A-body rear brake conversion question....effect on offset

[looter]

I can only speak in generalities right now because I have not settled on a supplier for this job.

my 71 Monte needs a rear disc conversion...my Monte also needs new wheels.
Before I go shoot myself in the foot and order wheels, I was thinking if doing the disc swap would change my wheel mounting distances and therefore effect my offset calculations.
am I thinking correctly or will it be so close between the drum and rotor it's a nonfactor.

I suppose if I was forced to choose a supplier, it would be a basic kore3 kit I'd be going with

Thanks for any input.

Warren

[looter]

dammit..posted in the suspension forum....sorry guys.
if a mod sees this can they slide it into the correct position?

[BulldawgMusclecars]

For the front, yes, depending on the kit, but for the rear your only real concern will be clearance for the type of caliper you are running.

[cheapthrillz]

For the front, yes, depending on the kit, but for the rear your only real concern will be clearance for the type of caliper you are running.

Why would the rears not be a concern? The backspace would change a good inch from one to the other.... if he shoots for as much wheel and tire as he can fit with the drums and then switches to discs, he could have some rubbing issues on the frame or inside of the fender under hard cornering....

[cheapthrillz]

Call Tobin @ Kore3 and tell him which brakes and rearend you have, and he will tell you the exact backspace change you'll get....

[looter]

I continue to hear he's a wealth of knowledge. Thanks for the lead.

[Apogee]

Warren, I'll save you the call...the rear is usually pretty simple since the track width change for any rear brake kit is going to be the difference in what you have now (.105" for an OE GM drum hat thickness) and what you're putting in it's place (.24" for a C5 rear rotor, .28" for a C6 rear rotor). Using the paranthetical dimensions above, you're looking at a track width increase of .135" to .175" per side, or more loosely 1/8" to 3/16" if you prefer fractions.

Front kits tend to vary to a much larger degree since an aftermarket hub is typically involved, which can typically be made in a variety of flange offsets for a variety of reasons. Some kits try to maintain stock track widths, others do not. Changing the track width substantially in the rear would require at least new axles and more often housing modifications.

Tobin
KORE3

[looter]

dang...now THAT is service!
Thanks Tobin..just waiting for funds to clear paypal and I'll place my order.

[cheapthrillz]

ok, so I wasn't thinking with that thing between my ears lol...... forgot that you are replacing drum thickness with the thickness of a new rotor lol duh

[looter]

still...I AM trying to wedge as much rubber as possible, so you were on the correct path.

[exwestracer]

ROTOR offset would be a concern, though. Depending on the type of caliper, you might have wheel spoke to caliper issues, which wouldn't have been an issue with the drums.

[BulldawgMusclecars]

ROTOR offset would be a concern, though. Depending on the type of caliper, you might have wheel spoke to caliper issues, which wouldn't have been an issue with the drums.. Exactly my point. If the minute difference in width between the average drum and average rotor hat causes your wheels not to fit, they were too close to begin with.

[exwestracer]

Just so we're clear, this is what I was referring to.
53458
Note how the calipers overhang the mounting face. This isn't a problem you'd ever have with drums, so the wheels that were ok with drums might not work with certain rotor/caliper combinations...

[looter]

so how do you even account for that when ordering wheels?

[LowFast]

so how do you even account for that when ordering wheels?

Thick enough mounting pad or depending on wheel style curve of back of spokes.

[looter]

I'm going to order my brakes and rear suspension before I do anything else...I think it's recipe for disaster otherwise.

[looter]

what are the pros and cons of a rear lower control arm relocate, like the one UMI offers?
is it $100 well spent or more drag racing related and I shouldn't sweat it?

[looter]

Thick enough mounting pad or depending on wheel style curve of back of spokes.
what about spacer and additional offset? I'm sure it's the less desireable way, but it would open wheel choice back up again.

[exwestracer]

IMHO, if you can do it without spacers, you're MUCH better off....

[looter]

what are your thoughts on the rear lower control arm relocates,Ray?
you ought to charge for the info you provide here....talk about a wealth of knowledge.

[exwestracer]

Ok, it's $35/hr! Make check payable to....HAHA, yeah RIGHT! LOL

I'm pretty sure that kit is designed to level out the LCAs on a car that can't be lowered due to rear tire size. I do believe that leveling the lower arms is a good starting point for the rear suspension; and best way to do that is by setting the ride height correctly. This actually gets everything in pretty good order for a street car. If you must go lower (ride height), you start losing anti-squat and getting roll steer effect in a hurry. In that case you would want to RAISE the frame end of the LCA. The stock geometry is designed for stability under braking, NOT acceleration or handling, so the IC is way out there. However, a tri 4 link PT type car doesn't live or die by high anti squat, because that can get you into trouble with bind in roll (as I recently was reminded).

Short answer is: If you can level the LCAs with a ride height you're happy with, I wouldn't see the need to adjust them further.

[looter]

thanks a bunch for the insight.

[looter]

placed my order with UMI.
after Ramey messaging me back when it was obvious he was home on personal time, I pretty much figured these guys deserved all of my business.
THEN I screwed up my order (talking on the phone and mashing buttons on the computer neanderthal style) I places a call to UMI and every single person I dealt with on the phone was top notch and fixed the issue immediately.
Business stays where it's appreciated,and mine is staying at UMI.

same day I also placed an order with Kore3 and what is there to say about Tobin other than again, all my brake business will be done through him.
I ordered some of the parts for my big brake kits locally (I get wholesale pricing on most parts) and it didn't offend Tobin or effect his level of service.

Nice to see there are still guys doing buisness like this out there.

And finally, to the guys who have pm'd me about doing business with them. I appreciate it and you'll likely be hearing from me.

[John Wright]

IIRC, Tobin has drawings on his site that you can download, and print out full scale to check for rim/spoke fitment issues. EDIT: the drawings were for his kits and to see if there were fitment issues. I didn't read your last post close enough to realize that you purchased something else from someone else and did not use Tobin's kit.