Technical Side effects of changing rear track width?

It’s too cold here to even think about going out to the garage, so I’ve been trying to research something I want to do in the spring. My 37 Chevy has glass fenders, wider than stock (advertised 2” wider). The rear axle is out of a 78 Malibu.

Looking at the rear wheel placement, I’d like to move them out, to better fill the fenders.

As is now:



The studs are 1 1/8” long, measured from the drum surface. Jacking the axle up to just get the tire off the ground, and putting the wheel so its mounting surface is on the ends of the studs:




I think a couple of 1 1/4” spacers will fit without the tire rubbing. That’s a lot cheaper and easier to try than replacing the axle.

I’m aware of the debate about whether the extra load on the wheel bearings is harmful. Let’s ignore that for now. What I can’t find is anything on how changing rear track width will or won’t affect drivability. There’s a lot about changing front track width, especially as it relates to under- or over-steer in race cars (or street cars at track days). Not racing, just road tripping in a hot rodded 30s sedan.

I can’t think of anything that would be negatively affected by moving the rear wheels out 1 to 1 1/4”. Am I missing anything?




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Tom like's

 

I would be more concerned over putting that much load on the studs than I would the effects it will have on driveability puttering around town. I have swapped rear ends out that we're 2-4 inches wider/narrower and it didn't have any effect.

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what size and backspace are those wheels? have you thought about changing them?

since you have 2" wider than stock fenders i suggest you fill the hole up with bigger wheels/tires

 

I wouldn't recommend that method, not enough thread engagement in the lug nut.

 

The spacers I’m looking at go on the studs with their own lug nuts, and have studs for the wheels. Something like these:



So there’s plenty of thread engaged on both sets of lugs. At 1 1/4” thick, the studs will be within the body of the spacer, so won’t interfere with wheel mounting.




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Using 'wheelspacers', also called wheel adapters, doesn't stress the existing lug studs. oops, I see you are onto that already..

Also, the rear axle bearings are not stressed (as much, if at all) as front spindle bearings because of the nature of the large and small hub bearings and how they are loaded by wheel offset.

Ray

 

I'm running some of those on the front of my car. My original lugs are almost flush with the adapter. Used them so I could go from 5x5.5" to 5x4.5" small Ford pattern. Never drove it without them, so I can't comment of if anything changed as far as driving goes, but so far I haven't had any problems out of them. I'm thinking of getting a Rotten Leonard kit and drilling my hubs so I can pull mine back in the fenders a bit.

 

On my rear axle ( 75 granada 8" ) on my 36 sedan I used 1" spacers made from 6061 aluminum. They attached to the axles via the lug studs and the wheel attached to the spacers via another set of studs,same as your picture. Had absolutely no issues running like that but eventually gotvwheels made with the proper back space. Tacoma- 4Runner guys run those style spaces in off road with no problems. Just run the spacers till you find a couple rear rims with the right back space. I got a 2 - 1"spaceers in 4.75 and 2- 1" in 4.5 that I'm not using if either of those might work for you. Just sayin,,,Mitch.

 

The wheels are 15x8, 3.75” backspace. American Racing vn515861. To pick up enough width, I guess a 15x11 or something around there might also work. It’s an option.



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Thanks. Tried to send you a PM, but it won’t let me? The 4.75 set I could use to see if I want to go thicker.



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I was running 15x7 Cragar SS with 4.125 back space. The 1" spacer put the wheel/ tire right where i wanted it. Honestly, if you are dead set on that style wheel, go with the 15x11 in the right back space. You'll probably be money ahead when it's all said and done .

 

Hmmmm, don't know why the PM thing won't work. Got a couple last week. Maybe 2018 doesn't like me . Mitch.

 

Getting those spacers custom made so they are hub centric on the axle with a hub register for the wheel makes them a whole bunch better.

Track width is the center of the tire contact patch.

I try to get the track width the same front and rear for aesthetic reasons and don't have much troubles. Many OEM applications have a staggered track front and rear and they don't have much troubles either. If it's really far off it will have an impact on low speed turning in tight cornering and parking due to Ackerman type tracking thru the tight turn- rear narrow makes it easier and rear wide makes it harder.

I won't mess around with spacers or goofy brakes up front that increas the track because that throws the scrub radius off and that will cause you problems. I have adjusted, modified, changed axles, Control arms, and crossmembers to change the front track width.

 

Increasing the rear track width will increase understeer, but you will never notice it on a the street.

 

I also used the 4.75 bc spacers on the front of my 36 Chevy truck because some a-hole ( ME) put a fat man suspension (bad idea) on it (years ago) with49 Chevy wheels and needed the extra track width. I drove that truck everywhere with those spacers without any indication of ill handeling . Spacer are not any different than a wheel with the same back space, just a bit more funky design. Dave,, i sent you a PM, lets see if it works..Mitch.

 

David, I made a set of wheel spacers exactly like those 4 stud ones that your pic shows only mine were the 5stud Ford pattern, 1" thick mild steel with Ford wheel studs pressed into the spacer from the rear, used them for about 20yrs on a mopar tapered axle rear end, the wheels were 15x10" Oz magnum rims with 2" wider steel rear fenders.............had no problems with the spacers, bearings or wheels.......replaced the whole rear end about 10yrs ago with a later Oz Ford rear axle due to easier parts availability & better gears..........andyd

 

Those type of spacers are in use and have been used for many moons, they are a relatively cheap fix/correction for what you want to do. You will not see any noticeable difference on a street cruiser.

 

put on stock fenders?

 

That’d be a lot harder, finding some that aren’t a mess, and also involving paint. I’m ok with the glass fenders, just they need to be filled in better.



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Couple things to remember.
1. After running them a few miles, take the wheels off and re-torque the adapters.
2. Those adapters are available with several thread configurations. Be sure to get a thread that matches your current thread. 7/16 for example. A lot of those adapters come with 12MM studs.
Should work great. I'm doing the same thing on another project.
SPark

 

Thanks. Yeah, good points.


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I had the same axle under my 50 chevy delivery. I solved the problem by using a 15X8 wheel with an inch and a half positive offset and a 285/70 tire. I actually had to flatten the wheel well lip a bit to get it all to fit underneath.
And to answer your question, no, the added track width won't affect your handling.

 

While you're doing mock up visualisations I'd be looking to simulate a lowering of the rear by what looks to be a couple of inches or more. You might be pleasantly surprised

Chris

 

Spacers are big with the 4x4 crowd and I have used them myself with no ill effects. I second the re-torque post and make sure the original wheel studs do not come in contact with the wheel. If they stick out even a fraction it will not allow a good fit. So if you go with a narrower style spacer (1",1 1/2") you will probably need shorter wheel studs.

 

I used spacer to un tub my '46 along with maximum backspace wheels. I have no ill effects after 5 + years of use. Go for it!

 

Any spacers / adaptors better than others as far as materials & safety are concerned? Any made in the USA?

 

https://www.uswheeladapters.com/

 

Yea, you're better off getting a wheel with more negative offset.
1. It'll better fill the opening.
2. the deeper wheel normally looks a lot better than a wheel with less offset.

Mike

 

^^^^^^^^X2