Trying to set up 3 link front

[flexj]

Here's what I'm trying to do: 2 lca's, 1 uca on pass side and a track bar. I have my brackets tacked in place and am cycling the axle up/down on both sides to see how it works. The pinion angle seems to change alot when cycling from the pass side. It's a hp D60. I used to have a hpD44 with long arms radius style w/the pass uca removed. That worked ok but I didn't have the angle of the drivers ucs right and it chewed through uca bushings like crazy.


I have my lowers mounted outside the frame rail right up against the floor pan, axle side is adjustable with center position being centerline w/1" either way adjustability. Upper is coming from the frame close to the stock lca mount, angled in and sitting real close to center of tube, maybe alittle back. Vert separation at frame is close, maybe 2" and 6" at the axle. This is comp/off road only so bump steer is not an issue. The track bar is not installed yet, could that be part of the issue? I was thinking it shouldn't matter since it just controls side to side movement

My upper is alittle long, I haven't modified it yet from it's former life. I need to shorten it about 2", so my pinion angle is high to start with. Should that matter? Length on lowers is 28" and upper is ~19 but will be shortened to about 17.5".

It would appear that the "easy" solution would be to put the upper over the pumpkin again, but I was hoping to stay away from the bridge thing again. I made a nice one for the 44 but it took awhile. Then I was reading about how some thought the pass side upper was the way to go so I'm giving it a try.

I've read everything posted by Goatman and others who have done this sort of thing and I know it can be made to work. Does anyone have any thoughts on what the issue is?

Thanks.

Hamy

 

[4ward]

Does anyone have any thoughts on what the issue is?

Length on lowers is 28" and upper is ~19

Thanks.

Hamy

You have your own answer right there. Think about 2 radii trying to travel together.

 

[RCP Phx]

Vert separation at frame is close, maybe 2" and 6" at the axle.

Hamy

And heres the other half of your answer,it behaves more like a radius arm set-up as you bring the rear points closer together.

 

[flexj]

You have your own answer right there. Think about 2 radii trying to travel together.

So I should shorten the lower or lengthen the upper? Either way, try to make them closer to the same length?


RCP Phx...yeah, I was thinking that might be part of it too but was hoping I could get away with it. If I move the uca frame mount back up to the stock location, it will hopefully solve both issues.

Thanks.

Any more input?

 

[hackedxj]

I run a 3 link and would agree that 2 inches at the frame is not enough separation. My upper is 19 inches and the lowers are 22 inches. I basically just dropped the mounting points down and back and tried to stay close the stock geometry so the pinion moves as normal.The ride and flex is very good and drives like a stiock XJ. Definately stay with it, you'll like it.

 

[XJoachim]

I have a radius style setup with the passenger side upper arm connected to the lower arm, also just 1 upper. As you mount the upper arm to the lower you won't have any change of pinion angle but you have to use some heavier material for the lowers as they will see a good amount of stress.

Don't forget to truss the UCA mount at the axle, i ripped mine off once. :wave:

 

[flexj]

All good stuff.

Thanks.

Any pics would be appreciated also.

 

[MaXJohnson]

So I should shorten the lower or lengthen the upper? Either way, try to make them closer to the same length?


RCP Phx...yeah, I was thinking that might be part of it too but was hoping I could get away with it. If I move the uca frame mount back up to the stock location, it will hopefully solve both issues.

Thanks.

Any more input?

moving the UCA frame mount up may or may not allow you to increase it's length, but the change in the angle of the link compared to horizontal will make your pinion gain problem worse, not better.

 

[flexj]

Is the length of the lower my biggest issue? or the lack of vert separation? If I radius armed it just on the pass side, would that be enough to hold the pinion?''

If you go by the 70% rule of thumb, my upper and lowers are pretty close, so maybe it is the separation. I guess I'll try that first.

Thanks all, keep it coming.