Outer Limits 4x4 Board

Hi all, wondering if i could get peoples opinions/experiences on what's the best castor angle to run your front diff at ? I spoke to Bj about it a while back and i *think* he said 6 Degrees positive, ie: steering arms pointed upwards 6 degrees from horizontal. Surf's getting a much needed wheel alignment tomorrow and just after some info, cheers. Jeremy

Don`t know what mine is set at at the moment but it drive really good Just ask cheezy to measure it for you

Oh and my toe is set even better, but it tends to wear tyres quickly

Thanks guts.... very very helpful info !!

Anytime

I have set Guts Lux with the tops of the tyres laying in 30% and towing in around 20%, It works reel good on the banked Nascar tracks but will wear out a set of Swampers within 100m on the road.

the nissans are about 2.5 to 3 degree pos

mine behaves shocking below about +2deg, above that it drives fine. Doesn't seem to behave any different between about +2.5 & +5 other than the steering getting heavier at low speed.

i read that if you draw an imaginary vertical line through the center of the upper and lower kingpins, the line should strike the ground at a point ahead of the front tyre contact point.

Which for most cars is around 6 degrees positive / the steering should demonstrate a self centering effect after cornering/turning the wheel

Thanks guys..... Well the report from the wheel alignment wasn't all that good. Toe is 6mm overall toe-out, caster is 0.45 positive on one side and 1.45 positive on the otherside I guess that explains the poor handling !!!

Surfection wrote:Thanks guys..... Well the report from the wheel alignment wasn't all that good. Toe is 6mm overall toe-out, caster is 0.45 positive on one side and 1.45 positive on the otherside I guess that explains the poor handling !!!

looks like someone didnt measure twice and cut once b4 rotating the knuckles

I've played with the adjustment [upper arm adjustability] a couple of times since then so don't be too quick to point the finger.....whether or not me adjusting it could give a degree of difference from one side to the other i don't know.

Surfection wrote:I've played with the adjustment [upper arm adjustability] a couple of times since then so don't be too quick to point the finger.....whether or not me adjusting it could give a degree of difference from one side to the other i don't know.

i didnt think it s possible 2 change castor on 1 side of the diff just by adjusting the links.

hypolux wrote:

Surfection wrote:I've played with the adjustment [upper arm adjustability] a couple of times since then so don't be too quick to point the finger.....whether or not me adjusting it could give a degree of difference from one side to the other i don't know.

i didnt think it s possible 2 change castor on 1 side of the diff just by adjusting the links.

Ben
I'd say that there could be a slight bit of adjustment allowed due to maybe a little play in all the joints. Slight but maybe enough to throw it out of wack. It is only 2 degree.

hypolux wrote:

Surfection wrote:I've played with the adjustment [upper arm adjustability] a couple of times since then so don't be too quick to point the finger.....whether or not me adjusting it could give a degree of difference from one side to the other i don't know.

i didnt think it s possible 2 change castor on 1 side of the diff just by adjusting the links.

yep, it's possible. But if it was set up right in the first place, you should be able to get castor & wheelbase to match exactly from one side to the other. Toe is easy to measure with a tape measure across the tyres front and back, castor is a bit of a bastard unless you have a really, really level grage/driveway..

Toyotas are 1 degree positive from standard. That will have been the figure I gave to you. Six is something else I was talking about (six sux or sex)

ok yes castor can be changed if the upper and lower links r adjustable but u cannot change the castor on 1 side so that it differs from the other side (unless the diff is really weak and wen u adjust 1 side the diff twists therefore alowing one side 2 have a different castor angle 2 the other) unless u cut and rotate the knuckles and fark it up

hypolux wrote:ok yes castor can be changed if the upper and lower links r adjustable but u cannot change the castor on 1 side so that it differs from the other side (unless the diff is really weak and wen u adjust 1 side the diff twists therefore alowing one side 2 have a different castor angle 2 the other) unless u cut and rotate the knuckles and fark it up

yeah, you can change one side to differ from the other.. That is the way I have adjusted mine in the past, just so that I can do one side at a time to make it easier.. Say you lenghten the lower arm on the drivers side 10mm. If the arms are seperated about 150mm that is gonna give you about another 2deg positive. The upper joint has to rotate 2deg. The upper and lower joints on the other side of the truck actually have to skew (the lower more than the upper) some infinitesimal amount (0.0005deg or some such number). Even the stiffest, most unfriendly joint will allow this without loading up the housing...

