Raised Shock Mounts - Shock Issue

I have raised my rear shock mounts. This has really helped clearance issues. After raising the mounts, however, I had to install stock shocks because of "extended" shocks I had were too tall. They did not allow enough compression.

I'm looking at getting new shocks. I want to address this issue so I am able to at least run shocks with 10" - 12" of total stroke. At ride height, the current measurement is 15" and I'm pretty sure I am not going to be able to as is.

Has anyone addressed this, and what have you done? I'd like to be able to raise the upper mount or increase the static distance eye to eye without lifting. Increasing the angle of the shock (I hear) reduces their effectiveness. I have some ideas what I could do, but I'd sure appreciate some feedback.

Thanks,

Les

PS: See sig for vehicle set up.

You need to build of by a crossover shock mount. Theres a company that makes one but its rediculusly expensive. Just biuld it.

csudman said:

You need to build of by a crossover shock mount. Theres a company that makes one but its rediculusly expensive. Just biuld it.

Click to expand...

I'd thought about that, and maybe a variation using shock towers off the existing cross member through the floor (if you can visualize my idea). I'd rather try and keep the floor sealed if possible ... dusty gravel roads are abundant around here. But I'm not beyond going that direction if I need to.

How much angle can I get away with on the shocks? Right now they are about 20 degrees off perpendicular to the axle using the original upper mount. If I move inward about 4", I'm guessing I'd be about 30-35 degrees. Is that too much? I'm wanting to run a "soft" shock anyway.

Thanks Csudman ...

Les

I'm at about 35-40 degrees. Its not that bad. The way to figure it, at 45 degrees you get 1/2 of the shocks dampining and travel. To run a long shock on raised shock mounts, you just about have to go thru the floor to run them verticly. If your comfortalble doing it fab up a box to cover the holes and shocks. And take pics.

I hate to offer any advice here, but your math needs some correction. At 45 degrees you would have 1 / √2 of the shock's damping and travel. This is roughly ⅔.

Jaredatriot:

You can't really use that much shock in the back. It's not that big of a deal. The key is to use all of the shock travel, so the shock length comp/ext is very important. I hate to rain on anyone's parade, but it's very marginal to tilt the shock in at the top with a new shock crossmember. This is done to allow the use of a longer shock, which then isn't needed because the shock travel is reduced by the shock being at more of an angle..........overall, an excersize in futility, especially considering the reduced shock dampening.

If you flex up your rig, and measure the comp and extended length that you need, and find a shock with those dimensions, you'll be doing just fine. If you're fine tuning the leaves for more flex, leave yourself a little room for improvement, and remember that the bumpstops will compress a fair amount if you hit them hard. I ran a 10" travel shock with the stock upper mount and the lower mount even with the axle. They are RS9116, 15.10" comp/24.92" ext (pics below). I have about 7.5" of lift and the stock bumpstops were lowered 5". (I now have 10" travel SAW's 16"/26" and I've adjusted the bumpstops, but still the same upper and lower mounts)



Here's a pic when I ran 9" travel RS9118, 13.94" comp/22.8" ext. When we still cared about such things, I ramped as high as 1175 with those 9" rear shocks. I'm not trying to make anyone tired of this shot, just showing what's possible with nothing exotic.


Same shot, from the front......12" shock in front and 9" shock in back, short arms and stock length rear springs.

Hey Deadeye ... I appreciate any advice or comments here, so don't "I hate to offer any advice here" ... I appreciate all contructive comments. Need the info as long as everyone does not mind sharing it. BTW ... if I understand your formula, you said at 45 degrees, the amount of travel = one over the square of two. Are all angles proportional using this formula?

I'm just trying to make some plans here. I will be getting shocks next and I want to ones with adequate travel. I already know I need more travel in the front, so now I'm checking the rear. I need to do some fine tuning to the rear leaf pack too.

BTW Richard G ... if I can get 67% of the travel you get, I'd be happy ... and thanks (again) for your info.

First thing on the agenda, I guess, is get my current compression/extended measurements, then see what shocks are available. No sense predicting a problem before I know for sure I have one.

Another question ... Does the dampening rate of shocks affect the "balance" of the supension or is this strictly a function of spring rate? My current plan is to run a higher DR in front with a lower DR in the rear to help balance the suspension somewhat. I've got the RE 4.5" ZJ coils up front with a combo of Dakota and XJ leafs, and .5" block in the rear.

Thanks for all the comments so far ...

Les

Be sure to flex and measure with the shocks unbolted, at least at one end, to see what the suspension actually does....unless you're testing what your current shocks will do. Shock valving/dampening does not affect articulation or travel, it is totally a function of the springs and any suspension bind (hopefully not steering bind).

The formula Deadeye posted is only valid at 45*.

If you take the angle of the shock from vertical the efficiency of the shock to vertical movement is the cosine of the shock angle

Efficiency = cosine(angle)

At 45* from vertical this is .707 or 70.7%
At 30* from vertical this is .866 or 86.6%

Although as your suspension travels the angle of the shock changes as does the efficiency of the shock....however in this case it is fairly small and can pretty much be neglected.

