Limit Strap vs Internal Shock Spacer

standfast

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I am working on a car right now that the builder is putting internal shock spacers to limit the shock travel for the CV's instead of putting a limit strap on. To me this is going to pound the c-clips badly on the shocks and doesn't seem right. I am telling the owner that we need to put straps on the car and get away from this spacer. What do you think? Does anyone else use a spacer like this? Doesn't seem like a good idea to me.
 

partybarge_pilot

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Depends on how much unsprung weight, spring pre-load and rebound valving. More of the first 2 will really start to hammer the seal head.
 
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Limit straps cushion the topping out of the suspension member.
 

Random Thoughts Racing

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Some manufacturers use an internal spacer but it is meant to keep the piston from crossing the reservoir port but not necessarily to be a droop limiter. If you notice, bypass rebound tubes stop short of full droop (100% rebound valving) to help slow down this last bit of travel. As partybarge says the available rebound valving vs. spring rate and unsprung weight is a factor here. What kind of vehicle are you talking about?

light buggy, maybe
class 1, no way
 

standfast

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It's a light buggy but BIG long heavy trailing arms.

Well this car has massive spring preload right now. (gonna change that) Probably 180+ lbs of unsprung weight per rear corner. The C/O's have no valving in them, There is 2-tube bypass's but not sure on the rebound valving since they are unmarked and I haven't pulled them apart.

So it is not common practice to limit droop travel with a spacer like this? I gather you are doing something that is not recommended by the shock manuf. most likely?
 

partybarge_pilot

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IMHO, Hard spacers should be there to keep the axles from getting ripped apart if your limit strap breaks. Limit straps are much easier on things than hard stops.

I would also put some valving into the C/O.
 

cosmo

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IMHO, Hard spacers should be there to keep the axles from getting ripped apart if your limit strap breaks. Limit straps are much easier on things than hard stops.

I would also put some valving into the C/O.
I'd second that too. Remember that most limit straps will stretch at least a 1/2".
 

Samco Fab

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Limit straps are always a good idea, but keep in mind all production vehicles including say a Ford Raptor, or in our case say a Hummer H2 or H3 running a Fox shock use the shock as a droop limiter, and have massive unsprung weight with no problems. And yes they get punished off road.

I think one problem as PB mentioned would be if the rebound valving was very light, and the suspension slammed into the snap ring on droop, or if like you mentioned you have massive preload on the springs to get the ride height. Fox puts internal rubber droop stoppers to cushion the extension on some of the 2.0's that I have seen. Also on many bypass shocks, the tubes on droop end about 1/2" to 1" from the bottom to force all the oil through the piston for the last bit of droop to help keep the slamming to a minimum.

I would like to see examples of failures of shocks with no limit straps, what does it actually take to damage a shock. I bet rockcrawler guys with huge one ton axles massive tires that run rock races would punish coilovers, but do they have problems? I personally have not heard of anybody having problems in even the rockcrawler world.

I am considering not running straps on a sand truck project that we are building, but I would always run them on a race vehicle.
 

Scott_F

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Yeah, I'd like to see some shock damage also. Does anyone have any first hand experience with shocks pulling apart on extension?
 

partybarge_pilot

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I have had them pull apart on the rear of a leafspring truck, but no pics. The front usually has the ball joints to help stop the droop........
 

standfast

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I can see how rebound valving and C/O preload could largely effect the load. I am just throwin on some straps on this car and not putting in internal spacers.
 

Shred918

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That would be my suggestion.
 

partybarge_pilot

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I would leave the factory spacers in to keep the length right. If you get the piston to close to the seal head on droop, the shaft will want to wobble wearing the bushing prematurely.
 

Random Thoughts Racing

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Some other factors to consider...

-If the valve stack base washer and the seal head are both flat, and come into contact with each other on rebound there will be some stiction when the parts try to separate again on compression (stiction could be mitigated with relief groves in the seal head).

-Repeated hard contact contact between the valve stack base washer and the seal head can cause the valve stack to lose its preload. This can happen from the valve shims augering into the washers or piston, thread stretch on the tenon or nut etc.

-Rod ends are designed with their strength in compression. Would every brands rod end design and material have equal strength if subjected to repeated pulling?

-Heim life. If the shock is used as a droop limit the heims are subjected to greater wear on rebound than they would be with a limit strap setup. Hammering on the heim in both compression and rebound will cause the heim to wear out more quickly. Once a heim begins to wear the rate of wear becomes exponential.
 

atomicjoe23

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Some other factors to consider...

-If the valve stack base washer and the seal head are both flat, and come into contact with each other on rebound there will be some stiction when the parts try to separate again on compression (stiction could be mitigated with relief groves in the seal head).

-Repeated hard contact contact between the valve stack base washer and the seal head can cause the valve stack to lose its preload. This can happen from the valve shims augering into the washers or piston, thread stretch on the tenon or nut etc.

-Rod ends are designed with their strength in compression. Would every brands rod end design and material have equal strength if subjected to repeated pulling?

-Heim life. If the shock is used as a droop limit the heims are subjected to greater wear on rebound than they would be with a limit strap setup. Hammering on the heim in both compression and rebound will cause the heim to wear out more quickly. Once a heim begins to wear the rate of wear becomes exponential.
I'm with RTR on this one. . .limit straps are cheap insurance to minimize the wear and tear and punishment on your expensive parts. . .even rod ends/heim joints are pretty pricy when you start adding them up. . .and installing straps is neither diffiicult nor does it add that much weight to a vehicle when looked at in proper perspective.
 

motochris

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I would like to see examples of failures of shocks with no limit straps, what does it actually take to damage a shock. I bet rockcrawler guys with huge one ton axles massive tires that run rock races would punish coilovers, but do they have problems? I personally have not heard of anybody having problems in even the rockcrawler world.

.
I've seen plenty of shocks from numerous companies literally come apart from the heavy unsprung weight of rockcrawlers and mud trucks. They either rip the sealhead out of the shock, or strip the bolt off the piston end of the shock.
Limit straps are just cheap insurance.
 

Giant Geoff

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I don’t have any limit straps on the front of my truck. It can be done with the right combination. Big shocks and light parts, I have not had any problems in 7 years of hard running and tons of races.

With the right amount of experience you can get away with less.
 

atomicjoe23

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With the right amount of experience you can get away with less.
. . .getting the "right amount of experience" you usually requires some breakage along the way. . .

I would use the limit straps as cheap insurance for that very reason. . .I don't have that experience and don't have the money to learn through unnecessary breakage. . .
 

atomicjoe23

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That's pretty much attitude as well. . .not to say you shouldn't do your homework and figure out how to set your shocks and suspension up correctly, but it is definitely cheap insurance for some VERY expensive hardware!!!
 
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