Question: Difference between 91-96 and 97+ calipers?

[4thGenPrelude]

I'm actually a Honda Prelude owner, but I bought a set of new NSX calipers on eBay without checking to see if their application is for 91+ or 97+ NSX's. Apparently, the 97+ won't mount to my knuckle, whereas the 91+ will, so I was wondering if there were any noticeable differences between the two. I could of course remove one of my calipers and try to mount the NSX one in it's place, but if there's any easier way to identify it, it would be helpful. Any help would be appreciated, thanks

edit: i found a picture of them, I hope this helps:

 

[Larry Bastanza]

I am not 100% sure about the mounting, but the pads for the front are the same for all years. The piston sizes changed and the mounting is further outboard for the larger rotors, but they may fit. Hopefully you will get someone to respond that has both handy

HTH,
LarryB

 

[ATERPAK]

The caliper itself is pretty much the same but the mounting bracket is different. It pushes the caliper out further from the center for the larger rotors it uses. This may not work for the rotors you had in mind with this bracket. The mounting holes are the same. Good luck.

 

[4thGenPrelude]

i see, so it's looking like the only way I can tell is by trying to install one of them? If my car only had the same bolt pattern as the NSX, I could just swap brackets (as another NSXP member informed me), use a properly sized rotor and be ok, but I know of no 4x114.3 rotor that would of the exact dimensions as the 97+ NSX rotor.

I'm not so sure about re-drilling NSX rotors, and even if were to, I'm not sure if the dimensions of a 97+ rotor would be an ideal fit. It just happens to work out perfectly (or close enough) with Prelude VTEC rotors and 91-96 calipers. Thanks for the help so far :smile:

 

[nsxtasy]

These are front calipers. (I can tell because there are two pistons on the front calipers, and one on the rear.)

You can tell which year they are for by measuring the diameters of the two pistons. On the '91-96 calipers, the diameters are 40 mm and 34 mm. On the '97+ calipers, the diameters are 40 mm and 36 mm.

Another way to tell is to look at the caliper as though it were mounted on the rotor (as though you were looking through the spokes of the wheel to check the thickness of the brake pad material). With the '91-96 front calipers, you can see the edge of the brake pads to visually check the pad thickness. With the '97 calipers, you cannot.

 

[4thGenPrelude]

Excellent, thank you nsxtasy. I measured the pistons, and while there's only a 2 mm difference between the smaller pistons on the two different calipers, I believe I was able to get an accurate measurement. The verdict? 34mm from end to end, looks like I have 91-96 calipers, and I'm good to go.

Now you wouldn't happen to have 91-96 rotor measurements handy, would you? :smile: The tutorial I've read for swapping Prelude calipers with those from an NSX claims a 5mm metal shim needs to be fabricated because the NSX rotor is 5mm thicker than the 93-96 VTEC/97-01 Prelude rotor, but I'm not entirely sure that's correct.

 

[nsxhk]

Ken,

Of all the people, you should know the pre-'97 brake piston sizes are 36 & 40. The post-'97 is actually smaller (34 & 40). I'm disappointed!

Henry.

 

[4thGenPrelude]

Ken,

Of all the people, you should know the pre-'97 brake piston sizes are 36 & 40. The post-'97 is actually smaller (34 & 40). I'm disappointed!

Henry.

doh! :frown: Guess that means I have 97+ ... drew cleared up my misunderstanding though, I guess all I need are 91-96 brackets and I'm all set.

 

[Larry Bastanza]

Yes, you do have 97+ calipers, just like you thought you originally purchased.

The 34mm-36mm thing has been around and discussed a few times. I recall even the FAQ having it backwards.

I actually think Ken mistyped. He knows the correct numbers.

HTH,
LarryB

 

[nsxhk]

I wonder why honda size down the front piston? Anyone? Bueller??

Henry.

 

[nsxtasy]

The 34mm-36mm thing has been around and discussed a few times. I recall even the FAQ having it backwards.

I actually think Ken mistyped. He knows the correct numbers.

Not off the top of my head, I don't. I looked them up in the Changes by Year section of the FAQ. So I perpetuated the error in the FAQ. Sorry! (I just sent an e-mail to Lud to alert him to it.)

As for the rotor sizes, the diameter of the front and rear rotors is 282 mm front and rear for the '91-96, and the '97+ is 298 mm front and 303 mm rear. The thickness for the '91-96 is 28 mm front and 21 mm rear, new (26 and 19 mm are the minimum spec for replacement); I don't know if the thickness changed for '97+.

 

[ak]

I wonder why honda size down the front piston? Anyone? Bueller??

Henry.

They increased the rear caliper piston by 2mm while the front was reduced by 2mm. I am assuming this was done to increase a little more rear bias and also the fact that the rear rotor disc size was increased more than the front. When I went from NA1->NA2 brake, I felt that the brake seemed a little more balanced while NA1 seemed to be more front heavy.

BTW, the picture above is 91-96 caliper/bracket.

NA2 looks like this.(I borrowed this picture from Shutokor's post)
You can see that the bracket has smaller dip on the NA2 brake.

 

[4thGenPrelude]

Haha, this is funny, I'm back and forth here. I think I have 91-96 calipers now, after looking at a picture from an older NSXP thread (thanks drew) and then the one from ak, and finally, taking another look at my own caliper. I remeasured, but I'm coming up with 35mm+-, so I'm just going to forget about the piston measurement for a sec and compare the brackets.

Looking at ak's pic above, and the comparison of the two calipers in this picture from an older thread (red is 97+, green 91-96):

then finally at my own, I believe now that I have 91-96 calipers. The bracket isn't as large as on the 97+, and from the front view from the ebay pic (top of thread) it doesn't look like ak's 97+ caliper.