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Old 09-03-2011, 04:56 PM
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what determins shock lenght ?

let's say you have 15''(or whatever, it dosen't matter here ) , between the top shock mount and the bottom mount, and you have a 'pile' of shocks to choose from. And maybe only 3'' or 4'' of clearance between the axle and the bump stop . How would you determin the proper shock length ? Would you push it together, then pull it out the 3or 4'' ? or center it and just measure the bolt holes ?

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Old 09-04-2011, 11:44 AM
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I'd pull the shocks off and measure the mounting points
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Old 09-04-2011, 11:44 PM
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you're probabley right.... Going at it in another direction....what would the most desireable axle clearance ? What would be the minimum to keep it from bottoming out ?
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Old 09-09-2011, 04:58 AM
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Quote:
Originally Posted by knighthawk
let's say you have 15''(or whatever, it dosen't matter here ) , between the top shock mount and the bottom mount, and you have a 'pile' of shocks to choose from. And maybe only 3'' or 4'' of clearance between the axle and the bump stop . How would you determin the proper shock length ? Would you push it together, then pull it out the 3or 4'' ? or center it and just measure the bolt holes ?
If your mounts are 15" apart you need a shock where the center of travel is roughtly 15 inches... make sense?
With 3" of bounce and rebound you need a shock that has at least 12" closed to 18 inches open of travel.
These measurements are eye to eye....
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Old 09-09-2011, 05:19 AM
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IMO, the correct measurements would be the extended and compressed lengths.

Take all weight off the vehicle and measure the distance between the mounting points for the "extended" length.

The compressed length would of course be the distance between the mounting points when the suspension was totally bottomed out. You may want to subtract 1/4" or so in order to prevent damage to the shock or mounting brackets.

Armed with these measurements, head on over to Monroe's website and download a copy of their Mounting and Length Specifications Catalog.

I don't know if any of you guys are Microsoft Access Database users or not, but I have actually written an application that I use to *quickly* come up with a part number (s) to do the job. PM me if you want a copy.

Last edited by 66GMC; 09-09-2011 at 05:24 AM.
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Old 09-09-2011, 12:12 PM
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i did the same as 66gmc when it came to shocks for my 58 truk
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Old 09-09-2011, 03:07 PM
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The distance between mounting points is not the extended length.
The distance between mounting points is the at-rest length.
You have to account for bounce (or bump, or compression), and also for rebound (or extension).
Read my previous post.
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Old 09-09-2011, 07:38 PM
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Quote:
Originally Posted by user151
The distance between mounting points is not the extended length.
The distance between mounting points is the at-rest length.
You have to account for bounce (or bump, or compression), and also for rebound (or extension).
Read my previous post.
I respectfully ask that perhaps you should re-read my post.
I specifically said that the measurements should be made at the fully extended and compressed ranges ... not in the "at rest" position.

I even suggested subtracting 1/4" from the compressed length so that the shock is protected from bottoming out. That will damage either the shock itself or the mounting bracket.

Assuming that the "at rest" length is smack-dab in the middle of the compressed / extended range of travel is foolhardy at best.
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Old 09-09-2011, 08:25 PM
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I think I'll go.....the shock 'at rest' measurement will be my....sitting hieght on the car, ..and it'll need to be able to go up 3'', (plus 1/4''), from the "at rest" and be able to go down ...........to whatever it measures out to be with the car jacked up, (plus 1/4'') Then these 2 measurements added together will give me the total working range , ........ I take this number and the 'at rest' measurement number ( from the mounting brackets ) and determin the shock ?........from a place such as Monroe?
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Old 09-10-2011, 05:45 AM
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Quote:
Originally Posted by 66GMC
IMO, the correct measurements would be the extended and compressed lengths.

Take all weight off the vehicle and measure the distance between the mounting points for the "extended" length....
.
Sorry GMC, I guess I misread your statement as saying that the distance between the mounting points would be the "extended" shock length.
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Old 09-10-2011, 12:15 PM
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Quote:
Originally Posted by knighthawk
I think I'll go.....the shock 'at rest' measurement will be my....sitting hieght on the car, ..and it'll need to be able to go up 3'', (plus 1/4''), from the "at rest" and be able to go down ...........to whatever it measures out to be with the car jacked up, (plus 1/4'') Then these 2 measurements added together will give me the total working range , ........ I take this number and the 'at rest' measurement number ( from the mounting brackets ) and determin the shock ?........from a place such as Monroe?
To clarify again.
All you need to measure is the *fully extended* measurement, and the *fully compressed* measurement. The "at rest" measurement is irrelevant.

IF, for the sake of example, your physical compressed length measurement (measured as per Monroe's specs ... i.e. eyelets center to center if you have "L1" style ends) is 12.00 inches, then you'd want a shock with a compressed spec of 11.75 inches.

This is a direct link to the catalog, which will open right up (assuming that you have Acrobat Reader installed on your PC). It will all make sense when you read it.

PS (edit).
You will also see a "Travel" spec listed there.
All that is is a calculated value ... the extended length minus the compressed length, so don't get all caught up in trying to measure "how much up, and how much down?" ... it simply doesn't matter.

Last edited by 66GMC; 09-10-2011 at 12:23 PM.
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Old 09-11-2011, 06:43 PM
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another classic example of thinking too hard!!!!! ........ thanks
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