My GMT400/ 88 Silverado is a C2500. I didn't want to run my 2013 tires any longer, so I bought a set of newer alloy wheels and used tires that were on Curtis' AWD van.
Installed them tonight, and the fronts have interference with the upper control arm. This is from driving the truck, a total of about 50 feet, forwards and backwards.
Obviously, if I'm going to use these, I will need a wheel spacer.
I've never used them, don't have an opinion or any knowledge on the topic.
I figure 1/2 inch should get it done. The bearing caps stick out further than that, but I don't think the center caps are essential.
Do I have to replace the lug studs? Is this a bad idea all together? Educate me.
Rule of thumb - you want your thread engagement to be about 1.5x the diameter. So for a 1/2" stud, you want 3/4" of thread engagement. Pull off one of those lug nuts, measure the visible threads and that'll tell you how much spacer you can use before a stud change. On a Miata, it's less than 3/16".
For something at the size you're talking about, I'd want to use the bolt on adapter type spacers. They bolt to the hub with the factory studs, then have their own studs for the wheel to bolt on. And they'll extend the center bore.
I've been running spacers of that style on the Jeep for years with no issues. 3/4" up front, 1" in the rear in my case.
The only problem with those is that they have a minimum thickness. They'll probably have to be thicker than 1/2", which can lead to problems at the fender depending.
They are usually 1" thick.
There MAY be room for a 1/2" spacer, if you have the original bearings. GM used long studs with lots of thread engagement and nice bulleted ends. Aftermarket bearings sometimes have the shortest studs they can get away with.
Some wheel spacer talk from our pals at BimmerWorld.
(FWIW, I had some wheel spacers fail the paper test.)
In reply to David S. Wallens :
Thanks David, I had forgotten about that video.
Regarding stud length - are the GM truck studs the same thread & diameter as the cars? A common swap for other GMs is to use the extra long studs from a C4 Corvette to give you plenty of thread when you run spacers. Also it just makes it easier to put wheels on anyway :) On a Saturn for example they are like 30mm longer, but I think in general they are way longer than any other GM wheel stud.
Keith Tanner said:
The only problem with those is that they have a minimum thickness. They'll probably have to be thicker than 1/2", which can lead to problems at the fender depending.
I think the thinnest I've seen them is 3/4". Mine are the BORA spacers from Motorsport-Tech. They'll make them in any thickness you want, but I don't think they go below 3/4".
The reason I mentioned 1/2" is because that's what Doc was looking for :) I usually deal with mm, and I think I've never seen them less than 20mm thick. Gotta have room for the nuts!
That interference didn't look too bad.... you might be able to run a much smaller spacer and even maybe clearance a little on the arm where it interferes.
I was going to ask about using those spacer/adapters recently and I should have. I wanted to be able to use a set of Swift GT wheels on the Spark, but elected not to because I thought the adapters were kind of hokey. Perhaps I will now
jfryjfry said:
That interference didn't look too bad.... you might be able to run a much smaller spacer and even maybe clearance a little on the arm where it interferes.
It looks small there, but what is it like when you turn the wheel? I know in the case of NA miatas for example there are wheels that only rub on the UCA at nearly full lock.
ProDarwin said:
Regarding stud length - are the GM truck studs the same thread & diameter as the cars? A common swap for other GMs is to use the extra long studs from a C4 Corvette to give you plenty of thread when you run spacers. Also it just makes it easier to put wheels on anyway :) On a Saturn for example they are like 30mm longer, but I think in general they are way longer than any other GM wheel stud.
Moet cars are 12x1.5, the trucks are 14x1.5.
Got a better look at it and took some measurements and pictures. They had a good start at the self clearancing process, but sacrificing the aluminum from the wheels isn't what I want.
The wheels barely cleared the upper control arms when I jacked it up under the spring perch.
The studs are 1.25 inches long measuring from the hub to the tip.
With the wheel seated, there is only 5/8 inch stud remaining, so there's no extra length for a spacer. I think a bolt on style one inch spacer would work, and leave only 1/4 inch of stud length beyond the spacer. The wheels have an 1/2 inch relief between the lugs, so that seems workable.
Suggestions, comments, recommendations for source or brand?
In reply to Floating Doc (Forum Supporter) :
I've used these with good results: https://www.motorsport-tech.com/bora.html
In reply to rslifkin :
They appear to be a good product. I had to enter my truck as a 1500 since I have the light duty 2500 with the six lug hubs.
