rotor diameter 250 mm .81" width
brake pad area: 5.787 inches squared
Single piston floating caliper 1.892" bore diameter
1.892" x 1.892" x .785 = 2.810 inches squared of functional surface area
2.810/0.518 = 5.425:1 clamping force ratio
Single piston floating caliper 1.181 bore diameter
1.181" x 1.181" x .785 = 1.095
1.095/0.518 = 2.114:1 clamping force ratio
rotor diameter: 298 mm one shown (variable in size) recommend using a .81" width
2 hat sizes that fit 89 to 94 GT(i): 6 x 6.25 171-8975 = 10.75 and 11" rotors 8 x 7.00 171-7671 = 11.75, 12.00 and 12.19" rotors
(There is a pre-drilled hat that is 4x4.5 but the bore diameter is too wide and cannot be machined to fit our bores exactly.)
brake pad area: 6.36 inches squared
4 piston fixed calipers (variable piston sizes; largest 4.8 inches squared; see other sizes below)
1.75 x 1.75 x .785 = 2.404 x2 = 4.808
4.808/0.518 = 9.282:1 clamping force ratio
5.425/9.282= the stock clamping force is only 58.4% of the dynapro calipers clamping force. Flipped: 9.282-5.425 =3.857/5.425= 71.1% greater, or 1.711 times the stock clamping force.
250/298.45= the stock rotor is 83.8% of the larger rotor. increase in rotor diameter. 298.45-250= 48.45/250= .194 or 19.4% greater, or 1.194 times the stock rotor diameter. This will increase torque stopping force.
Remember that changing to a radial mount 4 piston fixed caliper (balanced on either side) will all help braking performance.
Additionally, this setup will give you access to 10 different coefficients of brake pads, and the pads are larger.
5.787/6.36= the stock pads are 91% of the larger pads surface area. 6.36-5.787= .573/ 5.787= .099 or 9.9% larger. The pad installation and removal is the easiest I have ever seen and used. All this comes with much higher price.
I did some searching and it looks like the Honda Crx Si caliper is different between 88-89:50.8 mm or 2" and 90-91: 53 mm or 2.09". The Honda are float calipers.
88-89 2x2x.785=3.14 inches squared
90-91 2.09x2.09 x .785=3.429 inches squared.
3.429/ 0.518= 6.620:1 clamping force ratio (smaller ones 3.14/0.518=6.062:1 clamping force ratio)
5.425/6.620= the stock clamping force is 81.95% of the Honda clamping force. 6.620-5.425=1.195/5.425=.220 or 22% larger
5.425/6.062= the stock clamping force is 89.5% of the Honda clamping force. 6.062-5.425=.637/5.425= .117 or 11.7% greater.
Brake pads were listed on the sticky as being larger than GT(i)s by varying amounts. I did find a brake pad outer dimensions of length with metal tabs at 132.2 mm and a width of 49.3 mm. Our pad is 115.5 mm with metal tabs (98.425 mm without tabs) and 38.1 mm wide. However, the Honda pad is a different shape so you cannot directly compare end lengths. Best educated guess is that the Honda pad is right around 10% larger.
rotor diameter: 242 mm or 10.32" there may be some variation on rotor sizes.
242/250 = The Honda rotor is 96.8% of the stock rotor. 250-242=-8/242=.033 or 3.3% smaller This will decrease torque stopping force. However, you are not using the Honda rotors with the swap. You use our stock rotors, which means no gain or loss.
The Honda caliper will give you access to more brake pads. It sounds like the Honda pads fit all the way on the our stock rotors. In my opinion if your racing a car and want to use non-street legal pads the coefficient of the pad surface available for the Honda calipers will make it worth it. If your using street legal pads the gains in my opinion will be negligible. The Honda calipers on Rockauto are under $50 a piece. The front brake mount for those years Honda should be 5.51" and ours is 5.5". Wilwood does sell a Dynapro Honda Acura caliper with the 5.51 lug mount, but it would require more investigation to how it would fit or work. Given that our Stock brake rotor is 250 mm and the Dynapro Honda caliper is for 262 mm the pad alignment may be off. Either way the rotors that go with won't work. More information on this can be found on the Teamswift archives under Honda Brake Caliper Sticky
The following are for the different piston sizes surface area for the Dynapro Radial Mount Calipers
(they are four piston calipers, but you only use 2 to calculate not 4)
1.75 x 1.75 x .785 = 2.404 x2 = 4.808
4.808/0.518 = 9.282:1
1.62 x 1.62 x .785 = 2.060 x 2 = 4.120
4.120/ 0.518 = 7.954:1
1.50 x 1.50 x .785 = 1.766 x 2 = 3.533
3.533/0.518 = 6.820:1
1.38 x 1.38 x .785 = 1.495 x 2 = 2.990
2.990/ 0.518 = 5.772:1
1.25 x 1.25 x .785 = 1.095 x 2 =2.453
2.45/ 0.518 = 4.736:1
Some more math and things to think about. You do not want to just throw on the largest calipers in the front and do nothing to the rear. Here is a great article about that:
https://ebcbrakes.com/how-to-choose-the ... brake-kit/
The article explains roughly where the stock brake setup is. You have an uneven balance between front to back; heavier in the front. If I find the time I'll show the numbers. These are just a few of things to consider when calculating the bias: wheel base, maximum inertia force, driving style, base height, suspension setup, and of course front and back weight.
