John Lee's Heavy Duty Lower Control Arm U-Bolt Modification

[Sharps40]

Next to removing the single pot master and splitting front brakes from rear then adding a dual pot master, I think one of the best and likely cheapest ($30 or under) safety upgrades you can make on these old trucks....(Lasttombstone, listen up - that one of yours probably needs this mod!) is to replace the 7/16" lower control arm u-bolts with the more modern and less prone to breakage 9/16" u-bolts. If everything goes well, its about a 3 hour or less job and you won't loose the lower half of the suspension when one of them old and just a whisker larger than muffler clamp u-bolts lets go. Typically, on these old trucks the stock 7/16" bolts break when turning, especially backing up. Over the years GM upgraded to 1/2" u-bolts, which also break. Then finally to 9/16". Haven't heard of these breaking. They are a close fit, very close but follow along and we'll get em in and just enough room for a socket on the big prevailing torque nuts at the front inners with a bit of dimpling of the cross member.

If your rebuilding the front end, pefect time to do this mod when the lowers are off. If you just want piece of mind and safety, jack stands and jacks and don't get under the control arm any longer than you have to, always do one at a time so you at least have some extra margin of safety. i.e. I only removed one shackle at a time...installed the new one, torqued it and then removed the second shackle....!!!

When you have the jacks and stands right, loosening the stock u-bolt will see it become floppy but the control arm stays firmly against the cross member. If the control arm is moveing down, retighten, reposition jacks and stands and then loosen again. You want all that energy in the spring contained by the stands and the jacks, not torquin the control arm shaft against the other shackle while yer under it all.



On Ol John Lee, the 64 C10 I used the LMC u-bolts. At $15 each and w/o prevailing torque nuts, they were highly expensive but worked just fine. If there is an advange to the LMC u-bolts, its that they have taller nuts allowing standard sockets to be used. I almost had to go to a deep well socket to get these Dormans in place. By the way, these are available from Oreillys and Auto Zone for $8.99 a pair. Considering there was no shipping, about 1/3 the cost of four bolts from LMC. And, I like the prevailing torque nuts better, no lock washers required.



The old and the new side by side. A huge difference in brute strength. I'll be more comfortable with my lowers riding in these new beefy u-bolts. Got a lotta miles to cover starting in Sept, its hunting season all over again!



Drill bit is 9/16" diameter, rebated shank to use in a 3/8 reversible drill and available at Lowes under $10 per bit. Plenty good for this job, it'll go thru 8 holes lickety split, the crossmember is not hardened steel.



Working with a steel rod, held in vice grips, use the medium SmashWacker (or an air hammer) to dimple in the cross member where the front inner prevailing torque nuts will spin on. This clearance is needed to get a 7/8" socket onto the nut and spin it down to torque spec. The PS front inner will need a deeper dimple than the DS front inner. This was the same situation on Ol John Lee the 64. So, it seems that consistently in 64 and 65 the cross members had a shape that was slightly different from side to side. But in any event, its good news that there is just enough room to install these later model and much stronger u-bolts on the lower control arm cross shafts.



These dorman u-bolts are a bit finer finished than the LMCs. The LMCs are not coated with a gold rust proofing. In addition, the LMCs were too "open", I had to install nuts and smack em with a large SmasherWacker to close em up to go into the holes. These Dormans are just fine, drill the holes to 9/16 and tap them right on into place. Here I'm drawing up the prevailing torque nuts evenly, alternating back and forth until its time to put on the torque wrench and finish them up at about 80 foot pounds. (My spec, the 7/16 factory nuts backed off easy with 8" long 3/8 drive wrench!



Just to be sure, I compared the old and the new for thread depth....there is sufficient extra thread on the Dorman replacments that I will not need spacers or washers under the prevailing torque nuts...just run em on and torque em down.

[Sharps40]

The divers side front shackle completed and torqued.



A bit of cleaning to do before the winter suspension rebuild, but the dirt out of the way here so nuts and bolts can bottom on steel not on grit.



A shot of the Drivers side front and rear completed. Lather and repeat for the passenger side. Also, if you are running brake lines before doing this job, hump them up about 3" above the u-bolts on the rear of the crossmember. It'll give ya enough room to drill the holes from the bottom and wrench on the new ubolts from the top w/o pinchin a spanky new line.



That's it. Suspension safer and confident for the long drives to/from Hunting Camps starting in Sept. Time to clean up, smoke a cigar and go for a ride to validate the suspension mods and to see if I got the fuel stink fixed.