Topic: rear shock set up

[91 ex-cab]

I was wondering what the ups and downs of having your rear shocks triangulated or having them go straight up to the frame? My guess is having them triangulated gives you better flex and having them straight up to the frame is better  for road driving 

[87pickup]

I think you got it. I triangulated ine for more flex and i didnt have the room to mount them up and down but a shock dampens and controls body roll alot better closer to verticle.

[Gixxer Jon]

My rear shocks are triangulated 50 degrees. I angled mine so i could utilize the full travel of the shock since i have a double shackle set up.

I dont even notice body roll, But if i did im not complaining bc its a crawler not a DD.

[91 ex-cab [OP]]

ok. so how do you determine what angle to set them at? and is it really worth doing?

[Gixxer Jon]

ok. so how do you determine what angle to set them at? and is it really worth doing?

no, i just put them as far out as i could to still be able to weld the bracket with out removing the leafs. I put them out as much as i could to get the most travel and after installing them i measured what angle they were at for s**t and giggles

[91 ex-cab [OP]]

  got it. i think im gonna try this out once i get some new bilsteins.

[Gixxer Jon]

got it. i think im gonna try this out once i get some new bilsteins.

i got the 5125's and love em..

[91 ex-cab [OP]]

ya ive got them up front, not sure if there 10,11, or 12s though works great. but my back flexes like a honda civic so i wanna triangulate it and ditch the pro comp es3000's 

[rockin86runner]

just dont weld it to the gas tank cross member get a piece of tubing and welded it right over the rear axle then weld tabs on the back side of the axle housing


iv ran the shocks in the front and on the top for some reason it feels like it rides a lot better mounted on the rear

[91 ex-cab [OP]]

huh ive never actually seen one set up like that but i think im gonna try it out. What is the best way to do this? just mock the tabs up and hope there in similar locations or measure the angle the shock tabs are at so they match?

[mtm]

i have my shocks mounted inboard at the top and all works fine. i do have them fixed to anothe cross brace that doubles as an upper coil spring mount. 

[LD]

If you are going to run them traingulated with the bar above the axle i would measure the tabs off of the center line of the bar. Just find a angle you like on one side, and then measure from the center line to the tab and then make the other side the same. If that makes sense.

[dntsdad]

love to see some pictures if you guys have time to post.

thanks

Jason

[LD]

Heres what setup came with my rig when i bought it. Not to fond of it, im going to hack it off soon make something a little cleaner looking.

[GONZO97]

What are the advantages of mounting them like that? Like does mounting them straight up and down really affect flexing when off road? and does it help make a smoother ride when on road if mounted straight up and down?

[LD]

well i couldnt tell you about flex because i have never had them straight.  It does make sense though. Straight up and down should dampen more on the street because it travels mainly up and down(equal on both sides) over speed bumps pot holes etc.  At a angle like the pic should let it flex more because while wheeling the axle is never really moving up and down equally. On tires moves up and one moves down. With them straight when one tire moves up they tend to bind. Not really good at explaining. Someone can probably explain it more clearly than i can.

[GONZO97]

That makes sense the reason I ask is because mine will be my dd as well so I'm curious as to which way I should mount them. If it isn't too big of a difference then I will just triangulate them as they are in the picture for better flex and less binding issues.

[LD]

I get a little wooble going down the road sometimes if the road dips side to side. I think its because they are a little too steep but if i change that i will have to get a shorter shock.

[91 ex-cab [OP]]

if you move the shock mounts off of the top of the axle wouldnt that give you a little straighter angle without smaller shocks? I really have no idea im just guessing out of the blue.

[87pickup]

if you move the shock mounts off of the top of the axle wouldnt that give you a little straighter angle without smaller shocks? I really have no idea im just guessing out of the blue.

I had to mve mine to the side of the axle tube and down about center to get the needed room to fit my shocks even at an angle. i used these mounts to do it.http://polyperformance.com/shop/3-Radius-Shock-Mount-p-771.html

[coloradocrawler]

ive been told that you should get about the same amount of flex when it comes to mounting them triangulated or straight up and down, as long as you use the correct size shocks for each application. plus you can use a smaller shock and still get the same flex because of how the axle moves when its flexing. IE a 12 incher instead of a 14 incher.
i have mine mounted triangulated because i didnt want to cut up my body to mount the shocks. ( which is the reason why most people go /\ instead of up and down) but i have been told the best way to mount shocks is straight up and down. something to do with ride quality. sorry, i cant remember.
as for mounting them-- on the axle i went with putting the tabs on top of the axle- just personel preference. no real reason. but we have seen small enough rocks to get between the 3rd and the wheel making me think that there is a possibility of hitting a shock if it was mounted down on the tube somewhere. for the top angle, me and a buddy flexed the truck to the max limits it could go and mounted the shocks so that there was 1/4 of an inch of shock rod showing when it was compressed. we used a mixture of math and trail-and-error methods to get the shock right.
you can also build a top mount for the shock like mine. (in the pic) and drill some extra holes for the ability to fine tune your shocks. hopefully the pic isnt small.
as for body roll- i dont know. i only drive it to the trails and i drive it around on crawl pressued 39.5 in iroks. so this thing sways real bad.
oh- and my rear shocks are 12inch bilistien 5125's if i remember correctly.

but like i say with all my posts-- this was my experience- yours may vary.

[Volcom]

Just remember, mounting shocks at angles reduces the overall dampening effect of the shock.