The front to back system was setup in these ratios:
: Front clamping force/ (rear clamping force x proportioning ratio) I don't know actually what the proportioning ratio is. Next time I have my lines apart I will do a volume test between front to back over x amount of time. This should get me in the ball park. Let's take a guess 25%.
5.425:1/(2.114:1 x .75) = 5.425/ 1.586, 1.586/5.425 = the rear clamping force is 29.2% of the front clamping force, 5.425-1.586=3.839/1.586=2.42 or the front clamping force is 242% greater, or the front is 3.421 times the clamping force of the rear.
Remove the proportioning valve from equation to simplify the math; ratio comparison will work with or without because you will be applying the same proportioning valve to both systems and it can act as a constant. Additionally, as state I don't have the ratio of the stock proportioning valve which makes those number theoretical until that actual ratio is measured.
2.114/ 5.425 = 39%; the rear clamping force is only 39% of the front clamping force, or flipped the front is 2.566 times the clamping force of the rear. 5.425-2.114=3.311, 3.311/2.114= 1.57, or the front clamping force is 157% greater than the rear.
240 mm rear discs/250 mm front discs = the rear disc diameters is 96% the diameter of the front. 250-240=10, 10/240=.04, or 4%. The The front diameters are 4% larger than the rear disc diameter.
Front stock pads are 5.787 inches squared. I have not accurately measured out the rear pad yet; rough measure was 3.55 inches squared.
3.55 / 5.787 =.613, or rear pads are 61.3% the inches squared of the front pad area. 5.787-3.55=2.237, 2.237/3.55= .63. The front stock pads are 63% larger than the stock rear pads.
Comparison of the front to Back System with only the Front Wilwood Setup:
2.114/9.282 = .228, or the rears are only 22.8% of the front clamping force. 9.282-2.114= 7.168/2.114= 3.39, the front clamping force is 339% greater than the rear clamping force. 339%-157%= 182%, 182% ratio change forward from stock bias.
240 mm / 298.45 mm = the rear disc is only 80.4% of the front disc diameter. 298.45-240= 58.45/240= .244, or the front discs are 24.4% larger in disc diameter than the rear discs. 24.4%-4% = 20.4% ratio change forward.
3.55 / 6.36 =.558, or the rear pads are 55.8% or the front pads. 6.36-3.55=2.81/3.55= .792. The front pads are 79.2% larger surface area than the rear pads. 79.2%-38.7% = 40.5% ratio change forward
These numbers are ridiculous since a 10% change is a major change in braking balance. Currently I am running it this way and will post up some measured data to compare the stock 60 to 0 numbers with the out of balanced numbers. I am going to guess that I am still getting shorter numbers right now, but not where I want to be. Right now I simply am not taking advantage of the rear brakes which doesn't make sense. When I'm done for the type of driving I do I would like to offset the stock forward balance by 10% either through caliper and rotor change or through adjusting the proportioning valve.
Rear Forged Dynapro Low Profile Lugmount Rear Setup with Comparison Ratio to Stock:
1.12x1.12x.785x2=1.98/.518= 3.82: 1 clamping force ratio, and a reminder that 2.114:1 is the stock clamping force ratio.
2.114/3.82 = the stock rear clamping force is 55.3% of the Dynapro rear low profile caliper clamping force ratio. 3.82-2.114= 1.706, 1.706/2.114= .807, new calipers have a 80.7% greater clamping force than stock calipers.
9.282-3.82= 5.462/3.82=1.43, new setup fronts are 143% greater clamping force than rear,
5.425-2.114=3.311/2.114=1.57, old setup fronts are 157% greater clamping force than rear. 157%-143% = there is only a 14% increase in the bias toward the rear calipers.
