Mid perch – not for lifting, but to aid with added front end mass

[boarder1995]

Delete thread - misinformation. Sorry.

 

[Geo_Tactical]

I feel as if I just went back in time about 4 years...

 

[boarder1995]

So this has been beaten to death? Sorry guys... lack of historical perspective on my part.

Ok, so perhaps we should delete this thread and ban user... or at least the first part of the suggestion.

 

[HAYNES OFFROAD]

So this has been beaten to death? Sorry guys... lack of historical perspective on my part.

Yea pretty much... Just use the advanced search for mid perch. You'll get all 4 years worth of reading up to do.

 

[FP Forged]

First, I’d like to clear up one misconception that has been bugging me…
The moving up of the spring support ring (moving down of the shock) does NOT add pre-load to the spring. This is commonly referenced as to why the ride is stiffer – because there’s more preload in the spring. This is incorrect. The spring maintains its state of loading which is caused by the mass of the truck (fixed in this argument). It’s not getting compressed anymore. It’s merely moving the shock body and lower mount down, thus moving the truck up. What’s causing the increased harshness of the front end? First, you’re now in a different point of the shock’s stroke, which with the valving we have might put us in a harsher point of travel in the shock (maybe, maybe not? I haven’t disassembled this shock). Additionally, we’ve increased the angle of the A-arms in our suspension to a less compliant, steeper angle. The optimal nominal angle for A-arms is straight out horizontal. Picture them in a near vertical down fully drooped position – that’d be a very non-compliant angle. The steeper the angle, the harsher at the ride will be if that’s the nominal geometry. With just a couple inches movement down of the A-arms by going to mid-perch, I can’t imagine this would make a huge change in feeling.

I'd like to just say "search" like everyone else but the statement above is not correct. It would be if the coilover at bottom perch had zero preload and the spring just rattled around when the suspension was at full droop. In that scenario you would just be adjusting the coilover to a taller position but in reality there is preload on the spring/shock even at bottom bottom perch, so moving that spring/strut to middle or top perch is squeezing the spring more resulting in more "preload". And that added preload is why it rides stiffer at mid perch. Also why I went with progressive springs to keep my softer ride.

 

[boarder1995]

I'd like to just say "search" like everyone else but the statement above is not correct. It would be if the coilover at bottom perch had zero preload and the spring just rattled around when the suspension was at full droop. In that scenario you would just be adjusting the coilover to a taller position but in reality there is preload on the spring/shock even at bottom bottom perch, so moving that spring/strut to middle or top perch is squeezing the spring more resulting in more "preload". And that added preload is why it rides stiffer at mid perch. Also why I went with progressive springs to keep my softer ride.

Perhaps my misunderstanding and lack of hands-on with this... like I said, delete thread, ban user. Thanks guys. Perhaps I'll edit my top post to be blank, to be deleted.

I think my explanation of "not adding pre-load" wasn't very well explained. When at full droop, the shock rod is the limiting agent in extension, thus there's still spring compression load (that's why the spring isn't loose rattling around). This spring compression load is greater when at mid-perch versus original perch, when referencing full droop. The truck sitting on the spring will cause the spring to load up with the same compression force whether in low-perch or mid-perch, thus the spring nominal loaded height (truck weight load) is the same whether at low-perch or mid-perch. That's why the truck gets "lifted" when going from low-perch to mid-perch when keeping other factors the same (truck weight). So, once the truck loads up the spring while sitting stationary to the same compression length, the spring will be in the same harshness zone whether at low or mid perch.

 

[Jimbo]

Just kidding.

 

[DezertRaptor]

 

[KaiserM715]

I don't think there is any benefit to leaving this thread open.