Suspension : Stock spring replacement for softer ride

lucas287 · May 29, 2020

2 - KYB SR4544 loaded struts from RockAuto would be $300 delivered to my door. It's tempting just for my edification.

Eddie 70 · May 29, 2020

2 hours ago, lucas287 said:

2 - KYB SR4544 loaded struts from RockAuto would be $300 delivered to my door. It's tempting just for my edification.

If you decide to go this way I for one would love to know the outcome of your experiment. I have Bilstein 4600's with about 8000 miles on them if that much I would be giving up but I'd like to know about the ride. Expansion joints are rough in my truck.

lucas287 · June 3, 2020

Called Bilstein again. This time about the 6112 kit for 2015-2018 Tahoes/Yukon. The spring rate on that kit is 600#. That's quite a bit lower than the Silverado kit. Maybe too low. Also, I noticed that kit provides .25" less lift potential than the Silverado kit. Makes me think that Bilstein tuned that setup for ultimate comfort and lowered the spring rate accordingly, which inversely lowered the max lift potential.

If you put this set on a Silverado, and set it at max height, you'd probably pick up .9-1" of ride height but have a much softer spring. Would it wallow and feel like a boat? Highly doubt that when you have such a massive shock piston to dampen motion.

Edited June 3, 2020 by lucas287

Grumpy Bear · June 3, 2020

RCSB 4.3 is the point of reference for the remainder. Weight is a scaled 5,000 lbs with 50/50 bias. I use scales not the book values. The extra weight is a Line-X and cover on the back half. (Uses a 2" drop bell knuckle) Again for your reference.

King OEM on both ends. Front spring comes 750#. OEM has 4" of shock travel and a 2:1 wheel ratio or 8" of travel. King has 1/2 inch more shock travel, 9" wheel travel. Again reference.

With this spring and zero pre-load I had 1 inch shock, 2" of wheel rebound so it hit the upper stops often. I changed springs to 600#, Kings next step down on this setup. This lowered the set up with zero pre-load to 1/2" above mid stroke. I now have 4" at the wheel in rebound and 5" in compression. Reference N2 pressure is 250#. Yea, that is the factory setting. Shim pack is 12-flutter-12 and shock oil is King medium. This last part is standard King.

I took a bunch of castor out of it which helped the expansion joint jolt. Now around 2* with proper L/R bias.

Front is firm but not harsh at 35 psi tire pressure, 250# N2 pressure and Bridgestone Dueller HT. Shock uses 90% of the total travel. I use wire ties on the rods to measure this. It is not "Boaty" at all.

Out back the same valving on 150# N2 and a Deaver built spring pack 15% softer and 2" less arch. The 1.25 spacer is removed. On the hard stuff it will hit the bumper in compression. You have to land it pretty hard. I could fix this with a remote reservoir shock instead of the 'piggy back' set up and reclaim around 2" of compression travel shortening the bump stop.

I believe the front can be more car like by using 500# springs and some pre-load to restore ride height but it would give away some travel. A larger sway bar or a solid one would hold the roll in check. Modified valving perhaps for bounce control.

Had I given it more thought I might have tried removing the middle and overload spring before having Deaver build a set. See where that put the ride height then adjusted with de-arc, shim or shackle to suit the drop. If I wanted to carry heavy, bag it.

Anyway just some 'been there, done that' information you might find useful.

Thing is using a shock like King, Fox, Viking etc. you have KNOWN spring rates and a great deal of interchange flexibility.

Thank You Ben Brazda at Filthy Motorsport for the assist on the sorting this out.

lucas287 · June 3, 2020

@Grumpy Bear Thank you for that info! Good numbers, good personal experience. I find it a bit hard to believe that my CCSB 4x4 L86/8L90 combo only weighs 400# more than your truck! Guess I need to find a scale around here and figure it out the right way.

Grumpy Bear · June 3, 2020

1 minute ago, lucas287 said:

@Grumpy Bear Thank you for that info! Good numbers, good personal experience. I find it a bit hard to believe that my CCSB 4x4 L86/8L90 combo only weighs 400# more than your truck! Guess I need to find a scale around here and figure it out the right way.

I carry extra in spray in bed liner and cover remember. My spring packs / shocks out back are heavier too. Sulastic shackles are heavier. Step bar. Penny's make dollars and about now I'm 500 over as delivered. If you know anyone that does dirt cars they should have a 4 wheel scales for this sort of setup. Otherwise a grain elevator is pretty good.

lucas287 · June 3, 2020

1 minute ago, Grumpy Bear said:

I carry extra in spray in bed liner and cover remember. My spring packs / shocks out back are heavier too. Sulastic shackles are heavier. Step bar. Penny's make dollars and about now I'm 500 over as delivered. If you know anyone that does dirt cars they should have a 4 wheel scales for this sort of setup. Otherwise a grain elevator is pretty good.

And I've got a spray in bedliner and power running boards too!

Not many dirt tracks or grain elevators in my neck of the woods But lots of speed shops though that I could call around to and see.

