Measuring for shocks? - JeepForum.com

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post #1 of 20 Old 01-09-2011, 11:14 AM Thread Starter
VaCJ79
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Measuring for shocks?

I think I need longer travel shocks. I went through and replaced all of my shackles yesterday. I had not messed with the suspension in a number of years and because of this found an issue. When I swapped out the rear shackle I jacked up one side to take the pressure off, pulled the shackle out. I needed a little more room for the new shackles. Jacked the jeep up further but never could get the spring to drop any more. ??? dumb me forgot to take the shock off. yanked the shock bottom off and everything dropped down. The thing is it took almost nothing to jack the wheel off the ground with the shock on and a lot more with off. I think the shock has been holding the spring from fully dropping when one side is compressed. When I pulled the front shocks off they extended 2" or 3" below the the mount. I have no lift in the springs and the new shackles came with a 1/2" lift. The rear springs are heavy duty springs for when I had a hard top but I only have a soft top now.

I measured 20" from bolt to bolt where the shock should mount while the jeep was sitting on the ground normally.

I need new shocks for the rear, old ones are trashed, but how much travel should I get? Should I replace the front too?
the rear springs seem fine but should I swap them out as well?

I am just trying to figure out what to do. Thanks


1979 CJ7 258 / 4.0 head / J20 power Steering / T150 Dana 20 / EMU YJ 2" lift / Custom front bumper

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post #2 of 20 Old 01-09-2011, 11:30 AM
foggybottombob
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Just be sure that your bump stops hit before your shock compresses completely or you will be breaking off shock mounts. A longer shock has more travel but it is longer at full compression too.
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post #3 of 20 Old 01-09-2011, 02:35 PM
mikeonbike1962
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sounds like your springs are then virtually stock height (no real lift) and you went up... say .5" with the 1" over shackle. simple: 76 - 86 cj shocks! std height. I don't think that .5 " is going to create any real issue.

my opinion.

non gas and gas filled shocks:
pro comp 1000 shocks will feel like a stabilizer out of the box (not gas charged) you can compress them or lengthen them with your hands and they stay. The rest of their lineup should be charged and be fully extended out of the box.

the parts store monroe will also be fully extended as well.

mike

1978 cj5... it's next life
4" lift w/custom 3/8" shackled/shimmed, pro comp shocks, xfer case drop, rancho stabilizer, drop pitman, warn hubs, 2" spacers.
everything else either new or refurbished... by me.
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post #4 of 20 Old 01-09-2011, 04:44 PM Thread Starter
VaCJ79
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Thanks guys, I guess I should just try a new stock shock unless someone else has any suggestions? Since the rear springs are stiff, I might just get some parts store shocks since I dont need any heavy duty offroad shocks and I'm on a budget.

1979 CJ7 258 / 4.0 head / J20 power Steering / T150 Dana 20 / EMU YJ 2" lift / Custom front bumper

Looking for : Please PM, Carter 2 barrel Carb before you through it out
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post #5 of 20 Old 01-09-2011, 05:21 PM
foggybottombob
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Measure the distance from your bump stop to whatever it hits. Then measure your current shock as it is on your axle. Subtract the first distance and you have the longest shock you can use when fully compressed. Buy one that length or a little shorter. If your shock is mounted at an angle from vertical you can buy one that compresses to that length.
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post #6 of 20 Old 01-09-2011, 05:21 PM
gojeepin
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While you can limit downward travel with limiting straps, I prefer letting the springs limit downward travel, not the shock or limiting straps. So yes, you need longer shocks.

You can control upward movement with bumpstops.

Vibration? Bump steer? Wandering? Read the article (sticky) on Steering, suspension, and driveline.
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post #7 of 20 Old 01-10-2011, 11:53 AM Thread Starter
VaCJ79
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I measure real quick this morning

Shock mounting bolt to bolt L 19 1/2" R 20"

Bump stop to axle L 5 3/4" R 6 1/4"

So I have a 1/2 lean to the left side, which I guess isnt too bad. I looks worse than that.

So I can have a 13 3/4" shock? So should I get one a little longer and drop the bump stops?

1979 CJ7 258 / 4.0 head / J20 power Steering / T150 Dana 20 / EMU YJ 2" lift / Custom front bumper

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post #8 of 20 Old 01-10-2011, 01:33 PM
gojeepin
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What I did was remove a shock and take three measurements.
1) length from shock mount to mount with spring at rest
2) length from shock mount to mount with spring compressed
3) length from shock mount to mount with spring drooped (extended)

Then I went to Advance Auto told the kid behind the counter to get out the catalog (not the stupid computer) and gave him my compressed length and extended length.

We looked for any shocks that had those measurements with the correct ends (for CJs). NOTE: Shocks have 3 or 4 different ends in any combination.

