Rear shocks....
 

How many do you have? I have only one!

The other one broke clean off the other day when I had a heavy load on......

79 150 4X4 with a 9" rear. I knew my upper shock mounts were worse than bad for a long time, they've been rusted through since I've had the truck. The driver's side one finally broke the other day, and now the shock, and half the upper mount, are resting on the E brake cable, parallel to the road.

I'm a welder, so putting it back together is as simple as convincing myself to crawl under there, eat rust for an hour, and stick something together.

I do however have a few questions about shocks in general:

How badly do I need rear shocks period? I've assumed these have been dead for a long time.....

Is it an issue that I only have ONE shock (as opposed to having none at all, as in, is it bad to be uneven)?

If I really should replace my rear shocks, what do I have to look for in new ones? Travel length? Travel speed? Weight tolerance?

Thanks for any info, AleX

Shock real help soften the ride of a vechical!

Having only one shock will put more of the load on one side vs the other. Yes, it is a problem. Depending on what exactly you want out of the suspension will determine what specifics you should be looking for out of the shocks.

Dang. Failure caused by rust? That's hardcore. I'd start looking at other parts of yer rig for at-risk parts lest you look at the rear view mirror only to see your parts chasing you!!! I read a bumper on an old Jaguar that said, "The parts falling off this vehicle are of the best British manufacture".

A shock absorbs the jolt and controls/slows down a spring's rate of oscillation. Think of the physical behavior between a fully inflated tire with an underinflated tire. Boing.

IMO, a half-ton with more than 4 inches of lift requires extended shocks. My Rancho RS5000s are near their extended limit but there's not much droop so I'm oK. If you wanna get technical, measure the distance btwn the shock mounts at full compression and full droop. Then talk to the parts houses to determine the appropriate length and what they suggest for valving. The spec at-rest should leave 60 percent for compression (and 40 percent for droop).

Something I had previously posted that may be of help:

I used factors of 40% for compression and 60% for extension, meaning that I anticipated that the shock would not compress or extend more than those factors for my usage. I use the truck on our property, trailering, etc, no extreme off-road with lots of high angles, etc.
I used Pro-Comp ES3000 shocks with boots, they seemed to work fine for my use, but of course everyone has their picks on shocks. Not interested in debating that, just giving an example of how I picked shocks.

If you look at the Pro-Comp site, they list specs for their shocks. I happened to have had a chart on this, easier than sifting thru many web pages. But the info is there.

As an example:
At ride height, the distance between top/bottom mounts on my truck was 24" on one set of the front shocks (have quad shocks on the front).

Looking at the specs, after some trial and error and looking at several shocks to get me generally in the 24" installed height range, there was a ES332010 shock that shows 31.76" extended, 18.25" compressed:

• <LI itxtNodeId="1011" itxtHarvested="0">this shock has 13.51" of travel. <LI itxtNodeId="1010" itxtHarvested="0">40% of 13.51" = 5.4" for compression travel <LI itxtNodeId="1009" itxtHarvested="0">60% of 13.51" = 8.1" for extension travel <LI itxtNodeId="1008" itxtHarvested="0">24" ride height plus 8.1" = 32" extended
  
• 24" ride height minus 5.4" = 18.6" compressed.
  

My numbers of 32" and 18.6" were very close to the published 31.76" and 18.25" numbers so I went with the ES332010 shock. I went thru the same selection steps for the other set of front shocks and the rear shocks as well since these other sets had different mount spacing dimensions. That was in 2003 and I never ever had any issues with bottoming out or overextending.

This time around, when the truck is reassembled I will go thru the same process, especially since I'm changing the location of the rear axle shock mounts and also adding 2 more shocks in the back as well. If you are anticipating significant off-roading you can increase the compression and extension factors and the opposite is true as well. If its street driven, then the factors can be reduced.