NoLand · June 16, 2020

lucas287, what about the 2WD Suburban application, SR4545? It might be a good medium between the 2WD Tahoe and 4WD Suburban applications.

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lucas287 · June 16, 2020

47 minutes ago, NoLand said:

lucas287, what about the 2WD Suburban application, SR4545? It might be a good medium between the 2WD Tahoe and 4WD Suburban applications.

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This has been on the back burner simmering while I sort through some driveline vibes. But, if I had to put my money on it today, I think you're spot on. I'd go with the 4545 units. KYB told me they are brand new on the market so most distributors dont have them yet. For $350 to get new upper mounts, dust covers, softer springs, and monotube shocks...seems like a steal. Some may poo poo on Gas-a-just but in my experience they are good shocks. Heck even monroe reflex monotubes are good. On my NBS Silverado I used about 6 different brands of shocks, including Bilstein, til I discovered the reflex monotubes rode the best. And if they only last 5 years/60,000 miles....oh well....most of us get bored anyway and start looking for things to do.

lucas287 · June 20, 2020

On 6/3/2020 at 10:23 AM, Grumpy Bear said:

RCSB 4.3 is the point of reference for the remainder. Weight is a scaled 5,000 lbs with 50/50 bias. I use scales not the book values. The extra weight is a Line-X and cover on the back half. (Uses a 2" drop bell knuckle) Again for your reference.

King OEM on both ends. Front spring comes 750#. OEM has 4" of shock travel and a 2:1 wheel ratio or 8" of travel. King has 1/2 inch more shock travel, 9" wheel travel. Again reference.

With this spring and zero pre-load I had 1 inch shock, 2" of wheel rebound so it hit the upper stops often. I changed springs to 600#, Kings next step down on this setup. This lowered the set up with zero pre-load to 1/2" above mid stroke. I now have 4" at the wheel in rebound and 5" in compression. Reference N2 pressure is 250#. Yea, that is the factory setting. Shim pack is 12-flutter-12 and shock oil is King medium. This last part is standard King.

I took a bunch of castor out of it which helped the expansion joint jolt. Now around 2* with proper L/R bias.

Front is firm but not harsh at 35 psi tire pressure, 250# N2 pressure and Bridgestone Dueller HT. Shock uses 90% of the total travel. I use wire ties on the rods to measure this. It is not "Boaty" at all.

Out back the same valving on 150# N2 and a Deaver built spring pack 15% softer and 2" less arch. The 1.25 spacer is removed. On the hard stuff it will hit the bumper in compression. You have to land it pretty hard. I could fix this with a remote reservoir shock instead of the 'piggy back' set up and reclaim around 2" of compression travel shortening the bump stop.

I believe the front can be more car like by using 500# springs and some pre-load to restore ride height but it would give away some travel. A larger sway bar or a solid one would hold the roll in check. Modified valving perhaps for bounce control.

Had I given it more thought I might have tried removing the middle and overload spring before having Deaver build a set. See where that put the ride height then adjusted with de-arc, shim or shackle to suit the drop. If I wanted to carry heavy, bag it.

Anyway just some 'been there, done that' information you might find useful.

Thing is using a shock like King, Fox, Viking etc. you have KNOWN spring rates and a great deal of interchange flexibility.

Thank You Ben Brazda at Filthy Motorsport for the assist on the sorting this out.

Grumpy, I think I'm gonna try removing the middle leaf and keeping the overload. Concurrently I'll install some legit traction bars ad they'll be needed even more.

Grumpy Bear · June 20, 2020

10 hours ago, lucas287 said:

Grumpy, I think I'm gonna try removing the middle leaf and keeping the overload. Concurrently I'll install some legit traction bars ad they'll be needed even more.

Let me know how that works out! How much does it affect the ride? PM me please. I will forget I asked this.

Yondu · November 15, 2020

On 6/3/2020 at 9:19 AM, lucas287 said:

Called Bilstein again. This time about the 6112 kit for 2015-2018 Tahoes/Yukon. The spring rate on that kit is 600#. That's quite a bit lower than the Silverado kit. Maybe too low. Also, I noticed that kit provides .25" less lift potential than the Silverado kit. Makes me think that Bilstein tuned that setup for ultimate comfort and lowered the spring rate accordingly, which inversely lowered the max lift potential.

If you put this set on a Silverado, and set it at max height, you'd probably pick up .9-1" of ride height but have a much softer spring. Would it wallow and feel like a boat? Highly doubt that when you have such a massive shock piston to dampen motion.

Anything come of this?

This is some really good info. I've also considered using lighter front springs, like a 2wd Silverado springs or something. Even when my truck (2018 z71, crew / short box) was new it didn't have as much rake as some of the Silverado's I see on the road making me think mine has firmer springs.

Currently I have Bilstein 5100's at the 1.2" front lift, Sulastic rear shackles and Cooper at3 285/70r17 (P metric). I'm going to ditch my At3's for some Michelin 275/65r18's on my oem z71 wheels and then look at replacing my front suspension if needed. To add, you can get a lower strut spacer for 1/2" or 1" of lift so even if you lost a tad bit of height that spacer would put you back where you need to be.

lucas287 · November 16, 2020

22 hours ago, Yondu said:

Anything come of this?

