Some 15" rims work. I had a set of 8" aluminum rims with drag radials on board and they fit. I couldn't tell you what rims work and what rims don't fit, but it certainly is possible.
LS1 front brakes on G body spindle
- Thread starter 81cutlass
- Start date
Some 15" rims work. I had a set of 8" aluminum rims with drag radials on board and they fit. I couldn't tell you what rims work and what rims don't fit, but it certainly is possible.
in my instance the 84 steelies would not clear the caliper but the 85 alum wheels you see in my sig would
Btw in my mock-up, I found 5/16" to be the correct thickness needed. Not the 3/8" that the 81cutlass suggests. I made a 3/8 bracket for my first mock-up and rotor was not quite centered in the caliper.
He also has M12 X 1.5 listed for the bolts needed for the calipers. LS1 Calipers are M12 X 1.75 so he should correct that in his list.
I also opted for tapping the holes in the spindle to 7/16-20 instead of M10 X 1.5. The 7/16 is slightly bigger which I think is better here.[/QUOTE]
Width of the hub assembly, do you mean width of the hub and rotor to know how long of studs to purchase? I don't know off hand but the studs were 54mm and were a good length. 2" studs should work for your application for next closest standard size.
Yeah, M12x1.75 looks right, i fat fingered that one.
I am guessing the difference in 5/16 to 3/8 is a combo of tolerance stack. It's only 0.0625 and with the taper roller bearings, the hub, the rotor, the caliper bracket, the spindle, and the rough mill stock flat bar thats 6 parts right there, Even if the tolerances were +-.010" that could stack to about 1/16", plus I doubt aftermarket rotors are that tightly controlled.
I would be interested to see pix of these failed hubs. I have a hard time believing the hub with or without the rotor isn't up to the task of supporting its corner of the car no matter the situation.
This looks like an excellent way to upgrade on a budget.
I'm fairly certain I've run the LS1 brake upgrade on my GN for close to 100K miles and also other installations on other G-body cars I've owned or still own with no issues. I also have an 86 El Camino with this upgrade I performed on it 7 years ago, and 35K miles. So, all in all, I'd say it's a safe upgrade.
I had a friend that ran no RF caliper and machined the rotor off a hub on his dirt car with no issues. If it can survive a rutted track Im sure it can survive the street
In terms of failure of the hub due to removing the part that reinforces it-
Something to remember here, the bolts don't hold the wheel on (I guess they sort of do) but not in the way most people think.
The bolts are there to provide clamp load. Think of a wheel stud or any bolt like a C clamp, your wheel is held on with 5 c clamps effectively. Bolting the brake rotor and wheel on creates a pretty strong sandwich and the clamp load is spread out from the entire face of the hub where the wheel is contacting. Yes, the forces in the hub will be high in the direction the stud sits directly around the stud, but any load from the actual weight of the car is supported by the friction.
If you see a car that is hit hard from the side in an accident the hub doesn't usually fail, it's usually the wheel itself or something in the spindle or control arm. If a hub fails or the studs break due to a situation like sliding into a curb and the wheel doesn't bend likely the studs were fatigued or not tight. Even if a car is in a situation where all the weight is on one tire and it's pulling say 1G in a turn, and the car weighs 3500lbs, there is only ever 3500 lbs pushing the wheel sideways at the tire to road contact patch. I can do the exact math but considering a good stud has probably 80,000 pounds per square inch of tensile strength and there are 5 of them, you are going to have to put a HUGE side load on a tire, one that would have blown the bead or bent something else somewhere else.
Yes, fatigue cracking is a area of concern, but both steel and cast iron are relatively resilient to fatigue and a street car situation large loads at the wheels aren't seen. Might be a different discussion if we were talking about building rock crawlers or a baja truck, but for a street strip street car there is enough success with this method, enough OE's doing it and math that generally backs it up for me to feel safe.
Any risk added by this setup is much more greatly offset by the safety of actually being able to stop your car.
Something to remember here, the bolts don't hold the wheel on (I guess they sort of do) but not in the way most people think.
The bolts are there to provide clamp load. Think of a wheel stud or any bolt like a C clamp, your wheel is held on with 5 c clamps effectively. Bolting the brake rotor and wheel on creates a pretty strong sandwich and the clamp load is spread out from the entire face of the hub where the wheel is contacting. Yes, the forces in the hub will be high in the direction the stud sits directly around the stud, but any load from the actual weight of the car is supported by the friction.
If you see a car that is hit hard from the side in an accident the hub doesn't usually fail, it's usually the wheel itself or something in the spindle or control arm. If a hub fails or the studs break due to a situation like sliding into a curb and the wheel doesn't bend likely the studs were fatigued or not tight. Even if a car is in a situation where all the weight is on one tire and it's pulling say 1G in a turn, and the car weighs 3500lbs, there is only ever 3500 lbs pushing the wheel sideways at the tire to road contact patch. I can do the exact math but considering a good stud has probably 80,000 pounds per square inch of tensile strength and there are 5 of them, you are going to have to put a HUGE side load on a tire, one that would have blown the bead or bent something else somewhere else.
Yes, fatigue cracking is a area of concern, but both steel and cast iron are relatively resilient to fatigue and a street car situation large loads at the wheels aren't seen. Might be a different discussion if we were talking about building rock crawlers or a baja truck, but for a street strip street car there is enough success with this method, enough OE's doing it and math that generally backs it up for me to feel safe.
Any risk added by this setup is much more greatly offset by the safety of actually being able to stop your car.
Hairline cracks from the stud holes going down the entire side of the hub. The intregal rotor acts as a reinforcing band around the outside circumfluence. Generally that style hub has a thinner wall casting than hubs with a seperate rotor as the loads and stresses are displaced through the intregal rotor. The advantages of intregal rotor hubs are being cheaper to make, lighter, and stronger than seperate hub and rotor. Big disadvantage is they are harder and more expensive to service the brakes.
So when the rotor is machined off, the loads and stresses are no longer displaced. They just build up inside the hub casting with its thin walls that now lack reinforcing.
This is the part that is not correct.
The hub gains the reinforcing back when it's clamped together with the new separate rotor. Properly torqued lug nuts stretch the lugs which applies a constant tension that makes all the forces act upon the entire unit as if it were one single structure. This structure includes the hub, rotor and wheel.
Except the grain structure is screwed up from machining the rotor off and thd grains do not connect in two seperate pieces. With the rotor cut off, it exposes grain ends in the hub casting which acts similar to stress risers. The hub does not fully regain its full strength from bolting a seperate rotor back on, and there is still a slight airgap around the circumfluence, so you can center it with a dial gauge. It is not uncommon for these machined down hubs to crack from just pressing new studs in before they are even put into service.
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