4g S/SI to vtec brake swap: There’s a common misconception about the 4th gen’s popular vtec brake swaps, in that the calipers are different between S/SI’s and vtecs. They are NOT. In fact ALL 4th and 5th gens have the same calipers front and rear regardless of what trim level. The part numbers from Honda won’t match due to change in manufacturers, but the caliper pistons do have the same part numbers. The pistons will also measure in at 2 ¼� across for the front and 1 5/16� for the back. In addition, the 3g Si’s also use the same calipers front and rear as the 4th and 5h gens. The difference between the vtec and non vtec model Preludes is in the rotor diameter and caliper bracket. The vtecs have an 11.1� rotor where the non vtecs, including 3rd gens, have a 10.2� rotor. That 1" difference makes an 11% improvement in braking torque.
Other 4th and 5the gen info: Though you cannot swap the rotors between the 4th and 5th gen’s short of swapping the whole knuckle, the amount of break torque they produce is the same. However, the 5th gen has a bigger booster than the 4g but they share the same mounting gasket. This means that if you want less brake pedal feel you can swap it into your 4g Prelude Or use the 4g booster in a 5g for more pedal feel. If you put this in your 5th gen you should go with a 15/16� master cylinder to increase the brake line pressure. Of course this requires a custom bracket.
4th and 5th gen factory brake setup: Though they have different mounting, the master cylinder on all 5th gens and all Si/ vtec 4th gens is 1� where the S model 4g will have a 15/16� master cylinder. The biggest MC bore Honda makes is 1� but you can increase brake line pressure by going to a smaller MC bore. The drawback to doing this is that the pedal throw will increase slightly to get the same amount of braking. For the performance oriented, this isn’t a bad thing since a longer throw makes the brakes easier to modulate at the limit. The brake pedal ratio also differs slightly between the 5g and the 4g Preludes. The 4th gen has a pedal ratio of 4:1 where the 5th gen has a 3.3:1 ratio. Again you see that the 4th gen, between the smaller booster and higher pedal ratio, has an easier to modulate brake pedal with the same clamping power of the 5th gen.
Legend/ NSX brake swap: This was long thought to be the factory big brake setup. In fact both have less caliper piston surface area than the factory 4th or 5th gen Preludes. (see source at bottom) These calipers do have a benefit over stock in that the NSX clampers are a lighter alu alloy and also moves the brake bias rearward some. Just swapping the calipers is not worth the trouble for most. You could add the Legend GS’s thicker rotors on your 5g for added brake heat capacity. Since the brakes were designed for a car 600lbs heavier than the Prelude’s, they can withstand a bit more heat. The rotors would have to be redrilled with a 4x114.5 bolt pattern to be used on the 4g or the 5g knuckles swapped in.
The ultimate 4th and 5th gen brake setup? It depends on the drivers needs. Each setup has its pro’s and con’s. Probably the best setup using factory parts would have to be Legend GS rotors and calipers. You’d need the calipers, brackets, and rotors from a ‘94-’95 Legend GS 6 speed to do this. Remember, the Legend rotors have to be redrilled to fit the 4th gen Prelude. Prelude calipers would yield slightly better braking but you’d have to file 2.5mm of pad material from each pad to compensate for the thicker rotor. You could also use the more costly NSX caliper to loose some unsprung weight, but at the cost of slightly worse braking performance than even the Legend calipers. Realistically, there isn’t much difference in brake performance between the three calipers so the simplest way wins out.
More on 3rd gen calipers: We now know that some of the 3g’s calipers are the same as the 4th and 5th gen’s calipers. All 3rd, 4th, and 5th gen Preludes have the same rear caliper piston size. The SE and SI came with the afore mentioned 4th and 5th gen calipers. The abs equipped and S model 3rd gens have 21/8� caliper pots up front. Master cylinder bores are 15/16� for the SI’s and 7/8� for the ALB and S model Preludes.
Possible 3g brake setups: Since the 3g’s calipers are the same as the 4th and 5th gens, the Legend/ NSX swap may also be possible. Though not with the bigger rotors. Stay tuned on this.
2nd gen factory brake info: Now we start seeing more of the Accord. The 2nd gen Prelude factory brake set-ups were somewhat different between the 85-87 and 83-84 model years. The 85-87 fuel injected 2nd gen Preludes came with the same brake setup as the 86-89 non-Lxi Accords. Front caliper pot diameter is 2 1/8" where the rears are 1 3/16". Canadians got a rear drum set up with a 3/4" piston. The carbureted 2g got 2" front caliper pots and the same rears as the FI car. Both engine versions got the same 7/8" master cylinder bore. The front rotors on the BA3 are 9.5" where the rears are 9.4". They are the same part number as some models of 86-89 Accords (DBA). Now here’s the curve ball. There was a 2g with anti-lock brakes. It had 9.1" rotors up front. All 83-85 2nd gens had the carb'ed models brake setup. However, the 1984 year model Prelude has two different part numbers for the MC, but they have the same 7/8" bore.
2nd gen brake swap info: The 85-87 2g Si uses the same calipers as the 3g S and the 87-89 Accord non-LXi’s. The Accord LXi uses the same caliper as the 3g SI/ SE Preludes. Since 3g SI/ SE’s have the same calipers as the 4 and 5g Preludes, they can use their calipers or Legend and NSX calipers. Therefore I believe that if one swaps the front knuckles and brakes of a 3g SI/ SE or 88-89 Accord LXi into their 2g, they can use later model calipers. This is only a theory at this point. From all the part numbers I’ve cross referenced, it seems like it would work.
1st gen factory brake info: First gen Preludes again get separated into two groups. 1979-’81 and 1982. Both had the same 2� front caliper pot but the ’79- ’81 Preludes got an 11/16� rear piston while the ’82 got a ¾�. Even thought 1st and 2nd gen Preludes had 2� front pistons, they’re different and won’t swap as far as I know. The front rotors are 9.09�, same as the 2g but a different thickness because they’re solid instead of vented. The master cylinder has a 13/16� bore.
1st gen brake upgrading: There’s not much you can do. The brakes and knuckles for the 1st gen Prelude are not found on any other model in the US. If one were serious about getting veined rotors to fit, the best bet is to see if you can use 88-91 Accord Lxi or 83-87 Prelude Si knuckles. The rotors are the same diameter as stock but veined and 7mm thicker. The determining factors of whether or not you can use another models knuckles are steering arm location, hub offset, and overall height.
The most practical place to look for more performance is in the pads, cooling, and possibly change the pedal ratio. There is no bulky booster to mess with, only the master cylinder. One could move the mounting holes for where the mc mounts to the firewall and where the mc pushrod bolts to the brake pedal. The angle of the pushrod between the mc and the pedal is very important so both these set of holes need to be moved up as close to an equal amount as possible. For each ¼� you raise the point at which the pushrod connects with the brake pedal, brake torque at the wheels increases by 8%. This is about the extent of it for the 1st gen Preludes.
Rules of thumb:
-For every inch rotor scrub area is increased, brake torque at the wheels increase by 11%.
-For every ¼� pedal ratio is increased you gain about 8% in brake torque.
-For every .01 brake pad friction coefficient is increased, brake torque is increased by about 3%.
Sources:
West Side Honda Knoxville, TN
hondaautomotiveparts.com
Tru Torque factory re-man book
http://www.dba.com.au/dba_cata...x.htm
http://www.honda-tech.com/zero...age=2 (page 2 has the brake torque numbers for the diff calipers)
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