BUILD THREAD 86 GP 2+2~Blown 6.0

[Streetbu]

I bought adjustable uppers, but set them to factory length. I have no vibrations so I figured I didn't need to change my pinion angle. My upper had a spherical joint on the body side. I could immediately tell a difference from the stock arms which I had put all poly bushings in. I didn't realize it was binding until I changed them

 

[fleming442]

https://nasaspeed.news/tech/suspension/wheel-hop-causes-effects-and-cures/
I never understood the use of rubber/ poly mix, unless it's purely for ride quality. There are a few other factors at play as well, such as instant center, shock valving, etc. My 67 has a full UMI rear suspension with poly bushings and the rod ends at the upper frame side. It still hops on street tires; I think, because of the stiff rear springs jacking the rear up (it's a band aid to a long story).

 

[81cutlass]

Put a set of adjustable uppers in tonight

Still wheel hops.

That's new kyb gas adjust shocks, adjustable uppers set to 1.5 degrees pinion angle with rod ends on the car end and poly on the housing. Boxed lowers with stock rubber bushings.

Do I put 3 degrees angle in and see if it still hops?

Strange that it didnt hop last fall with blown shocks and a gov-loc diff but now it does.

 

[fleming442]

I'm not convinced that pinion angle has anything to do with wheel hop.

 

[Streetbu]

Lowers with rubber bushings aren't helping that's for sure....

 

[Turbolq4]

Instant center may play a part in this. I couldn't calm mine down (Ford 8.8) without upper control arm relocation brackets.

Witchcraft and voodoo for sure.

 

[81cutlass]

Instant center may play a part in this. I couldn't calm mine down (Ford 8.8) without upper control arm relocation brackets.

Witchcraft and voodoo for sure.

Yeah, I have heard that about the 8.8. Partially why I went through the effort to made the 8.6 rear for this car with the bolt on UCA plate. I was very sure to make sure the control arms on this are within 1/4" of stock (which they are).

Main reason I did the adjustable uppers was that is kinda the path everyone seems to go. I had a tough time seeing how the lowers, although rubber which were in good shape, could cause that much deflection.

I am going to change the lowers over to poly and see where that ends up. They are only $40 and probably an hr or 2 to change. If it then still hops I am going to have to look into moving control arm angles.

 

[motorheadmike]

Rubber bushings will introduce a lot of deflection and wrap up in the suspension when loaded. With rubber bushings you need to account for this is more downward angle at the pinion to compensate for the rise. Remember are dealing with a push and pull relationship with the control arms on either side of the pinion, as the pinion tries to rapidly climb around the crown gear under heavy acceleration. So, the mushier your bushings are the more prone to gaining unwanted upward pinion angle you are.

In the wagon I have -3* pinion angle with poly-urethane and roto-joints. Ideally I will have around 0* during max load (minimal deflection in the poly-urethane bushings). Additionally I have the LCA near parallel to the ground, and the uppers pointing down (the S60 has raised ears at the centre-section) which brings the Instant Centre to a good place.

http://www.onallcylinders.com/2015/...e-to-tuning-your-four-link-suspension-system/

Your LCAs appear to be pointed up, and your raised "ears" are looking like they are pointing the UCAs down.

 

[MC96]

Hes eliminated 1/4 of the flex by using those arms, they have a heim at the frame side.

Those are the Allstar (really made by DCA Race Fab) arms, they come with a cheapie heim I would recommend a good teflon lined one, Allstars heims are actually top of the line.

Heres another way to play with angles and instant centers easily, https://www.moog-suspension-parts.com/moog-k8823

Camber bushing for a ford taurus, uses the same shell as a g body bushing. Although you might need to shorten the inner sleeve a bit.

 

[motorheadmike]

Hes eliminated 1/4 of the flex by using those arms, they have a heim at the frame side.

Those are the Allstar (really made by DCA Race Fab) arms, they come with a cheapie heim I would recommend a good teflon lined one, Allstars heims are actually top of the line.

Heres another way to play with angles and instant centers easily, https://www.moog-suspension-parts.com/moog-k8823

Camber bushing for a ford taurus, uses the same shell as a g body bushing. Although you might need to shorten the inner sleeve a bit.

Where was this little nugget when I was building my last two rearends, huh?!