Patrol/Safari bits for Sani

[davidvdm]

Sorry this took so long, my pc is not on the internet at home and I can't get to this forum on my phone....

The manual shows that if your kingpin inclination is 7,3 deg, your castor will be 1,3 deg. So we have been working everything out according to that information. Saturday I took the car for wheel alignment and to get a report on anything that may be causing me these problems.

The guy finds no problem with the wheel alignment and no play on the hubs or ball joints on the draglink. The Castor however is 7,4deg. Exactly the kingpin angle I have been "creating" to achieve the 1,5ish angle according to the manual. So it seems that the kingpin angle is in fact the castor angle. Now I have to go fight back 6deg somehow.

I pulled the coils out and the nose dropped by 90mm. Castor is down to 6,5deg, but now there is nothing left to adjust with. In fact, the leafs are back to there inverted state, and after I took the car out onto the road, they seem to have dropped another 10mm or so as my bump stops are now constantly crashing.

I'll post some pics as soon as I can get them off the phone.

[davidvdm]

Peter, the reason for the coils on top of the leaf si to carry the weight of the Sani. I seemed to have made a mistake thinking that the Nissan Hardbody One tonner rear leaf pack would be up to the job.

[davidvdm]

the pics

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[Peter Connan]

Couple of comments:
1) Are those the full leaf packs from the HB, or did you remove some leaves? Those look wrong and are clearly too light for the application, but the way they bend in the middle (at axle) is a problem, and those springs will not last like that. You need more leaves, with more difference in length (bottom ones shorter) so that the flexing is spread more evenly along the length of the springs.

2) You need to have at least 40-50mm clearance between axle and bump stop. I do believe it is better to achieve this by adding more leaves than by adding a coil spring.

3) I am convinced your caster is running the wrong way round (negative instead of positive). This from the orientation of the diff casing, and confirmed by the fact that it reduced when the car was lowered by removing the coil (keeping in mind that the fixed spring hanger is at the front).

4) What manual are you referring to? The values from one for the car (with IFS) will not be correct now, you probably rather need to llok at the vehicle the axle came from, but even that is unlikely to be ideal for this hybrid.

5) As Grips said on the other forum, sort out the leaf packs, cut the spring seats loose, rotate the axle to correct the alignment, then take it for a drive before re-welding the spring seats.

[davidvdm]

Definitely running positive, and too much of it.

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I added 5mm of round bar for testing and managed to get down to 2,8deg. So I will be removing the spring perches and rebuilding those to get the Castor right, as soon as a new spring pack is under the car and I know what my height and new castor is on the new springs.

The manual is from the MQ that lists the C200 diff as found on the MQ Patrol UTE.

MQ Patrol FA page crop

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The difference between the Kingpin and Castor is surely factory set when assembly takes place. I can't even see how the kingpin could be different as they would have to be directly across from each other or they would bind. The kingpin would be the swivel point of the hub and would always be the castor..

Either way, I had worked on the manual and achieved a 7,4 kingpin angle. However the Castor was confirmed at the wheel alignment place as being the same as kingpin and not the 6deg difference I was expecting.

The spring pack is that which was bought brand new by another forum member for his One Tonner hardbody, and never used. He had it up for sale and donated it to the project. It even has it's original stencil markings on it.

[AndriesS]

Me thinks you have your king pin inclination and castor confused. They are in different planes. Though the kingpin has an inclination in both planes, wheel alignment specification normally calls them different. In Solid axles and most standard suspensions the relation are pretty fixed (as you indicated). I might be wrong but have a feeling you used the spec as base to actually tilt the axle to give you this number, and you should rather have tilted it to the caster no.

As a note: Even if they(left and right kingpin angles) are different only in severe cases will they ever bind as the tie rod ends will accommodate the difference in arcs of the steering arm on the hub. However you will have funky road manners. You should get a better wheel alignment guy as well - he should have cleared up the confusion.

[davidvdm]

Kingpin also has angle front to rear. Top of the kingpin bearing measuring from front to rear should give you your castor the same way you would measure the knuckle angle on a Dana diff for instance.

I specifically went to an old company that has just undergone a revamp over November/December with all the latest equipment being installed.

[AndriesS]

I'm no expert on Dana diffs etc but have played with lots of suspension.

The kingpin inclination referred to in wheel alignment specification is normally in a different plane, i.e. inclination of the bottom being closer to the wheel than the top.


When you did your setup, did you use the kingpin spec value to set up the front / rear angle? or top bottom angle?

[davidvdm]

Mistook kingpin angle and inclination. But used the front to rear kingpin angle as my guide to castor.

[davidvdm]

Should have spent a bit more time on google, but did not know I had a hole in my education anyways.

You have kingpin inclination and kingpin angle. KP angle is the same as steering axis angle and is your castor angle. Unless you have a BJ incorporated, your KP's will always be directly across each other so that the centre line through the KP will run directly through both of them.

Castor on it's own is only partially responsible for centring the steering when you lety go the steering wheel. KP inclination being the other factor. KP inclination actually lifts the car in relation to the wheel when turning and converts the weight of the car wanting to return to the lowest part of the arc/travel into returning the wheel to the centre.

So reading the manual, I thought KP angle and inclination was the same thing and hence my mess up. Either way, only once the new springs are under the car will I start correcting Castor.

I do see that my pinion angle on this diff will be around 9deg when my castor is at 1,5deg. I suppose that is why the standard MQ Patrol has a Double Cardan on the front propshaft. No way I can change that unless I want to be cutting tubes and turning the Birfield housing/knuckles.

Or am I still on the wrong track here???