Ok, so my rear wheels are more tucked in than my front wheels are. I have aluminum drums and I believe with no spacers back there. I have read that there are 3/8" spacers in the rear on stock rear-drum cars which is 0.375" thickness. Now, my front wheels have the LS1 front brake kit which makes the front wheels stick out an extra 0.3". This totals to a 0.675" difference between front and rear wheel track (the front sticking out 0.675" more than the rear in total) (0.625 inches = 17.15mm). I want the rears to match the front as close as possible mainly for more neutral handling (and will reduce rear body roll slightly, since I am going to be lowering the PHB/rear roll center, this will help as well), but also so that it looks proper (looks kind of weird having the rear wheels more tucked in than the fronts )

This is what I've come up with from Motortech on their site. I'm just about ready to buy this from them, but want to make sure it's the right ones.

Motorsport Tech


Spacer Configuration - Complete! *********************


http://www.motorsport-tech.com/

What do you guys think? Are these right spacers to buy? This is for stock 16" 1986 IROC-Z wheels in the rear only, not the front.

P.S. I don't want to get into the argument about leverage and stress and load etc. LOL I've read all those threads and have come to the conclusion that on street tires, I just need good studs, good thread engagement on the studs, hub centric spacers (the slip on ones) and I should be more than fine. I was even going to upgrade to ARP 1/2" studs (they aren't too expensive, although I'm not sure of which ones to buy for the stock 26 spline axles) just to be extra safe because the boogy man might come and snap them off while I'm taking a corner!

There are so many different options for ARP studs, which one is for our cars?:
http://www.summitracing.com/search/P...word=arp+1%2f2

Thanks!

Our wheels are not hub-centric.

I have 10mm spacers on the front (plain old $15 Mr.Gasket jobs) and they are fine. Lug-centric wheels are awesome

Oh, and I do have Ben-Hur style studs. I know they're ARPs, but not sure which.

So stock IROC wheels are lugcentric? Hmm... Which means that I cannot use a hubcentric spacer, right? I know Dean used hubcentric spacers on his 92 with IROC replica wheels.. Which lugcentric spacers are the best in your opinion?

For the studs, I know that ARP ones fit with the stock style rims and should fit in the rear axles. I will do hard cornering so I want to be sure that I get the BEST 17mm spacers and studs out there.

You could get 2 more Front wheels to go on the back....

Oh wait! I have an idea for you! (i love thoughts that come up as i type the first one).

Put the Rears on the front & Rears on the front. With your brake conversion up front, the rears should fit fine now. I swapped the Rears & Fronts years ago on my late wifes car & 10 years later by using the stock aluminum drum spacers, it is still going strong today. Her daughter has it now & has had no problems.

Never thought of doing that. Although it would look odd if someone were to read the "front" and "rear" writing on the wheel lol.. I guess that would put the rear at 0.075" farther out than the front.. Which is practically equal. I think I'll try this out, see how it looks.

I don't get what you mean by you using the stock aluminum drum spacers though? Maybe I shouldn't touch this until I get the LS1 rear disc brake kit.. Would that move the rear out a bit from where I have it now?

The stock 16" wheels won't fit on the front because of the shallower bs, but the OEM spacer pushes them out far enough to fit. With your brake setup being farther out already, you probably won't have any fitment problems.

But if you put a LS rear in there, I am 99.999% certain that Front wheels on the rear would stick out past the center of the fenders kinda like: (i don't know the specs on these wheels but 3rd gen wheels on a 4th gen rear typically end up like that).

i know for a FACT the factory 16" wheel are hubcentric, and 70.3mm, most likely the 15's are too, but i dont have any to check.

Let me rephrase- we do not *need* hub-centric wheels, even if the factory wheels are.

I missed the part about the LS brakes. You should absolutely swap front-to-rear in that case.

And Blackened- I'm not sure he's putting in the whole rear, or if it's just the brakes. If it's brakes only, I'm not sure how much offset change there will be, if any. Swapping wheels you have right now though is a no-cost option, so I'd try it.

Cool! Thanks I'll try the free solution (hopefully no one will notice the wheel mix up lol). If this doesn't work for some reason I'll see what other options there are spacer-wise.

And I was talking about just the LS1 brake kit for the rear (not the LS1 rear end that's 2" wider than the 3rd gen rear end).

