Why are bumpstops so critical in a Landy

[Redback]

Speaking to other 4b owners that don't own a Landy when mentioning i have to extend my bumpstops most just say, why bother? i didn't touch mine, aahhh don't worry about it.

So why is it that bumpstops are so important, aspecially on Discos, why isn't it that important on jap 4WDs:confused:

Baz.

[PhilipA]

Its just that they are ignorant.
If you put longer shocks on, its important that the upward limiter of suspension movement is NOT the bottom of the shock absorber for several reasons.
1 shock mounts are rarely as strong as bumpstops.
2 The piston and valve on the end of the shock shaft is unlikely to appreciate being rammed into the end of the shock.
3 The shock shaft is not very strong in bending stress and neither are the welds on the top and bottom shock attachments.
4 As the shock is the major thing that stops the spring popping out on a coil sprung suspension on full droop, a broken shock is not good.
Regards Philip A

[BigJon]

Baz - It could be that Jap 4WDs don't articulate as well as English ones...:eek:

[stevo]

after lifting mine and changing the shock's for longer travel ones did the checks on retracted length of shock's,springs did not fit the extended bump stop's I have had no problem's as with any mod's do the check's before changing

[Pedro_The_Swift]

its a question of leverage.
In a perfect world, bump stops should be at the extremety of the axel, after the shock. This provides maximum stopping power, and reduces the amount of axel available to flex or bend.


at no stage through articulation should the bottom of the shockie come near the axel mount.

[LandyAndy]

OK,I can see why you need to check the bumpstops.
OK,whats the best way of checking when you put a new suspension system in???One would thing a complete matching setup purchased would be OK.
Andrew

[mark2]

OK,I can see why you need to check the bumpstops.
OK,whats the best way of checking when you put a new suspension system in???One would thing a complete matching setup purchased would be OK.
Andrew

Take the spring out, let it sit on the bumpstops and make sure the shock still has about half an inch of travel before its at full compression. If it doesnt, extend your bump stops by an appropriate amount. Conversely, it the shock still has a lot of travel in it, you can use a longer shock and generally obtain more downwards wheel travel.

[Pedro_The_Swift]

and the good thing about doing "on car" measurements is,,
after you get extended and collapsed lengths,
all you need to add is the correct ends, (pins or eyes) and you can buy literally any shockie,,
non-public shockie books list them by lengths
could be a '71 torana,,
or a 70's cruiser,,
want a heavier shock? maybe a studebaker,,
or a lighter one? how about a torana,,
the choices are endless,,

[rick130]

you need to allow for at least 20mm compression of a stock Landy bump stop before your shockie goes metal to metal.
They definately compress that far, I have the broken non-Land Rover Koni bits to prove it ;)

[JDNSW]

Take the spring out, let it sit on the bumpstops and make sure the shock still has about half an inch of travel before its at full compression. If it doesnt, extend your bump stops by an appropriate amount. Conversely, it the shock still has a lot of travel in it, you can use a longer shock and generally obtain more downwards wheel travel.

The stop is inboard of the shock, so the measurement should really be taken with the other side shock fully extended, or you could calculate the amount - measure the horizontal distance from the bump stop to the opposite shock mount and from the bump stop to the shock mount on the same side and add this same fraction of the shock extension to the amount you need to extend the bump stop.
John

[Redback]

OK thanks guys, as far as i can tell it's only the rear that is the most critical, cause the front spring will bind before the shock bottoms out and a 50mm extension there will be OK.

Now the rear is a differant story, by the looks of it a 75mm extension will maybe just do it but i'm going to have to check this at length cause it articulates far better on the rear, but because of Discos poor articulation in the front it doesn't allow the rear to extend fully so it's hard to gauge how far to extend the bumpstop to the correct length unless you pull things apart.

Baz.

[Daniel]

Not only does one have to worry about the bump stop (as compressed) being the first impact point but also the compressed spring height.

If the compressed spring is reached before the compressed rubber bump stop then the chassis spring saddle will be torn off.

Some spring manufacturers are notorious for supplying incorrect springs that "bind" before the bump stop is "bound" - and removing a spring to test the shock limit will not assist in the determination of this.

A forklift tyne carrying a huge weight onto either front or rear chassis points is one way of testing this - has anyone else come up with a better test method?

[Martin]

Reading this thread got me taking a closer look under the car, and I noticed one of my front bump stops has disappeared. I am keen to get a new one before I head off on a big trip on 8th July. Anyone know where I can get hold of one this week? I am in South Australia.

Martin

[Daniel]

Reading this thread got me taking a closer look under the car, and I noticed one of my front bump stops has disappeared. I am keen to get a new one before I head off on a big trip on 8th July. Anyone know where I can get hold of one this week? I am in South Australia.

Martin

- it may be helpful to specify the type of truck and the model.

[Martin]

Good point - 110 Defender xTreme - 1999

[PhilipA]

Just a point on checking the length of shocks vs bumstop.
Once went over the Simpson with a guy with a stock Rangie , who had borrowed a set of 245.75X16 Mud Terrains.
They were catching on the front of the wheelarch.
When a gang of us stood on the rear bumper, and compressed the rear suspension onto the bumpstop, the tyre was about an inch away from the front of the wheelarch.
The front and rear bushes of the trailing arm had to compress about a full inch to allow the tyre to hit. When you look at the bushes its hard to understand how this happens as they appear really solid.

SO do not just allow for the height of a bumpstop, add half an inch travel AT LEAST, because coming off a Yump the bumpstop can compress significantly. On reflection this rebound is probably what causes the infamous Rangie "bounce" when you come down off a jump at high speed, where the back flips up in the air after the landing throwing your fridge and luggage in the air if its not tied down.
Regards Philip A

[Daniel]

Not just RRs that have that characteristic on jumps etc - You should have felt my Toyota in its heyday!

It's always been good policy to allow 50mm extra in these calculations and not the 1/2" that some espouse.

Don't forget that not only rubber bushes and bumpstops flex and compress but also chassis steel and other components alter their relative positions as well. Even radius arms, panhard rods and axle housings flex quite considerably - just ask any serious Toyota and/or Nissan 4wd'er - It's incredible how many Jap axle housings have been known to work harden and crack from persistant flexing!

[mark2]

Not only does one have to worry about the bump stop (as compressed) being the first impact point but also the compressed spring height.

If the compressed spring is reached before the compressed rubber bump stop then the chassis spring saddle will be torn off.

Some spring manufacturers are notorious for supplying incorrect springs that "bind" before the bump stop is "bound" - and removing a spring to test the shock limit will not assist in the determination of this.

A forklift tyne carrying a huge weight onto either front or rear chassis points is one way of testing this - has anyone else come up with a better test method?

To get an indication of whether a coil will bind, I count the number of coils, multiply by the wire diameter and add 50mm or so. If this figure is less than the space between chassis saddle and axle spring seat when sitting on the bump stop with spring removed I assume that binding wont occur. I havent proved this theory with actual load testing but so far I havent torn off any chassis mounts!

[Pedro_The_Swift]

heres an interesting page--- :D
http://www.swayaway.com/Suspension%20Frameset.htm

[incisor]

heres an interesting page--- :D
http://www.swayaway.com/Suspension%20Frameset.htm
excellent page mr petrol head... how bout you put it in the links section so it dont get missed :P

:clap2:

[Pedro_The_Swift]

ooops-- :bangin:

:D