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-   -   lowering/ u-joint ? (https://67-72chevytrucks.com/vboard/showthread.php?t=556233)

sumtercleaner 12-14-2012 04:57 PM

lowering/ u-joint ?
 
Do the lowering via drop springs put any extra stress on u joints or any other parts?
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sumtercleaner 12-17-2012 09:29 AM

Re: lowering/ u-joint ?
 
Reason im asking is after lowering the rear, i started getting a clicking when i first take off.
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CC69Rat 12-17-2012 09:50 AM

Re: lowering/ u-joint ?
 
How big was the drop? 2" .. 6" ? It sounds like a pinion angle issue to me.

Clyde65 12-17-2012 11:31 AM

Re: lowering/ u-joint ?
 
if your getting a ticking from the ujoint, it is already bad.

sumtercleaner 12-18-2012 08:22 AM

Re: lowering/ u-joint ?
 
The PO heated front springs down to the bump stops and only heated the rears and inch or so.... stupid look. So i heated the rears to bring it down some til. After christmas when the budget is a little better. Its by no means as low as it could go. Ill prob replace u joints but how can i change pinion angle? If it were leafs im familiar with those from my dirt track days.
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bk2life 12-18-2012 09:24 AM

Re: lowering/ u-joint ?
 
Quote:

Originally Posted by sumtercleaner (Post 5764770)
If it were leafs im familiar with those from my dirt track days.

pinion shims -same as your dirt track days.

cdowns 12-18-2012 10:25 AM

Re: lowering/ u-joint ?
 
with heated lowered springs that clicking can turn to a very loud crashing noises in less than a heartbeat// thats why they call cheapo heated drop jobs deathtraps

sumtercleaner 12-18-2012 02:12 PM

Re: lowering/ u-joint ?
 
Can some one post a link or part number so i can adjust the pinion? Again i am not familiar with adjusting pinion angle with coils. On coil race cars we never had a problems but on leaf cars we added 4° shims. My truck is coil
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CC69Rat 12-18-2012 02:46 PM

Re: lowering/ u-joint ?
 
Sumter - Realizing you're trying to make a bad (Previous Owner) situation better, we're here to help you man.

Two ways on the coil / Traling Arm / Truck arm suspension. It sounds like you know this, but when the truck is lowered, the pinion where it meets the drive shaft yolk that angle doesn't change much at all. So essentially what you'll run into is the pinion angle will point UP too far toward the bottom of the bed floor. We need t ofigure out a way to 'Roll" that pinion angle back down. you can accomplish this by:

Flip the front trailing arm brackets upside down. This will take away about 3-4" of drop that the truck sees. So, what I mean is by moving that hinge point UP - ( where the trailing arms meet the cross member) then you can lower the truck without changing that pinion angle. This will also help you with overall handling because the truck arms will be at (close to) stock angle. The front mounting point higher than the back. The only downside to this is it will cancel out about .75" of your drop. If you raise the front mounting points, then you also raise the angle where it meets the spring perch and it will raise the truck.

Otherwise when you lower it, the trailing arms will essentially be laying purpendicular to the ground. .. and the truck will be bad to squat in corners and hard acceleration. This is even more important with a LWB .. just my opinion.

The next option as you mentioned would be shims. you can buy pinion shims for the truck trailing arm suspension. 4 deg sounds about right. I usually do 1 deg per 1" drop. .. on a SWB, but on a LWB it might be slightly different. You want a little bit of nose up on the pinion so when you take off the pinion will roll DOWN. .. and the drive shaft and pinion angles will 'zero out' I usually do 1-2 deg UP at ride height.

On the drop springs, yes .. absolutely. Heated springs are dangerous brother. Not trying to make a situation worse for you but what I'd do would be maybe a 4-5" drop spring .. and a 1" block ? then maybe 3 or 4 deg shims. If you're around 6" drop or more, I'd consider flipping the front brackets AND shims. I happen to have some extra front brackets if you need them. They are ROUGH to get out of there but it definitely helps wit hsituations like yours. while you have the drive shaft out it would be a great time to throw a new Ujoint in there .. Hint. :D

Later. Let me know if I can help you.
Welcome to the Board!
Chad

sumtercleaner 12-19-2012 08:57 AM

Re: lowering/ u-joint ?
 
Ok i found some shims at a reasonable price. (Stockcarproducts) going with 4° . The center support bearing that the PO installed is in half now. So that will be replaced as well. Thanks for the help, tips and concern.
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