# A Few pics you brake guys might want to see... :) (and long explanation of theory and reasoning)

Posted by Matt (93SE) on September 07, 2002 at 11:45:00:

As many of you guys know about my wilwood kit and the problems I've been having with a HUGE front brake bias problem, I finally got around to fixing it last weekend.
I did a few calculations and figured that with the larger pistons in the front calipers and the larger rotors, there is now over 3 times the braking torque on the front brakes as there was before the change. That obviously means my front brakes way overpower the rears.
Soooo, instead of the stock brake bias of about 70% ft, and 30% rr, I now had about 90% ft and 10% rear..

I knew this was a problem the whole time I had the kit on, as I was going through rotors on the front almost as fast as I was going through oil. I've about worn out my SECOND set of front rotors since this time last year. Not good at $300+ /set.

Anyway, so I set out my quest on increasing rear brake bias.. First step was to figure out what rotors would fit under my wheels. Even though these are 16" wheels, there is very little room, due to the 3-piece design on the rims. the bolts that hold everything together are right where I need room for a caliper. DOH!

I did some searching around in hundreds of websites and many brake parts catalogs and blah blah blah.
Seemed the best solution I could have came straight from Nissan already- on the first Gen 300ZX. lucky me!
The rotor thickness and offset were identical to Maxima rotors, except they were an inch larger in diameter. Problem solved.

Now to get them mounted. As you can see, the mounting brackets on my car already had two sets of holes. This was from when I pioneered the rear disc conversion on my old GXE. When I totalled it, I simply swapped the rear suspension over to this car to save from having to tear down both sets of springs&struts to swap the Tokico/Eibach combo. Reason there's two sets of holes is that when I purchased the parts, the junkyard gave me calipers off of a different year Maxima than I got the rear struts and brackets. The struts and brackets were off of a 94SE, and the calipers were from a pre-90 SE model. They changed some dimensions of the caliper on the 91+ models to make the bolts easier to reach on the calipers for maintenance. (if any of you pre-90 guys have removed a rear caliper, you know what I'm talking about).
Sooo, when I bolted up the original rear disc conversion system on the old max, the calipers stuck way out past the rotors because of the design change. My fix then was simply to drill two new holes in the bracket so that I can get the car back together and have rear brakes without having to order MORE parts and wait another 2-3 weeks to finish. blah blah blah

so, for the last YEAR, I've been dreading having to repeat the bracket fittment hassle I'd had on the rear disc conversion.. I finally got my garage cleaned out enough to get to my drill press useable again, so I figured I'd start and see where I had to go. I had some spare pieces of metal and the tools to make a copy of the bracket available, and the time to do it. blah blha lbah.
So I pull everything apart and THEN remember I had to drill another set of holes in the bracket. *Hmmmmm... wonder if that will fit?*
So I stick the new rotors on and bolt the caliper to the old holes in the bracket, and VOILA! the pads only overhang about 1mm at the most, which is less than 1% of the pad area. Good enough for me!

So that's pretty much it. rear disc upgrade on my car in less than 2 hours! :)

As for driving impressions, there was an IMMEDIATE difference in braking. the car feels much more balanced now, and I can brake much later going into corners and stuff.. It's almost impossible to lock the brakes up, but if I really try it's doable. by that time, you're about to bend the steering wheel over from pushing so hard on it. 100-0 braking distance has significantly decreased... When I stomp on the brakes, the car almost immediately comes to a halt with no drifting or front-end lockup that I had before. Brakes are simply amazing now.
It's actually fun driving the car again!

A 4-5pt harness will be my next mod to the car, as soon as I finish putting the Z seats back in. Hmmmm, I think I may tackle that today even! ;-)

I'll quit rambling now and show you kids the pics.

