mounting points

tedmales

Well-Known Member
Posts
541
Reaction
10
what would be the downside to building a 4 link with all 4 bars above the axle instead of one below and one above. this would be a perfect design for what i need, but would like to hear some ideas. its not for a race truck, but it does nees to be very strong. i believe it might do strange things to the pinion angle when it was cycled because of how close the axle tube would be to the lower pivot, but i think with a little work it could be controled. i am not looking for long travel so i think this could work. any ideas, let me have them. thanks
ted
 

tedmales

Well-Known Member
Posts
541
Reaction
10
a quick idea of what i am talking about, and no jokes because i do not know how to use solidworks yet, but a ms paint pic anyway
 

Attachments

curt

Well-Known Member
Posts
402
Reaction
2
Being a 4link newbie I'm not sure but I would think acceleration and braking forces would have a major impact on the up and down travel of the suspension since your creating a lever instead of an approximate triangle. Strength might also be an issue again because your getting outside of a triangle...Curt
 

Kritter

Krittro Campbell
Posts
10,914
Reaction
296
when you got on the gas...the moutns would want to break off the axle or it would over rotate enough to bind the u joints and break them. Think of wheel hop with leaf springs...but now you have nothing to hold it back and the axle would want to keep rotating around.
 

tedmales

Well-Known Member
Posts
541
Reaction
10
thats true, i heard paradigm made a buggy like that, and i thought it would be a good idea to use on my excursion, that way i could have the height without having to make a monster truck style center section to mount everything on. but i guess if it worked, then the monster trucks would use it.
 

ntsqd

Well-Known Member
Posts
2,429
Reaction
27
I really don't see why it couldn't be made to work, but you'd better know what you're doing. You'll no doubt have to compromise some other performance feature to use it. If you want some reading on this specific linkage layout look up the WOB Link in Allan Staniforth's book.
 

AaronDixon

Well-Known Member
Posts
722
Reaction
8
It would work, but there would be way more leverage placed on your mounts and the links themselves. There is no way it will "rotate" or bind u-joints. You wouldn't do this on a race truck because the chassis pivot points would be way too high, not to mention strength, and it wouldn't articulate very well...
 

Junior

Well-Known Member
Posts
1,773
Reaction
52
What you need to design is a pressurized cabin for that Excursion of yours! hehe
 

Kritter

Krittro Campbell
Posts
10,914
Reaction
296
here is what I am seeing... this is under accelaration, braking, and reversing. Crappy simulation but I only had 10 minutes to do it. I fixed the link to simplify it...but you get the picture. THe only thing that would be holding it back from doing that would be the driveshaft.

www.animalhousedesigns.net/link.avi
 

dadomin8r

Well-Known Member
Posts
117
Reaction
0
it could work, you'ld just have to make the bracket that holds the top bar super gnarly. the top link as well. kinda defeats the advantages of having a 4-link (bar on each side to give larger moment for resistance to axle rotation). The axle would rotate a lot during the range of travel...not too good unless you like changing U-joints, or limited the travel.
 

Kritter

Krittro Campbell
Posts
10,914
Reaction
296
I was thinking that paint pic was in 3D...it could work but not well. Disregard my animation, it is how I interpreted that drawing.
 

tedmales

Well-Known Member
Posts
541
Reaction
10
i figure there are better ways and just was looking for some input about an idea. its just that that idea would work great for me. i probably will not use it, but i guess that it would not be any weaker than an axel with a lift block on it. it might need a little thought put into it, but i think it would work. maybe lots of time cycling it before anything permanent was made. will have to see
 

hoeker

Well-Known Member
Posts
2,004
Reaction
101
i'm kind of curious why you see it as an advantage? are you looking for 12" lift out of a 4-link and just don't want the bars in the way? at a minimum you could move the lower pivot to in front of the axle, that would be a huge improvement over what you're proposing.

www.rosshoek.com
 

dadomin8r

Well-Known Member
Posts
117
Reaction
0
That would work ton's better, hoeker. What was the point of the two bars on top? I missed the advantages...clearance? or are you worried about a short wheelbase being an issue?
 

tedmales

Well-Known Member
Posts
541
Reaction
10
i just wanted to keep the bars from hanging down. my excursion has 28" of lift and to make the bars hang under the rear end it would mean the hangers would have to hang down 12-16 inches from the frame. i can do that, but i wanted to avoid it if i could. placing the mounting points above the axel tube would only make 6" or so inches, that would help with the overall look of things. i want the truck to work right, but if it could work and look good, that would be great
 

partybarge_pilot

Well-Known Member
Posts
6,534
Reaction
1,361
The 4-link on Roger Mears old nissan had the lower pivot's about even with the center of the axle and theuppers way up. The shocks were also mounted to the uppers. The lowers came in to the center on either side of the 3'rd member. It worked well. Moving everything up higher would increase stress all around and with it goes wieght....
 
Top