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#291
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Mate defiantly the bore size difference is considerable , But between the 2 pots and brembos as a whole are physically the same size including the gap for the pad area . So the difference you see in size here is relative.
Hense why Doug and alot of others dont run rear Brembos . They even weigh around the same . Fronts obviously no comparison but rears are close to same size and shape just piston diameters differ . Your welcome to come past and compare in the flesh . The measurements are piston size the exposed part of the piston is tapered as you say and still big differences. Last edited by amtrapid; 23-12-2015 at 11:41 AM. |
#292
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Sent from under my Dok Dok |
#293
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I appreciate your measurements. Always good to have the data there. Further to the discussion. Pad size/area makes absolutely zero difference to braking torque. (It does however make a difference to pad life and heat handling capabilities and weight) And caliper size/length material and weight etc also makes bugger all difference to braking torque. It does however affect things like caliper rigidity, which influences pad wear characteristics. Aswell as heat handling, and also the weight. With braking. The important factors that effect the effectiveness of the system are : Pedal ratio (or lever ratio in the case of the hydro handbrake) this is the mechanical force multiplication to the master cylinder by way of the pedal (lever) mechanism. Master cylinder bore. The area of the master cylinder coupled with the force applied to it will result in the hydraulic pressure generated. Pressure = force / area. Hence SMALLER master cylinders generate MORE pressure for a same given force input. But the trade off is longer pedal travel and worse pedal feel because they move less volume. Brake caliper piston area. The LARGER the pistons, the GREATER the braking force, because a larger piston has more area for the hydraulic pressure to act on. Its interesting to note that opposed piston calipers dont make any more braking force than sliding calipers with half as many pistons, given the same piston size. But opposed piston calipers do usually give better rigidity and weight savings, dont have the same issues with sliding mechanism, And look way better too. Radius that the brake caliper/pads are acting on. This is effectively the disc diameter. Bigger diameter means more braking torque. More importantly with racing, it gives better heat handling due to bigger/heavier disc and more surface area to dissipate the heat away. With the trade off being more rotating mass. And lastly. Brake pad friction co-efficient. Also called 'mu'. This is effectively how grippy the pads are. This gets pretty complex with various pad compounds and is greatly effected by heat etc. In my quest to do a wicked skid in a Subaru. Ive tried playing with the lever ratio. With both the first twin cylinder arrangement i had, and also on the STi tandem cylinder. Ive tried changing the master cylinder bore. (By going from a twin side by side arangement with 0.625" bores, to a tandem arrangement with a slightly larger 0.7" bore.) Even though the STi tandem is bigger bore than the twins. Its inline design does not double its surface area like the twins do. I havent tried changing the rear calipers yet. Its a fair bit of added expense due to probably changing pads, discs rotors, and lines at the same time. But its not something im inpartial to, if i cant fix it other ways. Im hoping that maybe the Nissan calipers discussed before would be a straight swap onto my existing rotors, lines and even maybe pads. (Fingers crossed) i dont paricularily want to change rotors as i currently have 3 piece Biot rear rotors. And they cost a pretty penny. And they are sexy as. A cheaper alternative could be trying a more aggressive rear pad. I currently have Cosworth street pads. Oh yeah. While we are talking about brakes. These came in the mail yesterday. 355mm front Wilwood rotors. Straight swap onto my existing rotor hats. (With new bolts for safety) Still waiting on the hardware to space the calipers mounts out to suit. i opted for the slotted Spec 37 instead of the wanky electro coated, SRP drilled and slotted rotors. The drilled rotors are for 'show' and are considered a bad choice for track work. Unlike the old days of racing. The drill holes are purely an aesthetic thing now with advances in pad compounds that do not require drill holes to help with out gassing. Check out how big they are compared to a stock standard Forester rear disc. If they were a few MM bigger, i could fit the entire Forester rotor INSIDE the Wilwood rotor.
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#294
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So the rears you need are Subaru 2 pots which will bolt straight on . Or the Nissan ones . They cost the same I've researched it and thought about buying some Nissan rears and painting them a plain colour for use on Subarus If they were cheaper ,but they go for the same price so no point doing it . So the Nissan and Subaru rear factory suitomo 2 pots have pistons that are identical . Yes they are bigger pistons then the brembos . Ive had the nissan and the Subaru ones apart and measured . But the nissans do use a slightly larger rear disc with that caliper compared to the Subarus . Maybe try the Nissan project MU formula D spec pads on the rear if you get the subaru calipers as they will fit . Thats what Im using in my Subaru 2 pots with they Hydro setup Last edited by amtrapid; 23-12-2015 at 06:48 PM. |
#295
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Doing it for all the wagons out there Last edited by Bram; 23-12-2015 at 09:31 PM. |
#296
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R32 gtr rear brembos will fit a subaru as 2005 sti brembos will fit 32 rears with out modding . The Nissan r32 GTst , GTR 2 and 4 pot suitomo will interchange as well. Not sure about r33, r34 as Ive only owned and played with an R32 GTR . But Ive had the subaru suitomos and nissan ones side by side on a bench and yes there exactly the same. I'm pretty sure the 300zx twin turbos are the same as well . I was reading somewhere years ago that FC RX7 fronts and rears are also the same suitomos. An option I have seen used on Subarus with an adapter are Porsche Brembos mate
Advice on Porsche calipers....Which to go for? - Subaru Enthusiast Forum - ScoobyNet.com |
#297
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If so, then i will keep an eye out on Yahoo auctions for a set. As said, ive already got a set of multi piece rotors in the rear brembo size. So a simply caliper swap up to calipers with 40mm pistons would be easy and make a good improvement for very little financial outlay. But im not even gonna bother if i have to then dick about with rotors fouling etc. And that is my only concern there. If i was to have to do rotors aswell, then i wouldnt even bother with 2 pots. Id go straight to a small set of 4 pots. There are a few off the shelf kits with adapters and rotors. Like the APs etc. (But pricey) Or get a set of radial mount calipers and make/machine adapters to suit. There are literally tons to choose from from brands like alcon ap stoptech wilwood etc etc. For example, just now i am looking at the Stoptech STR-42 line up (smallest 4 pot calipers they do), they have a model that would even be a damn closr fit for diameter and width of STi rear rotors. And have them in multiple piston size too, so you could pick a really good match. All that would be needed is the adaters from STi backing plates to the radial mounting of the caliper. This would need to be custom. And possibly brake lines too. Being able to use the existing 3 piece rotors would be a positive. Quote:
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Doing it for all the wagons out there Last edited by Bram; 24-12-2015 at 12:31 AM. |
#298
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The other option is as I think you have tried to look at is mount another set of calipers and have them on their own circuit to the Hydraulic hand brake. Yeah you scored with the Willwoods they are now up to 2600 landed for fronts due to our shit dollar Last edited by amtrapid; 24-12-2015 at 08:30 AM. |
#299
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These are at a good price Import Monster | View Z33 Z R brembo K1995
But I dont know the specs of Z33 rears or weather they would fit . All the others ATM on Yahoo seem to be R33,R34,R35 and the Z33 Brembos |
#300
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