Post by jkdv8 on Dec 1, 2015 23:06:11 GMT -5
So is there a difference in the bore on the setups with 16" wheels vs the 15" that use different size calipers and rotors. I tried to take a pic of mine but couldn't get a clear photo and my phone battery was giving out
Different calipers/rotors, yes, different rim sizes, no.
All the Gen 1 Sports came with 15" rims even the '99 Limited. Those are all 15/16".
All the Gen 2 Sports came with either 15/16" or 1". I don't know what the relationship is between the rims and rotors. I didn't realize until fairly recently that there were two different rotor/caliper sizes on the Gen 2 Sports.
I got this from the 3G guys ... The BMC bore size is tied to the rotor/caliper size. They have two or three different rotor/caliper configurations. I am positive of two - the 'standard' size that came on the NA ABS and non-ABS GTs and the 'Big Brake' setup that came on the turbo VR4 GTs. I have read snippets that suggest a third size that I think is a different caliper but same size as the 'standard' rotors. They use 15/16", 1" and 1 1/16". The two 'standard' sizes use the 15/16" and 1" and the turbo 'Big Brake' versions use the 1 1/16". The BMC bore diameter is tied directly to the capacity of the brake caliper. So, there were no 'Big Brake' systems with a 15/16" or 1" BMC. Ever. Likewise, the 1 1/16" ONLY came on the BB setup. It was never used on the smaller brake setups.
This all makes sense to me since if you have a bigger caliper (more fluid volume) you have to have a matching BMC that can move that much fluid. This is the issue I theoretically have with my big Sport. I replaced the stock calipers with slightly larger Exploder calipers in the back and MUCH larger GM 1/2 ton calipers in the front. The fluid volume of the combined calipers is much greater than the stock calipers so I need a BMC that can move more fluid volume in the stroke of the brake pedal.
So, if you assume that Mitsu followed the same logic - and there's no reason not to since this is just engineering - the Montero and Montero Sport (Eclipse, EVO, etc.) would follow the same design. In the design, the size of calipers is not based on the bore size of the BMC. The bore of the BMC is dictated by the size of the caliper.
Following the same train of thought, if you have the smaller rotor/caliper setup, then you should have the 15/16" BMC. If you have the larger rotor/caliper setup, you should have the 1" BMC.
I would hesitate to say that if you have the big rotor/caliper setup and a 15/16" BMC, you should run right out and change to the 1" BMC. AFAIKT, in theory this is how it should work. But, I don't know that there isn't some hokey reason that Mitsu put an undersized BMC on the big brakes or vica versa.
The only absolutely positive way to find out is to supply Mitsu with the respective VIN and see what they say. The problem with that is Mitsu doesn't list the bore size of the BMC. You'd actually have to order one in, get it and look at the casting. It would also have to be a NEW one, not a rebuild or re-manufactured one, because the only castings that I'm sure have the size on at this point are the original OEM castings.
I'm going to dig through my FSMs this weekend and see if I can come up with some more information. This is one of those times when I wished I had a full set of Gen 2 FSMs.
Edward
That makes sense. Still haven't gotten another chance to check mine but when I do, I'll post.