[61bone]

I need to redrill the axle flanges on my T for the new brakes but have a problem, I am a math moron and have figured it several times and got a different answer each time. So, does any one know the lug center to center distance in thousandths for a 5 on 4 3/4 bolt pattern? Thanks

[Triaged]

The center to center measurement of the wheel lugs for a 5 on 4.75 bolt pattern is 2.792"

[BillyShope]

Maybe you've got a plan, but it seems to me you're going about this the hard way. If I had a flange on a mill, I'd center the rotary table, move away by the radius, and then rotate through the angles. I wouldn't consider this a job for the drill press.

[61bone]

Thanks for replies. Will lay that out and try it today. My plan is this- drill some holes, beat some studs in em, bolt on some wheels an go crusin

[xntrik]

Billy is correct. This is no time for a "hand job".

[61bone]

Oh ye of little faith. The project is done. Just me ,my lathe and trusty drill press. Measures out to exactly 5 on 4 3/4. RH axle lateral runout at .0005. Radial runout on the lugs .003. Actually 4 spot on, 1 .003 out. On the rotor .012 (factory machine work). LH axle at .0007, lug radial .002 1 out, rotor .014. Incidently, the original factory bolt pattern had .043 on one side and a whopping.077 on the other. The c-c distance varied up to .022. Score one more for the Wrenchbender.
I'll quit bragging now.

[xntrik]

Originally Posted by 61bone

Oh ye of little faith. The project is done. Just me ,my lathe and trusty drill press. Measures out to exactly 5 on 4 3/4. RH axle lateral runout at .0005. Radial runout on the lugs .003. Actually 4 spot on, 1 .003 out. On the rotor .012 (factory machine work). LH axle at .0007, lug radial .002 1 out, rotor .014. Incidently, the original factory bolt pattern had .043 on one side and a whopping.077 on the other. The c-c distance varied up to .022. Score one more for the Wrenchbender.
I'll quit bragging now.

you have an amateur machine shop..... good for you !!!!!!!

If you look at G body GMs around 80.... I have seen several with such horrible bolt circle eccentricity from the factory that the entire car felt like the tires were 2 oz out of balance above 50 mph. I remember one 80 Buick Century with a front rotor that was .090 out of circle...... wow.

[yesgo]

This thread has opened my eyes. I've never thought to read runout on lug eccentricy before. I'm wondering exactly how to do it.
All I have is a flexible (ball joint type) gauge. I guess I need to work in a machine shop for a while.
I have never owned a drill press or mill, but have to deal with strange vibrations sometimes, and sometimes run across drums which seem off center to the shoes... usually I find bent parts, other times I just assume (which I hate to do because I cant guarantee new parts are better).
Any advice or links would be appreciated.

[BillyShope]

Good for you, 61bone! Actually, I tend to do things the same way, but, when it comes to advising others, I'm much more conservative.

When I was a kid, my dad would walk by as I was working on something, shake his head, and say, "That's the way the Apaches would do it."

[61bone]

[QUOTE"That's the way the Apaches would do it."[/QUOTE]
That's actually a compliment. I have seen Apache handiwork and it is exquisite and very well done.
Any time I have a problem with balancing a wheel, runout is the first thing I check. It's not hard to do on the car. Set the axle firmly on jackstands. Remove the drum or rotor. Throughly clean the area where the drum sets on the lugs. I use a 1" steel plate 1' square on the floor for a base. If it has any rock at all, a small amount of sand spread under it will stabilize it. spread the sand and rub the plate back and forth a few times to uniform it. Set up your dial mike about midway on the throw with the plunger on the high spot of the bottom lug. Zero the mike. Now lift on the axle shaft. This will give you bearing play. When pressure is released the mike should return to zero. Now gently lift the plunger, turn to the next lug and gently set it down and write down the reading. Repeat for the rest. When you get to the original lug, the mike should read zero. If not ,something has moved. Try it again. Fronts are the same except you have to adjust the bearings to zero. Don't forget to reset when done.
For myself, I would accept anything under .030 runout on the lugs. I don't have any specs, but think that would be within manufacturing tolerance.
Have fun.

[yesgo]

Runout checks are no problem. I thought you were talking about eccentricy, like if the bolt circle was slightly off center.

[61bone]

Exactly what your checking. The runout from axle center is the same as the eccentricity. Look at it this way. If the lugs are all measuring the same, except one, you have a misplaced lug. If you have three the same and two out ,again misplaced lugs. Now if you have one high ,two lower and two lower yet, you have a pattern that is not concentric to the axle center. Note that this is not all possible combinations of lugs and you can have misplaced lugs and excessive runout in one pattern. In the last instance, you have to measure c-c spacing to determine the problem. In any case, the only way to fix is to redrill the axle or replce it with a good one.

[yesgo]

OK, I think I get it. You are checking axial runout on the lugs themselves? I re-read what you wrote about it. All I have ever really checked on a hub before was lateral runout.
Thanks.

[xntrik]

Originally Posted by yesgo

OK, I think I get it. You are checking axial runout on the lugs themselves? I re-read what you wrote about it. All I have ever really checked on a hub before was lateral runout.
Thanks.

not axial run out.... radial run out

[yesgo]

Yup. Radial. D'oh. Thanks again.
The more I know the less