Option 2: Dynapro Lugmount Caliper
I realized that the mount for these are the same 5.25", and the offset is only .01 different and the mount height is only .03 different. This would be some easy changes either in Freecad, or when you enter your G-code. This caliper offers a smaller piston and two larger piston selections. The larger ones would not be good, but the 1.58" bore pistons would still be an improvement from stock, and would be a larger brake pad of 6.36 . This would be the same size as the front, which is not great, but there are positives for these calipers. First the 6.36 uses a pad blank that is more readily used with more pad options, and they are a cheaper price. Second, the clamping force is less for the calipers smallest pistons. The lesser clamping force might be more appropriate with someone that uses 11" rotors in the front, or even someone who goes for a smaller piston up front.
1.0x1.0.785x2= 1.58 in squared
1.58/0.518=3.05:1 clamping force ratio. A reminder stock rear clamping force is 2.114:1
2.114/3.05=.693, or the stock clamping force is 69.3% of this option 2 rear calipers clamping force.
3.05-2.114=.936/2.114=.443, or option 2 has a 44.3% greater clamping force than stock rear clamping force.
((1.75x1.75x.785)2)/.518=9.282-3.05=6.232/3.05=2.04, this caliper setup leaves the front calipers being 204% greater clamping force than the rear.
5.425-2.114=3.311/2.114=1.57, old setup fronts are 157% greater clamping force than rear. 204%-157%= 47%, the front clamping force in this setup is 47% greater than stock. I would use this if you were stepping down in caliper pistons size in the fronts say to 1.62".
7.95-3.05=4.9/3.05=1.61, this caliper setup leaves the front calipers being 161% greater clamping force than the rear. 161-157= This is only a 4% increase in clamping force toward the front over the stock setup. This setup would potentially decrease the chances of needing
a larger brake booster.
240 mm/279.4 mm = .859, the stock disc diameter is 85.9% of new disc diameter. 279.4-240=39.4/240=.164, the new disc are 16.4% larger than the stock rear disc diameter.
279.4 mm (11" discs)/ 298.45 = the rear disc diameter is 93.6% of the front. 298.45-279.3= 19.5/279.3=.07, or the front disc diameter is 7% greater than the rear. 7% - 4% = 3% increase in rotor size toward the front.
Brake pad surface area: 5.1 inches squared.
3.55/5.1= .696, or the surface area of the old rear pad is only 69.6% of the surface area of the new rear pad. 5.1-3.55=1.55/3.55=.437, the surface area of the new pad is 43.7% larger than the surface area of the old pad.
5.1/6.36= .802, or the surface area of the rear pad is 80.2% of the surface area of the front pads. 6.36-5.1=1.26/5.1=.247, the surface area of the front new pad is 24.7% larger than surface area of the rear new pad.
63%-24.7%= 38.3%. The bias ratio front to back for surface area of brake pads has decreased by 38.3%. This increases the bias toward the rear for brake pad surface area by 38.3%.
The whole idea here is not to throw the stock front to rear ratios off by much. I don't have a way to accurately compare the percentages from clamping force, rotor diameters, pad surface area, and other variables like brake pad coefficients. Therefore, the comparison ratios all need to be kept separate. As long as the separate ratios are not drastically altering from stock I'm taking advantage of the laborious testing that Suzuki engineers did in the first place. Although, I cannot add the separate variables I can still in a general sense talk about the outcome scope that I would like. I would like to offset the front biased toward the rear by 10% collectively. My reasoning behind offset the stock balances rearward by up to 10% is the lowering of the vehicle will reduce the kinetic weight transfer forward, and like the article above my driving style is more hands on.
Total difference between new and old:
clamping force front: new 9.282:1, old 5.425:1, 71.1% greater
rotor diameter front:new 298.45 mm, old 250 mm, 19.4% greater
brake pad surface area front:new 6.36 in sq, 5.787 in sq, 9.9% larger
rear clamping force: new 3.82:1, old 2.114:1, 80.7% greater
rotor diameter rear: new 279.4 mm, old 240 mm, 16.4% larger
brake pad surface area rear:
Thoughts on Rotor Selections:
You would not want to use 10.75" rotors in the front, and 11" rotors in the rear. If your using 11" rotors in front and in back, my suggestion would be to increase proportioning valve bias toward front. If your running 10.75" or 11" rotors in front and no changes in the rear (stock setup in rear) I would suggestion not going with 1.75 pistons for the caliper, and instead go with 1.5 or 1.62" pistons and still increase the bias of the proportioning valve bias toward rear. You can crunch through the numbers to see how the bias would change, and real world testing will be the only way to achievement maximum results.