No more panhard

[THE 109]

What are peoples thoughts on building a type of triangulated 4 link for the front end of a coil sprung rover?
The aim of this is to gain flex and do away with the panhard rod, it still needs to be drivable on the road and handle reasonably well.
My idea is to run upper axle links similar to how safari guard had theirs, the lower axle links would mount directly below the uppers and go back to a heavy duty crossmember(Sort of forming an a-frame but facing the wrong way and upside down compared to the rear end).
Vertical separation of the links(Both at chassis and axle ends) and length of links would need to be worked out.
So, could this idea work or will it drive and handle terrible?

Eric

[wagoo]

Bump steer may be an issue, although i did a geometrically similar thing some years ago by replacing the Panhard rod with a Watts Link and it handled and drove ok.
Wagoo.

[THE 109]

Bill,

Would there be enough triangulation to overcome the side loading when steering?
From what I've read on rear 4 links on rovers they can't get the upper links on the axle close together enough, where as the standard a-frame ball joint works well. All to do with length of upper links and so on.(Longer they are, the more stress on the joint)
In a front application and trying to keep the lower links as long as possible would you have to try and use a single mounting point?
Like you say there could be bump steer and possibly some unwanted steering as the suspension cycles up and down, where a panhard rod stops this issue.
Portal rover on pirate has this style of set up but uses a panhard rod aswell, mind you his lower links haven't got much triangulation.

Eric

[uninformed]

I think the physical room will let you down....double triangulated 4 links are popular on built rigs in the USA...But I doubt youd have the room. You would need a minimum of 40° combined angle in the lowers to locate the axle lateraly...MINIMUM! So you may be able to do this with shortish links.....I would rather have 3° axle roll oversteer with a 1500mm long link than a 1° axle roll Understeer with a 300mmlong link, if you get what I mean....

now you may get great numbers at ride height with your desiered set up...but becarefull, see what happens when you cycle the axle both in bump and droop.

also remeber the relation, in lenghth, between the uppers and lowers with determine the pinion angle change AND anti-dive change through bump-static and droop heights.

A good three link + panhard may be a better solution....

[wagoo]

Bill,

Would there be enough triangulation to overcome the side loading when steering?
From what I've read on rear 4 links on rovers they can't get the upper links on the axle close together enough, where as the standard a-frame ball joint works well. All to do with length of upper links and so on.(Longer they are, the more stress on the joint)
In a front application and trying to keep the lower links as long as possible would you have to try and use a single mounting point?
Like you say there could be bump steer and possibly some unwanted steering as the suspension cycles up and down, where a panhard rod stops this issue.
Portal rover on pirate has this style of set up but uses a panhard rod aswell, mind you his lower links haven't got much triangulation.

Eric

I think Serg answered your questions better than I could Eric.I've had a couple of whiskeys tonight,Purely for medicinal purposes mind,:angel: so my minds eye isn't seeing too clearly :eek: I do think however that asingle mounting point for the triangulated lowers may causethe suspension to bind.
Did you mean Portalrover on lr4x4.com? I ask because I used to be Portalrover on Pirate a few years back.
Wagoo.

As Serg mentioned a 3link plus panhard,providingyou can fit it all in with 2 lowers and one upper, offset to the left and angling down slightly from the axle mount to the crossmember to counter torque roll will give allthe flex you need.

[isuzurover]

Eric - why not a 3-link + panhard?

IMHO it seems to give as much flex as a 4-link.

Plus - as mentioned, it is MUCH easier to fit in.

Unlike the SG setup, it is much stronger to have two lower links and one upper (Bush65 has posted this many times). SamO (HTE/Strangerover) has built a couple of setups with an offset upper link for clearance. By all reports it flexes well and may be acceptable on-road.

If it was me I would be going 3L + P.

[wagoo]

Eric - why not a 3-link + panhard?

IMHO it seems to give as much flex as a 4-link.

Plus - as mentioned, it is MUCH easier to fit in.

Unlike the SG setup, it is much stronger to have two lower links and one upper (Bush65 has posted this many times). SamO (HTE/Strangerover) has built a couple of setups with an offset upper link for clearance. By all reports it flexes well and may be acceptable on-road.

If it was me I would be going 3L + P.

Unlike a 4 link a 3 link doesn't require soggy compliant bushings to give flex. In fact you could use heim/Rose joints everywhere and it would still flex better than a bushed 4 link. Further more you can dial in a desired amount of antisquat geometry into a 3link, also helpfull in keeping the diff pinion pointing at the t/case as the suspension cycles from bump to droop.
To paraphrase John (Bush 65) from some years ago,A 4 link that is set up for optimum flex would require almost parrallel arms when viewed from the side.Parrallel arms won't give antisquat geometry.
Wagoo.

[THE 109]

Thanks for all the very helpful replies, the front mounted trackrod on the volvo portals started this whole idea.
Bill,
The one on pirate I was referring to is Franken rover, sorry my bad.

A 3 link plus panhard will work so long as I can move the panhard rod out of the way of the trackrod on up travel,

Hopefully there will be enough clearance from the sump to the upper link with the isuzu engine in there.

How have others done this before?

Any pictures would be great.

