Technical Changing the backspace on a steel wheel

On a steel wheel that has the centers apparently plug welded into place to the rim, is there any decent way of grinding out the plug welds that hold the center section in place without destroying the center section and or the rim? I have a pair of steel wheels that I'd like to change from 4" backspace to about 3 or 3.5" backspace.

Lynn

 

You say plug welded, is that as in heavy-duty electric spot weld ?

 

Yeah, spot welded I assume. It could be done, a lot of work. I think you would have to drill out all the weld in order for them to come apart with out great violence, then some means of mounting them to spin and check for true, then weld all holes shut without an air leak

 

Thanks. Spot welds, plug weld I wasn't really sure which term would apply. My thoughts/hope would be to work from the inside to minimize effect on the rim portion. Honestly, even I question whether the result would be worth the effort for just 1/2" or 1" of backspace difference, although that could affect the look and clearance of the tire to body gap.

My guess would be that some HAMB over-achiever might have done what I'm considering. Sort of like spending a day making a bracket that could have come via the "brown truck" for $20.

I have replaced rims on wheel centers before when I had a dirt track stock car. Truing them up does take some patience but it can be done.

Lynn

 

Drill out the weld
Whack em loose with a hammer

 

Here you go

 

IF you have access to a mill, that would be the best way IMO. Use an end mill to cut the weld from the rim side until it's released, knock out the center move it into it's new location and plug weld thru the milled hole. I've done similar many years ago but with a pilot hole and an aviation 'spot facer'. Normally used to create a precision flat spot for a round head rivet. I had a source for used spot facers and it's a good thing as I needed several.

 

Pics would help alot. If it's tack welded in at the edge of the center I'd take a 4" grinder, put 2 cutting disks on it making it 1/8" to 3/16" thick and gently cut the tack welds loose.

Then as Anthony said, a sharp smack with a hammer and knock the center loose.

Find an old hub/axle with the same bolt pattern and mount it so it can spin, mount the center to it, put the hoop on and spin and tap and true the hoop to it, measure the hoop to the depth you want and put a small tack weld, rotate and check to make sure it's still true, another little tack weld and so on until your around the hoop.

Then come back and do complete welds.

One thing that you can do is once you get small tack welds around the hoop you could remove it, install the wheel on the car and see if it's positioning is correct. If so weld it up ! If not knock the little welds off and try again.

...

 

I too swapped a lot of hoops and centers around when we were dirt racing. Once you figured out how to do it and keep everything spinning pretty true, it became just another thing you expected to do. Fits right in with shortening your drive shaft, after a few, its no longer a huge mystery, just another thing on the list of what you do.

 

I can only attest to this working on the set of Mopar 15x7 wheels I am using using on the back of my coupster. The wheels I had on it were a set of 15x5 1/2 widened by 3". They had less backspacing than the 4" these had and still rubbed occasionally.


The first step was to mark the perimeter ridge of all the spot welds. You may have to look hard to find some of them. Also the shapes of the ridges were hardly ever round on my wheels.
Next measure the weld ridges longitudinally and laterally across their widest points to find what will be their centers.
Center punch that for drilling.


The fixture to hold the wheel when drilling on the drill press.

Wheel in the fixture.

Some things I found when drilling.
The holes I had to drill were way smaller than I thought they would be based on the size of the spot weld ridge.
If I remember right I only had to go to 11/16" before I saw the dirty line separating the rim from the center, meaning I had drilled through the weld.
It also meant that my way of finding the center of the welds worked for that particular pair of wheels.
To fill the holes in the rim I cut the heads off some 5/16"(?) carriage bolts. After welding and paint, a coat of RTV for insurance sealing.

I bolted a spindle and hub to this for truing up the wheel and tack welding.



On the backside I cut the flanges off through holes I drilled. That allowed me to get a 3/4" change in backspacing (4" to 3 1/4"). I could have reversed the center and got more but I didn't want the back edge of my beauty ring hanging in the air.
Longer studs and a 1/4" spacer and now I'm good to go.

 

X-cpe....Great job and description of what you did. Thank you!

Lynn

 

“Made” these wheels for my 36 Ford that had a nine in Ford rear that was just a bit too wide. Used early Ford centers with 7 in wide Chevy outers and the backspacing was 5 1/2 in to move the wheels more inboard.

 

Did you use 15” or 16” Chevy outers?

 

I have done a few sets . . Drill out the welds .

I made a driver out of 4" heavy flat bar bent and bent and ground it to fit tight to the rim so when your trying to beat the center out you have something to push on the lip/ edge of the center and not beat it all to hell and distort it so it will run true when slid back together.

My advice is after you get the centers out is to sand blast everything now and then take a flap wheel and polish up the area were the center goes and sand and prep everyhing for primer while apart . If the rim and the center are smooth then they won't gall as bad going back together and makes it so medium taps will adjust it.


I just use a rear end and a jack stand to get it true a little tap at a time .
Make sure the axle is not bent and is true first
Most factory wheel are not perfect and you will find the hoops them selves will not be perfect either so isn't expect zero run out . The area were the hoops is welded together likely will be a bit off even on a new wheel.

I bubble balance the wheel separately and if needed add a little more weld were needed when it's tire time the wheel is already good.

I also mounted a tire on the wheel when truing and triple check all my clearances and fit. .

My rears needed a 5" back space so I had to flip the centers around plug/ weld the valve stem holes and make new ones it was the only way to get my calipers to clear .

Custom fitting the rears was the only way I could get the wheel inside the fender and still clear my rear brake set up as I had about a 1/8 to work with but it worked out .

 

You're welcome. I consider myself as being underfunded, not an overachiever.

 

I have done many sets of these recentered wheels . I used a milling machine a cutter . It punches through the weld like sticking a ball point pen through news paper . I would clamp a TIG welding rod to the frame and slowly rotate the wheel bolted to rear axle to center it up . Pretty crude but it worked great . Not one issue . I would tack all four feet remove them and weld about an inch at a time skipping all around until finished .A piece of copper as a backup to weld the old plug weld holes up also . Very little sanding was needed . The most I did were GM Ralley centers with spacer rim . 4 in front runner on the cheap . Steel wheels are not really accurate when new years ago .

 

My brother reversed wheels in metal shop class in the 60's. They used the lathe to center and stick welded them. Most cars in the parking lot had reversed wheels on them. Decades ago, I sold speed parts. The warranty runout on many brands was .050" If you get them closer than that, I think you will be satisfied.

 

I am working on some with riveted centers. Drill press, carbide spade drill an a piece of channel to rest the wheel on. When I pushed the centers out, there was a considerable amount of press fit to overcome. Like a bunch, maybe +- .090". I didn't want to grind the centers to fit, the press is there for a reason. To facilitate pushing them together in the press, I made this "pusher".

Worked a charm. It takes most of what my 20T air/hydraulic press has, to push them in. The OD of the pusher is just a schoche smaller than the ID of the rim. Pushes the center in by it's edges. Mike

 

I have seen the guys that make the custom aluminum wheels heat the outers so that centers drop in, I wonder if that would work with steel wheels?

 

Yes it works very well.

 

Robert Palmer did some rims for his dirt track car. It’s in his thread, but I don’t remember the title. Probably easy enough for the computer literate to find. Me, nfw, I’m computer illiterate