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Brake Experts???

G

Gojeep

NAXJA Forum User
Location
Australia
Better to read from the bottom up but does make you wonder about a company when what they say needs to be done changes and then you pick them up on a point and make a pretty bad argument to support their mistake.
I cant believe a company such as this didn't even take into account that fitting a 3/8" bracket between the knuckle and the hub and spacing out the wheels and not keeping the alignment of the driveshaft uni to ball joint is OK because no one has had trouble yet!
Anyone that would like the PDF can take a look here as I put it online for you to see.

www.go.jeep-xj.info/DiscBrakeFrontConversion.pdf



Cheers


Marcus Ohms
( aka. Gojeep )
Victoria, Australia
Ohms Engineering
[email protected]
http://go.jeep-xj.info

Invention is a combination of brains and materials.
The more brains you use, the less materials you need!

......_____
/ | | \_____\
|¯) |¯ |---[]|||||||[]
()_)¯¯()_) ()_)

----- Original Message -----
From: Billy
To: 'Marcus aka. Gojeep'
Sent: Tuesday, February 14, 2006 10:17 AM
Subject: RE: Cherokee


Marcus,

In relationship to the ball joints…..YES the axle moves further outboard. However, the relationship between the centerline of the knuckle and the orientation of the hub/bearing assembly remain the same. Maybe we are on the same page here. I say the axle rides in the same centerline in relationship to the ball joints, you are saying this changes, I agree that the 2 move outboard “together” but they still lie center under the ball joints, in other words no left to right movement. I think you are saying the center pivot of the universal is no longer in line with the ball joints, right? This I agree with, however we have had no complications with this kit thus far as we have sold many of them.



Thank You,





Billy Mullin

Technical Sales Representative

Precision Brakes Company

1010 Benson Way

Ashland, OR 97520

1-866-992-7253

541-488-2604

Fax 541-482-2873

mailto:[email protected]


--------------------------------------------------------------------------------

From: Marcus aka. Gojeep [mailto:[email protected]]
Sent: Monday, February 13, 2006 2:46 PM
To: Billy
Subject: Re: Cherokee



But the axle seats hard against the back of the bearing hub. So if you move that outwards, the axle and universal comes with it? I changed a hub for a customer last week as have done others before. I have pictures if you would like to see them.






Cheers




Marcus Ohms
( aka. Gojeep )
Victoria, Australia
Ohms Engineering
[email protected]
http://go.jeep-xj.info



Invention is a combination of brains and materials.
The more brains you use, the less materials you need!



......_____
/ | | \_____\
|¯) |¯ |---[]|||||||[]
()_)¯¯()_) ()_)

----- Original Message -----

From: Billy

To: 'Marcus aka. Gojeep'

Sent: Tuesday, February 14, 2006 9:33 AM

Subject: RE: Cherokee



Marcus,

I understand your concern here but let me explain it this way. Since the Universal joint pulls tight against the backside of the bearing/seal after the axle nut is tightened to the proper torque specification, there are 2 things that change…..1 of which is NOT the alignment of the Universal. Here is what actually changes.



First, since the caliper relocation bracket is sandwiched between the hub bearing and spindle the “TRACK WIDTH” changes by .380” per side.
Second, since this bracket is sandwiched between the hub bearing and spindles the position in which the axle nut rides on the threads is different. Even with our 3.80” thick bracket in place you will still end up with plenty of axle threads to torque down the axle nut correctly.


Also, the only way to change the alignment or position of the Universal (as you say) would be if we placed a spacer between the hub bearing and actual axle shaft. The point here is we do not! Also the only way you’d see the universal ride in a different location would be if you left the axle nut loose! We advise that you don’t!



In other words the spacing between the axle to hub bearing is not changed at all…..so the universal rides in the EXACT same location. Only the hub bearing is pushed out .380” which is how you would end up with a track width change.



Thank You,





Billy Mullin

Technical Sales Representative

Precision Brakes Company

1010 Benson Way

Ashland, OR 97520

1-866-992-7253

541-488-2604

Fax 541-482-2873

mailto:[email protected]


--------------------------------------------------------------------------------

From: Marcus aka. Gojeep [mailto:[email protected]]
Sent: Monday, February 13, 2006 2:00 PM
To: Billy
Subject: Re: Cherokee



Thankyou very much for that.

