Shock Mount Extention (High Tech) (2 Viewers)

[akarilo]

After raising the lift a little I started playing around with the shock travel. They are the non-L's on a 3" lift. Apparently they were only 2" from full extention at static height; that blows. After taking some measurements it became obvious that the shocks only need about 4.5" of compression (even with factory bumpstops).
Didn't really want to weld in a lowered mount to the shock tower, as I will probably change things again one day.

Solution: A 2x3" piece of box steel, drilled on both ends, with a bolt welded through the bottom. The shock is in a position to "droop" approximately 5" now. Too bad the binding control arms are working against this progress; better than it was though.

 

[Ebag333]

I'm not particularly impressed with the travel of the stock OME shocks. The L's work much better IMHO, for any lift 3.5" or under.

I am concerned however that you could overcompress your shocks.

Model		Body	Min	Max	Range		Upper	Lower

N73			13.57	23.40	09.83		Stud	Stud
N74E			14.57	24.40	09.83		Stud	Eye
N73L			15.23	26.26	11.03		Stud	Stud
N74L			15.23	26.26	11.03		Stud	Eye

If the L shocks and my measurements are anything to go by, with 315's you have about 16" of room to play with at full compression. With what you've done, you've moved the range to be 3" biased toward the compressed side than what it was previously.

So if you were sitting at 16" fully compressed, you had 2.07" of compression left. Now when you fully compress, you will have 3" less, or -0.93" of compression.

I'm pretty sure you will fully bottom out the shocks unless you have dropped your bump stops down. But if you drop your bump stops down, then all you're doing is trading 2"-3" of up travel for 2"-3" of down travel.

I'm not sure what size tire you're running, but if you have 315's I think you would be pretty safe adding a 1" tall box at the end, giving you an inch more extension and losing an inch of previously unused compression. Even 1.5" would have been probably been safe (though with only .5" to spare you run a higher risk of blowing your shocks out if you bottom out hard). Adding 3" is too much in my experience, and you will over compress your shocks.

The bad part about those fancy metal guards is that you cannot see how much compression you actually do or don't have left, which is why I can only guesstimate based on the numbers OME has given.

If you want a pure bolt in option the OME L's are a great choice (for length, IMHO they are too soft of shocks). Pro comp has some great options for the rear that are a straight bolt in, but the front doesn't have as many choices (though doing what I did to convert to eye/eye isn't very hard, and opens up a metric ton of new options). There is the 925553 model which you only need an adapter to eye for the lower mount, otherwise is straight bolt in. Has approx the same travel as the standard OME's, but is spaced more appropriately for our trucks (15.22" min instead of 13.93" min).

 

[inkpot]

Howdy! Neat little bit of backyard engineering. If you lifted it 3", and you extended the shock 3", then you should be pretty close to where you started. But, they do sell extensions for the bayonet end of the shocks at most parts stores for around $10. I have used them with good results in the past. John

 

[akarilo]

I'm not particularly impressed with the travel of the stock OME shocks. The L's work much better IMHO, for any lift 3.5" or under.

I am concerned however that you could overcompress your shocks.

Model        Body    Min    Max    Range        Upper    Lower
 
N73            13.93    24.17    10.24        Stud    Stud
N74E            14.57    24.40    09.83        Stud    Eye
N73L            15.23    26.26    11.03        Stud    Stud
N74L            15.23    26.26    11.03        Stud    Eye

If the L shocks and my measurements are anything to go by, with 315's you have about 16" of room to play with at full compression. With what you've done, you've moved the range to be 3" biased toward the compressed side than what it was previously.

So if you were sitting at 16" fully compressed, you had 2.07" of compression left. Now when you fully compress, you will have 3" less, or -0.93" of compression.

I'm pretty sure you will fully bottom out the shocks unless you have dropped your bump stops down. But if you drop your bump stops down, then all you're doing is trading 2"-3" of up travel for 2"-3" of down travel.

I'm not sure what size tire you're running, but if you have 315's I think you would be pretty safe adding a 1" tall box at the end, giving you an inch more extension and losing an inch of previously unused compression. Even 1.5" would have been probably been safe (though with only .5" to spare you run a higher risk of blowing your shocks out if you bottom out hard). Adding 3" is too much in my experience, and you will over compress your shocks.

The bad part about those fancy metal guards is that you cannot see how much compression you actually do or don't have left, which is why I can only guesstimate based on the numbers OME has given.

If you want a pure bolt in option the OME L's are a great choice (for length, IMHO they are too soft of shocks). Pro comp has some great options for the rear that are a straight bolt in, but the front doesn't have as many choices (though doing what I did to convert to eye/eye isn't very hard, and opens up a metric ton of new options). There is the 925553 model which you only need an adapter to eye for the lower mount, otherwise is straight bolt in. Has approx the same travel as the standard OME's, but is spaced more appropriately for our trucks (15.22" min instead of 13.93" min).