Also, I tend to disagree with Goatman on one issue. Having a shock at an angle does indeed increase the amount of articulation you can achieve with a given length shock. Those efficiency numbers are actually the perctage of travel the shock experiences with a given amount of downward movement...i.e. if you assume the angle change is negligible and your shock angle is say 30*. If your axle drops say 10" down the shock will experience an elongation of 0.866*10" which is 8.66". Now you can see how having a shock at a great angle lowers it's efficiency because the total movement in the shock is less when compared to the total downward movement of the suspension.

It should be said though that you generally want to keep the shocks as vertical as possible if you can. This means determining how much travel you have in the rear suspension and finding a shock to match it. If you can't find one to match or if you want to make shocks that you already own fit with your new mounts, then you can start angleing them by building a shock hoop.

Here's a simple and easy hoop.
http://community.webshots.com/photo/64838123/71467807cnOlfb
http://community.webshots.com/photo/64838123/71467817sixSpP
http://community.webshots.com/photo/64838123/71467800zkBzBO

I do not consider my setup ideal as my shocks are too long for the amount of travel I get so they are at an unnecessarily large angle. Unfortunately the shocks were only a month old when I relocated my lower mounts so I wanted to use them.


Good luck

When I swapped my 44 from the MJ into the trail-rig XJ,-went from 3" to 6"- I foolishly placed my homemade shock mounts into a stockish one ahead/one behind config... but with the lower bolts maybe 2" above the center of the axle tubes. Sure enough I sheared the front-facing bolt off on it's second trip into the woods. I butched things up so now it also faces rear... but that all needs rehabbed & beefed.

I then had a crossmember built out of notched 2x2 that bolts up between the rails at the bumpstops. It has a bunch of holes (4 on each side of center, 2" apart) so there is a wide range of upper mount spots.

The shocks I reused are 'really stiff-gascharged' deals (unknown maker, white in color) 25" extended, 12" compressed and they only fit at the two centermost holes... Maybe at a 45* inward angle. At full stuff, I still have 1" or so of chrome showing on the rod...and I have a few more inches of downtravel left on tap that my springs/MJ shackles won't let me use. It isn't real stiff but it isn't real sloppy... I got lucky for cheap.

Keep in mind these are really stiff compression shox...and I haven't used any rear bumpstops to keep the tires off the fenders. With boomerang shackles and some dropped bumpstops, (or hogged out fenderwells) I think it'd be better.

When I build up my 44 for the red XJ, (+3-5") I'll use ORGS type mounts on the axle. both rear-mounted, and maybe use 2x3 for the upper x-member to get the upper mounts a tad higher. At that point I'll measure the compressed vs extended length and shop for shocks.

does anyone make the high clearance shock mounts or should i just make my own?

Yes ... It sure would not hurt to go through the front end to check for any binding there. I installed the RE HD TB so I could get away from the TRE style joint at the frame mount, so I'm pretty sure I'm OK there. The rest of the steering is still stock (except for a Goferit bushing), so I should check the TRE's at full extension. U&LCA's are RE HD Adj. so they should be fine.

In the rear, I made the same mistake as a lot of others, and used the sway bar brackets as a BPE's, so I need to make up some new brackets. I may be getting some binding there. I'll check with the shocks removed.

Thanks ...

Les

Thanks Bender and Woody ... I appreciate the formula info and experience ... it really helps me out.

Woody ... I welded the shock brackets to the axle front and rear too, but the bottom of the shock is about level with the bottom of the axle. I made sure the brackets I installed are plenty strong ... used .25" wall welded inside and out.

Do you think the mistake you made was having the shock mount too high or welding the brackets front and rear (or both)?

Les

BTW ... I currently am running some Gas Ryder shocks that are stiff as heck on compression ... hate em!

For mounts, I used one RE spring perch cut in half with 1/2" (?) grade 5 bolts welded through new holes. The smart deal would have been to use nuts on the outboard sides (between the shock & the mount instead of welding the bolts to the mounts) to facilitate replacing them.

I am unclear what caused failure/bolt shear. I 'think' it was from gonging that forward facing shock onto a hungry rock... (I tend to be a little rough on the equipment.) Listening to, or just having a spotter probably would have avoided it... :dunno:

Like I say though, 'next time' my shock mounts will be a little lower. I still like them no lower than the axle tube, but for practicality, want the bolt center as low as possible.

Bender said:

Also, I tend to disagree with Goatman on one issue. Having a shock at an angle does indeed increase the amount of articulation you can achieve with a given length shock. Those efficiency numbers are actually the perctage of travel the shock experiences with a given amount of downward movement...i.e. if you assume the angle change is negligible and your shock angle is say 30*. If your axle drops say 10" down the shock will experience an elongation of 0.866*10" which is 8.66". Now you can see how having a shock at a great angle lowers it's efficiency because the total movement in the shock is less when compared to the total downward movement of the suspension.

It should be said though that you generally want to keep the shocks as vertical as possible if you can. This means determining how much travel you have in the rear suspension and finding a shock to match it. If you can't find one to match or if you want to make shocks that you already own fit with your new mounts, then you can start angleing them by building a shock hoop.
Good luck

Click to expand...

Bender, actually we're agreeing. The angled shock will allow more travel. But, angling the shock will use less shock travel for the same amount of suspension travel. So, if a longer shock is angled, but the suspension travels close to the same, the longer shock isn't needed.

Stability is also important, and like you said, keeping the shock as vertical as possible is best.