The factory wheels, 15's and 16's (and I believe the 14's) are all hubcentric. I'm sure you can get away with non hubscentric wheels on them (I don't know what car you couldn't if you're running tapered lug nuts w tapered holes in the wheels), but I'm also sure that keeping things hubcentric is going to be stronger and work better.

The factory iron drum spaers are like 1/8", not sure why GM bothered but that was about the difference in thickeness between the aluminum and iron drums.

As far as dealing with your problems, I always felt that these cars tend to look right with bigger tires and the fronts spaced out about 1/4" from the stock location for the 15" wheels (1/2" offset in, in other words with the fronts 1/4" in, the rears 1/2" in). The 16" wheels put them at 0 offset in the front and are supposed to be 16mm in on the back (that's 5/8", though i've measured factory wheels with as much as 7/8" offset on the rear).

Swapping front and rear 16's and possibly running very thin, like 1/8"-1/4" spacers on the front might solve your problem quickly, and I would try that first.

Spacers in the 3/8-1" range are sort of a no man's land, they are not thick enough to be made bolt on with separate studs (unless you made some custom ones out of steel and ran wheels with pockets behind the middle of the space between lug holes) and slip on spacers that thickness put excessive loads on the studs. If you _really_ want to run a spacer in that range I would strongly recommend making them at least hub centric, but I would custom make them so they also fit the studs tightly and support them.

Last I checked ARP only makes 2 lengths of 12mm studs, I might be able to come up with the part number but the longer ones, something like 2.25 or 2.5" long work well and are strong. 1/2" studs will work with factory wheel holes, will be slightly stronger and are dead common (used on fords, chryslers...), but will mean buying all new lug nuts and that your car will have some unexpected size lug nuts for a GM if you ever need to replace them.

Thanks for that info! Wow.. alot to absorb here.. So it looks like the spacer in the rear was sort of like a quick fix for GM. Great lol. In any case, I prefer the look of all around evenly spaced wheels on the car, and plus in my case it will help with countering the increased rear body roll when I lower the rear PHB with unbalanced engineering PHB relocation brackets (getting them welded on sometime this week).

I've decided to keep the fronts on the front and the rears on the rear so what I think I am going to do is get the ARP studs and matching size lugnuts (for the rears only). The studs will be the ARP 1/2" thickness ones (as you mentioned, and I think I also remember Dean saying he used these ones as well, along with custom Hubcentric spacers). Let me know if you can find the correct part# and i'll order them from Summit. I'll have to run open lugnuts right? The closed ones probably won't work.

For the custom made hubcentric spacers (17mm), I was thinking calling Motorsport-tech.. What should I be specifying to them when ordering the spacers?

im pretty sure our wheels are hub centric .

i have a front c4 brake conversion and learned this the hardway the front shakes if i dont use rings

as for the offset problem put rears on the front
or do what i did and buy a 2nd set of wheels run 4 fronts or 4 rears

with big brake kits you can almost always run rears on the front

i personly like the wheels to look the same axle to axle so i use 4 rears on my car

also the front wheels can rub the inner fenders in hard corners if you have "front wheels on the front" with a brake kit

swap the fronts to the rear easiest fix for you

Hey Azrael,

My concern was that the LS1 brakes wouldn't fit because the rears have a different offset (they are more inside the fender). I think i'll end up just trying this out anyway because the rubbing is silly when I turn it (the last 1/4 turn is obsolete as it rubs.. So I lose a 1/2 turn in total making my steering very difficult to turn now.. It's now reduced to 1.75 turns lock to lock from 2.25 lol)

This change will help handling actually by increasing front body roll and decreasing rear body roll!

lmfao, and so the hubcentric subject arises again...

search my posts...

funny ****

ahhh.. here it is:

https://www.thirdgen.org/forums/whee...ings-size.html

i mentioned it because the tops of the inner wheels got rubbed out in hard turns ie tight freeway on ramps going to fast

and then i was thinking wow ya it did rub like crazy in parking lots and what not
used to not even get a full lock out of it before it rubbed reverse was the worst

Reverse is worse probably because the weight is being transferred to the front wheel rather than the rear ones. When turning front wards, pressing the gas fast helps but isn't practical in a parking lot lol.. You can scare alot of old grannies with their groceries lmao