Eric

[wagoo]

Ah yes, sorry I forgot about the Isuzu Eric. A quick look under an Isuzu powered hybrid in the paddock shows that the left hand engine mounting bracket on the chassis is directly above the axle tube and would interfere with with the upper link, which from memory of the 110v8 I did, sat about 200mm above axle centreline to give sufficient vertical separation between upper and lowers. The owner of that vehicle hasn't as yet resurfaced from his cape York trip, so I have been unable to measure the position of the relocated panhard rod for you. However I've just measured my Rover axled portalled thingy and the panhard mount on the axle is 75mm behind the trackrod, centre to centre,and 70mm abve axle centre line to keep both panhard and trackrod parrallel. The panhard bush centre at the chassis mount is 190mm behind the pitman arm ball joint centre and 50mm below bottom of chassis rail.I turned the panhard rod upside down so that the bow that was intended to clear the pitman shaft now clears the diff bowl.I think these numbers would work with the volvo axle as from memory the effective steering arm lengths when measured from swivel pin to tie rod end is the same as Landrover.
I was re reading some of our earlier correspondence.have you thought more about moving the bolt on crossmember back a bit and doing a 'one link' plus panhard rod? Don't know what, if any disadvantages there are when compared to radius arms re handling, but it does positively locate the axle against torque reaction, and does give unrestricted articulation, plus it only requires a single albeit large bushing vs 8 for a 4 link and 6 for a 3 link.Further more it would be relatively easy to fit around the engine etc, requiring no vertical separation of links. Perhaps the radius arms could be bent inwards to converge at a single, or even two mounts at the centre of the crossmember?
Wagoo.

[uninformed]

with regards to clearence, links dont have to be staright....its the points where they locate that are important. Careful though, a bent/cranked link has to be alot stronger than a straight one.

[wagoo]

with regards to clearence, links dont have to be staright....its the points where they locate that are important. Careful though, a bent/cranked link has to be alot stronger than a straight one.

My sleeved,bent/cranked and reinforced top link, made from a rear lower link,mounted above the diff for packaging vs good engineering reasons, has been giving me some bother lately with straightening out and cracking under high torque loadings. Will have to try to replicate the length and shape but using an old radus arm instead.Or maybe do a One Link myself.
Wagoo.

[uninformed]

My sleeved,bent/cranked and reinforced top link, made from a rear lower link,mounted above the diff for packaging vs good engineering reasons, has been giving me some bother lately with straightening out and cracking under high torque loadings. Will have to try to replicate the length and shape but using an old radus arm instead.Or maybe do a One Link myself.
Wagoo.

Bill,

I always admire your ability to make something from nothing..with good design and know how....But arent those rear links about as strong as a candy cigarette.

[uninformed]

Bill, regarding the different links styles: 3/4/1 RA etc...the one thing that the RA has that the others dont (and please correct me if im wrong) is Roll Stiffness...that is the RA's and axle are like a big swaybar....the longer the RA's the less Roll resistance

[wagoo]

Bill,

I always admire your ability to make something from nothing..with good design and know how....But arent those rear links about as strong as a candy cigarette.

Yes Serg you're right about the strength of stock rear links. The reason i chose to use one for my top front link was for reasons of expediency and basic laziness:) as I also elected to use the 3 bolt trailing arm chassis bush on the 3rd link crossmember. Due to too much compliance on that bushing I soon had to replace that with a A frame ball joint. I'm now finding after all these years that the 2 piece chassis end bushings of the front lowers are too compliant, allowing too much axle housing rotation from torque reaction.If I don't go one link I'll probably have to replace them with ball joints too.
You are of course correct about the radius arm bushings providing roll resistance, but the roll resistance is not readily disconnectable for high articuation cross country work like an anti roll bar link is.The longer RAs would provide lower roll resistance and more articulation though.
Would still like to do a controlled articulation rollover test on a vehicle with good flex, and then with the flex restricted by limiting straps or similar.
I'm reasonably certain that the roof on my vehicle would be totally destroyed if it didn't have as much front/rear balanced articulation as it does
Wagoo.

[THE 109]

Been having trouble getting on the forum lately,
I think the one link plus panhard should fit and flex very well but am worried about the handling on the road, might need to fit adjustable shocks or a swaybar with disconnects.
As far as the one link goes offroad the only situation that might be bad is down hill across a side slope, the whole body may want to lean over as the front end won't bind up as it does now with radius arms.
If only kinectic suspension were still around and developed kits for rovers, forced articulation would be ideal here.
I won't be able to measure up anything for a few weeks due to work, keep the ideas coming though.
How long would you make the one link?
Is there a formula or something to work it out?
The removable crossmember can go as far back as the rear tail shaft.

Eric

[wagoo]

One links as with radius arms with portals should ideally be as long and as horizontal as possibe to reduce antidive geometry. Three links like one links also have no roll resistance, but those measurements I gave for the relocated panhard rod raise the roll centre of the front suspension, and should produce similar results to the v8110 on volvos and my own vehicle. That is good stability on and off road without the need for an anti roll bar.
wagoo.

[uninformed]

to what extent would the size and material type play in the Roll Siffness of a RA for a given length? Could you "tune" them like a tortion bar???

[wagoo]

to what extent would the size and material type play in the Roll Siffness of a RA for a given length? Could you "tune" them like a tortion bar???


I'm not certain that radius arms are intended to either flex or resist flexing to provide roll stifness.That is determined by the stiffness of the bushings, and as you pointed out earlier, longer radius arms will require stiffer bushings to maintain the same roll stiffness as shorter RAs on rubber bushings.
It would be interesting to know if the taper of an RA could be modified to flex and provide additional articulation once the bushings have run out of compliance.The material does flex back a long way when cold bending them in a press to alter castor angle.
Wagoo.