Thread: Castor correction & uni's

Originally Posted by Psimpson7

Grimace is correct here Trav. Castor corrected swivels will have no bearing on pinion // uni angles etc. The swivels are roated around the hosuing, so the housing stays exactly where it was.

Rgds
Pete

Went away and had a think about it and after reading Petes reply it makes sense to me now and what I was thinking wouldn't work. If it had been explianed like that I wouldn't have started the debate. I never said I was right but it makes sense since you put it that way Who's the idiot now

Trav

It's ok, I had an incling you were confusing yourself all along. No one is an idiot.

Hey all
The whole reasoning behind this is to state that cranked arms do change the angle of the uni,s and shaft in a negative direction. Trav, corrected swivels only change the steering geometry which Grimace pointed out. My point is why fit cranked arms when it is going to create problems due to increased uni angles. The point of the photos is to show that you can get away with a 4" lift and retain happy uni angles etc with standard radius arms. I would say anything over 4" you would need cranked arms etc to roll the diff back to help the panhard and spring mount etc. But you would need a flash front shaft with a double cardan joint etc and a modified crossmember.
Sorry to go on a bit but people keep saying cranked arms dont change the Uni angle. well yes it does. Unfortunately in a negative way.

Justin

Hi all,

Following this thread with interest.

Why don't you consider a D2 front shaft? With the t/c flange suit, its a bolt in solution to uni problems.

The pic shows my front flex: Nothing exotic, just Landcrusher Bilsteins, Haultech holey bushes, slotted swivels, & the D2 shaft.

Regards
Max P

Just break it down into simple terms.

What happens?

As you increase the height between the diff housing and chassis with a fixed point of rotation you rotate the diff housing in an arc. In the case of the front diff it rotates the spring mounts forward and the pinion upward. It also rotates your set castor angle from a positive towards zero and sometimes into the negative.

To make your car steer comfortably at speed, ie not skittish, you need a positive castor angle, so you need some way of returning this.

Driveline angles work best with minimum deflection from zero degrees and matched(or as close to) angles on both uni's.

Up to a certain point, correcting just the swivels will return castor with acceptable driveline angle.

Beyond that point, the diff housing needs to be rotated back to align the spring and rod mounts, or alternatively these could be cut and rewelded.

I think the arguement from Justin is, why go for cranked arms and place increased deflection on the pinion end universal.

Depending on the application, both have their merit. I prefer the swivel method, but in saying that, in larger lifts, the cranked arms may help bring the 2 deflections closer together, rather than a small one at the pinion end and a large one at the gearbox end, thus possibly relieving driveline vibration.

CC

Grimace, wasn't confusing myself it was more of a misunderstanding of the concept of castor correction that's all so it all now makes sense . I'm no oxford schollar but I'm not a dumb **** either

I have a simple sollution, don't overlift your Land Rover problem solved

Trav

Originally Posted by Col.Coleman

Just break it down into simple terms.

What happens?

As you increase the height between the diff housing and chassis with a fixed point of rotation you rotate the diff housing in an arc. In the case of the front diff it rotates the spring mounts forward and the pinion upward. It also rotates your set castor angle from a positive towards zero and sometimes into the negative.

To make your car steer comfortably at speed, ie not skittish, you need a positive castor angle, so you need some way of returning this.

Driveline angles work best with minimum deflection from zero degrees and matched(or as close to) angles on both uni's.

Up to a certain point, correcting just the swivels will return castor with acceptable driveline angle.

Beyond that point, the diff housing needs to be rotated back to align the spring and rod mounts, or alternatively these could be cut and rewelded.

I think the arguement from Justin is, why go for cranked arms and place increased deflection on the pinion end universal.

Depending on the application, both have their merit. I prefer the swivel method, but in saying that, in larger lifts, the cranked arms may help bring the 2 deflections closer together, rather than a small one at the pinion end and a large one at the gearbox end, thus possibly relieving driveline vibration.

CC

Thats making the assumption that a standard propshaft is being used. As Tusker has stated, you can also run a Disco2 shaft with a Double cardin joint at the transfer end, which has an ideal setup of just off no angle from the pinion and whats required at the transfercase. This does away with the need to produce equal angles at both ends of the tailshaft.

Originally Posted by Slunnie

Thats making the assumption that a standard propshaft is being used. As Tusker has stated, you can also run a Disco2 shaft with a Double cardin joint at the transfer end, which has an ideal setup of just off no angle from the pinion and whats required at the transfercase. This does away with the need to produce equal angles at both ends of the tailshaft.

Given that the discussion was centered around rangies and castor correction, no double cardan is a given. Fitting one, or a D2 shaft would only then be to fix a created problem.

A second arguement would also be, on a budget, slotting the balls is cheaper than buying cranked arms and a double cardan and new shaft.

I have a double cardan front shaft from a stage 1 laying around to go into mine

CC