[coloradocrawler]

Just remember, mounting shocks at angles reduces the overall dampening effect of the shock.

 
thanx volcom, i knew there was a reason but wanst sure exactly what. the price i pay for forgetfullness. looks like my next mod is going to be rear shock redo- 

[Volcom]

thanx volcom, i knew there was a reason but wanst sure exactly what. the price i pay for forgetfullness. looks like my next mod is going to be rear shock redo- 

Here's mine (bad picture, all I've got of the shocks)


I want to redo my rear shock setup as well.  I shouldn't have welded the shock mounts to the top of the housing.  They should have been welded to the rear of the housing (extra couple inches could have helped get those shocks more vertical).

[coloradocrawler]

Here's mine (bad picture, all I've got of the shocks)

I want to redo my rear shock setup as well.  I shouldn't have welded the shock mounts to the top of the housing.  They should have been welded to the rear of the housing (extra couple inches could have helped get those shocks more vertical).

a buddy of mine told me to not do that- fear of catching rocks on your shock shaft or denting the can. but i guess its the same amount of risk as having them on top and having the front tires kick back a rock on high speed dirt road driving.
does that dampining percentage include mounting your shock perpendicular to the axle but leaning back on the frame?

[BigMike]

Volcom is correct. It is simple trigonometry. Multiply the sine of the angle by 100% and you'll get the effective dampening. For instance, the image Volcom posted, 100% * sin(80-degrees) = 98.48% (80-degrees is 10-degrees less than 90-degrees). Interestingly, that image is incorrect for all angles except for 10%. I could be mistaken, but here is what it should be:

10%  98.48%
20%  93.97%
30%  86.60%
40%  76.60%
50%  64.28%

So the dampening effectiveness will determine how much body roll the truck will have, as well as how it will ride over bumps. Lower effectiveness = lower dampening = more body roll.

Now in terms of flex, what you want to do is figure out exactly how much flex you have, and run the shortest shock possible at the smallest angle possible. If you have a lot of flex, chances are you may need a 12" or 14" shock. As coloradocrawler mentions, if you run these tall shocks vertical, they will likely protrude through your bed. So you have to lay them down at some angle in order to fit them.

The trigonometry also makes it a cinch to determine how much vertical movement the shock will have depending on the angle it is mounted at. Using the same trig. function, if you have a 12" shock that is mounted at 90-degrees, then the amount of vertical movement will be 12" * sin(90-degrees) = 12", which is expected since the shock is just going straight up and straight down at a 90-degree angle. But if you mount this same 12" shock at a 50-degree angle, then the amount of vertical movement (maximum vertical distance between lower and upper shock mounts) will be 12" * sin(50) = 9.19".

Now you can measure what shock you need and at what angle to mount it depending on how much vertical flex your suspension can manage. Don't worry about the articulation of the axle, just worry about the absolute vertical measurement between the shock mounts on each side. It is also likely that you may have more flex on one side than the other, but it's standard practice to mount both shocks at the same angle to provide a neutral or balanced handling feel on road.

So ideally you want the shocks mounted at the smallest angle from 90-degrees as possible to maximize the dampening of the shock (shock absorbers are designed to absorb shocks after all), so find the shortest shock you need and mount it at the most vertical angle you can with out 1) going through the bed, and 2) running out of vertical shock extension.

BigMike

ps. If you noticed, all you have to do is multiply the effective dampening by the shock length to get it's vertical movement ie. 12" * .766 = 9.19

[BigMike]

does that dampining percentage include mounting your shock perpendicular to the axle but leaning back on the frame?

The only thing that matters is the maximum absolute angle from perpendicular. They do not compound each other. If you have a shock mounted at 10-degrees to the side and 10-degrees to the front, it's effectiveness will still just be calculated at a 10% angle. But if your shock is 10-degrees to the side and 20-degrees forward, then it's effectiveness would be calculated at a 20% angle.

BigMike

[crazykooter]

When I set up my rear shocks I angles them in but never had a set amount.  Basically I just mounted the shocks on my axle 1" from the leaf pack.   Then I measured the shaft of the shock for 4" which would be my set up travel.  Once I marked the shaft with tape I then compressed the shock to the mark I made. With it compressed I then moved it upwards till the eye of the shock matched the level of my hanger.  So basically with the shocks I have I made them as vertical as I could while maintaining the 4"s of up travel I wanted.  I did give myself a little extra up travel since I did this without my bed full of camping gear, tools ect.  When I was done I was at 4 1/2"s with some load in my bad.  Do take into consideration that not all springs are the same and some will sag under load more then others.  My rears are the older MCREAR4 springs which have seen plenty of trail use so I knew it would drop another 1" when I did fully load the bed.  Btw I am running 14" RS5000s in the rear right now.
  Not sure if this makes sense but I guess its just how my mind works things out.
Here is a bad angle pic of them but basically I ended up with about a foot between the tops of both shocks. I do drive this rig everywhere and it does fine even on the windy rounds of a canyon near me.  It does even better if I keep more weight in the back which is sort of a given.

[zembalayan]

Here are some pics.  For better or worse, mine are mounted fairly perpendicular.  I definitely use the EVS foam bumps on the shocks through the uptravel.  For a heavy 4Runner, body roll does not seem too bad.  (BTW, these are 12" 5125s with Marlin's 5" HD rears.)  



Here is a pic of max uptravel before I got the Daystars.  You can certainly see some shock-bottoming stress here, but I haven't had any problems since I got the foam shock bumps.

[crazykooter]

Glad you posted I couldnt for the life of me remember who made the bump stops that went on the shock. How much shaft is exposed ? Hard to tell by the pics.