My only concern is with the bracket between the hub and the knuckle is that the axle has also been moved further outward which means the universal will no longer be centred directly inline under the ball joint centre. When you look at those that fit WJ Grand Cherokee knuckle to get the 305 rotors and twin pot calipers, they supply a 1/4" spacer just to align the universals back directly under the ball joint to keep them inline and they have the opposite problem of the hubs too far inwards.






Cheers




Marcus Ohms
( aka. Gojeep )
Victoria, Australia
Ohms Engineering
[email protected]
http://go.jeep-xj.info



Invention is a combination of brains and materials.
The more brains you use, the less materials you need!



......_____
/ | | \_____\
|¯) |¯ |---[]|||||||[]
()_)¯¯()_) ()_)

----- Original Message -----

From: Billy

To: 'Marcus aka. Gojeep'

Sent: Tuesday, February 14, 2006 7:27 AM

Subject: RE: Cherokee



Marcus



Here are the install instructions for your Jeep.



Thank You,





Billy Mullin

Technical Sales Representative

Precision Brakes Company

1010 Benson Way

Ashland, OR 97520

1-866-992-7253

541-488-2604

Fax 541-482-2873

mailto:[email protected]


--------------------------------------------------------------------------------

From: Marcus aka. Gojeep [mailto:[email protected]]
Sent: Friday, February 10, 2006 4:29 PM
To: Billy
Subject: Re: Cherokee



Thank you for the extra information. But I don't think I would buy something without at least being able to look at the install instructions to see if that is something I would want to do. Do you have those I can look at? Also, is there a 4 pot caliper available at a cheaper price as seems there would be a market for you that does not involve such a large jump from 1 pot to 6? I don't feel that maybe such a large jump is necessary for a non race situation which 99% of Cherokees are found in. Just trying to over came the extra weight and leverage that tall tyres that these now typically run induce.






Cheers




Marcus Ohms
( aka. Gojeep )
Victoria, Australia
Ohms Engineering
[email protected]
http://go.jeep-xj.info



Invention is a combination of brains and materials.
The more brains you use, the less materials you need!



......_____
/ | | \_____\
|¯) |¯ |---[]|||||||[]
()_)¯¯()_) ()_)

----- Original Message -----

From: Billy

To: 'Marcus aka. Gojeep'

Sent: Saturday, February 11, 2006 10:49 AM

Subject: RE: Cherokee



Marcus



Minimum wheel size you will have to run will be a 17”. I must apologize for information I gave you in an earlier e-mail, this specific system will require you to make a spindle modification. The modification will consist of you cutting off the old slides and drilling and tapping a couple of holes.



Thank You,





Billy Mullin

Technical Sales Representative

Precision Brakes Company

1010 Benson Way

Ashland, OR 97520

1-866-992-7253

541-488-2604

Fax 541-482-2873

mailto:[email protected]


--------------------------------------------------------------------------------

From: Marcus aka. Gojeep [mailto:[email protected]]
Sent: Thursday, February 09, 2006 1:45 PM
To: Billy
Subject: Re: Cherokee



Can you tell me what the minimum wheel size is to run any of the these please. I presume you must supply a whole replacement knuckle as the pad slides that are cast into the existing knuckle prevent any rotor bigger than the stock 280 mm from fitting?






Cheers




Marcus Ohms
( aka. Gojeep )
Victoria, Australia
Ohms Engineering
[email protected]
http://go.jeep-xj.info



Invention is a combination of brains and materials.
The more brains you use, the less materials you need!



......_____
/ | | \_____\
|¯) |¯ |---[]|||||||[]
()_)¯¯()_) ()_)

----- Original Message -----

From: Billy

To: [email protected]

Sent: Friday, February 10, 2006 3:47 AM

Subject: RE: Cherokee



Marcus



I apologize for the delay in response. We currently have a few kits for your Cherokee. The kits will be listed below.





