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Bolt-on 4 Link Kit


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Hi all, this is my first post on any forum, i don't usually get involved in discussions like this, but seen as though it involves me directly, i thought i would. Most of the points that are being made from a photo an not actual fact, I'm sure all of us are aware how misleading a photo can be. So I'm not really sure were all this is really leading, im sure from a photo you could have a concern about the wall thickness everyone presumed it was tube (its solid) people are now presuming the rear arms are higher than the LR a-frame when in fact they are as near as dam-it (within 5 or 6 mm) in the same position it just looks different because its not the LR a-frame (looks can be deceiving), the difference is when the axle is at the lower end of the shocker its movement hasn't been restricted by the fact that when a ball joint move's from the middle of its socket it's second axis of movement starts to get restricted, a ball joint only has its maximum movement (what manufacturers quote) when in the centre, when it is at the back of its socket it has considerably less free movement without fouling on the edge of the socket, yes everyone has done it like that for years an it works to an extent, but every thing is that tight when in full articulation it squashes bushes, it also marks the socket an pin with compression bruises were it has been crushed together, has anyone cut a fulcrum ball joint open to look at the damage you get after one weekends use with extended travel shocks and rear arms that don't lock out in the chassis brackets (I'm presuming, no). the EX-ART 4 LINK kit is designed to move freely without any crushing of bushes or damage to ball joints which makes every thing move smother when going over the terrain,when it come to its road manors they are very good indeed due to two things, one because it has ball joint's an normal bushes (an not really soft bushes to compensate for the lack of proper movement when taken past where LR intended) so it has very positive feed back as well as very good control over the axels, two the caster angle stays the same though out the movement from bump stop to 14" of drop which stops the loading of the steering which stops it trying to steer its self when it articulates (ie same as body roll on the road and a god send if you run a heavily off set wheel), making it easy to handle at any speed on the road, I regularly sit at,,,, erm 70,, ish in the fast lane of motorways in my v8 disco without being scared for my life if I hit a cats eye!

Just incase people think this kit is something that has been cobbled together in a shed, it has been in development for over two years by a team with over 60 joint years of experience in several engineering sectors. We also have several other kits in the pipeline, the two kit that were at Peterborough show are just the stock bolt on kits for RRC, disco1 and defender up to but not including the puma,

There will be another editorial by TOR later this year with the defender kit an the challenge kit, I'm hoping this will put to rest any more question of build quality or the pedigree of were it came from but if anyone would like to know any thing about it please feel free to ask rather then just guessing an then having a good old slating session.

If you've got this far without getting board, thanks to tho's who put sensible points across, I'm all for discussion so long as its not a slanging match,

Cheers

Gordon Jackson

4xForce

Do you have a website ? I seRched but did not find any
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I believe that's why, for example, ashcroft ran their lockers in various challenge events. With 2 years development I'm sure there is a certain amount they don't want to divulge on an open forum.

Possibly, but those numbers are nothing you can't find out by measuring a few things and putting it into one of the calculators (although this one probably won't work properly in the 4-link calculator due to the panhard).

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The thing that bothers me with the bumpsteer issue of the triangulated four-link, is that how come an old leafer doesn't have it? At least it is not enough on an old Series Landie that I've ever felt it on any of the ten or so various Series I've driven both off- and onroad. These should in theory act a lot like a four link, and there is no panhard to keep it all aligned. What am I missing? Is it simply a matter of not having so much 'droop' that you can feel it? In that case, I'm sure I persocally could live with the same amount of 'droop' on a fourlinked offroader. But then again I'm no desert racer (kinda missing the desert part :D)

And another thought. If one were very eager to have a triangulated link suspension up front, and didn't wan't any bumpsteer, and would like to keep it mechanical linked for road legality or whatever, why not fit a rack and pinion hydrosteer setup to the axle? surely you could then run the steering shaft for the steering wheel in such a manner that it wouldn't have any bump steer. Or am I just ten hours past bedtime? :D

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IMHO there's a lot more compliancy in a leaf spring setup, so the axle movement isn't forcing the steering, but the other way around.

The stock radius arm setup has a bit of bump steer too, especially if the linkages aren't adjusted right. It's noticeable, but not too bad. On a huge travel setup where the axle doesn't move in an arc somewhat following the steering rod, you'll get a lot of bump steer.

