack of ducting, the more open the wheel the more the temperature differential. If the rotor doesn't float, then the thicker pad (usually the outer) touches the rotor first and puts side load onto it before the thinner pad (usually the inner) contacts the rotors, this obviously creates stress if the rotor doesn't float enough (at all) which leads to premature cracking.

The AP strap drive is an example of a fully floating rotor design. As well as the above, the straps have the added advantage of reducing the heat transfer to the inner half of the rotor and hence the hub. This lowers the heat in the hub, wheel bearing and drive shaft (CV joint) thus extending their life in long distance races where heat build up occurs over a long period of time. There are other designs that utilise insulators around the bolts which limit the heat transfer and allow the rotor to float. I have used most of the designs (Brembo, AP, Outlaw, DBA, Willwood, Alcon etc) and I can't really say that any one floating design is better than another in all circumstances.

If you have decent ducting and run shorter distance races (1/2 hour or so), then I wouldn't be overely concerned with an all out fully floating rotor. It's would simply be a waste of money, unless the bragging rights and/or bling are important factors in the choice.

Tip, spend the money on increasing the corner speed and you won't need to go overboard on the brakes.

Cheers

Gary

[T04GTR]

yes. i looked into the ap kit. but after working on the brute utes, i did not get them. the cp 5555 caliper is shit. pads are expencive. and they leak.we were advised to replace them every 12 months. just not a real good caliper.

alot of people would not find these short comings on a road car, but a race car there not much better than willwood.

the rotors are very good. but expencive. the strap drive is good, (been around a while now) but changing pads is a delicate exercise, they bend easily and get runout. ie: shudder.

floating is always better. especally on rotors greater than 340~ mm

evan a completly flat bolted disc will still warp under hard braking. also it puts alot of thermal stress on the disc and can lead to early cracking. the bigger the disc the worse it is. ive recently changed from fixed 355x32 alcon. to pfc direct drive 355x35.

about the same money as ap. but the shizel. i have to get custom hats made to suit but will be alot better.

the only real problem is that floating rotors on a road car ware out depending on there design. iether the holes in the rotors flog out or the slots in the hats flog out. i went the pfc option because there is no holes to ware out.

[Roy]

I rate the PF pads and rotors as the best too... just from what i have read and like yourself, talking/witnessing the gear bsing used on race cars.

But calling the CP5555 caliper crap? That is the opposite to what i have seen, and observed. They typically go from car to car with the owner never getting rid of them. If there are any layign around at seasons end that are getting turfed i would buy them!

Do they leak through the seals or do the bores / pistons get damaged to the point that they leak?

I do hear you re the pad price, thats the main reason i have never really looked at them that closely as i am a tight ass and prefer the pad prices of the Brembo GT calipers

[sav man]

I havn't driven a car with floating hats, but our Targa car dosn't have them (does have knock-off valves though). And I don't have them on my car eather (got 355mm dba 5000, with porsche 6 pot monoblock). Now i've got a big master cylinder in my car i barly have any knock off. And the Targa only gets knock off in long, down hill stages.

A guy with a 997 turbo goes to our track days, and he just put brembo floating hats on, and he said the only diference he noticed was they were noisy. But that's only at super sprints, are you planning to do more than super sprints?

[T04GTR]

ok, i will put it into perspective. the utes weigh min 1810kg. we have had temp strips on them and in the hard braking tracks, hidden valley,simonds plains etc etc. they have reached over 180 degrees. at wich point the seals just perish. once they have reached that temp, the caliper warps and you are forever replacing seals.you go to change pads and the knock back springs just push the piston out...

but we did have a driver melt 2 pistons to a backing plate once .

the utes are way underbraked. and and show the shortcomings that not many classes would experiance..

[Roy]

So how do the Alcon Type B caliper, Brembo etc calipers fair? All i see on the Brutes are te AP setups

[LotusGTR]

What do you use the car for? What tyres are you using (street , "R" type, Slicks)? Ducting? What wheels? If racing, the length of the races? This is important to know, because the main advantages of 2 piece fully floating rotors is heat related. If you are doing only street driving then you won't get the rotors surfaces hot enough to need low heat transfer rates or reduce the heat differential.