The OME specs don't add up, as I had similar concerns when planning this mod. When you put a tape measure to it it is a different story. You can see some of the marks on the housing that I made when doing measurements. The truck would have to compess the factory bump stops a good inch or better to bottom the shock out. By bumps are in effect, lowered, as they are mounted below the spacers. I do not have a full 3" of spring lift.

From my experience, a shock can touch bottom without damage, as I am not catching air or anything.

 

[Ebag333]

If you lifted it 3", and you extended the shock 3", then you should be pretty close to where you started.

Seems it should work that way, doesn't it?

The fact is that lifting your truck doesn't change the travel of your shocks, but it does change where your vehicle sits in that range of motion.

Lets say that a stock lifted truck with OME shocks looks like this:

|-----:-------|

Where | is the min/max of the shock travel, and : is where the truck sits.

If you add in a 3" lift, it would change it to look something like this:

|---------:---|


You have the exactly same total travel, but what you did is exchange down travel for up travel. Same total range of motion, just more biased towards one end or the other.

By adding the spacer what akarilo did was something like this...

|-----:-----[]|

So you are trading some of that up travel back for down travel. The problem is....you can only have so much compression before you bottom out your shocks.

The OME specs don't add up, as I had similar concerns when planning this mod. When you put a tape measure to it it is a different story.

Something I'd meant to do, but never actually did, was measure the OME shocks for min/max.

The numbers I got (and I rounded off to the nearest half inch, so they're relatively accurate) are:

Model		Body	Min	Max	Range		Upper	Lower

N73			13.50	23.50	10.00		Stud	Stud
N74E			14.50	24.50	10.00		Stud	Eye

Compared to the original specs:

Model		Body	Min	Max	Range		Upper	Lower

N73			13.93	24.17	10.24		Stud	Stud
N74E			14.57	24.40	09.83		Stud	Eye

I suspect that the way OME measured the front shocks is a little weird due to the difference between stud and eye. For one, the L's have the same specs front and rear, when the rears should be about 1" different because of the difference between eye and stud.

Regardless, you have a little bit more room on compression for the front than the original specs I posted, but less than half an inch more.

The math still doesn't add up. If you were sitting at 16" when fully compressed, your mod basically turns that 16" into 13". You're still half an inch of too much compression.

By bumps are in effect, lowered, as they are mounted below the spacers. I do not have a full 3" of spring lift.

I would still measure your front fully compressed and make sure that you are not over compressing the shock. Even with the spacers, you are going to be awfully close to maxing out your shocks.

From my experience, a shock can touch bottom without damage, as I am not catching air or anything.

From my research, not true.

Over compressing or over extending shocks is bad on them, and can blow them out. Many shocks (such as the Pro comp's, and I suspect the OME's) have internal bump stops on the end so that if you extend them all the way it will not damage the shock. AFAIK they cannot or do not provide the same bump stop when fully compressing.

Bottoming out the shocks is more likely to cause damage than over extending them.

If you fully extend them, the only weight that you have is the axle/wheels/tires, and only half the weight at most (as the weight will be split between the two shocks). Additionally, over extending is more likely to happen at low speeds than high unless you're jumping the truck.


According to my '97 FSM, the front curb weight (measured at the front axle) is just under 2600 lbs. Bottoming out means that you will have up to that 2600 lbs (less the weight of the rear axle/tires/wheels, and split between the two front shocks, though depending on the situation it may not be a 50/50 split) coming down.

force = mass x acceleration

Considering the weight difference between the axle alone (maybe a couple hundred lbs) and that (up to) 2600 lbs, which do you think is going to have more force, especially given that the second scenario is far more likely to have a higher acceleration?

Adding spacers to your shocks is not a bad idea, in fact I specifically mention it in the Pro Comp thread (or at least I did before Woody wiped it out...hmm, should check and see if it's still in there). But you need to be absolutely sure that you are not going to over compress your shocks in the process.

TBH I really don't think you are going to, given how bound up the front end is and considering that you did space down your bump stops some. But I think that you are a lot closer that you realize, so I would suggest going out and measuring it just to be on the safe side.

 

[akarilo]

Theoretically we could debate the ever living hell out of this, but no need. I measured the actual shocks, on the actual truck they are mounted on, and the setup will work fine. The 80 is about the "least" modded wheeler I've ever built and all the others worked really well.

 

[Tools R Us]

Measure the rears, if you have shock travel, spacers are easy to do and will gain droop/flex.

IH8MUD.com - View Single Post - What shocks for more travel

 

[akarilo]

Measure the rears, if you have shock travel, spacers are easy to do and will gain droop/flex.

IH8MUD.com - View Single Post - What shocks for more travel

I've run across that thread before; very cool.