The setup you describe is what I used when I built my Lego buggy (different league, I know, but still 4-link without hydro steer). It works well bump steer-wise, but you do get some flex steer.

The cable setup on the Poison Spyder KOH buggy a few years back was a cool concept too, full hydro assist to a mechanical link with cables.

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With my spring over setup i had bumpsteer because the steering rod was on a steep angle. Very noticeable going over speedbumps as the steering wheel went to the right. I now have high steer on my lc80 axle, steering link is on a very shallow angle now and bumpsteer is gone.

Standard leafers have very limited flex on the front axle and the steering rod is close to horizontal. So no bumpsteer.

Reducing flex on a triangulated 4link to keep standard steering to avoid bumpsteer is just plain silly. A 3link with panhard would be the answer.

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With my spring over setup i had bumpsteer because the steering rod was on a steep angle. Very noticeable going over speedbumps as the steering wheel went to the right. I now have high steer on my lc80 axle, steering link is on a very shallow angle now and bumpsteer is gone. Standard leafers have very limited flex on the front axle and the steering rod is close to horizontal. So no bumpsteer. Reducing flex on a triangulated 4link to keep standard steering to avoid bumpsteer is just plain silly. A 3link with panhard would be the answer.

Another way of dealing with the bump steer is to add a panhard bar lol I know it does fight the leaf springs but it works, I did this with an Izuzu Mu that I SAS'd with hilux rear leaf springs.... panhard bar stopped the bump steer

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It will probably help destroy bushes in no time at all. They already have a very short lifespan as it is. I know they use a panhard on old leaf sprung racecars to increase handling.

A mate has a couple of Daihatsu Rocky's and these have a Panhard on leafs, no apparent problem with bushing life, but that might be down to the fact that it has huge bushings in the springs, so they might be able to flex more.

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In the case of the Mu he was doing spring bushes every yr and the panhard bushes every 6 months... but the pay off was well worth it, 4" lift and a solid axle and it handled better than when it had the IFS with the sway bar removed and no lift... it did take a bit of tuning tho lol

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With the bolt on A frame ball mounting, raising the roll centre on a Salisbury diff just requires a spacer and longer bolts. Does this 4 link arrangement offer any significant advantages ?

I have done some articulation experiments with my 100" hybrid, with both standard and lifted rear springs. When the axle, fitted with the softer lower springs articulates, the inner sidewall of the tyre (std 7.50x16s on std offset LWB rims) on the compressed side, rises up and over the upper coil spring mount with clearance. When fitted with lifted springs the sidewall rubs heavily on the outside lip of the spring mount. The problem would be worse with the larger diameter springs of 110" wheelbase vehicles, unless the A frame ball joint was raised the appropriate amount to suit above standard ride height, or rims with sufficient offset to provide clearance.

Deranged. It's just a gut feeling not based on any science, but building in anti dive characteristics by angling the links up from axle to chassis as you suggest would IMO have a detrimental affect on ride quality, and stability under heavy braking.

I am really only questioning the geometry of the system. I personally have no criticism of the construction or material quality of the kit. It looks well made, and if tie rod ends,with tapered pins and sockets are strong enough to withstand the impact forces that steering gear is occasionally subjected to, why wouldn't they be suitable for suspension link ends ? Front propshaft telescopic joint length is not actually where my concern lies. It is the safe UJ angles that could be exceeded by the link geometry keeping a constant pinion angle as the suspension cycles that is my concern. The front prop looks ok in the photo, but that is with the axle articulating ! What about at full droop both sides?

Bill, I also think that the above set up in the photo will have a lower Roll Center than stock , as it will be where those to arms project further back and converge.

Regarding the front, If the arms are parrallel, then anti dive would be determind by drawing a line from the front tyre contact patch, parrallel with the arms. Where this line intersects the COG line and the front to rear brake bias split line would show you its point of anti dive (I think!!) I also think that having them angle upwards towards the chassis will result in the same characteristics as our RA, maybe a little worse as they are shorter...

IMO I would have thought that ball joints in the front make bumps etc harsh with little shock absorbstion???

Regarding of your comment on longer RA and there effects. I know a truck with 118"wb, runs stock height 187lb front springs, 750/16 tyres and has its body (LR) lowered at least 50mm.....no dive under braking ;)

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