I can see that working ok in a 5 link.... but what do you reckon about my 3 link carlton ?! Same theory but the links arn't seperated etc -<

what scares me with yours, is the y-shaped link is welded solid somewhere along the lenght of the lower arm (is this right? I am relying on memory) so as you adjust the length of one of the arms, the seperation is changing as well. So your bushes will be constantly distorted, and if you have too adjust it a fair bit, you probably won't be able to get the bolt back in..
I may be wrong about this, I can't remember if the link is welded together or if there is another bush where they intersect??

leafs are cool

Cartlon..... The top arm joins the bottom arm via a heim joint, so that's where the adjustability comes from....the bottom arm is fitted with orbital type joints at both ends and the diff end of the upper arm is a rubber bush. When i adjusted it i was winding the heim in so as to pull the top of the diff back, for positive caster... and i had to put all my weight into rolling the tyre back an inch or whatever to get the bolt back in.

on a solid axle hilux they are about 2 degrees positive standard.
On mine when i rotated the axle and knuckles i set it to about 4 degrees positive, that has given me a nice and light steering. I can run 13.5 claws on 4 psi and still turn the wheel without powersteering. I wouldn't like it with any more positive caster on the road because it would start to wonder .
Dont know if a surf should be the same caster?

Was the extra 1 deg positive caster on the passenger side?

If so, that is how it is supposed to be. It is common practice to have an extra 1 deg of positive caster on the passenger side to offset the crown of the road.

I'm not sure mick, i'm gonna wind the heims the little extra adjustment they still have and throw it back on the aligner..... i'll have to remember to check.

realux wrote:Dont know if a surf should be the same caster?

This Surf has a full custom 3link coil over solid axle swap.

realux wrote:On mine when i rotated the axle and knuckles i set it to about 4 degrees positive, that has given me a nice and light steering. I can run 13.5 claws on 4 psi and still turn the wheel without powersteering. I wouldn't like it with any more positive caster on the road because it would start to wonder .

Reading that, it sounds like you have your positives & negatives back to front??

ok i still cant understand how u can make one side different 2 the other unless u cut and rotate the knucles

i understand that wen adjusting the links that u can do one side at a time due the the movement in the bushes but it still wont make one side different 2 the other unless u actually weld it on so they r different

I am assuming that u just had a alignment report and no actual adjustments done, so if that is so and your castor readings are 0.45 on the drivers side and 1.45 on the passengers side and your toe is 6 degrees total toe, then the first thing is to set the toe to 0 degrees. This will improve drivability out of sight. It must drive pretty ordinary at the moment.
Can you tell us what the individual camber and castor readings are because camber can cause as many drivability problems as castor problems.
Also there are offset swivel bearings available to change left and/or right wheel camber and castor settings individually.

Great info... thanks Juzza !! I'm gonna play with it on the weekend, i've stopped driving it now for a while, i'll wind in the remaining thread on the heims for some more positive castor, and do as you say and try for 0 degrees toe, then i'll take it back in to work and get it on the aligner [not actually at work unfortunatly] and this time i'll go down there myself and get all the readings properly. I've also been told to move my steering dampner mount to my panhard rod so it's working in parallel with the tie rod, at the moment it's mounted to the chassis and is on quite an angle to the tie rod where it's mounted. So i think i'll do this too, a trip to the steel supplies place is in order !!! Thanks again, Jeremy