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In board shocks


will_warne
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A few weeks ago I managed to get hold of a set of 12", adjustable Pro Comps for a price I really couldn't refuse and I've been thinking about mounting them. At the front, I'm planning on mounting them in front of the spring but the back's causing me more problems. I'd like to mount them vertically (less stress on bushes and easier to set up although I'll loose some travel) and the easiest place looks like running them inboard of the chassis rails and up through the floor of the tub. Has anyone run anyhting like this before as I'd be interested to know any issues people have had (shocks too soft etc).

TIA

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its gonna muller the damper travel/wheel travel ratio - effectively reducing the damper effort available, on the flip side you would end up with silly amounts of travel

I thought yours was going to be a trayback? cant you fire top mounts to the cage at all?

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its gonna muller the damper travel/wheel travel ratio - effectively reducing the damper effort available, on the flip side you would end up with silly amounts of travel

What he said. It might also be worth pointing out that the further inboard you bring your mounts, the higher the forces they will see for the same effective damping. If you take it to extremes you'll need meatier damper rods and stuff to cope. Mounts stuck on with bird-turd coupled with high damper forces could be a recipe for ... *BOOM*

Just a thought...

It can be done, of course. IMHO you've kinda gone about it the wrong way - take your shocks back, recoup the money, lay out your frame and suspension, figure out where your shock mounts might go, cycle the suspension checking for clearances the whole time, when it all works, measure the required max and min shock lengths, and use some grey matter to figure out the damping required based on the geometry you ended up with. Finally, go out and buy shocks that meet the specification. You can't just buy dampers and hope they'll work (well you can, but the probably won't be very good).

Hope it helps. Al. :)

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Well, the pure bump travel, forces and rates will be the same, but the roll damping will be as above. I was discussing this with SimonR last week (taken to extremes!), considering putting the damper onto the A-frame. Apparently Paul Wightman had tried something similar and it was undriveable because the wheels were all over the place.

It depends what you want it to do but for a given 'roll' damping level, it'll be over damped for pure 'bounce' IYSWIM.

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The QT/Whitepeak Engineering HI Flex Rear set up runs inboard dampers....

Having driven the green QT/WPE demo 90 it's not actually that bad on the road - although it runs adjustable GAZ dampers... and it definetly flex's quite well.

The dampers are set in at an angle though, not in a vertcal position.

Ian

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Gon2Far and White Peak both run the rear shocks inclined inwards over the axle, the Gon2Far version was fairly cunning as the new x-member had multiple holes drilled to allow you to tilt the dampers further in/out to adjust for length/stiffness. Obviously you lose damping the further you tilt the shock, so you need stiffer ones to compensate, but you do gain travel without eating into the load bed.

Oh and... Twelve inches, is that all? I thought coilers were supposed to have more travel than leafers? :ph34r:

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I was discussing this with SimonR last week (taken to extremes!)

Don't bring me into this Mr Charger!

I, as it happens, know a couple of people doing this. One is Alan Davis from Chichester off-road. He fabricated a nice mounting in the middle between the chassis rails for the top mounts and the shocks sit at about 45 degrees normally.

This reduces the dampers effect as the axle moves up & down while level, but increases the amount of damping on articulation - (this may not apply to an 'E-Truck' however? HFH will know).

I think this is possibly an advantage! It is going to slow down any surprises while articulating - which are generally less welcome than on the flat.

If you adjust it so it gives you acceptable damping on the road - I think it will be even better off road than standard.

It also gives you more travel than you can wave a stick at!

Do it!

Si

P.S. When I run out of other projects ;) , I'll drill a couple of holes in the front of my rear winch mount tray - and use those to mount diagonal dampers.

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IMHO straight up and down shocks outboard of the chassis do the best job. Mounting them on those pivoting upper mounts (Devon 4x4?) to diminish bush stress on axle cycling would probably be a good idea too. If the trade off is greater articulation by mounting them inboard, I do not believe that the ride and handling characteristics of an offroad biased Defender are so delicately balanced that there is a tennable case for not seeking the articulation benefits over the alleged diminished damping effect.

If you dont mind taking them up into the bed anyway, why noty mount them as vertically as feasible with the shock tower up in the the wheelbox? :huh:

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I reckon it will work to get loads of travel, with small stroke shocks; that kind of ruined your plan with the long stroke jobbies. My opinion is that straight on the axle, exactly in line with the travel is best for control. Especially if you are planning on long travel, which generally means soft springs, I think the damping becomes more important. So I would fit them up straight inside the coil. (what I did and happy with it). Feel free to prove me otherwise, innovation is always a good thing.

Are you going to go for dislocating or dual rate springs, or whats the plan?

Daan

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I reckon it will work to get loads of travel, with small stroke shocks; that kind of ruined your plan with the long stroke jobbies. My opinion is that straight on the axle, exactly in line with the travel is best for control. Especially if you are planning on long travel, which generally means soft springs, I think the damping becomes more important. So I would fit them up straight inside the coil. (what I did and happy with it). Feel free to prove me otherwise, innovation is always a good thing.

Are you going to go for dislocating or dual rate springs, or whats the plan?

Daan

One of the main reasons for shock inside the spring is it is symetrical (as it is if it's parallel to the spring) - i.e. the damping is the same whether you are turning left or right. This is one of the main reasons they are always parallel on the front as it makes handling more predictable.

It matters less for handling on the back and you get more travel with an angled shock - which is why manufacturers often angle them on the back (saves money!).

The stroke of the shocks in this config is not too much of an issue if you decide how much travel you want and make the shocks as vertical as possible and still achieve that. That will give the best compromise between handling & articulation.

Si

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Some interesting thoughts... Daan, I can't run the shocks inside the rear springs as I'm going to run Si's springs all round. The Pro Comps I've got can be charged so, if I get hold of the specs, I may well be able to get the pressure upped.

Al, the shocks themselves are pretty meaty - they're a set of MX-6s like these:

mx6_500x375.jpg

My theory was that on road I'd wind them right up and, as they were vertical, you'd still get good damping. Off road I'd back them right off and the back end would articulate really nicely. I guess I may have to run some tests.

Jez, no trayback for the moment. I've decided to keep it looking like a 90 although I'm cutting the hell out of the bodywork.

Tony, you may well be right....

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Some interesting thoughts... Daan, I can't run the shocks inside the rear springs as I'm going to run Si's springs all round. The Pro Comps I've got can be charged so, if I get hold of the specs, I may well be able to get the pressure upped.

Al, the shocks themselves are pretty meaty - they're a set of MX-6s like these:

mx6_500x375.jpg

My theory was that on road I'd wind them right up and, as they were vertical, you'd still get good damping. Off road I'd back them right off and the back end would articulate really nicely. I guess I may have to run some tests.

Jez, no trayback for the moment. I've decided to keep it looking like a 90 although I'm cutting the hell out of the bodywork.

Tony, you may well be right....

Do some resurch in to how the racers run their's they have been running these type of shocks for years.

bd_hinkle_rti.jpg

bd_alan_rti.jpg

CIMG0108.jpg

turbo.jpg

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Jules, that white one was pretty much what I had in mind. So, if it'll work on a racer it'll work for me! I'll get some mock up photos done shortly...

Well, yesterday was spent stripping back the dashboard so I can get to the bulkhead as it need a little patching (nothing serious but worth doing while its appart). I've also got a call to put into VWP to order some wiring goodies so I can sort out the birds nest that is the in cab wiring (which will, in turn allow me to get a the underdrive and get some photos for you, Tony :ph34r: )

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