4 Link Suspension

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robbh

robbh

Crazier than a box of frogs on acid
Posts
1,755
Location
Edge of the New Forest. Wiltshire
Righty then.

4 Link Suspension!

Now me project disco is underway im thinking ahead and slightly outside the box in terms of suspension setup.

Because as we all know articulation on the front is limited in standard form even with all the fancy springs, shocks and aftermarket radius arms and what not.

The biggest problem in the front suspension design is the radius arms. Think about it. The radius arm travelling up is trying to roll the axle backwards whilst the arm dropping is trying to roll the axle forwards. (sorry for pointing out the obvious but its for the benefit of people who dont have a clue how it works)

A brilliant idea with the standard setup would be to put a bearing in the centre to allow it to twist but how strong would it be etc?

Obviously there are other limiting parts but i dont wanna blabber on for too long.

Now options i have:
3 link Suspension
4 link Suspension
5 link Suspension
X link Suspension


Ive looked into the 3 link Suspension. But from reading into it there are a lot of downsides to it. So gave up on that idea.
Gave a thought to 5 link and x link but want to keep things simple.

So now im looking at 4 Link.

Ive got 2 options as far as i can tell.

1. Triangulated 4 link.
2. A frame with ball joint. (similar setup to the rear)

Either way i know the limiting factor with 4 link is going to be the engine sump.

So anyone got anything to add?
Anyone done it? Pictures of setup etc?
 
As you say triangulated 4 link is near enough impossible on a tdi because of the sump, im in the process of doing a 3 link plus panhard with the third up top running off the top of the pumpkin back past the sump to the drivers side of the chassis.

Both lowers are lengthened.

Im using ballistic 2" joints on all ends and very thick walled cds for the links because i couldn't be bothered to stress calc so im going for major overkill with the expense of extra weight.

whatever you do make sure you have good separation of the links and calc it so your not gonna end up with any characteristics that are too bad.

land rovers are hard to get good anti squat/ anti dive numbers etc on
 
You can fit parallel 4 link with panhard which is what tk jeeps have at the front.
You dont say what engine, but tdi takes upper third well a v8 needs lower 3rd.
people worry alot about as and ad numbers but one vital thing that is forgotten is roll centre figs, get that wrong and it will rock about like a boat and end up needing a rear anti roll bar.
The rear set up and a landrover is very strong and has more articulation than most people could afford proper shocks for.
One good mod for the rear end is to make longer rear trailing arms which cuts down on rear steer(axle tuck in)
 
Cheers for the input guys.

Pressbrake i will be running with a 3.9 v8. Which is why I dont like the 3 link setup as id have to use a lower 3rd link.

Not going to give up on the 4 link idea i shall get some measurements up together once the motors in and have a play around on autoCAD too see if i can figure something out.

But have been researching the X link Suspension a bit more. Heres a picture i stole.

000_0912.jpg


Basically you retain the stock radius arms (or castor corrected depending on lift). Weld a pivot in the centre of the axle. Cut of the front radius arm mounts then attach the crossbeam between the radius arms and onto the pivot.

From what I've read you can also pin the setup to stiffen it up for road use.

Thoughts on that design?
 
lower third isnt as bad as it sounds, I think the pos qt four link gives the wrong idea if made strong the lower 3rd can be on the axle centre line.
there has to be more to that x beam as with a fixed centre pivot you ll have articulation but no suspension like a fork lift
 
Hi mate, I'm going to be doing the same in the next couple months.. looking at 3 or 4 link.

What are the problems with a 3 link?

Is there room to do a straight 4 link on the axles, or would you leave the lowers straight and do triangulated uppers? or even both triangulated and ditch the panhard?

I also read that 4 link with no panhard creates bump steer!?
 
Last edited:
there was a 4 link (i think) set up at harrogate show by KORC on a D1, iv got pics but it kinda give away his design which is going into production soon.
 
200tdi ayre said:
Extended A frame and lengthened trailing arms is good. Gigglepin use that set up and win everything :D
Click to expand...

the winches win it;)The extended a frame he uses are a weak pos.

the advantage gained by longer rear links is 100" wheelbase and less rear steer on full droop.

there are two types of four link, parallel with panhard as found on jeeps and triangulated four link which has so much travel with out hydro steer the bump steer and rebound would be horrendous though with short travel shocks should not be a problem as the akerman angles are not effected
 
pressbrake said:
the winches win it;)The extended a frame he uses are a weak pos.

the advantage gained by longer rear links is 100" wheelbase and less rear steer on full droop.

there are two types of four link, parallel with panhard as found on jeeps and triangulated four link which has so much travel with out hydro steer the bump steer and rebound would be horrendous though with short travel shocks should not be a problem as the akerman angles are not effected
Click to expand...