Replys:

- Nice! Now that it's done, maybe you could find an aftermarket brake-bias adjuster and fine tune the system... nm Jacob ('93 SE) 10:20:50 9/09/2002 (1)
  - Yup.. Wilwood makes one for about $45. It's the best and cheapest from what I understand. Will do that when it rains, as I'm sure setup will change then. nm Matt (93SE) 11:31:21 9/09/2002 (0)
- I got a question or two MIKE (93VE) 21:24:29 9/07/2002 (13)
  - answers.... Matt (93SE) 00:41:35 9/08/2002 (12)
    - I understand and know advantage of using a longer handles MIKE (93VE) 10:44:51 9/08/2002 (11)
      - As Mentat said, it doesn't change the pressure exerted on the rotor... The same pressure is applied farther from the center point to provide more torque to stop the car. nm Matt (93SE) 13:26:53 9/08/2002 (0)
      - I'm well out of my knowledge here but I think the key is putting the point of application of the force (the caliper) further from the actual center of rotation would increase leverage? I'm picturing a line drawn from the hub to the caliper here... and the longer that line, the more leverage? am I on the right track here? mentat (93se 5spd) 12:24:24 9/08/2002 (9)
        - Yes, another example would be.. Maximamike (92 SE) 12:37:12 9/08/2002 (8)
          - Dont get we wrong I totally understand the longer handle for more leverage, but MIKE (93VE) 14:00:07 9/08/2002 (5)
            - Uhhhh, the axle? Since that's where it's turning around, and attached to the moving part of the car. hmmmm. nm Matt (93SE) 14:58:42 9/08/2002 (4)
              - Interesting MIKE (93VE) 17:10:56 9/08/2002 (3)
                - I would say you're correct as far "clamping force", but thats only part of the "Stopping Force" equation.... mentat (93se 5spd) 18:20:37 9/08/2002 (2)
                  - Thank-you MIKE (93VE) 20:26:34 9/08/2002 (1)
                    - Yup, you're getting it... mentat (93se 5spd) 10:56:21 9/09/2002 (0)
          - OT mike any update on your friend's rims... email me n/m mentat (93se 5spd) 12:44:27 9/08/2002 (1)
            - Oh shit, sorry bout that. I'll send ya an email when I get back to school tomorrow.. Maximamike (92 SE) 13:10:18 9/08/2002 (0)
- Now that you can brake later and turn in to the corners without locking up the front brakes so easily, your next SoloII will be even more fun. :) nm MarkP (Maxima) 15:18:48 9/07/2002 (1)
  - Exactly. that's why I was so dissappointed in the last one.. I KNEW I could do better, but the brakes were holding me back (or not holding me back) nm Matt (93SE) 00:33:23 9/08/2002 (0)
- Very nice sir.....very nice!...watch for copy cats...nm oE (91se) 14:33:20 9/07/2002 (2)
  - what's wrong with someone who wants to copy a good idea so they can have good brakes too? Isn't this why he shared? n/m Bryan (91 SE, 92 SE) 19:54:05 9/07/2002 (1)
    - Exactly. Actually, I'm not the FIRST one to do this, but the other guy made custom brackets. I used all OEM equipment for zero add'l cost. ;-) nm Matt (93SE) 00:34:27 9/08/2002 (0)
- Wow....good job! nm James (2 VE's) 13:46:41 9/07/2002 (0)
- good job Matt DanNY (91SE) 12:07:09 9/07/2002 (1)
  - Re: good job Matt Matt (93SE) 12:20:40 9/07/2002 (0)

