Wanted: Shock absorber expert

[Toy-Roverlander]

Ok, for the shockie experts among us..

I've got a SIIa 109" stationwagon.

This Landy is completely different from your standard 109" or military/one-ton.

The problem is in the rear suspension.

The front mount of the leafspring has been lowered by 3cm
The rear shackle mount is lowered by 5cm
Reason I guess (PO has done it) is to lift the rear of the vehicle (the chassis is a lengthened 88" chassis, with a self-made mid and rear end. Made to very high standards.) So with completely flat springs the Landy sat level.
Now with the para's fitted the rear is lifted a fair bit, like 9cm.

Today I wanted to put the shockies on there, I bought those Pro Comp ES3000 ones, and they don't fit... they're too tall.
When the chassis was made, not only did they lower the leaf and shackle mounts, but they lowered the shockabsorber mount as well.. Instead of it sitting above the chassis rail, nearly touching the bottom of the tub, mine sits in the main chassis rail, with the top of the shockie flush with the top of the chassis rail on the bit where it slopes down.

So, my problem..

ES3000's are too long. When fitted they can only compress about 2cm before bottoming out.
Original shockies are the right length but they don't really have the rating for soft parabolics.

So what to do? Are adjustable shocks available in standard lenght? Gas shocks perhaps. I saw that Monroe's are available, or DeCarbon. I believe both are gasdampers.

I know ****all about shockies to be honest.

What to do?

I really don't want to change the top mount of the shockabsorber.

Many thanks!

Koos
PS, I've just ordered some original ones, just to get me on the road. My old springs were incredibely soft and it worked, although it needed some tougher shockies...

 

[revor]

What I did on my 109 might not apply because of the 88-ness of you chassis.

If you can imagine, I put a crossmember across the chassis that mounted where the limiting straps of the 109 rear axle would normally mount on the inside.
I was then able to add a "pin mount" to the spring plate and put pins on the crossmember to mount the shocks which not move perpendicular to the motion of the truck rather than parallel, they mounted at a slight angle say 30 degrees but the setup works a treat.

The only potential problem is that the pin on the spring plate faces forward and could suffer damage. the upside is that you can get quite a long shock in there.

Might be mor work that you want to do but considering the project at hand...

 

[Antichrist]

I'd jack up the rear end so the wheels are off the ground. Measure the distance between the two shock mounts, that's your max extended length. As Thom says, add a couple inches safety factor.
Then put the wheels back on the ground and measure the shock mount distance and subtract the distance from the top of the axle to the bump stop. That's your min distance.
Then start looking for shocks that fit in that range with a rate to suit you.
If the previous owner installed limiting straps like the stock vehicles have, you can fact those in for your max length requirements.
If you can't find any shocks to suit the max length, and it doesn't have limiting straps, you can either move the shock mounts or install limiting straps. Just depends on how you're going to use the vehicle.

 

[Toy-Roverlander]

Good input! Thanks guys!

Ok. For now I'll fit the original ones so at least I can drive it around.

I like the idea of having them facing inwards mounted on a crossbar, like Revor suggests. On LandCruisers they've done that as well.
I've seen it on LR's as well.

That makes it also quite easy to fit a good length shockie on there.
I can take a long shock, make sure there's a safety margin, than see how short it is when compressed, and with the suspension comressed (on a ramp for instance) I could decide where the top mount needs to be, and where the crossbar needs to sit.
That way I can also get some stiffer shocks to compensate for the angle they'll be on.


True, I've already done so much. With a little extra work I can get the full benefit from the massive flex I can get from the springs.

Coilers beware :sombrero:

 

[UK4X4]

"Pro Comp ES3000 ones"

they don't all come in one size whatever make you buy

Each shock has diferent extension and compression lengths
and also have diferent attachement types top and bottom

Getting detailed shock details from manufaturers can be quite a struggle even after you've completed the tests above.

Google is your friend to search out a suitable shock.

 

[ntsqd]

Prime importance is that you do not over-compress the dampers, so start there. With a fully loaded rig drive one rear tire up a ramp or something similarly suitable. The idea is to get that one side to it's fully articulated and compressed point. If it is touching any bump-stop that might be present, remove it. Bump-stops compress when they are there, altering your minimum dimension. When they aren't there, and they used to be, then your dampers are likely to become the new bump-stops. They're not fond of that treatment.
Measure the distance between the mounts.

Now you know what your minimum damper length needs to be. I'd add 1/4"-3/8" (6mm-9mm) to that dimension for a little extra margin.

Next jack the rear off the ground from the frame and not the rear axle. Let the axle assembly hang in space. Once the tires are off the ground, secure the frame on jack-stands and measure the mounting points distance.
That is your extended length need.

Note that the maximum drama and violence of fully extending the dampers can not come close to the maximum drama and violence of fully compressing them. So first selection criteria is the compressed length followed by the valving. The extended length is the last thing to consider. Should you find that the only option that fits the first two criteria results in limiting the fullest extension of the suspension by a minor amount it is not the end of the world. It is very much preferable to any other possibility excepting a damper that can extend further than the suspension can.

 

[dieselcruiserhead]

Measuring based on extend and compressed lengths, particularly when not moving, is actually a secondary measurement system and is not even always 100% required. It is good for more information but often/usually you can figure it out without it.

There are many lengths and applications for each of the shocks you mention. The best route is simply measure the length between the shock mounts as it sits level. Then look at the extnded and compressed lengths of different shocks and try to find one in the middle. The Pro Comp and other several other manufacturuers generally make their shocks stiffer with their higher model numbers. So 3000 is a much softer shock than a 9000. You may want to look into this for sway and general handling purposes - food for thought and make sure you take this into consideration when figuring out which shock you end up with.

