Shocks too long?

[PhullD]

I recently put in an AAL and got about 1.5 inches of lift and then had a PRG shackle set to 1.5 inches. So my total lift is approximately 3", maybe a tad more. I ordered 3-4 inch shocks.

In order to put them on, I had to compress the shock quite a bit even after I dropped the axle. Something did not feel right in my gut, but I never installed rear shocks before so I didn't know better.

The new shocks seem to be bottoming out, bumps return a bang where my stock ones did not.
Is there a way to measure this on the truck? I read you can see the remaining shock length (ie the shaft remaining sticking out of the shock body at rest) and it should be greater than the lift amount so that the bumpstops hit the axle before the shocks bottom. Is this correct?

[Morpheus]

Sounds like they're too short.

Take the bottom shock bolts, and lift the back of the truck until the tires lift off the ground.

Measure from the top mount on the truck, to the bottom mount on the axle.

This is your completely extended length.
Next, orient the truck on something to stuff one of the back tires.

Ie:


Measure again. This is your fully compressed length.

IF your shocks don't fit these measurements, they will act as the bump stop during compression, and as a limiting strap during extension.

Shocks aren't meant to do this. They will eventually break.

I broke 2 rear rancho 9000's before I realized they were bottoming out, and had to extend my bump stops.

[Snafu]

I might have the opposite. 3" suspension but with shocks for 2-3" and they seem to reach the end. I was going to measure their length at rest while the truck is level. Then contact the manufacturer with the model number and resting length to see if it is right or if they recommend a different shock.

I figure at rest the shock should be sitting at its ideal length.

BTW I measured it but I am not sure if I remembered the right length...I recall 18.5" but I could be off...time to remeasure.

[PhullD]

I don't have time or the tools to do as you mentioned right now. Maybe this weekend if I can drag Adam out to his parent's place to help me.





Measurements are to within 1/8th of an inch (it was windy and -12 C out). FYI, that is not shock oil, just oil spray for rust. This is at rest. Even still, from the eyelet to the point where the shock body begins is only 1 inch more than the distance from the axle to the bumpstops, and that may be including parts of the shafts that are not functional. Also, my length from the ground to the fender is 38.5 inch, so about exactly 3 inches higher than stock.

[PhullD]

Also note no contact marks on the bumpstop!!

[PhullD]

Sounds like they're too short.

To be clear, the shocks are not over extending (ie. like when you go into a deep rut), the shocks are bottoming out on compression (ie. like when you go over a speed bump). There is not enough shaft length to buffer the compression and the length is also shorter than that from the axle to the bump stop, resulting in a bang at the shock. If the shock was smaller, it would have to extend a bit more to bolt up, thereby increasing the shaft length able to buffer the compression.

[6spdnisse]

I'm not sure I'm fully understanding how this is happening..if your fully compressed shock 4 1/4" less resting hight which you measured and your bumps would technically make contact at 3 1/4" how are you determining your shock is bottoming out ?

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[PhullD]

The 4 1/4 is from the eyelet at static ride height, in reality there is maybe 2 inches there left to compress into the shock body when I hit a bump which isn't enough to dampen either and it bottoms out before the bumpstop gets hit by the axle. It looks a bit counter-intuitive until you realize that. Basically at static ride height you want enough of the shock shaft extended out of the body so that the axle bumpstop hits first in a worst case scenario (big bump) and that would be like 6-6 1/2 inches for this setup.

[Drizit]

Also keep in mind that the bump stop has a bit if squish. For polly bumps you ideally want them about 3/4" longer than the available chrome shaft on the shock.

On a side note, have you considered cutting the boot off? In Ontario they serve to hold contaminants and water against the shaft causing more damage than they stop.

[Morpheus]

Maybe I didn't understand exactly what you we're saying

When do you get the noise?

When you're cresting a speed bump - rear suspension unloading or
As you're hitting the speed bump - rear suspension loading?