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: As many of you guys know about my wilwood kit and the problems I've been having with a HUGE front brake bias problem, I finally got around to fixing it last weekend. : I did a few calculations and figured that with the larger pistons in the front calipers and the larger rotors, there is now over 3 times the braking torque on the front brakes as there was before the change. That obviously means my front brakes way overpower the rears. : Soooo, instead of the stock brake bias of about 70% ft, and 30% rr, I now had about 90% ft and 10% rear.. : I knew this was a problem the whole time I had the kit on, as I was going through rotors on the front almost as fast as I was going through oil. I've about worn out my SECOND set of front rotors since this time last year. Not good at $300+ /set. : Anyway, so I set out my quest on increasing rear brake bias.. First step was to figure out what rotors would fit under my wheels. Even though these are 16" wheels, there is very little room, due to the 3-piece design on the rims. the bolts that hold everything together are right where I need room for a caliper. DOH! : I did some searching around in hundreds of websites and many brake parts catalogs and blah blah blah. : Seemed the best solution I could have came straight from Nissan already- on the first Gen 300ZX. lucky me! : The rotor thickness and offset were identical to Maxima rotors, except they were an inch larger in diameter. Problem solved. : Now to get them mounted. As you can see, the mounting brackets on my car already had two sets of holes. This was from when I pioneered the rear disc conversion on my old GXE. When I totalled it, I simply swapped the rear suspension over to this car to save from having to tear down both sets of springs&struts to swap the Tokico/Eibach combo. Reason there's two sets of holes is that when I purchased the parts, the junkyard gave me calipers off of a different year Maxima than I got the rear struts and brackets. The struts and brackets were off of a 94SE, and the calipers were from a pre-90 SE model. They changed some dimensions of the caliper on the 91+ models to make the bolts easier to reach on the calipers for maintenance. (if any of you pre-90 guys have removed a rear caliper, you know what I'm talking about). : Sooo, when I bolted up the original rear disc conversion system on the old max, the calipers stuck way out past the rotors because of the design change. My fix then was simply to drill two new holes in the bracket so that I can get the car back together and have rear brakes without having to order MORE parts and wait another 2-3 weeks to finish. blah blah blah : : so, for the last YEAR, I've been dreading having to repeat the bracket fittment hassle I'd had on the rear disc conversion.. I finally got my garage cleaned out enough to get to my drill press useable again, so I figured I'd start and see where I had to go. I had some spare pieces of metal and the tools to make a copy of the bracket available, and the time to do it. blah blha lbah. : So I pull everything apart and THEN remember I had to drill another set of holes in the bracket. *Hmmmmm... wonder if that will fit?* : So I stick the new rotors on and bolt the caliper to the old holes in the bracket, and VOILA! the pads only overhang about 1mm at the most, which is less than 1% of the pad area. Good enough for me! : So that's pretty much it. rear disc upgrade on my car in less than 2 hours! :) : As for driving impressions, there was an IMMEDIATE difference in braking. the car feels much more balanced now, and I can brake much later going into corners and stuff.. It's almost impossible to lock the brakes up, but if I really try it's doable. by that time, you're about to bend the steering wheel over from pushing so hard on it. 100-0 braking distance has significantly decreased... When I stomp on the brakes, the car almost immediately comes to a halt with no drifting or front-end lockup that I had before. Brakes are simply amazing now. : It's actually fun driving the car again! : A 4-5pt harness will be my next mod to the car, as soon as I finish putting the Z seats back in. Hmmmm, I think I may tackle that today even! ;-) : I'll quit rambling now and show you kids the pics. : <img src=http://www.ee.utulsa.edu/~mblehm/pics/car/brakes/rear1.jpg> : <img src=http://www.ee.utulsa.edu/~mblehm/pics/car/brakes/rear2.jpg> : <img src=http://www.ee.utulsa.edu/~mblehm/pics/car/brakes/rear3.jpg> : <img src=http://www.ee.utulsa.edu/~mblehm/pics/car/brakes/rear4.jpg> : <img src=http://www.ee.utulsa.edu/~mblehm/pics/car/brakes/rear5.jpg> : <img src=http://www.ee.utulsa.edu/~mblehm/pics/car/brakes/rear6.jpg> : <img src=http://www.ee.utulsa.edu/~mblehm/pics/car/brakes/rear7.jpg> : <img src=http://www.ee.utulsa.edu/~mblehm/pics/car/brakes/rear8.jpg>