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Wheel adapter question

Old 02-06-2016, 12:42 PM
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hamrad
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Default Wheel adapter question

1973 base corvette. All stock except below:


I have searched and read for a couple days now. I have got a set of chrome rally wheels that have a 4 1/4 inch backspace. I have installed 255/60 15 tires. They touch both the parking break cable and the leaf spring. Looking an either spacers or adapters. Thinking a 3/8 spacer would work or a 1" adapter. So, for all the experienced corvette owners out there what is the best option? Please don't reply with get new wheels or such. Already have these wheels and tires just have to figure out best option to use them...............Also, what is the minimum amount of clearance from tire to parking break cable and leaf spring that would be acceptable?
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Old 02-06-2016, 01:16 PM
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fishslayer143
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Spacers and longer Lug nuts will work .. ! " adapter is stronger, so question is how much power do you have?
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Old 02-06-2016, 01:32 PM
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hamrad
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Power around 300 horses. Just a little concerned the adapter might put the wheels outside the wheel wells. Don't know if this would be an issue or not.


Originally Posted by fishslayer143 View Post
Spacers and longer Lug nuts will work .. ! " adapter is stronger, so question is how much power do you have?
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Old 02-06-2016, 02:19 PM
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I have the same size tired as you and I think my wheels are 4.5" back space. I used a set of 1" hubcentric wheel adapters and they don't stick out past the wheel well. The adapters bolt on to your existing lug studs. Don't let anyone tell you that spacers or adapters put more load on the wheel bearings because it's not true.




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Old 02-06-2016, 02:37 PM
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hamrad
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Looks good. Did you have to trim the studs any? Seems like the 1 inch adapters might have to have the studs trimmed so they won't hit the wheels.


Originally Posted by Sacred Steel View Post
I have the same size tired as you and I think my wheels are 4.5" back space. I used a set of 1" hubcentric wheel adapters and they don't stick out past the wheel well. The adapters bolt on to your existing lug studs. Don't let anyone tell you that spacers or adapters put more load on the wheel bearings because it's not true.




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Old 02-06-2016, 06:05 PM
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I have 4.5" BS wheels, I used 1/2" spacers and new, longer ARP studs.

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Old 02-06-2016, 06:13 PM
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Sacred Steel
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Originally Posted by hamrad View Post
Looks good. Did you have to trim the studs any? Seems like the 1 inch adapters might have to have the studs trimmed so they won't hit the wheels.
When I put them on and torqued them down, I took a straight edge and ran it across the lugs and a few of them just barely so I ground them down a hair.
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Old 02-06-2016, 06:16 PM
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Originally Posted by Barry's70LT1 View Post
I have 4.5" BS wheels, I used 1/2" spacers and new, longer ARP studs.

where did you get these? Do you have a link? I was actually looking to go this route with the 1/2 hubcentric spacers but couldn't find any.
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Old 02-06-2016, 10:52 PM
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Originally Posted by Sacred Steel View Post
where did you get these? Do you have a link? I was actually looking to go this route with the 1/2 hubcentric spacers but couldn't find any.
Long story, here are the highlights.
The spacers are not hub centric, I made steel inserts for the stud holes to make it a snug fit, and also made a hub insert to make the spacer hub centric. The spacer can't move.

Since the wheels are Lug centric, I didn't try to get spacers that were hub centric to the wheel.
I got the spacers here..... (Canadian Supplier)
http://www.wmsracing.com/wmsweb/perf..._moreinfo.html
Jegs and Summit also have spacers.
I chose "Billet" spacers, reason, precision and strength.

I used ARP studs,
http://performanceparts.com/part/ARP/100-7701
More info - http://arp-bolts.com/kits/ARPkit-detail.php?RecordID=61
They're a bit long, however can be trimmed.
Also the knurl in the stud is a bit large for the hole in the hub. They may have pressed in ok, however I reamed the hub holes a bit (to 15/32" / .46875) to make a still very snug fit.

Last edited by Barry's70LT1; 02-06-2016 at 10:54 PM.
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Old 02-07-2016, 11:11 AM
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Originally Posted by Sacred Steel View Post
where did you get these? Do you have a link? I was actually looking to go this route with the 1/2 hubcentric spacers but couldn't find any.
You can have spacers made to your specifications from motorsport-tech.com.
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Old 03-21-2016, 07:48 PM
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Originally Posted by hamrad View Post
1973 base corvette. All stock except below:


I have searched and read for a couple days now. I have got a set of chrome rally wheels that have a 4 1/4 inch backspace. I have installed 255/60 15 tires. They touch both the parking break cable and the leaf spring. Looking an either spacers or adapters. Thinking a 3/8 spacer would work or a 1" adapter. So, for all the experienced corvette owners out there what is the best option? Please don't reply with get new wheels or such. Already have these wheels and tires just have to figure out best option to use them...............Also, what is the minimum amount of clearance from tire to parking break cable and leaf spring that would be acceptable?
Stock C3 backspace is 4" 1/4" spacers should do the job with plenty of clearance.
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Old 03-21-2016, 09:30 PM
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Originally Posted by Sacred Steel View Post
Don't let anyone tell you that spacers or adapters put more load on the wheel bearings because it's not true.
I have seen this a few times.

Not that I question your view, but

Do you have the math that shows this to remove the myth once and for all.