There is no reason for you to hit the bump stop under normal driving

[PhullD]

Also keep in mind that the bump stop has a bit if squish. For polly bumps you ideally want them about 3/4" longer than the available chrome shaft on the shock.

On a side note, have you considered cutting the boot off? In Ontario they serve to hold contaminants and water against the shaft causing more damage than they stop.

I did not cut the boot off because I will most likely be returning the shocks. I have the stock bump stop attached to a 2 inch extension (basically a block of steel). They don't have a lot of squish so you would definitely know in an "oh poop" scenario that you made contact haha!

Maybe I didn't understand exactly what you we're saying

When do you get the noise?

When you're cresting a speed bump - rear suspension unloading or
As you're hitting the speed bump - rear suspension loading?

There is no reason for you to hit the bump stop under normal driving

I get the bang as I hit the bumps (shocks compressing). You are right, I should not be hitting my bumpstops under normal driving, which is why the bang must be from the shocks.

[Morpheus]

Also double check your swaybar end links.
I've seen them make a bang/rattle noise, even if there isn't any visual play in the ball/socket

If it's coming from the shocks, and they are indeed bottoming out, you will very quickly destroy the valving inside the shock.

[PhullD]

Also double check your swaybar end links.
I've seen them make a bang/rattle noise, even if there isn't any visual play in the ball/socket

If it's coming from the shocks, and they are indeed bottoming out, you will very quickly destroy the valving inside the shock.

I took my sway bar off last year.

Putting in the stockers today until I get word back from Nisstec. At least the stockers still rode nice even though I can't flex them enough to make use of my lift.

[Snafu]

Not sure if the stockers with the lift would be a good idea. They will likely max out too early (if you can stretch them long enough to get them on).

[PhullD]

Not sure if the stockers with the lift would be a good idea. They will likely max out too early (if you can stretch them long enough to get them on).

Agreed, but for now I am not going offroad or flexing so it's ok.

So today we took some measurements.

Stock 4600 Bilsteins are:
Collapsed Length: 13.34 in
Extended Length: 20.59 in
5100's are:
Collapsed Length: 15.1 in
Extended Length: 24.35 in

What we measured:
Extension length: 22 3/4 in, at full droop with shocks off, wheels off the ground, and axle jacked
Collapsed length: 17 1/2 in, one side flexed out with wheel stuffed and bump stop resting on axle (keep in mind I have the 2 inch bump stop extensions)

Ideally you would have 2 inch less collapsed length on the shocks to allow the bump stop to work and as for extension probably 1-2 inches left over to prevent over extending the shock. On paper the 5100's should be perfect, HOWEVER, I measured the collapsed length a bunch of times and it was ~17 3/8th give or take 1/8th of an inch (keep in mind we flexed it and the bump stop hit at 17 1/2 so the shock was bottoming out), so there is something going on there.

EDIT: After scratching our heads I decided to crunch the shocks way harder out of frustration and managed to get them down to 15 1/4". So the shocks are good then... The only other thing it could be is the combination of the stiffer shock and the Hellwig Helper Springs I have on. I didn't think the bang was just the super stiff leaf pack. I think going up on my shackle to 2" and removing the Hellwigs should solve the problem. I will report back once it is done.

[PhullD]

So it seems the Hellwig Helper Springs were too tight. They were tightened while the wheels were off the ground and was the reason they were over-torqued. We took them off, put the shackle up to 2" and put the 5100's back in and the banging noise is now gone.

[Snafu]

LOL...such a simple thing. Did you reuse the u-bolts?

Out of curiosity which u-bolts did you use and what torque did you use? I have after market that are beefier than stock but they did not come with torque specs.

[PhullD]

The Hellwig 550 helper springs come with hardware. It was all tossed after we took it off. The u bolts were bent and the threads ruined and the underplate was also bent. I kind of want to give them another chance, just having a problem locating a place to just buy the hardware.

[Snafu]

Thx