I have searched about this in the forum, but haven't been able to find anything to help. My wife has a s5 Vert and the LR caliper is sticking causing issues. We have already rebuilt it, but it's still acting up. The calipers for the rear of these cars are getting harder to find. My question is are there any other cars where a rear caliper is close or able to be modified to fit on the rear of an FC? Any help would be greatly appreciated, and if there are any other questions, I'd be glad to try to answer. Thanks in advance!!

 

[QUOTE=wankel1988;12429652]The calipers for the rear of these cars are getting harder to find. My question is are there any other cars where a rear caliper is close or able to be modified to fit on the rear of an FC? /QUOTE]

That's a question I've been pondering myself. The Rx-8 looks to be of a similar design and the rotor width I believe( from my Rockauto searches) is the same. I'm sure it won't bolt on though I haven't held one in my hands yet. I've been thinking about buying a used one from Ebay and seeing what it would take to retrofit it.

 

Thats a thought, I really hadn't thought about a RX8, but looking at it, the possibility is there. I may have to check some of the salvage yards around here and see what I could come up with as well. Beyond that, I'm not sure. Thanks for the idea though!

 

Damn I didn't know the rear calipers were hard to find now. That's not a good sign.

It looks like you can still get caliper slide pins. Maybe a new set of those will keep it from binding?

Also, FWIW, the FD front calipers work. Rears are not interchangeable.

 

That's good to know about the FD front calipers. However, the FD front caliper pistons are smaller than the FC. FD are 1" versus FC which are 1.4".

 

Wait, really? I have a set of FD fronts on my FC, but still have yet to drive it since doing the conversion (from single piston front + solid rear to FD front + vented rear). Will the difference in piston size cause a noticeable difference in driving?

 

Single piston front caliper is 2" dia or 1 x 3.14 in^2 cross sectional area
Quad piston FD caliper is 1" dia or 4 x 0.79 in^2 = 3.14 in^2 cross sectional area
Quad piston FC caliper is 1.4" dia or 4 x 1.54 in^2 = 6.2 in^2 cross sectional area

So in your case, there's no change in theoretical breaking performance since cross sectional area of front pistons are the same as FD 4-pistons. That was a cleaver move on your part. Replacing 4-piston FC calipers with 4-piston FD calipers would would lead to decrease in theoretical braking performance by about factor of two since cross sectional area of front pistons are half the area. This assumes no change in master cylinder.

Keep in mind that the FC is about 550 lbs heavier than the FD, so the FC's increase in breaking performance is a worthwhile improvement.

 

that is incorrect, the FC and FD have the same size pistons, 36.1mm or 1.42" i think they literally are the same part number. pretty sure they take the same rebuild kit too

 

That's what I got off the Rockauto website.

FC: RAYBESTOS RC3841 Bore Size 1.42
https://www.rockauto.com/en/moreinfo...192395&jsn=379

FD: RAYBESTOS FRC10383 Caliper Piston Diameter (IN) 1.000
https://www.rockauto.com/en/moreinfo...192496&jsn=446

 

The FD and FC 4-Piston caliper pistons are the same size. The FC is heavier than the FD for some models (S5 turbos, Verts, etc), but not 550 lbs heavier.

 

Yeah, I went back to the Rockauto website and checked p/n's for the FC and FD front caliper rebuild kits (as j9fd3s mentioned) and p/n's are the same. So, Rockauto screws-up again with presenting data on FC and FD front caliper sizes. So, don't shoot the messenger.

Regarding the weight, the FC weight varies from 2,696–3,492 lbs (according to Mazda RX-7 - Wikipedia) depending on trim line and FD weight varies from 2,685–2,954 lbs (same source) depending on trim line. So, the weight difference between the FC and FD can vary significantly depending on the trim lines (from 11 to 538 lbs) based on these numbers. Not my numbers so again don't shoot the messenger.

 

Yeah those numbers are inflated. The FD sounds about right, but no FC weighed 3,500 lbs.

I thought there use to be a sticky that listed the weights, not sure where it went...

See this thread:

https://www.rx7club.com/2nd-generati...istory-552354/

The​ weights are listed at the beginning and most are in the ballpark. Icemark commented later stating the S5 convertible weight listed was incorrect. The heaviest FC didn't make it over 3,100 lbs.

 

Rockauto just shows you the unedited catalog for whatever brand you're looking at, and these things vary from decent, to being from Mars. for any spec it is best to just use the Mazda manuals, they are correct, everyone else is suspect

 

Yeah, I agree. Mazda sources are always the best first choice. The Mazda RX7 Technical Data (TD) sheets are always my first source for data. The FC TD sheet (P. Braking System, TD-13) specifies the "wheel cylinder bore" (i.e., piston diameter) for all available braking configurations. However, the FD TD sheet (P. Braking System, TD-14) provides no specifications whatsoever for the "wheel cylinder bore".

 

lol it was in the service highlights book, which is the only place i looked.... that is the pitfall with the Mazda stuff, its usually there, but there are a lot of books it can be in

 

Just a heads up. Rockauto has rear calipers again. Unfortunately they only have the right side which doesn't help the O.P. That said maybe they will have left ones soon since some right ones popped up.