Spring rate ponderings.
#1
04-30-2019, 02:08 AM
Spring rate ponderings.
Ok so my 04 3.7 2WD quad cab rides pretty rough over small bumps.
I put some Bilsteins on and i LOVE THEM because they soak up the big dip and bumps like they weren't even there,
No after bounce. the rebound control on the Bilsteins is amazing.
However, on small bumps like under a half inch the suspension does not move and it's left to the tire to soak up the hit.
Little ripples and rises are common road conditions in my area scene the roads are weathered and flood beaten which results in a high vibration ride.
And yes i know its a truck and i shouldn't expect it to ride smoothly
However that being said..
After researching it i find that the spring rate on the quad cab 3.7 2WD is the same as the 4.7 2WD, that being 880
which i expect is the reason for the somewhat harsh ride on the little bumps with the 3.7
(I mean , there is probably a 40 to 60 pound difference in the weight of the two engines)
In contrast, the standard cab 3.7 spring rate is 780.
So...I could maybe add a tad bit of weight to the front of the truck which might smooth out the small bumps and force the spring to move.
OR i could swap out the springs with the lower rated 780's
Mind you, i don't do a lot of heavy hauling and i drive like an old fart because i am one.
The rear leafs seem properly calibrated
On a side point,, i noticed the swaybar link bushings might also be over tightened as they are squashed flat. not that that would effect spring rate as much as it would uneven pavement.
Anyway.. Thoughts? Ponderings?
I put some Bilsteins on and i LOVE THEM because they soak up the big dip and bumps like they weren't even there,
No after bounce. the rebound control on the Bilsteins is amazing.
However, on small bumps like under a half inch the suspension does not move and it's left to the tire to soak up the hit.
Little ripples and rises are common road conditions in my area scene the roads are weathered and flood beaten which results in a high vibration ride.
And yes i know its a truck and i shouldn't expect it to ride smoothly
However that being said..
After researching it i find that the spring rate on the quad cab 3.7 2WD is the same as the 4.7 2WD, that being 880
which i expect is the reason for the somewhat harsh ride on the little bumps with the 3.7
(I mean , there is probably a 40 to 60 pound difference in the weight of the two engines)
In contrast, the standard cab 3.7 spring rate is 780.
So...I could maybe add a tad bit of weight to the front of the truck which might smooth out the small bumps and force the spring to move.
OR i could swap out the springs with the lower rated 780's
Mind you, i don't do a lot of heavy hauling and i drive like an old fart because i am one.
The rear leafs seem properly calibrated
On a side point,, i noticed the swaybar link bushings might also be over tightened as they are squashed flat. not that that would effect spring rate as much as it would uneven pavement.
Anyway.. Thoughts? Ponderings?
Last edited by XSubaruJeepDude; 04-30-2019 at 05:24 AM.
#3
04-30-2019, 09:27 PM
Legend
Drop the front tire pressure a couple pounds (not more than 5) if the tread wear pattern will allow.
You can add some weight to the front to put a little elasticity in the spring, but I'm not sure how much difference it will make. Spring dynamics come in to play, which made it a bit of a puzzle selecting the custom front springs for my truck. You have to reverse engineer the dynamics to establish the exact differences.
What you're really asking for is a progressive rate spring that is soft at the hit but stiffens on a curve with compression, rather than linearly. I don't think those exist in a 5.5" OD 13" long spring (I'd have to measure the ones I took out for actual length).
You can add some weight to the front to put a little elasticity in the spring, but I'm not sure how much difference it will make. Spring dynamics come in to play, which made it a bit of a puzzle selecting the custom front springs for my truck. You have to reverse engineer the dynamics to establish the exact differences.
What you're really asking for is a progressive rate spring that is soft at the hit but stiffens on a curve with compression, rather than linearly. I don't think those exist in a 5.5" OD 13" long spring (I'd have to measure the ones I took out for actual length).