Increasing flex on the rear

[thinfourth]

Is there any cheap way of increasing the flex on the rear of a90/rangerover hybrid.

The shocks i have aren't reachng full travel in either direction after i bought a cheap and cheerful 2" lift kit so i guess something in the bushing is stopping full flex.

Its a pure offroader so non road safe mods will be considered.

[doda456]

Cranked Trailing Arms should help, as well as suitable bushes either new rubbers or poly bushes

[thinfourth]

Cranked arms are over a hundred.

How about cutting the end off the arms and machineing them to accept a large rose joint?

I've got a lathe so machining a thread on is easy and making up the brackets shouldn't be too hard

[parrotveasey81]

[thinfourth]

Thats beautifully simple and screamingly obvious

[clbarclay]

Standard trailing arms with standard rubber bushes in good condition should allow a plenty of flex. Mine was getting pretty near full travel out of Gwyn Lewis challenge mounts with +5" dampers without trailing arm or bush mods. What bushes has it got fitted and how old are they?

How close does the axle get to the bump stops when the spring is compresses as far as it can go?

[sitrials]

standard trailing arms are made of cheese get some angle iron and weld it along the length of it to strengthen them.
I like the rose jointed idea as to buy rose jointed arms is rediculous! They just cost an arm and a leg!

[clbarclay]

The older design trailing arms made from tube take a lot more effort to bend than the later ones made from smaller diameter bar.

[d86]

going to get flamed for this....

as its a off roader only......just crank the arms you already have..also you could slacken off the mounting bolt at the axel end to allow some free movement...but not loose..
also i have seen on the front..removal of the left hand radius arm front bolt to give the front axel more movement.

now i can't condone this for road use but its a redneck fix that works very well.....

oh yes i will be cranking the trailing arms on my trials cr till i can afford some gwyn lewis ones ..nice...

tony

[unimogler]

hi , i put tractor top links on mine . companies such as sparex sell them and you want cat 1 because they have the smallest holes . the hole in the traiing arm bracket is 5/8,the hole in a top linkis 3/4" so you will need a piece of thin wall pipe . at the chassis end remove the original trailing arm and bush , there is then a plate bolted to the out rigger with three bolts , i welded 2 tabs onto this plate , the tabs have 3/4holes cost of top links about £15 each and the are adjustable in length so match the original trailing arms .i have given my rangy plenty of stick and nothing has broken yet

[david p]

On the trailing arm mount on the axle . if you grind a c section out it allows more travel

( 4x4 is born tip )


david p

[teamidris]

I think the spring rate works against us on this chassis? I have a nagging doubt that flex would be a lot better if the spring were twice as long But havn't worked out how to stack two rear springs on top of each other yet (though there are plenty of bad idea on 'scary steering' web site ).

And the other snag is that fox gas struts sort this spring rate problem out in one

The other dodge is to move the springs in-board of the chassis rails. Pott's-Brother did this on their Vit with Mcfearsom struts off something? Stability is way down , flex is way up

[burko_uk]

I'm not sre the double length spring will have any effect. I admit it's a long time since I did any SHM and spring rate calcs, but if the spring rate is the same for both springs, the length makes no difference as 1 unit force deforms the whole spring by x amount - so a short spring will compress as much as a long one for a given load, but on the long one each single coil will deflect less.

This only changes if you hit maximum compression on the short spring. In that case a longer spring will allow more movement, but needs a greater quantity of force to do so: a spring twice as long, will require twice the force to compress to maximum (closed) compression. - F=kx - F is force, x is compression distance and k is spring rate. You could make the suspension stiffer, by fitting two springs side by side, as that would double the spring rate... think of bouncing the car on a corner compared to bouncing a car in the middle of the bumper - it's harder in the middle of the bumper (although that is a bit of a simplification of that scenario).

The big fox coil over shocks are much longer than "normal" springs, but that is mainly down to them typically having a much softer spring rate, which means that if the mass of the vehicle is a constant you will realise more compression distance with the soft spring than the stiff one, so you need the length to stop bottoming out.

[clbarclay]

Stacking 2 springs will effectively half their rate. each spring will compress the same amount for a given load but the total deflection is the combined deflection of both springs.

Many big coil over shock absorbers use 2 springs with a sliding seat between the 2 springs. A stop on the body of the shock absorber limits the movement of this seat to make the unit dual rate. When fully extended, both springs are active contribute to the spring rate making it softer*. As the shock compresses the sliding seat reaches the stop and then only one spring is active and the rate raises to the rate of the active spring. The X-spring from X-eng effectively does this without the damper body for to slide along. There is a European company that does a similar stacked spring set up for Land Rovers which IIRC used 3 springs, two in parallel and another in series (that's just greedy really), but I can't remember what they were called.



*Maths is available on request to fellow geeks, but if both springs are the same rate then the combined rate is halved.

[boss]

if you want the rose joints that badly just screw some FEMALE rose joints on the threaded end and fab up a bracket that screws on the the existing mout. like davidp said grinding out a c section on the link tab on the axle.