You know..I'll have to look again but the print catalog specs it as 1.88/1.38/1.38 bores and the on-line listing is 1.75! Gotta love a good mystery. ? If it's 1.75 then the your numbers pan out. (I had a body half here somewhere I hacked on and I'll see if it's still here in a pile of scrap)

As for the other comments I will agree, however the race cars did have twin cylinders and more manageable bias adjustment which is a plus. I still think I'd look for more rear rotor mass for a track car if it were me even if I were to keep the 1.375 bores. His limiting factor might prove to thermal capacity and the thin pad nature of the D8 parts.

Another plus with doing something along the BSL4/FSL line is that they share the same pads. You may not end up with the same on each end but testing is much cheaper to do it this way to find the sweet spot. And if you're looking for an affordable robust caliper today you might want to consider the W6a or W4a part.

 

Technical discussions aside I'd like to put up a bit of a summary of some of this for those who are just looking for some basic ideas.


For C2/C3 applications:

D8 caliper replacements. This is your base offering and will be a direct fit to the car, require no wheel change and have a modest assortment of pad compounds to choose from. Some suppliers are offering them in pairs of four wheel kits. They come in a variety of finishes for the buyer; clear silver, black, red and even polished. Cost vary some by supplier and by finish so inquire before you order. Being a direct replica of the D8 they do not require a mc change or anything beyond what you do now for your needs with the old iron parts. They won't transform your car into a fire breathing race car, just offer a more reliable part with improvements in appearance and reliability. However with proper pad selection they'd be quite track day worthy- rotor life probably being the limiting factor.

13 and 14" BSL6 front kits. These kits will require you move to a 17 or 18" wheel (14" kits) and will be fit with a radial mount BSL6 caliper. The piston area of these kits will be less and thus pedal feel will go up and effort to push them also. Often the move to less area is desirable for improved 'feel'. If it's found that the required effort is too great a step down in mc bore may be necessary for some folks. The larger rotor will be more efficient for thermal needs and function at a lower duty cycle. Wheel fit with the kit is very good given the narrow body. Thinner pads than some more 'hard core' calipers are standard. Stock wheels will not fit again.

13 and 14" BSL4 rear kits. These kits convert the rear to a two piece set up and come with four pot calipers matching the six pot fronts. Again piston area is reduced and countered by the larger diameter rotor to counter a bit of clamping loss with more leverage. The kit shares the same pads as the front kits and wheel fit issues are also the same.

The above factory front and rear kits are best paired as a package. Mixing the BSL6 kit with D8 kits etc would or could be a problem for users and offers no real benefits.

Custom kits and tuner kits. A number of suppliers offer other 'house' kits that are not factory kits. Nothing wrong with that and it should not deter you from reviewing the options. But be certain you understand the whys and hows of their design and compatibility to your car and needs; intended use, wheel fit, weight, ease of fit etc.

Race kits. For some who are considering full blown race car builds much of the above remains a consideration but you may wish to move to much beefier calipers with much fatter pads. This can present alternate issues such as wheel fit, rotor width choices and maximum diameter issues. Building the most bad-*** kit of 14" could be a problem if you plan to run 17s....Plan ahead and consider your options and pros/cons for your parts.

 

I stand corrected the book on the GNIII states 1.75 not 1.88. I was flipping through and apparently looked at a wrong number.

As a side thought to using a GNIII, the BSL4 comes 1.88/1.75 for 5.6sq" app if one wishes. And I know it can be pushed to about 13.5"d rotor fit without issue.

 

Todd: Very good summary. I'd like to add my combo as I feel it is cost effective with good results:

I'm using SL4's (Superlites) on the fronts and DL (dynalites) on the rear with stock rotors and 17" rims. I think the SL's could fit behind 16" rims also. The calipers were from corvettengineering.com.

What I found with this setup is that the SL4's have a slighlty smaller piston area compared to stock and that combined with sticky 17" tires meant I was not able to lock the wheels even with power brakes.

To fix this I switched to a manual brake master cylinder (kept the booster). The manual MC has a 1" bore, power MC is 1 1/8". This gave me enough line pressure to lock the wheels.

I do have premature rear lockup, although it is slight. I'm planning to switch to a 13" rotor up front with no other changes and see if that fixes it. If not I will add a prop valve.

Edit: Originally wrote that I have front lockup, I meant rear and edited it above.

 

Two thoughts here:

1. Moving to a 13" rotor will technically add more front torque. If you have front lock up now this could make it worse.

2. A prop valve should never be installed in a front system. They are based on line in pressure to reduce line out. In other words, the harder you push on the pedal the less front brake you have. I'd take foot modulation over that.

You may want to review the rear piston size in use now and consider enlarging that some. Inexpensive purchase. A pad compound review might also be in order as you can swing bias 5% or more with a pad change.

Hope that helps.

 

zwede,
A slight bit of front wheel lock up is always preferred over rear wheel lock. And follow Todd's advice to NOT use a prop valve in the front line. It's absolutely the wrong dynamic. The 13' rotors are going to add front brake torque. If the front wheel lock gets unmanageable with the 13" discs, you could also consider going back to the 1 1/8 power master cylinder to stiffen the pedal and take a little leverage/pressure away.

 

Sorry, don't know what I was thinking when I wrote that. I have premature rear lockup, not front.

 

The front brake upgrade should play well then. In the mean time on the rear wheel lock-up, the adjustable prop valve in the rear is the next item to consider, if you don't already have only. And in the case you have adjustable shocks, you can slow the dampening down on the rear to front weight transfer with more bump control on the fronts and more rebound control on the rears.

 

I'm running the forged superlites in front and 1.38 dynalies in the rear. I order the narrow dyanlites so had to struggle with making my own adapter plate. Do not get the narrow (mounting ears) ones!

I just bled the rear calipers last night. Ran the SL's on the front for tow years and they work very well. Hope to have it back on the road in a few weeks but becuase this is part of a 5 link modification this has taken a lot of time and effort. Tonight Ihope to get the parking brake back together and working.

 

[QUOTE=DaveL82;1569410370]I'm running the forged superlites in front and 1.38 dynalies in the rear. I order the narrow dyanlites so had to struggle with making my own adapter plate. Do not get the narrow (mounting ears) ones!

The Narrow Mount Dynalite and Narrow Mount DynaPro (3.5") mount calipers were made to go on in place of the same 3.5 mounting that is used on the Superlites....it's the same mounting...but it's not always a cinch making adapter brackets for anything....