14-CH-0018

Front Brake System - Jeep Cherokee, 1990-01 - 325mm x 32mm, 2-pc. - Plain

Rotors, Wilwood 6 Piston - GNIII Calipers, Brackets, Pads, SS Flex Hoses,

Hardware, Instructions $1699.00



14-CH-0018-D

Front Brake System - Jeep Cherokee, 1990-01 - 325mm x 32mm, 2-pc. - Cross

drilled Rotors, Wilwood 6 Piston - GNIII Calipers, Brackets, Pads, SS Flex Hoses,

Hardware, Instructions $1699.00



14-CH-0018-S

Front Brake System - Jeep Cherokee, 1990-01 - 325mm x 32mm, 2-pc. - Slotted

only Rotors, Wilwood 6 Piston - GNIII Calipers, Brackets, Pads, SS Flex Hoses,

Hardware, Instructions $1699.00



14-CH-0018-X

Front Brake System - Jeep Cherokee, 1990-01 - 325mm x 32mm, 2-pc. - Drilled &

Slotted Rotors, Wilwood 6 Piston - GNIII Calipers, Brackets, Pads, SS Flex Hoses,

Hardware, Instructions $1699.00



Unfortunately I do not have pictures of how it attaches. If it helps these are “Bolt On” kits, you will not have to weld, cut, or grind to install. Please contact me with any other questions you may have.





Thank You,





Billy Mullin

Technical Sales Representative

Precision Brakes Company

1010 Benson Way

Ashland, OR 97520

1-866-992-7253

541-488-2604

Fax 541-482-2873

mailto:[email protected]








--------------------------------------------------------------------------------

From: Marcus aka. Gojeep [mailto:[email protected]]
Sent: Wednesday, February 01, 2006 1:14 AM
To: [email protected]
Subject: Cherokee



Just wondering if you have a kit to suit 95 Jeep Cherokee's?

If so can I have any specifics and a photo of how it attaches to the knuckle would be nice too.






Cheers




Marcus Ohms
( aka. Gojeep )
Victoria, Australia
Ohms Engineering
[email protected]
http://go.jeep-xj.info



Invention is a combination of brains and materials.
The more brains you use, the less materials you need!



......_____
/ | | \_____\
|¯) |¯ |---[]|||||||[]
()_)¯¯()_) ()_)
 
The other bad part of the mounting bracket is that it forces the 3 hub bolts to take the bulk of the load instead of the hub being properly seated into the knuckle. Plus you've pulled the shafts outboard by 3/8" so you might not have full engagement with the spiders. I presume this kit is a no-go for disco axles. Looks like a hack job to me.
 
food for thought. how about mounting the caliper bracket inside of the knuckle where the heads of the bolts are this would eliminate the movement of the hub and u-joints but you may run into some clearance issues with the u-joint and also turning radius.
 
bj-666 said:
food for thought. how about mounting the caliper bracket inside of the knuckle where the heads of the bolts are this would eliminate the movement of the hub and u-joints but you may run into some clearance issues with the u-joint and also turning radius.
Click to expand...

That is exactly what I had already designed but wanted to see how they did it in case they had a better way of doing it. Looks like that was not the case at all. The plate will pick up the three hub bolts on the back of it but you cannot not have quite the same shape as theirs. The reason is the the lower ball joint gets in the way but will be able to still come over the top in a hook shape. It will all be laser cut from 10 mm plate. Just deciding to run 298 or 325 mm rotors at this stage. The bigger ones will just fit in my 16" rims but anyone with 15" wont be able to run them. The bigger rotors also will cost me at least another $300 so not sure if that is worth it and the caliper will still be the same.
 
For $1700 I wouldn't even bother reading the instructions.
 
Dirk Pitt said:
For $1700 I wouldn't even bother reading the instructions.
Click to expand...
You do when you are looking for ideas to make up your own cheaper version. ;)
 
What do you guys think about how important rotor size will make a difference to overall braking power for what I do? With the same caliper I can get a 298 mm rotor or a 322 mm one. Would have to pay $300 extra for the bigger one.
 
Gojeep said:
What do you guys think about how important rotor size will make a difference to overall braking power for what I do? With the same caliper I can get a 298 mm rotor or a 322 mm one. Would have to pay $300 extra for the bigger one.
Click to expand...

That's a good question, your braking surface area is only 85% of the larger rotor on the smaller one, or in other words you have 116% of the surface area on the second compared to the first- and you get exponential increase in surface area for every mm larger you go in diameter. I would think it's more a matter of how much you want to spend, clearly the 1700 clams is a lot of money for very nice (?) brakes, but I would balk at the extra $300 myself.

