4 link not quite right

[new2zukes]

well got the rear suspension all tacked in and flexed up to see if its going to work. it doesnt seem to droop very far. i dont quite know why but i have a few pics of the suspension. the top arms are 550 long and the bottom arms are 916 long. the pictures are of full articulation with chassis level. i only have about 100mm droop from where id like the ride hight to be.at a guess i would say the top arms are a little too short but i dont have too much choice as i dont have slot of room. if anyone can shed some light on this that would be great thanks. here are some pics.





thanks

martin

[turoa]

why is it triangulated 4 link and panhard?

[cool__bananas]

have u got rubber bushes at each end? i think if u put a Ohaleron joint at one end you may get more because they twist better?

[Lynx]

why is it triangulated 4 link and panhard?

Im with tu's, possibly panhard rod binding up. Take it off and see what happens.

Cheers Daniel

[rokhound]

Top arms are too short, bushes are to heavy and ditch the panhard. If you have worked the system out properly with the correct amount of triangulation on the uppers, there is no need for it.

So pretty much what the others above have said

[haydgq]

And you can see the outer sleeve of the Bushes binding up in all the mounts aswell, maybe fit Rose joints to all the arms at the Chassis end.?

[darinz]

It is really simple. You have a trianglulated 4 link that will only let he axle move up and down. You then also have a panhard rod that requires the axle to move in an arc as it goes up and down.
So the 2 are fighting each other and will ultimately cause one to fail.

Also you upper arms are to short. They should be close to 640mm long being 70%. This is to ensure that your pinion angle stays within acceptable tolerances.

Also how far apart are the links on the axle? They should be 25% of the tyre diameter.

Do you know what you antisquat figure is? ie is the truck going squat or lift under acceleration or on a hill climb.

You really should set the height of the link at the axle end and have it adjustable at the chassis end. That adjustament is to change antisquat but if you calculate it correctly then you will be making adjustments to carter for different track conditions. ie I designing mine so I adjust the antisquat depending on if it is wet or dry.

So what the arm ends are will effect it but fundamentally there are a couple of problems with the design.

[darinz]

Since you are relatively close to home, you supply the beer and I can come and help you measure things up. I will bring my laptop and work out all the points to if you want. I have a couple of clients to see in Kerikeri so can do it all at the same time.

[meatc]

I thought you were going to use the stock surf arms that came with the diff.

Give us a shout and I'll shoot down one night (after the kids go to bed) and go through a few bits with you. I have a really good simple (for 4 link design) how to that covers the basics.

The way it is you will prob find if you flex it the other way you get no/little up travel on the left and the right drops okish

Dan

[new2zukes]

hey thanks for the offers guys would be good to have someone see it and give me a better idea of what im doing. as for stock surf arms this was a little bit of a hassle as the arms went in the wrong place to the chassis. everything is just tacked on so can easily be bashed off. as for the joints all the bolts are loose so it can move free. (was not going to leave them loose.)
i am at work till next monday then i have time off work till 18th january but would like it to be moving sooner.

i have adjustments on chassis and diff so i have plenty of adjustment but would be good to get it right first time. will give you a call dan and see if you can help me out a little will suply beer:) it wasnt really a calculated link design it was just from reading lots of stuff on pirate4x4 and trying to get some sence out of it. thanks all for input.


martin

[flyingbrick]

Wy dont you just take off the panhard and try the flex test again?

[new2zukes]

have just done that and it works now, have as much droop as i want now, the diff head tilts down because of the length of the top arms but i dont think this is going to be a problem as it is very rare for both wheels to drop that far at once. if i jack 1 wheel off the ground about 700mm the other is on the floor the chassis is flat and the diff angle hardly changes. might have to change a few things but that will all be at a later date when i get all the info to make things right.

martin

[Bolo]

have just done that and it works now, have as much droop as i want now, the diff head tilts down because of the length of the top arms but i dont think this is going to be a problem as it is very rare for both wheels to drop that far at once. if i jack 1 wheel off the ground about 700mm the other is on the floor the chassis is flat and the diff angle hardly changes. might have to change a few things but that will all be at a later date when i get all the info to make things right.

martin

post up pics of your change and what it now does

[new2zukes]

hey will get some pics taken tomorrow.

[darinz]

When I come and plan the turbo install on Dans truck (!) we could come and look at yours as well. I have to bring a mates plasma cutter back so he can do some work for him anyway.
I am assuming that Dan is fitting a turbo as next year is approaching fast

[new2zukes]

lol would go awsome with a turbo not that it doesnt go good as it is but everyone needs more power.

[meatc]

Goes better now the Crank angle sensor isn't all sloppy. But yeah needs more. But will be supercharged not turboed. (just have to convince the minister of finance and entertainment.)

Back on topic have you got the flex where you want it?? Talk to you Sat

[new2zukes]

yep have got the flex right where i want it, in fact proberly more than i need but my limiting factor will be the shocks now. pic of the flex with chassis flat and the rear fully flexed the other wheel is just about to come off the ground. i get one wheel 700mm off the ground while other is 0mm off ground.diff is still pointing at t case output just might need a limiting strap to stop the diff from going too far down and stuffing up the angle but thats no problem. i will have a bit of rear steer when at full flex but i dont mind that as you very rarly have it on full flex.well anyways heres the pic

[Bolo]

NICE

[new2zukes]

well tacked everything and took some pics, didnt lift it to full flex as its all tacked in and didnt want things to let go at a great hight.


they are vitara springs. new need to get the front done.