Bilstein 5100 vs 5125 Different valving question

Txs to @memario1214 I was able to get the following info:

At rest (extended) length, the 5100 is 22.94" whereas the 5125 is 24.41".

5125 is just longer, and has slightly different valving.

Can someone explain what the different valving means to you?
Does it have to do with more weight in the rear??
Does it physically lift the rear???

Which one would you buy?

Thoughts?

 

Does not physically lift rear. No rear shocks do. 5125's are for if rear in lifted over 2" Valving is a question for Bilstein to answer.

 

You will have the same travel with either shock unless you move your shock mounts as well. If you are lifted in the rear (blocks, AAL, new leaf pack), you can get more droop with the 5125's but will need to extend your bump stops 2" or you will use the shock as the bump stop and be buying new ones very soon. You will also need longer break lines. If you are not lifted in the back, stick with 5100's.

The valving has to do with how much fluid can transfer from one side of the piston to the other. Most shocks have a compression rate and a rebound rate...typically different. If you are heavier, you want a stiffer valve so the truck doesn't bounce, if you are lighter, you want a looser valve so the truck doesn't ride hard and absorbs the bumps. When talking cheaper shocks like the 5100 series, they are "all in one" shocks so they will be very close to each other in the valving.

 

It all depends on how your rear is configured. You need a minimum length long enough for when your springs are fully compressed, articulated and on the bump stop otherwise you will destory the shocks.

Stock height you want the regular 5100s. Add a 1in block or replace the springs with a thick enough one and you want the 5125s. 5125s are available in multiple lengths but the ones usually used on 3rd gens are 15.01 compressed and 24.38 extended.

If you add even more lift in the rear there are longer 5100s available but if using a different spring you will likely need longer bump stops to protect them.

As far as valving I am not sure how they compare. I am running 5125s with a 1in block and they are working great and are an improvement over the oem off-road shocks.

 

Lift blocks and thicker springs move your lower shock mount down by the extra thickness allowing you to run longer shocks.

$112 33-230337 Monotube Shock Absorber, 46mm

33-230337 5125s need atleast 3/4" of extra length. No need to extend bump stops if you have that.

No need for longer brake lines with these shocks but you do need a bracket to reposition the e-brake cable.

 

You are correct on the blocks since the spring is still in the same location but AAL or different leaf packs can very well blow out a shock. Best to find the mechanical shortest limit of the shock and then verify the bump stop is at least an inch before that stop.

At full droop, I was pulling really hard on my brake lines with 24.5" rear extension.

 

At 24.38 I believe the 5125s are basically the same length as the TRD lift kit rear shocks so Toyota seems to think it is fine. When I fully drooped my rear with them I didn't see any issues. Anything longer would definitely need it though. The e-brake bracket definitely needed to be relocated to keep from pulling on it.

 

I cant speak to the valving of 5125s but I can to fitting for mechanical specs. The 3rd Gen Offroad stock bump is 2.5" of hard rubber up from the frame.

The compressed shock length is your biggest concern so the bump can halt compression before zero on the shock.
I went in the garage just now to measure my bump top from frame for my 15.2" compressed length Fox 2.0 shocks, and mine are 3.5" hard rubber, no soft top. This is on 1" lifted leaf springs, 23" rear hub center to fender edge (amount of lift after a year of settle, 100 lbs cargo in bed and spare underneath).

The gap between the max compressed bump and zero shock compression is your longevity concern. My gap is 3.5"- 3 5/8".

My amount of exposed shaft until zero shock compression is 4 1/8" or so, not counting the inline shaft rubber.

You definitely need the 2" extended brake lines for this (24.8" extended length v. 23" extended length of stock OR and 5100s) and e-brake line lowering brackets. I would install 2" longer brake lines for 5125s as well.

 

Thanks for your posts guys.

I have been happily running a 1" block in the rear, and my biggest concern with going with 5125's, was the valve compression, and whether I would need to worry about the brake lines. Still getting mixed views on whether you need to extend them or not.

 

Unbolt your lower shock mount and slowly full droop your leafs while watching your brake lines stretch. Measure it. Can stock brake lines stretch 1.3" more?

 

I have had no problems with my 2022 OR DCLB. 1in OEM block and stock leafs even fully drooped with no shock dont over extend the brake lines. The Toyota TRD lift kit which includes 1in rear blocks and longer shocks only comes with a an e-brake spacer and not longer brake lines. I dont know the exact specs of their shocks but there are pics in the TRD lift kit thread next to 5100s and length looks right about the same as the 5125s. With the 5125s the leaf springs themselves seem to be the limiting factor at full droop anyway.

Now if you add an AAL, swap leaf springs or install hammer hangers you may need those extended brake lines.

 

Overland outfitters did their series of shock testing. Their test truck has Devear aal in the back ( 1.5" lift ). The rest is stoke. They even ran a long shicks by mistake and did not destroy anything.

 

Keep in mind this will be all static numbers with the 5125's. With one side stuffed and the other in the air and putting a heavy load on the drivetrain, the rear axle will wrap and do weird things. 2" longer brake lines are $40 of insurance that can be catastrophic on a trail if they bust.

 

No shock lifts or lowers anything. That's the job of springs. Dampers (shocks) are valved to control the spring oscillation.

Some will argue that shocks like front 5100's provide lift. What they do is provide spring perch options and preloading the spring provides the lift.

 

I recently edited an older post on 5100s explaining this by using a slightly thicker and harder top coil insulator on the drivers side and a softer coil insulator on passenger side, to preload my drivers side by a couple of mm to correct taco lean to get an even side to side front. No tophat spacer or circlip adjustment needed for it; only greater spring compression prior to load, and that is down, not up, even on a 5100.