I have been looking at different shocks from various brands and I am confused with the Bilstein's. They claim the 4600 is factory replacement and the 5100 is for small lifts however, if you look up the specs on them they are identical lengths (compressed/extended).

So what's the difference for the money?

I know the 5100 front struts have height adjustment which if nothing else, warrants some price difference. But why pay the premium in the rear?

 

Following as i need new shocks as well.

 

I looked at that for a long time. I like the way the 5100's look better than the 4600's, but I don't care about lifting the front. I bought the 4600's. I have them on the back. I think it rides better, but that's purely subjective. I haven't installed the fronts yet.

 

On my past Ford trucks [2000 and 2002 superduty diesels, 2wd, then 4wd], one of the first things I did was replace the stock shocks [in each case, vehicle had 80-100k miles] with Bilsteins, in blue/yellow [i.e., 4600s]. Improved the ride significantly, loaded and empty.

With my new-to-me 2014 5.0L 4wd supercab, I will soon do the same. I'm not lifting the suspension, and don't perceive a significant difference between the 4600/5100 for my anticipated, on-road towing usage. If anyone believes there is a difference, for occasional towing usage, between the blue/yellow and silver, please educate me. I'm cogitating on the 5160 external reservoir, but don't see the value if I'm loading my 1648 payload rating truck with 700 or so in hitch weight. My impression is that my towing performance will be addressed with a WD hitch and, if necessary, Roadmaster [RAS] or a rear springs upgrade [unfortunately, I have the 8.8 rear end, not the beefier 9.75]. The shocks will be incidental to that, and the 4600 Bilsteins are, in my experience, a significant improvement over OEM shocks with some age/miles on them .....

 

Good point, the adjustability is the difference. I think many want 4 matching, or never look up the 4600 and just follow the hype.

 

I called and talked to Bilstein yesterday and they said the shocks are basically identical parts and construction. The difference is that each shock is valved to work in its most common travel range. So the 5100 used on a 2" lift is adjusted to perform its best at the extended lengths. The 4600 on a factory suspension is adjusted to work best in the mid length. He said that a 5100 on stock or lowered suspension would be a rougher ride than the 4600. I don't quite understand how they can both have the same parts/dimensions and similar valving but they are optimized for different "sweet spots" but that's basically what they said.

If that makes sense to everyone.

 

Makes total sense, drill the valve hole in a different spot, it's going to act differently. I'm not a dampener engineer, but have enough sense to understand it. I'm surprised the valving is actually that similar between the two.

 

I didn’t think about the location of the hole. I am familiar with different sizes holes and shim stacks but didn’t think of that. Perhaps that is what they do. As little technical info as it is I hope the general answer helps people out.

 

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