Different pinion angle question.

[68LSS1]

I should be getting my HOTRODSTOHELL kit this week and I have a question. I would like to weld this up with the 8.8 and install to the frame. Will the pinion angle change later with all the rest of the truck on the frame? I know that the rear won't. That's relatively stationary to the frame (except of course under a load). But as the rest of the front end is put on the truck (along with cab, bed, etc.) won't the angle of the trans yoke maybe change slightly? My thinking is that the suspension will "sink" a little on both the front and back as the truck is put back together. More so in the front. Say I set it up for a +1 degree at the rear and -2 degrees at the trans. (I disagree with running a 0 degree pinion angle). Well now that I'm typing it out I think that although the tail may move down, its angle will stay the same. What do you guys think? I haven't finished the motor mounts in case I need to tweak some here. I know I'll need to finish that first before welding the new saddles to the rear end but I'd prefer to do this one time only.

[Rooster's 67]

Is the rear coil or leaf?
The trans angle and pinion angle should be the same under normal operating weights, ie: -1 deg at tranny out put should be met with -1deg at the pinion.
Has to do with phasing of the joints during rotation. Too great an angle or unmatched angles can cause vibration and high wear

[crazy longhorn]

Leaf springs "jack" the angles under acceleration, & racing with leaf springs you want the pinion anlge a little low, so that under acceleration the angles are on when the pinion twists up. the tough part is that this creates a "busy" ride under normal cruise conditions(driveline vibe). The long trailing arms will move the angle somewhat under full throttle. The rear squats, so the angle moves down instead of up....it shouldnt be too much tho. with the trailing arms, I would try to simulate the weight that will be on the truck, & set the angles on plane.......if 3 degrees down on the trans, you need 3 degrees up on the pinion. Good luck,crazyL

[68LSS1]

It's a coil spring being modified with the HOTRODSTOHELL kit. My question is not what to set the pinion angle to but can I set my rear end up (meaning weld the saddles to it) with a bare frame? The truck is down to the frame. With the engine and tranny in place can I set the pinion angle where I want it without rest of the body (meaning cab, bed, fuel system, etc). I'm changing out rear ends. Will all the added weight change anything when it's all back together? Let me say it like this: I've got a bare frame with engine and tranny and front crossmember. Now I want to swap in my 8.8. So if I take my measurements now and weld my saddles to the rearend to get my desired angle will anything change as I start putting rest of the truck back together (or on the frame)? I disagree with Rooster's 67 in that a same angle setup can cause a vibe (even 0). crazy longhorn, I agree about the trailing arms moving down (hence the suspension kit) but I disagree with the separation you gave. I say no more than 3 degrees. But I don't want to debate pinion angle settings here. I want to know can I set it now and weld everything together or should I wait and get the truck back together as the angle may change with a fully loaded frame? I don't want to mess around with shims later if I don't have to.

[crazy longhorn]

the weight on the truck is bound to change the pinion angle , if its added later......how much, I couldnt say. on some of the lowered trucks that run blocks as well as springs, the blocks are cut to correct the angle. As far as angles, the sum of the 2 angles need to equal a straight line to be in phase. That way, as the u joints speed up & slow down as they work, they cancel ea other out(no vibe). my 3 degree figure was given as an example, but probably isnt far off in the real world on pinion /trans angles. The u joints or rather the angle the u joint runs in compairison to the shaft needs to be greater that 0 degrees, but not more than 3 degrees to work properly http://www.streetrodderweb.com/tech/0203sr_driving/ on extreeme example of U joint angle problems would be a jacked up 4x4...... the trans & pinion angles can be equal/opposite angles, but the U JOINT angles are very severe. crazyl

[Stroker]

68LSS1 I also think it would be difficult to determine the proper pinion angle untill the truck is more complete. Your best bet may be to take a stab at it and just tack the brackets to the rearend untill the chassis is fully loaded. I ran across that kit about a month ago and thought it was kinda cool to hear of muscle cars and street rods converting suspensions to one simular to our trucks. I've got a few questions about their kit if you don't mind. What kinda rear drop does the kit have? Do they relocate the shock to be oriented inboard to outboard or are they forward and aft but just at a different angle. The adjustable preload or wedging is a nice touch and the panhard assemble looks interesting . Be sure to post some pics when you get it installed. Thanks......Stroker