Most folk in his class have the same winches so really makes no odds the triple bypasses are good and everything else makes it an awesome truck. Helps that he's a pretty good driver too and has some of the best co drivers in the world

The a frame is a weak point although he has a talent for breaking so called unbreakable axles too so they're not getting usual treatment :rolleyes:

Can you have extended rear trailing arms and extended a frame without changing wheelbase ? I don't see why not
 
200tdi ayre said:
Most folk in his class have the same winches so really makes no odds the triple bypasses are good and everything else makes it an awesome truck. Helps that he's a pretty good driver too and has some of the best co drivers in the world

The a frame is a weak point although he has a talent for breaking so called unbreakable axles too so they're not getting usual treatment :rolleyes:

Can you have extended rear trailing arms and extended a frame without changing wheelbase ? I don't see why not
Click to expand...


Yes but you need to move the mounts forward might be tight for space but couls be done. The guys run 90's and extend the A frame and radius arms to save messing about with welding mounts on the chassis.
 
If you move the mounts without changing the wheelbase you have to move the fueltank, worth doing for geometry improvements though.

Longer radius arms give slight improvement on genuine articulation though if you are going to lengthen them only do rover forged arms as its to much for the fabricated junk

The junk a frame is made out of 1.75x 10swg tube, not really enough when you think rover despite their thriftyness decided a lump of forged steel was needed.

Jim Marzipans main advantages are hes a damn good driver and he has more money than god meaning he pushes til it brakes cos he can buy another, king shocks and bump stops dont do much on the uk winch challenge scene
 
pressbrake said:
If you move the mounts without changing the wheelbase you have to move the fueltank, worth doing for geometry improvements though.

Longer radius arms give slight improvement on genuine articulation though if you are going to lengthen them only do rover forged arms as its to much for the fabricated junk

The junk a frame is made out of 1.75x 10swg tube, not really enough when you think rover despite their thriftyness decided a lump of forged steel was needed.

Jim Marzipans main advantages are hes a damn good driver and he has more money than god meaning he pushes til it brakes cos he can buy another, king shocks and bump stops dont do much on the uk winch challenge scene
Click to expand...


It's what I'm thinking about doing to mine instead of going to 100 would mean gabbing a new a frame crossmember though but I think it would be better than 100 in tight situations just slightly less stable at speed and slopes etc but better on lumpy undulating ground

It does help he's got bags of money but the king shocks and that are essential for KOH big European events etc

It's just shown as he's gone from last to first in 1 day at the Breslau challenge so there's gotta be something right with his setup
 
The thing you have to remember is all these guys have full support spare everything and a team willing to jump in and fix it no matter. Its like the AWDC comp safari racing you need not apply unless you run your own successful garage that can support the team. Having seen the teams rock up in 100K trucks with 2 full on motors ready to race its kinda ****ing in the wind. But it depends are you playing to have fun or there to try and win??

Challenge type events have historically were made up of ex comp safari guys that stoped racing because of cost and triallers that wanted more time behind the wheel. Now its gone full circle and its a natural progression of the sport which is a good thing.
Its the reason the more local classes have been getting more entrants as its still clubman level. Its like playing with the big money and support. You will have fun and it will be enjoyable. Depending on how you are and your mind set depends how much it costs in time and money./ If I had a £1 for every comp safari guy thats gone out paid lots of money for a stonking setup and then given up 2 years down the line because of cost and not getting up the rankings or even finishing events i'd be a rich man.

My mind set has to be its for fun because I could not support even the entrance fee's and time off work let alone running repairs to both road and comp motors plus fuel for both and the nessasary upgrades you need to be competitive. Even trialling a weekend is £120 minimum in reality if you run a V8 as a tow motor then that could well be just the fuel for the weekend. Comp its going to be £200 min depending on what event etc and Challenge i guess around the £200 plus mark.

I'll stick to my trials I may do some local events it would be nice to have a std class fot the challenge events tho just for giggles¬
 
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