If you have room for a longer length shock (which I wouldn't anticipate) then start moving more towards more travel on the droop side but if you have room for 3-4" of room before the bump stops but you have 8" of overall travel then push the longer side (5") on the droop side. It is sort of all common sense or make sense when you start thinking about it.

 

[dieselcruiserhead]

Helpful link for determining shock lengths. Get the correct part number before you order of course... In the case of several of the 4 digit shocks usually the last three digits are the length/model and the first digit is the series. So a Rancho 5113 is the same length/application a 9113 but the 9 is their 9 position adjustable shock (the 9000 series).

http://yotatech.com/f116/shock-length-thread-141193/

 

[Toy-Roverlander]

Helpful link for determining shock lengths. Get the correct part number before you order of course... In the case of several of the 4 digit shocks usually the last three digits are the length/model and the first digit is the series. So a Rancho 5113 is the same length/application a 9113 but the 9 is their 9 position adjustable shock (the 9000 series).

http://yotatech.com/f116/shock-length-thread-141193/

This one is going to be very handy, thanks heaps!!

I'll have to have a good long hard look on this one.

I know the springs have got some potentital, expecially as they can reverse arch as well (I know, not really good for long spring life, but boy do they flex), and it would be ashame to limit that by short shocks..

 

[Antichrist]

If it is touching any bump-stop that might be present, remove it. Bump-stops compress when they are there, altering your minimum dimension.

Nothing wrong with that is if one is really compulsive, but series Land Rover bump stops are really hard and aren't going to compress much. Subtracting another inch or two just to be safe would be more than enough.

 

[dieselcruiserhead]

It really depends on the stops and the architecture and flex you are looking for. Droop is not "all that" especially with lockers but it is also very nice to have. These are all factors to consider...

 

[Toy-Roverlander]

The original bumpstops are indeed made of a very hard rubber and only 2inches or so tall. So 2 inches will be enough of a safety margin.

I'm always very carefull when driving offroad so it's not like it's going to do high speed jumps or something.

It's just that I would like to get the full amount of flex available from the springs. They can reverse arch a fair bit before hitting the bumpstop, and as the springmounts are lowered I should be able to get a lot of droop travel as well.
I'm going to need a high-angle yoke propshaft with longer slipjoint too I'm affraid, and I'll need to notch the crossmember where the prop passes through.

I like one of these shocks:
http://www.bilstein.com/offroad_5125.php

They're valved for a leaf sprung vehicle, are rebound and compression adjustable and come in a variety of lenghts.

If a fit them to a crossbar between the chassisrails I can install quite a long shock in there.

Don't know about theprices though...... But they're one of the simpler ones in their catalogue.

 

[TeriAnn]

A couple of things:

1. Great Basin Rovers can supply you with custom propshafts with high angle U joints and much longer slip joints and the correct length for your vehicle's measured mounting surface to mounting surface length. I'm a happy customer.

2. Land Cruiser spring leaves are very close to the same width as Land Rover's. There is a model of land Cruiser that has mounts for eye type shocks on the bottom plate. You can source a pair and put them on your LR's rear springs. You will need to upsize the diameter of your rear 'U' bolts a little, but that never hurts (I had a truck shop make a set for me). This swap gives you a bottom shock mount just inside the bottom of the spring pack so all you need to do is add one on the inside of the frame rail.

3. When you do a ramp test to determine maximum needed shock length, be sure to do it with the stock shocks disconnected, at least on one end. This is particularly important at the front because the shock travel is so very limited. When you have one wheel off the ground you can measure max travel on the extended side and min travel on the compressed side.

Some pictures I've collected from what others have done:

These three are on a Series I 109 pickup

Front shocks:

​

 

[ntsqd]

Nothing wrong with that is if one is really compulsive, but series Land Rover bump stops are really hard and aren't going to compress much. Subtracting another inch or two just to be safe would be more than enough.

Tom, My advice comes from experience with damper lengths being set including the bump-stop, only to have bump-stop disappear from something (usually many somethings) unexpected. If it is rare for a an LR bump-stop to de-vulcanize and evaporate then I'd use 1/2 of the bump's height as the max up travel limitation point. Though going metal to metal for the measurement is still the safest. All a matter of how the rig is used. There is the idea in desert racing that hitting the bumps regularly is not a bad thing and it means that you are using all of the available travel. My right foot seems to have taken that to heart.

When mounting dampers bare in mind that their effectiveness is a trigonometry function of their installed angle. The further they are leaned over from vertical, the less effective their damping will be. My goal in such projects is to mount them such that they are vertical in the parallel and transverse planes when the suspension is at it's most compressed limit. The idea behind that goal is to create a situation where the valving is "soft" at ride height, but gradually increases in firmness as full bump is approached, i.e. slightly rising damping rate.

 

[R_Lefebvre]

When mounting dampers bare in mind that their effectiveness is a trigonometry function of their installed angle. The further they are leaned over from vertical, the less effective their damping will be. My goal in such projects is to mount them such that they are vertical in the parallel and transverse planes when the suspension is at it's most compressed limit. The idea behind that goal is to create a situation where the valving is "soft" at ride height, but gradually increases in firmness as full bump is approached, i.e. slightly rising damping rate.

I'm glad you brought that up as it's a very good point. Installing shocks with a high angle, that only gets worse as the suspension compresses, removes damping effectiveness just when you need it most. Obviously one can't always achieve the perfect shock angle, but it should be considered when one is trying to balance all the variables.