The big advantage of a fully floating rotor is that it allows the rotor to move to the centre of the pads. This is important when one of the pads (usually the inner) wears out faster than the other. This is caused by heat differential, the outer pads gets cooled a bit more as the wheel rotates. If there is a lack of ducting, the more open the wheel the more the temperature differential. If the rotor doesn't float, then the thicker pad (usually the outer) touches the rotor first and puts side load onto it before the thinner pad (usually the inner) contacts the rotors, this obviously creates stress if the rotor doesn't float enough (at all) which leads to premature cracking.

The AP strap drive is an example of a fully floating rotor design. As well as the above, the straps have the added advantage of reducing the heat transfer to the inner half of the rotor and hence the hub. This lowers the heat in the hub, wheel bearing and drive shaft (CV joint) thus extending their life in long distance races where heat build up occurs over a long period of time. There are other designs that utilise insulators around the bolts which limit the heat transfer and allow the rotor to float. I have used most of the designs (Brembo, AP, Outlaw, DBA, Willwood, Alcon etc) and I can't really say that any one floating design is better than another in all circumstances.

If you have decent ducting and run shorter distance races (1/2 hour or so), then I wouldn't be overely concerned with an all out fully floating rotor. It's would simply be a waste of money, unless the bragging rights and/or bling are important factors in the choice.

Tip, spend the money on increasing the corner speed and you won't need to go overboard on the brakes.

Cheers

Gary

Gary et al, R specs, R34 GTR / BB LM rims, sprinting and 'spirited' road use. No racing, I'm too chicken. No ducting. I guess if the brakes get too hot I just slow down as it doesn't matter if I do. From the various posts it sounds like they're a good thing, but not necessary for my application.

I might spend the 'savings' on a decent clutch and perhaps a Nismo diff as I suspect mine is tired.

Suspension I've got old and stiff coilovers and some swaybars. Most of the critical bushes have been replaced and I'm running a small amount of castor and camber. Lower ball joints are stuffed but $$ to replace so I'll wait for another day.

Thanks for your input.

[Ronin 09]

nah don't worry about extra $$ on floating.

a big rotor with lots of heat capacity will be more than enough for street.

give me a call if you want to have a chat - I'm back in melb

cheers

[LotusGTR]

nah don't worry about extra $$ on floating.

a big rotor with lots of heat capacity will be more than enough for street.

give me a call if you want to have a chat - I'm back in melb

cheers

Thanks - will call this week.

[T04GTR]

So how do the Alcon Type B caliper, Brembo etc calipers fair? All i see on the Brutes are te AP setups

they are better. pads are easier to get. not saying that they are rubbish, just under the extreems of the utes racing they just barely cut it.

but as a road caliper they would be faultless. they would benifit from some better pistons but.

[LotusGTR]

they are better. pads are easier to get. not saying that they are rubbish, just under the extreems of the utes racing they just barely cut it.

but as a road caliper they would be faultless. they would benifit from some better pistons but.

I'm pretty sure I get what you're saying, but my application is road and sprints. Far less arduous than the racing utes, so I'll assume your description of 'road' extends to light track applications?

[Roy]

Dont be weak...if you are going to go 18" wheels just grab the 380mm brembop rotord with F50 calipers....BIG DADDY BRAKES!!!!!!!

[LotusGTR]

Dont be weak...if you are going to go 18" wheels just grab the 380mm brembop rotord with F50 calipers....BIG DADDY BRAKES!!!!!!!

Troy! I'm confused enough. I'm sticking with AP. I don't reckon 380 will fit under my rims and I'm sure 356 / 365 is more than enough for me. I bet your option is bigger $$ too.....

[Ronin 09]

troy has had more sets of brakes pass through him than bad curries.

he's never used any of them though...

[Roy]

I am crook as a dog at present, from silly curry. I have to say the 380mm rotors are just big enough to sit cooly in the corner of the lounge room. Very cool looking things...and were relatively "cheap" like the birdy Just to find a cool V35 to put them on

[Beer Baron]

I am crook as a dog at present, from silly curry. I have to say the 380mm rotors are just big enough to sit cooly in the corner of the lounge room. Very cool looking things...and were relatively "cheap" like the birdy Just to find a cool V35 to put them on

you think they are cool, until you see the 400mm mines curved vane jobbies I just sold to russ. when he's farked them and onto the second set hit him up for the old ones for lounge room display duty I reckon.