i just searched and could not find what i was looking for

i wanted to put rockwells under my jeep
and run pinon brakes

but i do drive my jeep on the road on the weekends

would you beable to drive on the street at 55mph
for 30 miles at a time or would this cause to much heat

or mabye 5000 miles a year around town

i would like to know so i could buy them next week

and is heat a factor when you are just driving and not useing the
brakes like on the hiway

You should be able to drive at that speed without a problem, but they are not designed to go any faster.
The brakes are different story. When you put the brakes on the pinion, the speed is multiplied by 6.72 (gear ratio). So, if you are traveling at 55 mph, your brake rotor is traveling 370 mph.
You then get unbelievable amounts of heat buildup when you try to stop. You will probably smoke a set of pads pretty quick.
I don't drive mine on the street, but there are some that do.

I have been driving mine fairly regularly on the road for about 6 mths with just a rear pinion brake. Haven't noticed any ill effects at all. The brake pads look as good as the day i put them on, and the rotor has not worn either. The longest i have driven at highway speeds is about 1 hr, at 50mph. The brakes were fine as i pulled off the freeway. I also have not noticed any significant brake fade, which surprises me. If i had a front brake, it would take a lot of stress off the rear one, i think. I say go for it!!!

Unless you want to wait for brakes at the hub, there are a few places to get them now...

FYI with a pinon mounted break it gets tons more air movement than a standard disk. it is getting cooled much more effectively.

I would advise using a vented rotor. I have posted my setup before, in case you didn't see it, it uses a 1987 2wd Mazda B2000 rotor and a 1987 (IFS) 4wd toyota truck 4 piston caliper.
The rotor is abot $18
The caliper is about $33 plus core charge

I don't know for sure the individual laws for state to state, but Boyce Equipment said that the pinion brake is not DOT approved, and can't be LEGALLY used on the street. Just watch out for the fuzz. :D

i was going to use vented and driled rotors


does any one know the rpm of the axle at 50 mph with 44 in tires

and the rpm of a axle at 50mph with 26in tires

if the radius of the 26in tire is 3 times as small as the 44in tire

wont the pinon on the on the rockwell be spining a little over

twice the rpm as the 26in tire

i am going to figer out the math on this

i dont think that rotor on the rockwell pinon is spining much faster then a rotor an a street car with 26in tires going 100mph

ps what is the number for pie 1.34

and also how many feet are in a mile

5,280 feet are in a mile

if my math is right the pinon rotor on a rockwell will spin 127.74 rpms faster then a rotor on a car going 100 mph with 26in tires

if the truck with rockwells is moving 50mph with 44in tires


127.74 rpms is nothing

---- car at 100mph -----
8800 fpm, car @ 100mph
6.8067 ft/rev 26" tire
8800/6.8067 = 1292.84 rpms at the wheel.


----- rig at 50mph ------
4400 fpm, rig @50 mph
11.52 ft/rev with 44" tire
4400/11.52 = 381.94 rpms at the wheel

381.94*6.72 = 2566.66667 rpms at the pinion.

I don't know where you learned math, but you should ask for your money back. Cruising down the road at 50mph with 44's is the same as driving a car with 26" tires about 200mph down the road.

Is this safe?? Probably not...
Do I do it anyways? Of course...

whow my math does suck

there is no reason why a rockwell can't go 70 if you are using tires bigger than 40 inches. The trucks never did this but that didnt mean that they couldn't. originally they ran 39s and they could do anywhere from 55 to 65 depending on the truck so 70 should be no problem with 42s or especially 44s. Remember the bigger the tire, the slower everything in the axle turns. Also the TSL swamper is alot lighter tire than the stock tires and wheels so they put less stress on the axle to turn it. Talk to chucks trucks in FL, he has been building rockwell clad street trucks that were just set up for mudding for years and when I was researching my project he told me that they work great on the road. Also pie is 3.14 ont 1.34. You must be using that new math! HAHAHA!:D

pi = 3.1416

pie = $1.95 at the corner diner...