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3-4" lowering U-bolts

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Been trying to find longer U-bolts for my truck, cant any here in the UK but still not finding what i need,

 

axle is 3" diameter

I need 12" length

1/2" thread size or are they metric M12 ?

 

Anyone point me in the right direction ?

 

Also for a 3-4" drop should i be using a block with an angle, how many degrees ?

And does the angle go down on the leaf spring ?

 

Thanks for any help!

 

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https://www.stengelbros.net/U-Bolts_c_23.html?gclid=EAIaIQobChMI5PatzNTx5AIVj6_sCh0aigUDEAAYASAAEgLZh_D_BwE

 

Don't know about the angle shim. I would get a cheap inclinometer/protractor/angle finder and measure the pinion angle before and after you lower it. Measure the angle at the tailshaft of the trans too. They should be within 1 degree or 2 at rest (with all the weight of the truck on the ground).

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Isn't the angle of the pinion shaft supposed to stay parallel with the trans shaft?

What you really need to be concerned with is keeping the front & rear drive shafts in line as much as possible, and that means raising the center bearing up.

I run 1" spacers under mine.

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The transmission and the center bearing are fixed in relation to each other. If you raise the center bearing, the angle at each U joint should change equally. The rear drive shaft is different as the differential swings in an arc around the front bolts on the leaf springs. It isn't much but the pinion angle changes as it is raised or lowered. Raising the center bearing equalizes the angles at the two rear U joints. With drive shafts... angle in should equal angle out.

 

2PieceShaftA.jpg

 

 

The U joint at a bend does not rotate at the same speed all the way round. It's actually trying to follow an ellipse and it has to speed up and slow down to do this.

 

jD9eeG7.gif?noredirect

 

Left side is turning at a constant speed but right has to speed up and slow down causing severe vibration. The cure is to have a second U joint 180 out BUT having the same bend or angle. One is trying to speed up while the other end is slowing down. This will cancel out almost all vibration.

 

 

 Measure the center bearing U joint angle and the differential U joint angle with someone sitting in the driver's seat and tuck on it's wheels, tank full. The angles must be equal. Shim between the axle leaf spring perch and the leaf spring to tilt the pinion up or down.

 

I did this on my 710 when I lowered it slightly. Didn't even realize there was a low vibration till it was gone! It's the little things like this that make driving such a pleasure.

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21 hours ago, Stoffregen Motorsports said:

https://www.stengelbros.net/U-Bolts_c_23.html?gclid=EAIaIQobChMI5PatzNTx5AIVj6_sCh0aigUDEAAYASAAEgLZh_D_BwE

 

Don't know about the angle shim. I would get a cheap inclinometer/protractor/angle finder and measure the pinion angle before and after you lower it. Measure the angle at the tailshaft of the trans too. They should be within 1 degree or 2 at rest (with all the weight of the truck on the ground).

 

THIS

 

I used a washer on a string and a protractor. Crude but effective.

 

71OuUGpW7cL._SX466_.jpg

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You know Matt, it's amazing what you can put up with and get used to. I drove it for weeks with a subsonic rumble and only when gone did I notice it. Same with bump steer. You can get used to it easily and only after the bother to correct it do you appreciate how nice it is now.

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I bought U-bolts from summit racing. I know they're not in europe but they ship worldwide and have heaps of options for lengths so it was the easiest option...

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