This is some really good info. I've also considered using lighter front springs, like a 2wd Silverado springs or something. Even when my truck (2018 z71, crew / short box) was new it didn't have as much rake as some of the Silverado's I see on the road making me think mine has firmer springs.

Currently I have Bilstein 5100's at the 1.2" front lift, Sulastic rear shackles and Cooper at3 285/70r17 (P metric). I'm going to ditch my At3's for some Michelin 275/65r18's on my oem z71 wheels and then look at replacing my front suspension if needed. To add, you can get a lower strut spacer for 1/2" or 1" of lift so even if you lost a tad bit of height that spacer would put you back where you need to be.

Hey man. Nope, never actually did any of this. Found a great deal on a set of Koni shocks and bought them for all four corners. They ride very nicely! Especially the rears comparing them to the Bilsteins I had back there. NIGHT AND DAY softer than the Bilsteins. I've had several road trips with good weight in the bed too and the Koni's never seems stressed. Great shocks.

The fronts, though, they didn't quite transform the front suspension to be super compliant. I think that's the springs. I can attest that the damn front springs are super stiff when swapping them over the Koni's.

I ended up removing my front sway bar to see how the ride would be with more travel and less spring rate (a sway bar effectively increases spring rate and limits travel BTW) and the results were subtle but very nice. One could hardly call it harsh in nearly any scenario. But the downside is that there is increased roll and certain undulations on the freeway mean you have to pay more attention. Based on this experiment I would say that softer springs would help and also a setup that has more travel would help too. It's expensive, but I would probably entertain a coilover conversion just to get more travel which means you can use a lower spring rate right off the bat.

Also, Michelins aren't exactly a supple ride. I have Michlein LTX MS2 on my truck and they are honestly pretty bad. They look sharp and grip decently, but they are all out of round and don't seem to balance worth a crap. I've done lots and lots burnouts and they are finally somewhat smooth on the highway. Same problem with my wifes SUV. I bought Michelin Premier and had to go through 10 tires in total just to get all four under 15 lbs of road force and even then they still vibrated on the highway. Swapped them for a set of Falkens and the first set all were under 10 lbs of road force and it's back to being smooth as glass. Saved $350 too. Do they Falkens have the same road feel? Nope. Are they as whisper quiet? Nope. But they are smoother on rough roads and don't vibrate. I'm pretty disappointed with Michelin here lately.

Edited November 16, 2020 by lucas287

Grumpy Bear · November 16, 2020

42 minutes ago, lucas287 said:

Hey man. Nope, never actually did any of this.

So never removed the middle leaf?

Yondu · November 16, 2020

49 minutes ago, lucas287 said:

Hey man. Nope, never actually did any of this. Found a great deal on a set of Koni shocks and bought them for all four corners. They ride very nicely! Especially the rears comparing them to the Bilsteins I had back there. NIGHT AND DAY softer than the Bilsteins. I've had several road trips with good weight in the bed too and the Koni's never seems stressed. Great shocks.

The fronts, though, they didn't quite transform the front suspension to be super compliant. I think that's the springs. I can attest that the damn front springs are super stiff when swapping them over the Koni's.

I ended up removing my front sway bar to see how the ride would be with more travel and less spring rate (a sway bar effectively increases spring rate and limits travel BTW) and the results were subtle but very nice. One could hardly call it harsh in nearly any scenario. But the downside is that there is increased roll and certain undulations on the freeway mean you have to pay more attention. Based on this experiment I would say that softer springs would help and also a setup that has more travel would help too. It's expensive, but I would probably entertain a coilover conversion just to get more travel which means you can use a lower spring rate right off the bat.

Also, Michelins aren't exactly a supple ride. I have Michlein LTX MS2 on my truck and they are honestly pretty bad. They look sharp and grip decently, but they are all out of round and don't seem to balance worth a crap. I've done lots and lots burnouts and they are finally somewhat smooth on the highway. Same problem with my wifes SUV. I bought Michelin Premier and had to go through 10 tires in total just to get all four under 15 lbs of road force and even then they still vibrated on the highway. Swapped them for a set of Falkens and the first set all were under 10 lbs of road force and it's back to being smooth as glass. Saved $350 too. Do they Falkens have the same road feel? Nope. Are they as whisper quiet? Nope. But they are smoother on rough roads and don't vibrate. I'm pretty disappointed with Michelin here lately.

Thanks for the detailed response. If we could find the right spring that comes on the Suburban 2wd or Tahoe 4wd that would be a cheap option...my brother had one too, but sold it a few months ago. Would have been easy to find out.

I'm disappointed to hear about the Michelins, I've always heard the opposite but not used them myself. Can you tell me what size yours were? LT load range? My biggest draw I was told they were super smooth. I don't off-road my truck and don't want aggressive tires anymore. I need road tires that work well in MN winters.