Big rotor developement

[Gojeep]

I just did some stepup 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 I was thinking about as well ) 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 $750 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.


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



Above in a stock 15" rim



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 will be making up a mounting bracket that will use the three hub bolts going around the hub centre. Will then be spaced down to meet the caliper bracket and all cut out on a laser machine.

[Laz]

Go jeep - fantastic - have been postulating my navel of front disk upgrades.

I'm interested in this for my TJ (wrangler not wife) - happy to chip in a bit to cover your R&D mate (saves my ass from running around) - keep me in the loop Mr GO (and now STOP)

[Gojeep]

Will do mate. I just got back from showing my plans to Competition Engineering and they are very pleased with them. They want to produce and market the kit afterwards so have been happy to help me so far. I will still have to pay for my own kit that I develope which sucks though. Getting a replacement knuckle would be handy as I am supposed to return an un-modified one back to someone else who loaned this to me!

[Gojeep]

While at the engineering place 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 some up speced HSV's 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.



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.



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.

[Gojeep]

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.



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.



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.



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.



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.

[Laz]

schweeet ....

[Gojeep]

OK, what I have done is to transfer the template to some 12 mm HD plastic that I normally make my coil spacers from. This will make sure I have every thing right as far as fitment issues go before then using the plastic piece for the CNC machine to follow and cut it out of 10 mm plate.



Made sure that all the holes lined up perfectly and that it would clear everything. I also checked my fathers XJ which has ABS and the sensor will actually sit under the bracket so will not interfere at all.



This shows the part that will be the spacer, although it will be much thicker than this, but it is just to make sure the holes all line up.



Bolted in just fine and wondered if I could have made the centre hole even smaller.



This shows the front view.



Now I see why I cant make the centre hole any smaller as at full lock it gets very close to the uni. You can see how the stock bolt actually just touches. I cannot use these anyway as 4 mm too short in length.



But now I have a problem that could end this project!!! This is looking down on top of the bolt and remember that I cannot use these bolts otherwise I would just shave a little off the integrated washer to clear the uni as the head itself is fine. But I don't think I can get these in a longer bolt anyway as have never seen them aftermarket? So was going to use a socket head cap screw or some times called a Allen key bolt. I was looking at this chart, http://a-sp.org/Standards/chapters/assembly/F1-23.pdf and in section F6 they have low profile head ones. The hub takes 12 mm 10.9 grade bolts. I only have 10 mm from the centre of the hole to the inside edge of the bracket where the uni is at it's closest. That head is 18 mm in diameter which means the radius of 9 mm would just sit short of the edge of the bracket. If you look at the last photo and follow the edge of the bracket down and then out vertically 8 mm, which is the height of the head, I think it will just clear! That stock bolt head is 15 mm and there is fraction over 1.5 mm of clearance between that and the uni.
So this should just work but anyone know of any other solutions? I cannot even use a counter sunk socket head as they are around a 1" in diameter so would hit the uni and be off the side of the bracket.