Any engineers here that can provide the final math answer.

My first impression is it could, but I'd like to see the math to change my mind.
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Old 03-21-2016, 11:27 PM
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If the center line of the wheel ends up in the same place relative to the hub there is no increase in load on the bearings.
The bearing does not care or know the path the load takes and the amount of load does not change.
A wider wheel and tire will increase the load.
If the wider wheels center line is still on the face of the hub the increase will be minimized.
The length of a lever is still the same whether it is straight or S shaped.
No need for math or enginemanures.
If the outside edge of the tire tread is in the same place on the pavement the length of the lever is the same.
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Old 03-22-2016, 12:42 AM
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Originally Posted by Sacred Steel View Post
where did you get these? Do you have a link? I was actually looking to go this route with the 1/2 hubcentric spacers but couldn't find any.
Our son, Matt, is a CNC machinist and has made MANY billet hub centric adapter-spacers for CF members. Adapter-spacers (3/8") for Boss wheels (4.5" backspace) are "standard", but he can make them for any brand wheel given the wheel hub ID.




If you don't install longer wheel studs, then you at least need to switch to conical extended lug nuts to grab more wheel lug threads (bolt diameter MINIMUM).


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Old 04-22-2016, 06:31 PM
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KevinK
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Originally Posted by cagotzmann View Post
I have seen this a few times.

Not that I question your view, but

Do you have the math that shows this to remove the myth once and for all.

Any engineers here that can provide the final math answer.

My first impression is it could, but I'd like to see the math to change my mind.
It's not the spacer that adds load, it's the typically increased width of wheel/tire that does it...
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Old 04-22-2016, 06:34 PM
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To the OP, 1 inch adapter would be the rout I would go....but....BUT...with 255s, I would replace those old studs for some ARP studs. The ones you can find have a knurl width that is a bit too wide for the holes...so you need to cut the metal a bit...a TINY bit. You might even just try one of those circular rasp files...and then pull the studs through with a good long wrench. I did it without a press, so it can be done!

And BEFORE I did it, I snapped 3 of the 5 lugs on the driver side rear wheel while driving. So trust me, this is something you are going to want to do.
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Old 04-22-2016, 07:17 PM
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Use the spacers and ARP studs and you'll be just fine.

I find the concerns about having hub centric adapters a little comical. They can't do anything useful unless they are an interference fit that was pressed onto the hub and into the wheel. The same applies with wheels that are supposed to be hub centric.

Think of it this way. Stand your wheel up and put the "hub" of the spacer into the wheel. Now roll the wheel. The spacer will roll inside the wheel center so it's always touching at the bottom of the hole. So, if you car was actually relying on that hub to carry the weight, the hub would be constantly rolling inside the center hole of the wheel wearing out both the spacer hub and wheel center.

It's the same reason the rear wheel bearing on a C3 need to be press fit and not loose fit onto the spindle. Otherwise, the spindle would roll inside the inner race of the bearing destroying both the bearing and spindle with each revolution of the wheel.
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Old 04-23-2016, 12:19 PM
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Originally Posted by Sacred Steel View Post
Don't let anyone tell you that spacers or adapters put more load on the wheel bearings because it's not true.

In and of themselves, spacers or adapters wouldn't change how loads are distributed among the inner and outer bearings. Rather, it's any track width variations at the wheel/tire CLs that would alter these loads, regardless of whether spacers or adapters are used. That said, we're only talking about a minimal deviation in the OP's somewhat less than severe duty application. FWIW, I don't happen to care for spacers or adapters, but would highly recommend anyone using them to install HD studs and to verify sufficient thread engagement. My $.02
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Old 04-23-2016, 01:10 PM
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Originally Posted by hamrad View Post
1973 base corvette. All stock except below:


I have searched and read for a couple days now. I have got a set of chrome rally wheels that have a 4 1/4 inch backspace. I have installed 255/60 15 tires. They touch both the parking break cable and the leaf spring. Looking an either spacers or adapters. Thinking a 3/8 spacer would work or a 1" adapter. So, for all the experienced corvette owners out there what is the best option? Please don't reply with get new wheels or such. Already have these wheels and tires just have to figure out best option to use them...............Also, what is the minimum amount of clearance from tire to parking break cable and leaf spring that would be acceptable?
You say that the tires touch the parking brake cable and the spring. Was this with the car off of the ground and the wheels at full droop?

If it was, you may be surprised when you lower the car to the ground to find that you now have clearance between the spring and the tire. Because of the unequal lengths of the half shaft and the strut rod, the wheel moves in an arc and you have less clearance at full droop. At normal ride height and suspension travel, you will have additional clearance. I would want about an inch to call it good. If that is the case then all you really need to do is move the parking brake mount to the top of the control arm.

Good luck... GUSTO
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Old 04-23-2016, 01:38 PM
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Barry's70LT1
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Originally Posted by lionelhutz View Post
It's the same reason the rear wheel bearing on a C3 need to be press fit and not loose fit onto the spindle. Otherwise, the spindle would roll inside the inner race of the bearing destroying both the bearing and spindle with each revolution of the wheel.
Don't forget the inner race is being compressed/held in place with a 100+ ft lb of torque. If the rolling resistance in the bearing is great enough to overcome the 100+ ft lb on the inner race, then slip fit or press fit is the least of your problems.
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