Vibration? Bump steer? Wandering? Read the article (sticky) on Steering, suspension, and driveline.
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post #9 of 20 Old 01-10-2011, 01:46 PM
foggybottombob
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Quote:
Originally Posted by VaCJ79 View Post
I measure real quick this morning

Shock mounting bolt to bolt L 19 1/2" R 20"

Bump stop to axle L 5 3/4" R 6 1/4"

So I have a 1/2 lean to the left side, which I guess isnt too bad. I looks worse than that.

So I can have a 13 3/4" shock? So should I get one a little longer and drop the bump stops?
If you get a longer shock and drop the bump stops you will get more axle droop capability but your up travel will be limited and you will bottom out more when the spring compresses. I personally hate getting pounded when my bumpstops hit so I would try to keep at least 5" of up travel.
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post #10 of 20 Old 01-10-2011, 10:26 PM
coloradocj7
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If you are looking for a good deal 4 wheel parts has a set of 4 pro comp shocks for $109.99 right now.

Here is the link: http://www.4wheelparts.com/Lift-Kits...ShockingES1000
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post #11 of 20 Old 01-10-2011, 10:36 PM Thread Starter
VaCJ79
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[quote=What I did was remove a shock and take three measurements.
1) length from shock mount to mount with spring at rest
2) length from shock mount to mount with spring compressed
3) length from shock mount to mount with spring drooped (extended)[/QUOTE]

I'll try later this week to get these measurements


Quote:
Originally Posted by coloradocj7 View Post
If you are looking for a good deal 4 wheel parts has a set of 4 pro comp shocks for $109.99 right now.

Here is the link: http://www.4wheelparts.com/Lift-Kits...ShockingES1000
Thanks, Hope they end up working for my application

1979 CJ7 258 / 4.0 head / J20 power Steering / T150 Dana 20 / EMU YJ 2" lift / Custom front bumper

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post #12 of 20 Old 01-15-2011, 02:00 PM Thread Starter
VaCJ79
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I wasn't able to get the suspension to fully compress but here is what I am thinking. If the suspension at rest has 20" bolt to bolt for mounting the shocks. There is 5 1/2" between the axle and the bump stop. So in theory I should need shocks that compress to 14.5 inches and expand to 25.5", right? Does this logic seem like it would work?

Found this as well... http://www.monroe.com/catalog/documents/08_MountingLengthSheet.pdf


these seem to be as close as I can find ... http://www.napaonline.com/Search/Det...029_0117631936

1979 CJ7 258 / 4.0 head / J20 power Steering / T150 Dana 20 / EMU YJ 2" lift / Custom front bumper

Looking for : Please PM, Carter 2 barrel Carb before you through it out
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post #13 of 20 Old 11-16-2011, 02:39 PM
Renegade82
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Quote:
Originally Posted by gojeepin View Post
What I did was remove a shock and take three measurements.
1) length from shock mount to mount with spring at rest
2) length from shock mount to mount with spring compressed
3) length from shock mount to mount with spring drooped (extended)
Now how did you go about extending and compressing the springs? I'm thinking of using a highlift jack and squeezing together or jacking apart the frame and the spring, and using the angle of the shackle to determine my limits. This should give me my maximum range of travel(bolt to bolt), and help me to locate my bumpstop. The drawback is that I would be doing this with no tub on it so i couldn't tell how close the relationship between the tire and fender flares is.

Theoretically I'll have a 2 1/2" spring lift and 1 1/2" of shackle lift, giving me 4" over stock.... at rest. But some springs flex more than others and longer shackles add to that range of motion. So using the manufacturers chart based on height over stock may not be quite accurate. I don't want to order shocks and then have to return them if they are too short, so I guess that means not to order ahead of time.

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post #14 of 20 Old 11-16-2011, 05:04 PM
Area.3.Fiftyone
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A friend with a fork lift is the best way to extend/compress your springs. You need the body on the Jeep.

Get the forks under a tire and lift the Jeep until you are satisfied with how the wheel looks stuffed into the wheel well before hitting anything.

Measure for your bump stops. It will vary depending on where you mount them and what you want them to stop against.

Measure the compressed side and extended side and you will have both numbers you need. It would be best to allow about 1-2" shorter on the compressed side so that you are sure that will not bottom out your shocks.

Repeat for the other axle.

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post #15 of 20 Old 11-16-2011, 05:38 PM
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We are way overthinking this.
Setting on the tires, measure the distance between the eyes bolts on the shock.
Measure the distance between the bump and where it strikes the axle.
Subtract the two, then subtract one inch more (shorter).
This will give you your eye to eye collapsed length.

Jack up the vehicle and set the frame on jack stands. Measure the distance between the eye bolts. This is your extended length. Add whatever additional length you think the springs will flex. Add an inch beyond that. If you think the suspension will be stopped by the shocks length when full flex, but don't(or can't) go any longer, then install limiting straps.
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