Can someone explain Wheel backspacing to me? (1 Viewer)

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The drum brake models had the 4" (or 4 1/4") back spacing. The disc brake models went to the 3 1/2" BS. As pointed out, the steel 3 1/2 clear TRE's easier than the 3 1/2" Aluminum. Which is what brought people around to the 2" or 2 1/2" BS. Also, with the 2", you have more offset, giving a "wdier" stance, which many prefer. OF course, the dowside is additional load on the bearings.
 
woooody said:
The drum brake models had the 4" (or 4 1/4") back spacing. The disc brake models went to the 3 1/2" BS. As pointed out, the steel 3 1/2 clear TRE's easier than the 3 1/2" Aluminum. Which is what brought people around to the 2" or 2 1/2" BS. Also, with the 2", you have more offset, giving a "wdier" stance, which many prefer. OF course, the dowside is additional load on the bearings.
Click to expand...

The wheels I am looking at are steel, but is there going to be a problem with clearance on the back with 3 1/2" BS and drum brakes?

Thanks!
 
So, how do I measure the backspacing on the wheels I currently have? It looks like I have a different BS on the rear than on the front.
 
tlcruiser66 said:
So, how do I measure the backspacing on the wheels I currently have? It looks like I have a different BS on the rear than on the front.
Click to expand...

If I learned anything from the respomses to the question I asked originally, you lay a straight edge across the back of the wheel from one side to the other and measure down to the back of the surface the bolts come through.

I hope I'm not an idiot... (again) :doh:
 
Wheels hit Calipers

Rick.... someone mentioned it earlier, so I just want to emphasize the point that you are likely to hit the calipers with your new wheel regardless of what backspacing you have. I just put on the black Rock Crawler wheels (76 FJ-40), and I had to grind off my calipers to get them to fit.

I have the GM disc brake kit on the rear and no problems with hitting.

Good luck....
 
atazman said:
Rick.... someone mentioned it earlier, so I just want to emphasize the point that you are likely to hit the calipers with your new wheel regardless of what backspacing you have. I just put on the black Rock Crawler wheels (76 FJ-40), and I had to grind off my calipers to get them to fit.

I have the GM disc brake kit on the rear and no problems with hitting.

Good luck....
Click to expand...

I put the same wheels on mine after I first asked the question and didn't have any problems with clearance, but mine had them before I bought new ones. I only replaced them because the old ones were out of round and wouldn't balance right. The PO may have already ground off the calipers to make the previous set fit. I didn't look at them while the wheels were off, 4 wheel parts mounted and "balanced" them (and did a pretty crappy job of balancing, I might add) so I didn't get to take a look. I'll probably take one off and look at it some time, if I need to do it for some other reason. These things with 33x12.5 Super Swampers are HEAVY!!

Thanks for the reply!
 
Is backspacing that much of a concern if I were to buy 16" wheels?
The wheels I want only go as low as 4" backspacing.
 
69 stock rims (rivet style) onto a 76 with discs.(FJ40) Will I need to grind down the calipers, or will they even fit at all?
 
The main concern with the backspacing is the tires rubbing on the springs while turning and the wheel rubbing the steering arm.

As for the stock rims from a 69 onto 76 hub, I don't know but I wouldn't grind your calipers down, I just did that last weekend and now I need new calipers. I ground down a little, then installed the wheel until they didn't rub anymore just to find out I ground right through.

Once I get new calipers, I'm going to just get some 1/4 inch spacers.

Good luck, Kevin
 
They both are attempting to solve the same problem which is giving your wheel clearance of the brake caliper. Backspacing is safer as it is one less part. However those who already have and investment in wheels that do not fit often go with spacers.

In my case I got backspaced wheels that worked just fine but added spacers for a wider stance.

Alf
 
To answer a question with a question, how much do you need? Different needs will have different solutions.
 
I have 2" spacer and not worried about it.

kls
 
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