Oem shocks and springs

[CharlieS]

You guys are way smarter than me, and I love reading what you write explaining this stuff. Granted, I don't understand most if it, but it gives me a better sense of how the magic happens.

As a driver and DIY wrench turner, for me the system works well in practice and I prefer to have the shutter valve screws opened (no more than 3 turns) or else it makes for too much hassle and cursing.

 

[bloc]

When the shutter valves are open, everything is at the same pressure (say ~400PSI). There's no net force on the ram because the fluid can flow from the upper to lower chambers. This mode lets us swap suspension parts with less donations to the swear jar.

View attachment 3275770

Just had another look at your diagrams on a larger screen. You have this one wrong.

The system pressure of 400psi is in relation to the conditions outside the cylinder. Hypothetically if the rod is a 1 square inch cross section, this means there is a 400lb force outward, at least until the rod/piston hits the end of its stroke.

And this one has been observed by many of us that did suspension work.. in a healthy KDSS system even with the shutter valves open a fair amount of force is needed to push the arm up into place and connect the link. It is not a net zero force.

 

[AnyMal]

@daneo why dont you make something for us in the AHC shock thread? Sounds like you’re enjoying it lol. I need clarity there.

 

[daneo]

I'd be happy to try to diagram things up over time for both @TeCKis300's AHC knowledge base and @bloc's KDSS knowledge base with an invite from the authors.

 

[WMDad]

I am investigating a rough ride in my 200 and I’m wondering if it related to KDSS issues. I get a lot of rough shaking side to side on the highway especially when one side of the vehicle is reacting to a bump. I had this before and after a suspension upgrade. I went from stock to a 2” dobinsons lift front and rear. I replaced LCAs and UCAs when I did this job. I loosened the KDSS valve when changing out parts and the sway bars behaved exactly as expected. When I got it back down it was dead level. Given the knowledge on this thread. Do you think I might be experiencing an issue with the KDSS system? How would I troubleshoot this?

 

[bloc]

I am investigating a rough ride in my 200 and I’m wondering if it related to KDSS issues. I get a lot of rough shaking side to side on the highway especially when one side of the vehicle is reacting to a bump. I had this before and after a suspension upgrade. I went from stock to a 2” dobinsons lift front and rear. I replaced LCAs and UCAs when I did this job. I loosened the KDSS valve when changing out parts and the sway bars behaved exactly as expected. When I got it back down it was dead level. Given the knowledge on this thread. Do you think I might be experiencing an issue with the KDSS system? How would I troubleshoot this?

You’d need to check pressure in the system and that tool is so rare most dealers don’t have it, they often move one of them around a region as needed. Someone here did build the tool, but I can’t remember their username and it would be quite the investment just to check.

That said it doesn’t sound like a KDSS issue.. working sway bars shouldn’t dampen any violent shaking, that’s the job of the shocks, and the front end geometry to avoid feedback loops like death wobble (far more common in other platforms).

 

[CharlieS]

I am investigating a rough ride in my 200 and I’m wondering if it related to KDSS issues. I get a lot of rough shaking side to side on the highway especially when one side of the vehicle is reacting to a bump. I had this before and after a suspension upgrade. I went from stock to a 2” dobinsons lift front and rear. I replaced LCAs and UCAs when I did this job. I loosened the KDSS valve when changing out parts and the sway bars behaved exactly as expected. When I got it back down it was dead level. Given the knowledge on this thread. Do you think I might be experiencing an issue with the KDSS system? How would I troubleshoot this?

Nope, that doesn't seem like it could be kdss related.

 

[TeCKis300]

I am investigating a rough ride in my 200 and I’m wondering if it related to KDSS issues. I get a lot of rough shaking side to side on the highway especially when one side of the vehicle is reacting to a bump. I had this before and after a suspension upgrade. I went from stock to a 2” dobinsons lift front and rear. I replaced LCAs and UCAs when I did this job. I loosened the KDSS valve when changing out parts and the sway bars behaved exactly as expected. When I got it back down it was dead level. Given the knowledge on this thread. Do you think I might be experiencing an issue with the KDSS system? How would I troubleshoot this?

Doesn't necessarily sound like KDSS but stranger things have happened and perhaps somewhat depends on your experience maybe with other rigs.

KDSS ultimately serves as a stiff sway bar for cornering, that auto relaxes for warp type motions between the front and rear axles. There's cases where it's not quite cornering and not quite off-road articulation, where the sway is still largely engaged. This creates more stiffness than what would be expected from a softly sprung 4x4. This manifests in situations where it hits a larger bump on one side, or uneven corrugations in fire road type running, where it can seem to have less independent compliance from each wheel as the sways transfer some forces across the axles, and into the chassis. The KDSS system has small accumulators to add some compliance for those motions but it only goes so far. Later generation KDSS systems (GX460, 4Rs) add electronic valves to fully relax the system under a certain speed, but still experience the issue above 12 MPH. There's aftermarket solutions to fully turn it off above that speed. But neither are for the LC200 as a fully mechanical system.

If that is what you're describing when you say rough shaking side to side, than it could very well be related to normal KDSS behavior. It's wholly possible there's other unforeseen mechanical issues completely unrelated, as KDSS has proven pretty robust. You can possibly isolate it by removing the KDSS endlinks temporarily to see if that makes a difference?

 

[Drogon]

Is there a reason there are two different coils offered for the front right? One is part 48131-60640. This part is less expensive and is only listed for front right. However, part 48131-60D21 is listed for both front sides and is more expensive...
Which part should i be using for my front coils?

 

[bloc]

Is there a reason there are two different coils offered for the front right? One is part 48131-60640. This part is less expensive and is only listed for front right. However, part 48131-60D21 is listed for both front sides and is more expensive...
Which part should i be using for my front coils?

-60D40 is right hand standard
-60D21 is left hand standard

-60D21 is right hand “Mexico spec”
-60C81 is left hand Mexico spec

I don’t know what constitutes Mexico spec.. but you are in a good position to compare spring lengths of that D21 to whichever other one you get in the event it’s a length difference.

 

[AnyMal]

-60D40 is right hand standard
-60D21 is left hand standard

-60D21 is right hand “Mexico spec”
-60C81 is left hand Mexico spec

I don’t know what constitutes Mexico spec.. but you are in a good position to compare spring lengths of that D21 to whichever other one you get in the event it’s a length difference.

Sorry i thought the front coils were the same? Maybe on mine? I could’ve sworn i triple checked before doing a side swap.

 

[bloc]

Sorry i thought the front coils were the same? Maybe on mine? I could’ve sworn i triple checked before doing a side swap.

That’s what is listed in the parts system for a cruiser 15+