1 ton guys.... I need some help.

[Texasbigblock]

So on my 1969 dually (HO72) that I bought a little while back I have run into some problems. I went to replace the tires and rebuild the rear brakes and here is where the head scratching started.....
From my understanding, if original, the truck should have flat, 1/2'' lug nuts all the way around. My truck (Vidalia) has 9/16'' studs on the front (still drum brakes) and 9/16'' studs on the passenger rear but 1/2'' studs on the drivers rear.
Brake shoes and hardware kits for a '69 model fit in the rear and everything appeared to be the same as the stuff I took out. What is going on here?

Also, the 1/2'' studs on the drivers rear are tapered. I thought the original 1/2'' came flat on these trucks.
And the 9/16'' lugs are flat. I thought the later model 9/16'' duallys used tapered lugs and a retainer ring.

If I look for original lug nuts for this truck on Rock Auto, it calls for tapered 1/2'' lug nuts....
Any idea where to even start figuring out this mess?
Thanks

[71Dually]

Greetings Scott,

Let me see If I can help. I bought my truck about a year ago and have done considerable research on this wheel stud topic. While this is my first Chevy truck I have wrenched on lots of different vehicles over the past 46 years. Some of my experience comes from dealership service bays and some of it comes from gravel parking lots and driveways. I have the upmost confidence in my mechanical repair abilities and thought processes.

You have stated:

Originally Posted by Texasbigblock

So on my 1969 dually (HO72)...

That is enough information to get started and identifies your truck as a 10,000GVW vehicle. That is good to know as it affects the wheel studs. 14,000GVW vehicles are totally different animals in the rear axle (HO110) and the wheel stud department. 14,000GVW vehicles are also very different in many other areas but we are not dealing with those areas in regards to your inquiries.

All of my responses will be in regards to 10,000GVW C30's.

Originally Posted by Texasbigblock

From my understanding, if original, the truck should have flat, 1/2'' lug nuts all the way around.

Correct, 67-70 C30 duallies were originally equipped with 1/2" "Flange" or flat lug nuts all the way around.

Originally Posted by Texasbigblock

My truck (Vidalia) has 9/16'' studs on the front (still drum brakes) and 9/16'' studs on the passenger rear but 1/2'' studs on the drivers rear.

Sounds like there has been some modifications. Either drill bits or hub swaps.

Originally Posted by Texasbigblock

Brake shoes and hardware kits for a '69 model fit in the rear and everything appeared to be the same as the stuff I took out.

Sounds like your good to go there. Wheel studs wouldn't normally have an effect on shoes and hardware, those parts are backing plate and drum related.

Originally Posted by Texasbigblock

Also, the 1/2'' studs on the drivers rear are tapered. I thought the original 1/2'' came flat on these trucks.

Never heard of a "tapered" wheel stud. Conical (tapered) seat wheels and lug nuts but never wheel studs. From your previous statement of "truck should have flat, 1/2'' lug nuts" I will presume you mean the lug nuts and not the wheel studs. You are correct your 1969 C30 should have 1/2" flange (flat) type lug nuts

Originally Posted by Texasbigblock

And the 9/16'' lugs are flat. I thought the later model 9/16'' duallys used tapered lugs and a retainer ring.

Your thoughts are correct, with one exception. 71-72 C30 duallies used 9/16-18 wheel studs and flange lug nuts. Starting in 1973 C30 duallies used conical seat (tapered) clamp rings and lug nuts.

Originally Posted by Texasbigblock

If I look for original lug nuts for this truck on Rock Auto, it calls for tapered 1/2'' lug nuts....

I'm finding both flange and conical 1/2" lug nut applications for your truck on Rockauto. Rockauto is all over the map because the aftermarket manufacturers are all over the map. Wouldn't be the first time I've seen incorrect aftermarket manufacturer information. Aftermarket manufacturers also "supersede" parts to reduce costs. When seeking a reference I normally stick with GM's original design part references and match to those.

I believe that normally the 67-72 single rear wheel (SRW) applications used conical seat wheels and lug nuts (C30's were available with SRW applications). Dual rear wheel (DRW) applications in these same years use flange lug nuts and flat wheel mating surfaces.

Originally Posted by Texasbigblock

Any idea where to even start figuring out this mess?

Stick with GM's original design if desired. Obviously a prior mechanic has modified GM's design. And rather poorly in my opinion with the mismatch of wheels studs and lug nuts present. Sounds like a "that's good enough" job when compared to a "that is correct" job. Everyone has different standards when it coms to craftsmanship and pride in workmanship.

Careful with this as it may prove to not be the only mechanic design change.

Regarding your direction. What do you want to do? Do you want to run aftermarket aluminum wheels? Do you want to run stock configuration steel wheels with flange lug nuts? Do you want to run clamp rings and conical seat lug nuts?

You can run the clamp rings and conical lug nuts but be careful. Verify the stud stand out is sufficient for clamp rings. When GM implemented the conical seat clamp ring and lug nut the wheels studs were lengthened to accommodate the additional thickness of the clamp ring configuration. 71-72 factory wheel studs (both front and rear) are shorter than 73 and up factory studs.

Don't be confused by Dorman's claim that their part number 610-182.1 stating that 71-99 front wheel studs are the same. They are not. The 71-72's are shorter. This is simply a case of aftermarket supersession to save cost. It's more cost effective to make one length stud that fits both applications rather than make 2 different lengths.

Here is a discussion regarding wheel studs I was previously involved in and may help with further detailed information and related pictures:Longer wheel studs for newer style aluminium wheels.

Ever heard a story of someone loosing a wheel and borrowing lug nuts from the other wheels to limp home? If you loose the 1/2" lug nuts your out of luck with only 9/16" nuts to borrow. If it was me, since you already have 9/16" studs on 3 wheels I'd go ahead and change the 4th to match. Use the longer 73 and up studs, they certainly won't hurt and will allow more wheel options than the shorter 71-72 wheel studs.

Personally if you do drill out the 1/2" hub for 9/16" studs don't use a drill bit. Use a reamer and a drill press. Drill bits are sloppy and you won't get an accurate hole size when compared to that of a ream. Also check the prior mechanics work. If you have loose studs it's possible a drill bit was used and substandard results were obtained. You can not properly torque your wheels if the studs are loose in the hubs.

Originally Posted by Texasbigblock

Thanks

You are very welcome, it has been my pleasure and I hope I have been able to help. Good luck with your trucks wheel studs and lug nuts. Please, keep us posted on your solution and what you end up doing.

And please, last but not least, don't forget pictures, they are worth a 1,000 words each.

Best regards.

[Texasbigblock]

Thank you a ton (no pun intended). I have been a wrencher and a 67-72 guy my whole life but this is my first dually. I am a "fix it right and make it safe" guy so I always go through that part of my trucks first. Tires, brakes, replace unsafe wiring, lights, etc. I'll give everything a second look today and keep you posted on my game plan. Thanks again!

[Texasbigblock]

After looking at the rear again today I have come to the conclusion that the drums were drilled out to 9/16 on one side. On both sides the drums and hubs look and measure the same. The only difference is stud size. I plan to ream out the 1/2" side to accept the 9/16" studs. These drums appear to be the original type.