What is the diameter of the original rotors? How much additional braking surface are you already getting with the 298mm rotors? You might be getting enough to make a considerable difference without the extra $300.

Also, will your pad actually have any additional contact area with the larger rotor (ie; larger pad?), or will the caliper simply sit higher on the rotor? If you can't get more pad contact area I don't see the point-
 
in a perfect world surface area will have no effect on how hard the brakes stop. consider this (all vairiables except force applied being constant), the surface area has no (in physics there is alwasy some but for our case unmeasurable) effect on friction of two hard surfaces in contact. the only thing that changes the friction between the two would be the force applied pushing the two surfaces together. try it! take a 2x12 piece of wood measure how much force it takes to drag it on a smooth hard surface on the 2" side and then on the 12" side there will be 0 difference. all this changes with softer materials that mold into each other and deform.

with that being said, surface area does help dissapate heat so it is good. and the diameter helps braking ability in the same way larger tires hurt braking ability.

now with a jeep or any other non race car your really looking for stoping power not heat dissipation so calipers that can apply more force and rotors that are larger are good. slotted and large surface area rotors only help cooling like is needed in racing with repeated hard braking going into turns and such.

i know there is a formula to figure out how the diameter of the rotor is proportional to braking but i dont' know it.
 
bj-666 said:
in a perfect world surface area will have no effect on how hard the brakes stop. consider this (all vairiables except force applied being constant), the surface area has no (in physics there is alwasy some but for our case unmeasurable) effect on friction of two hard surfaces in contact. the only thing that changes the friction between the two would be the force applied pushing the two surfaces together. try it! take a 2x12 piece of wood measure how much force it takes to drag it on a smooth hard surface on the 2" side and then on the 12" side there will be 0 difference. all this changes with softer materials that mold into each other and deform.

with that being said, surface area does help dissapate heat so it is good. and the diameter helps braking ability in the same way larger tires hurt braking ability.

now with a jeep or any other non race car your really looking for stoping power not heat dissipation so calipers that can apply more force and rotors that are larger are good. slotted and large surface area rotors only help cooling like is needed in racing with repeated hard braking going into turns and such.

i know there is a formula to figure out how the diameter of the rotor is proportional to braking but i dont' know it.
Click to expand...

Yes, torque = force*distance so in theory you would get better brake torque by having the pads further out on the rotors, or larger rotors with pad on the outside edge. But if you get rotors for an extra $300 and put your same pads in the same place, all you have is extra rotor spinning around for no reason. If you get the braking out on the outside edge of the larger rotor it may be an advantage.

I worry about warping rotors all the time, I'd like the largest cross-drilled rotors around, but I'm not convinced it's worth $300. The best brakes I have ever used were on 5-ton International trucks I used to haul milk (back in another lifetime). They weren't all that large in diameter but the rotors were massive enough that you had to be on the brakes for a REALLY long time to warp them. That was 4-wheel disk on that truck.
 
Thanks guys. I just did some setup tests with the new brakes I am putting together. The stock rotor size is only 280 mm so just going to 298 with now twin pot caliper should help quite a bit. The 298 fitted even just into the stock 15" rim but was surprised that when I tried it in my alloy 16" rim that I did not have the extra 12 mm ( half the difference in rotor size to the 322's ) clearance I needed. The extra thickness in the alloy and this particular rim has quite a deep well also. So now I have no choice but to make up a kit to suit the 298's. The whole thing including 2 of rotors, caliper, brackets, brake lines and pads and any bolts will cost around $500 all up. I think that is worth it for the increase over the stock ones don't you think?

Here is what I have gotten so far.
DiscBrakes%20020.jpg


So this is using a 298 Ford Falcon rotor with matching PBR twin pot caliper.

DiscBrakes%20022.jpg


Above in a stock 15" rim

DiscBrakes%20026.jpg


Mounted in my 16" rim. You can make out how much it setup in the middle so dont have the extra clearance you would expect.
 
I like the price-point. I'm very curious what you use to mount the caliper to the knuckle, any pics of it?

I assume that is the stock steel rim, any trials with alloy rims? I'd like to change over to steel rims in the long-term anyway, but it's just another thing I guess.
 
