AAL and blowing 5100's

Sad DSM isn't up here.... Seem like good dudes for sure.

 

Hey all, sorry to drag up an old thread but I've now blown my second Bilstein 5100 by RCD. I'm trying to understand why you guys are worried about the measurement when hitting the bumpstop. From what I can think, no matter whether you have an AAL or whatever you should always hit the bump stop the same? The only thing that the travel of the shock would limit is the extended length; ie you wouldn't have as much extension.

The only thing you may be thinking is affecting the shock to bottom before hitting the bump would be if the leaf pack is a different shape is my thought? Please help me understand

 

I've lifted just about every auto manufacturer's model trucks (Ford/GM/Dodge, etc & out of all of them the 1st gens are the hardest to config as for matching lift with shock travel & I think the difference in shock length is a major factor when trying to dial it in within acceptable specs.

 

But for you to be blowing the same shocks in the same manner it almost HAS to be a bottoming out issue.. From pics I saw, the seal cap where the tube comes thru is pushed in (down?) indicating severe "down stroke" limitations

sounds like they're too long or excessively loaded then hitting hard bump maybe....

 

Bilsteins have an internal bump stop for on road applications. Do the 5000 series not have any? I wouldn't imagine bottoming out would be the issue.

Hell, on mine for the cars i pull them apart and half the bump stop to gain a little more travel.

PS i only have experience with on road vehicles.

 

Damage to shocks from over compression or over extension is unlikely to happen on the street. The kind of damage being discussed in this thread is from high flex situations typically found off pavement.

If your shocks are mounted in the stock locations, there are 4 important measurements, 2 for each side. It is 4 measurements because the distance between the mounting locations is asymmetrical. The drivers side is not the same as the passenger side.

Having a shock that is too long for the application will damage the shock when the shock is the limiting factor on full compression. Having a shock that is too short for the application will damage the shock when the shock is the limiting factor on full extension.

To do it right you must know the length from top bolt to bottom bolt when each side is fully compressed and fully extended. It is a guessing game without knowing this.

This is partially correct but remember that when you lift, the stock bumps end up in the wrong place, they are too short.

I usually use a forklift to flex the suspension as much as possible to know exactly what the 4 measurements are and get correct length shocks, both compression and extension, for the situation.

 

I don't do any offroading, so I don't see my truck ever being fully extended unless I hit a bump with a load on the highway and it were to bounce up. My plan is to remove the shock(s) and with removed I will measure the shocks when I compress them (bolt hole to bolt hole which I will refer to as bh-bh). I will then measure the distance between where the leafs should hit the bump stops to the bump stops, and subtract this from the bh-bh position on the truck as it sits without the shock, this should effectively give me my required compressed length. I can't load my truck up any ways but this should be the same.

To measure the extended length, I can just extend the shock and measure bh-bh. For the truck with the shocks removed, I'll have to lift the truck from the chassis with a jack and then measure bh-bh when uncompressed. This may be tough, not sure I have enough 2x4"s laying around to get a jack that high and I may have to do one side at a time. Hoping that all I'd have to do is add spacers under the bump stops (if this is possible?). Either way this will narrow down if it is a shock length issue. I rarely hit the bump stops by the way, though I did have a big load in it this spring and hit it a few times. I wonder if this caused it, and it slowly leaked out until now I am feeling it.

 

Well I did the measurements and none of it makes sense. Here it is in metric as it was easier to measure (and I'm a Canuck eh?):

Truck with wheels off the ground bh to bh dims:
Left 563mm Right 572mm

Truck at resting state bh to bh dims:
Left 465mm Right 500mm

Truck gap distance at resting state between bump stops:
Left 135mm Right 135mm

Therefor if leafs were on bump stops bh to bh dims would be:
Left 330mm Right 365mm

Shock at fully extended bh to bh:
Left 548mm Right 572mm

Shock at fully compressed bh to bh:
Left 375mm Right 425mm

To me this means that I would never rest on the bump stops, I would have a 55mm gap on the left side and a 60mm gap on the right side if the wheels were all the way in the wells.

Seems my shocks don't compress near enough or I need taller bump stops, yet they advertise the 5100 to allow a 1.5" lift! It also seems with no lift I wouldn't hit the bump stops. Thoughts anyone?

 

I forgot to mention I inspected the leaking shock, and it did not look damage or like the seal on the rod had been pushed in, its condition was fine.

 

I just realized my mistake in the calculation, obviously the shocks don't go down in a straight line, it's at an angle. So I'd have to figure out what atleast one of the angles are in order to determine if they are too short.