evilstuie

Hey All,

Hoping I can get EBMiller88 to chime in on my C5 BNrake upgrade.
I've read through a bunch of posts of everyone doing it and watched a very videos as well.

I have the C5 brackets minus the bolts, the c5 calipers and hoses in transit, and a set of new hubs to get cut down and milled.

My complexity comes from my wheels. Currently the car has stock 15" rims which I'll be removing and I have a set of 18" ones to go on. The problem is i got the wrong stud pattern and they 127mm x5 (5x5) instead of 4.75x5. Centre bore is the same and being in Australia there's nopt much of a market for wheels for the thirdgens, as the only cars that came out here for the same fitment were Holden HQ and WBs and they were 15" from factory. The aftermarkets are available but pricey.

So in order for these to go on, I need to get 20mm spacer adpadtors to go from 4.75"x5 to 5"x5.
To get the spacers made up, I need to know the length I need on the studs so everything will go on, and to do that I need to the know the thickness of the C5 rotors where they bolt up to the hub so I can give that information to the spacer guys.

So it will be, a new hub milled down to fit the C5 rotor, the rotor, then a 20mm spacer adaptor, then the 5"x5 18" wheel.

So main question is, what is the thickness of the C5 rotor at the hub seating point?
And other than offset and possibly rolling the guards to fit, are there any other issues anyone can see?

TTOP350

iTrader: (8)

Do you have a machine shop local that could redrill the hubs to 5x5? Or you could possibly use the c10 or b-body 5x5 rotor? Those were 5x5 already, just turn those down maybe?

evilstuie

Possibly. C10's and B-bodys will be even rarer here in Australia.
I also have a Z28 LT1 10 bolt rear end sp I'd have to do the same to the rear which would be a bit more work than a spacer.

Fred SS

iTrader: (3)

I have a pair of C5 rotors for my brake upgrade that I bought from Rock auto some years ago. I measured the thickness you are looking for. I got .300 inches.

Fred

QwkTrip

iTrader: (22)

Get the right wheels. You'll thank yourself in the long run.

Anybody that has built a custom car has bought parts multiple times or parts they never use. Can't get everything right first try, and anybody that's been in the hobby long enough has a story of a knucklehead decision. It is just part of the learning process. Don't get hung up on making crap work that is totally wrong. Sell the wheels and start over and do it right.

evilstuie

Yeah I've definitely been down the path before, but trying to find a buyer for 5x5 wheels will be even harder than trying to find a set of 4.75x5's.

evilstuie

Thanks for that!

QwkTrip

iTrader: (22)

Have you taken into account the effective change in wheel backspacing with an adapter? I assume that you got exactly the wheel backspacing you wanted and that adding a spacer will not be what you wanted.

I have parts in my garage that I can't get rid of too. I don't install them on the car though just because I have them....
My current record is advertising something 8 years before it sold.

evilstuie

Haha, yeah, but where's the challenge in that! :P
I tend to keep any 3rdgen parts just because they're so scarce here in Aus.

The offset will actually match out nicely for the front. The back already sticks out a bit because of the 4th gen rear end, but won't be too affected. I've got a mate who can roll the guards out a bit if needed.

QwkTrip

iTrader: (22)

LAFireboyd

iTrader: (3)

Since you'll need adapters on the front, not spacers, to account for the 4.75 to 5.5 change, then you'll only need standard 1.5 studs in both, the hubs and the adapters. Longer studs in the hubs, such as 2.125, which I believe is the next length, will stick out too far through 20mm adapters, and you'll have to cut them down because they'll interfere with mounting the wheels. On the other hand, cutting down longer studs would, at least, give you maximum stud length through the adapters for the lugs.

But regarding the rear, since you already know they're going to stick out past the wheel well, and you'll need adapters back there too, then I agree with the man above, who suggested you start over and get wheels with a correct offset and bolt pattern. Or, at least, get new wheels for the rear that fit correctly, which will only be half the cost of starting over completely.

Like him, and probably a lot of us, I, too, have inventory. Not because parts were the wrong fit, but because I tend to upgrade beyond my original plans, so I end up not using parts I'd originally purchased. It begins as a money thing, where my plan is to not spend too much. But then after I get into it, I decide, what the heck, it's only money lol. I'm usually able to return a lot of the parts because I never used them, but not always. Or I might hang onto them because, just in case. Or I might get parts for test fitting and then not return them because, you never know. Or I'll find something "invaluable" at a junkyard and buy it, even though I don't need it, figuring I'm saving it from "junkyard people," and I might find someone who needs it. I believe it was Hawkeye who once said, "an army marches on its inventory."

evilstuie

I thought of another option of getting the wheel drilled for the correct stud pattern, which might work out cheaper.
Waiting on a quote to find out.
These are the wheels, 18x8

https://boydcoddingtonwheels.com/pro...-dog-polished/

ET is 0, so on an 8" wheel width, this equates to a 4" backspacing yeah? as in 4" each side of the center line where the wheel mounts to the hub?

QwkTrip

iTrader: (22)

It's going to be more like 4.5 inch backspacing because the wheel is always about 1/2 inch wider each side (1 inch overall) than the advertised width. The advertised width is for tire sizing, but the structure of the wheel itself is a bit wider than where the tire bead sits.

You can directly measure the backspacing with a straight edge across the back side of the wheel, and measuring distance to the wheel pad.