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WesBrooks

Suspension Mods for Faster Off Road?

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Having diverted the Grenadier topic by mistake I thought I'd spin off the suspension talk to a seperate thread!

Most talk on these forums around suspension centre around increasing articulation and low speed off roading performance. So out of curiosity what mods are made to make the typical coil landrover suspension behave well at speed?

I've seen a couple of clips of hill rallys on TV and they look great and there is a large green oval contingent which implies there must be a reasonable body of knowledge on the subject.

So stock ride height is probably preferable along with good condition/new shocks and springs and Poly bushing. What about tyre size, how large can you go before tyre size and weight becomes a hindrance? Wider track / offset rims a little?

 

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By 'at speed' I mean a little faster where theres a enough pace for wheels not to remain permanently planted, but I'm not thinking massive pace.

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Look at the comp safari vehicles.  They ride lower than standard and trade long suspension travel for soft compliance.  You’d also want tall tyres with soft sidewalls to absorb shocks and bumps.

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For the hill rallies/comp safari and like I believe there are tyre size restrictions in the regs, so that's why they all look a bit smaller than you might expect. Also helps CoG, in fact it is common to run 15" rims help further.

For sustained higher speed running the place you spend your money is the shocks -standard stuff just ain't up to it, and you can forget using the likes of pro-comp/all makes whatever. Good shocks are expensive....

I'm not sure they are actually lowered much, but can appear that way as they use lower profile bodywork, which has that effect.

Tall sidewalls that flex ,yep, and you run higher pressures because of the likelihood of pulling a tyre off the rim at speed is much greater than at 2mph... The use of 15" rims also helps here... More sidewall, and less easy to de-bead.

 

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Posted (edited)

Comp Safari and Hill Rally. Hill rally looked to be closer to stock vehicles?

Bowler advertise a fast kit which merely namedrops Bilstiens (have them on my daily - skoda superb - very happy with them) and says different anti roll, stearing damper, new bushes, etc.

Tyre choice appears to be more modest in terms of diameter. I've seen 245 75 16" mentioned which would be about 30" diameter. Bigger than Disco and Range Rover but within stock range for a Defender?

Regards the Caster correction kits you see listed for lifts what is the effect of incorrect caster on the handling of the vehicle? Likewise if lowered and the caster is the other side on normal what would that cause?

Edit: Wrote before Bowie's post!

 

 

Edited by WesBrooks

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Increased caster can be preferable in a racer, more stable, better self centering, just slightly heavier steering.

Leave it alone :)

 

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8 minutes ago, Bowie69 said:

Increased faster can be preferable in a racer...

 

Sounds logical! 😄

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So micky taking aside caster mainly effect self centering which is lost as suspension is raised from stock?

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19 minutes ago, WesBrooks said:

Sounds logical! 😄

Stupid auto correct(!)

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Posted (edited)

Yeah I hate auto correct but even with that off my thumbs and touch screens still aren't on best terms!

Cheers for the link. I guess the side effect of caster correction is it increases the angle on the prop shaft joints.

Saw the caster angle and had instant recollection on frame angles on my road bike. I got nasty wobble on my steel frame bike if I hit over 35 on a decent. Caster angle significantly out of spec may well be a significant factor in the infamous death wobble.

Edit: as in caster angle reducing or worst case going negative.

Edited by WesBrooks

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7 minutes ago, WesBrooks said:

Yeah I hate auto correct but even with that off my thumbs and touch screens still aren't on best terms!

Cheers for the link. I guess the side effect of caster correction is it increases the angle on the prop shaft joints.

Saw the caster angle and had instant recollection on frame angles on my road bike. I got nasty wobble on my steel frame bike if I hit over 35 on a decent. Caster angle significantly out of spec may well be a significant factor in the infamous death wobble.

Edit: as in caster angle reducing or worst case going negative.

You could maintain the diff nose angle by clocking the swivel flange to the axle casing but you might need to weld up some holes on the axle casing and redrill them.

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I think you'd need to rotate the mount points of the radius arms about the axle too? An appropriate degree of both clocking the hubs and rotating radius arm mounts would sort out caster and prop angle, but not cheap. You'd likely need to drill through part weld part casting to get the required degree of correction.

Interesting discussion  around caster but I guess irrelevant as people have said stock-ish height which means caster should be fine.

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1 hour ago, WesBrooks said:

I think you'd need to rotate the mount points of the radius arms about the axle too? An appropriate degree of both clocking the hubs and rotating radius arm mounts would sort out caster and prop angle, but not cheap. You'd likely need to drill through part weld part casting to get the required degree of correction.

Interesting discussion  around caster but I guess irrelevant as people have said stock-ish height which means caster should be fine.

No, keep the axle tube as mounted to keep the diff and prop alignment, and just rotate the swivels a little.  It would move the track rod away from the diff nose and toward the radius arms,  but not by much.

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in regards to the topic of  wheel size, theres not a great choice of tyres available in 15" rims, majority are now running 16" with some including myself running 17" wheels,

personally i have 4 link F&R with 3" coilovers all round,

suspension is the key component with going fast & there is a lot to be said for keeping the wheels on the ground,
in reality even if you had a 1000Hp, without the suspension to back it up, its no faster than 400hp & dialed suspension

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I second the advice to spend money on shocks - good suspension that can handle a pounding at speed is ££££, I'd expect to spend at least £1000 for a set of shocks at a bare minimum.

Also very much as Mike says - good shocks / suspension are worth a huge difference in overall performance.

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the slow motion in this shows to a degree the movements of the suspension,

 

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the suspension on my own car in action
 

 

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Great videos. Interested to see no anti roll bar on your video there?

I was interested interested in this partly because I thought the efforts around caster correction etc when lifting is focused on making the road manners better for an extreme lift. So with air suspension that can lift an extra 50mm if needed I was wondering where the wise money goes to make sure the truck is well behaved in most circumstances, which in terms of hours use would be road by a long shot.

So shocks top of the pile. Check straps if there is any chance of air time. Uprated bump stops for heavy hits. Are uprated anti roll bars always bad off road or on trail? That video didn't appear to have any at the back? That said with hydrualic steering it will never sniff tarmac so I guess the equation is completely different.

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Posted (edited)

we run a sway bar / anti roll bar on the rear only, however some people run one F&R , depends on how they are setup,

hydraulic steering is a different discussion but i have driven mine on road at 60-70 mph without any issues

 

 

Edited by RedLineMike

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Posted (edited)

Interesting on the anti roll bars.

Regards hydrualic steering I forgot the international aspect of the forum. As far as I'm aware it's only farm and construction vehicles that can run hydrualic steering - legally - on the road.

Edit: I'm referring to construction and use regs in the UK. Irony is up until hose failure hydrualics are probably more predictable handling.

Edited by WesBrooks

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in regards to the caster angles etc its becoming more common place to build axles from bare tubes so the pinion angle is set to begin with, & then set the caster angle 2nd

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Thanks for the comments. I'm certainly not going down the four link route any time soon but when choosing a path to take I like to know the extremes between stock and serious investment.

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Do the Bilstein B6 range take a reasonable amount of abuse?

Yes I am interested in the setup on the race vehicles to understand the gold stanard but my spec isn't that fast. Aiming for a more rally inspired setup than a massive articulation as I think that will suit the truck most.

I can see how the prices rack up quick. £550ish on shocks without hitting specific sport models. Probably close £800 for hydrualic bump stops (will probably drop these) and mounts. £500 anti roll bars...

Thats without going mad on toughening up the drive train, or of course brakes!

Regards drive train it's a body of work I'd save for another time, but LSD over lockers?

 

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