Hope this helps. This may seem like a lot of work but it's important to stay within the normal operating range/travel of the shock to avoid shock or mount damage. Maybe someone has a different and better way, this is what I did and it worked fine for me. <!-- / message -->


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Hmmm.... that's interesting there Steel Toy.

I like more compression than extension. Seems to me the more length on the compression side would be better to absorb up the impact.

Hmmm OK, well all great info as usual guys, thanks!

HIO though, to your first post, yes failure by rust, and yes it is hardcore haha. Bodies rot through in 5-7 years up here, and alot of trucks rot in half (seriously, the whole frame) around their 15th birthday. Any concave surface is just an invitation for rust and rot to form, and that's what the upper shock mounts are.

I've been up and down this truck dozens of times, and rust repair is always first on my list, so I know where my problem areas are, and almost all of them are currently repaired. I knew though that the shock mounts were going to go soon, just figured I'd get as much time from them as I could, and the bottoms mounts on the axle are very solid.

Anyway thanks for the help again, guess I'll start looking into shocks.

AleX

Yes, I understand what you are saying, it can go either way depending on what use is anticipated. My original recommendation came from a pretty knowledgeable guy that does a lot of off-road, his application is more on the lines of what you noted on compression. But in my case the truck is 90% on paved/gravel road and 10% on little more than a bumpy field so that's why I used the factors I did, also why I mentioned that if someone does more off-road the factors would change. Mainly just wanted to describe how I figured out what shocks would work for my lifted truck/use ;)

I'm a little different than most. I buy the shocks, cycle the thing and build shock mounts, bump pads and limiting straps depending on what I get from cycling. More work than most are willing to do, and it's mainly for a hard core off road truck, but hey - it's what I do.

I like bilstein for general replacement type shocks.

Well the second shock quickly followed suit today. Must have been all it could take to have to dampen the back end by itself. And geez with no shocks back there at all you really know you have springs..... I was bouncing like a pogo stick on ever little ripple in the road haha. It's actually sort of fun, but within just one day of driving, I noticed a big difference in maintaining traction on corners with ANY bumps. The wheel would just bounce into the air over and over.

Guess I'm making 2 perches.....

I'd be interested in what Bilstein PNs you have used to start with and at what lift height.

Double holy smoke Kimosabe!!! Not just hardcore... that's NUCLEAR RUST. Now you get what I meant by "Boing!" in my previous post.

Suggestion: Why not fab up a crossmember with integral shock mounts. It might be simpler... some mounting plates, a gusset there, a gusset there,.. just thinking.

Steel Toy: thanks for sharing that tech section. I see your points too.. depends on the application/use/typical conditions.

Hmmm, a crossmember, that's kind of a cool idea, and with a bunch of different holes drilled, I could fine tune my mounting heights, even raise them if I knew I was gunna be CRUSHING my truck that day. Kind of a cool touch too, which I always like to add when I replace something.

I'll post up if I end up going that route, cool idea!

AleX

Don't have any sorry. It's been a long while since I've really done anything stock - or even a "4" lift" type deal. I used to go to the parts counter with my overall length needed on them and look up/cross reference what I could make work in the parts book. I'd use F-150 or bronco rear shocks on the front of my ranger, etc.

Closest I am doing now is I just pulled a pair of bilsteins off the '87 bronco I am parting and am going to throw them on the rear of my toyota, but that's about as close as I get to anything stock-ish

For all my other trucks I am making custom mounts and using rebuildable shocks. For those the shocks are sold by stroke length typically and the mounts are built around the shocks - not vice-versa.
Here's the type of shocks I typically use. I had to cycle the suspension multiple times in making the upper and lower shock mounts for these things on the crew... Yes this is the front, but I will be using similar stuff on the back - just haven't gotten there yet. I will be using Fox 2.0 shocks with a 10, 12 or 14" stroke (most likely 10's but I need to see how/where I can build the mounts before I decide).
http://i453.photobucket.com/albums/q...wap/1048-2.jpg