Are the stock steel rims and I dont have a 15" alloy to test at this stage.
I will be making up a braket that will pick up the three hub bolts out of 10 mm plate and then space blocks added under it to align it with the caliper mount. Hope to make the templates for it today.
But just ran into something I didn't expect. The Ford rotor is much thicker on the mounting surface just enough that due the large chamfer on the back of my wheels, the centre of the hub no longer supports the wheel. So all the centering is done by the wheel studs. I have run wheels with a bigger hub hole before without worry but would like to know what you guys think about this? I have noticed though that the 00+ hubs have a taller hub centre.
513084-HA597449.jpg

They have a different hub offset too though I have been told but just trying to find out how much. If it is something like 3/8" shallower I could use these hubs and place my caliper bracket under the hub like the Precision ones but have perfect ball joint to axle alignment! :) But if does not look like much in the photo. Anyone know the difference in the offset? I looked and the rotors have a only a 3 mm difference in offset so might just be that?
 
i have spacers in the rear that are alligned by the lugs and bolted to them are rims that are alligned by the lugs they are good.
and in the front my rims are much larger than the hub so they too are alligned by the lugs.
 
bj-666 said:
i have spacers in the rear that are alligned by the lugs and bolted to them are rims that are alligned by the lugs they are good.
and in the front my rims are much larger than the hub so they too are alligned by the lugs.
Click to expand...
Glad I was not the only one doing that then. Anyone running Explorer rims will be in the same boat too as their wheel hub hole is 82 verses our 72 mm.
 
Had another chat with Competition Engineering to make sure I have every thing on the right track and they have provided me with the rotors and caliper to play with. He was pretty surprised what I came up with and have over come anything so far that looked like it might stop the project. I also had the caliper I am using next to that of the ones fitted to the Corvette's with the bright red PBR brakes ( same company ) and they looked the same down to even the mounting bracket. Pity I did have my camera with me to show you guys.
So I started by seeing exactly where the bracket needed to sit on the rotor in relation to the knuckle.

DiscBrakes%20030.jpg


Then I have started to lay out the template for the caliper bracket. It wont be sitting on the back of the hub of course but the back of the knuckle. Just easier to make sure it is sitting correctly this way.

DiscBrakes%20032.jpg


All looked great when I held it in place against my knuckle on the Jeep until I checked clearance at full lock. It is just too close between the bottom mount of the caliper and the back of the ball joint part of the axle. So I will have to cut away the last of the old caliper mount from the top of the knuckle. This will allow me to rotate the bracket up higher and at an angle similar to where the old one sat. So time to redesign it to do that.
 
Well after cutting out many just to perfect the template I am finally happy with it. Doesn't look much but took hours to get it just right as clearance is super tight once the axle is running through it and also the axle housing part of the knuckle getting in the way at full lock.

DiscBrakes%20034.jpg


This shows how after cutting the last of the old caliper bracket away I was able to rotate the caliper to sit higher. This was necessary as when it was lower it would foul on the axle housing knuckle at full lock.

DiscBrakes%20035.jpg


This is the near finished template ( made about another 3-4 after this shot just getting it perfect ) and where it will sit on the back of the knuckle picking up the 3 hub bolts. With it sitting at this angle it is now exactly square to the hub holes with equal distance to each of the caliper mounts holes. This middle third or front hole in the hub lines up between the caliper mount holes.

DiscBrakes%20036.jpg


There is now a distance of 40 mm to make up between the underside of the bracket and the caliper mount. Will have two spaces of 20 mm thick steel the same shape as the caliper bracket where the mounting holes are. The distance is too great just to use bar stock as spaces as the leverage will have increased.

DiscBrakes%20037.jpg


This photo shows how I wound out one of the bolts the 10 mm that will be taken up by the mounting plate. It is very close but does not hit the axle uni and should have a little extra space when I use 12.9 grade longer cap screws instead.
 
Good stuff, I just got back on the computer after a week offline and had to look up this post to see what has progressed.

It looks like you had to hack the knuckle quite a bit, at that point is there any reason for this mod compared to using the Grand Cherokee knuckle and brakes? I guess with this you don't have to replace any other steering parts...

I guess if the mounting brackets are finished you could do the entire mod without removing the knuckle at all?

And I wouldn't worry at all about wheels not bearing on the center hub, the lugs will be fine as long as the wheel is put on right.
 
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