Rough ride after KING Coilover install

[Carolina82]

I installed a set of King 2.5 remote reservoir coilovers and Cognito uca's on my 2013 GMC Sierra 4x4 about 5 months ago. Adjusted the height so the truck sits almost perfectly level (factory rear height). Spanner nut is roughly 1/3 of the way down the threads. The truck rides like a 2 horse wagon. I am wondering if it is possible to lower the PSI in the shock or some other way to make the truck ride better. I do not believe the spring is overly compressed based on how much more adjustment I could actually get out of the shock. I installed a OME kit on my previous vehicle and was hoping for the same or even better results. New to adjustable coilovers and any help will be greatly appreciated.

 

[bknudtsen]

Have you tried lowering the front a tad to see if the ride improves?

 

[Carolina82]

Have not tried that yet. I will try lowering it 1/2 inch or so to see if that helps, drive it a while and then get it aligned.

 

[XJLI]

Whats your tire pressure?

 

[DaveInDenver]

What is the spring rate of the coils and did you change anything on the back suspension? Do you have additional weight over stock in front? When you turn the coil seat down to level the truck did the compressed length of the springs change?

 

[Buliwyf]

Set ride height much lower. How much sag does the suspension have? What temp is it outside?

What size wheels and tires?

Might want to try a softer coil spring if that doesn't help. Big shocks can handle softer linear rate springs better. Filthy Motorsports has a good selection of springs last time I checked.

Too many people set the truck up with too little sag "for looks". Can one of the GM guys confirm what angle the front universals should be at for optimal ride? IIRC, they should be only a hair above level. You can't level an IFS by just cranking the spring preload. That makes them too stiff every time.

 

[TCICapn]

I installed a set of 2.5 Kings on my 2011 Sierra about 4 months ago and the ride is really nice, much better than stock and bilsteins despite the lift and load range E tires. They are currently set to ~1.75-2” of lift on 700lb/in coils (standard for this application).

I talked with Ben at Filthy Motorsports (great guy and company by the way!) and he told me these springs are linear so unless you are getting coil bind on compression or hard stop on droop it should not ride roughly. It was also recommended that I not lift the front more than 2.5” for ride quality and that 2” is kind of the sweet spot for up and down travel.

As was asked by others - What else did you change at the same time you installed UCAs and Kings? Wheels, tires, etc

 

[AlexCold]

Did you over tighten the upper control arm bolts, thus binding the UCA? Everything I've read about the Kings in this application, is a great improvement in ride.

 

[Carolina82]

Thanks for all the replies.

Whats your tire pressure?

35 PSI on the street.

What is the spring rate of the coils and did you change anything on the back suspension? Do you have additional weight over stock in front? When you turn the coil seat down to level the truck did the compressed length of the springs change?

I believe it is a 700Lb spring and nothing was changed in the rear, it is 100% factory. No additional weight in the front. I did not measure the spring before or after turning the spanner nut.

Set ride height much lower. How much sag does the suspension have? What temp is it outside?

What size wheels and tires?

Might want to try a softer coil spring if that doesn't help. Big shocks can handle softer linear rate springs better. Filthy Motorsports has a good selection of springs last time I checked.

Too many people set the truck up with too little sag "for looks". Can one of the GM guys confirm what angle the front universals should be at for optimal ride? IIRC, they should be only a hair above level. You can't level an IFS by just cranking the spring preload. That makes them too stiff every time.

By sag I assume you mean when the tire touches the ground until the jack is free to move under the truck, I have not measured this. Anywhere from 100* F to 35* F. 285/70/17 BFG KO2's on factory wheels.

I installed a set of 2.5 Kings on my 2011 Sierra about 4 months ago and the ride is really nice, much better than stock and bilsteins despite the lift and load range E tires. They are currently set to ~1.75-2” of lift on 700lb/in coils (standard for this application).

I talked with Ben at Filthy Motorsports (great guy and company by the way!) and he told me these springs are linear so unless you are getting coil bind on compression or hard stop on droop it should not ride roughly. It was also recommended that I not lift the front more than 2.5” for ride quality and that 2” is kind of the sweet spot for up and down travel.

As was asked by others - What else did you change at the same time you installed UCAs and Kings? Wheels, tires, etc

Only thing changed was Coilovers and UCA's

Did you over tighten the upper control arm bolts, thus binding the UCA? Everything I've read about the Kings in this application, is a great improvement in ride.

I torqued the UCA's to spec, then had the truck aligned after driving it a week. I would think the shop that did the alignment did not over torque them, pretty slick bunch of guys.



I measured the truck before adjusting anything and it was about 1/4" higher in the front vs the rear. I lowered the shocks 2 full turns on the spanner nut per side last night. Truck seems to ride a little better but that could all be in my head. I will drive it more this week if I have time and see how it does. I do not have the factory measurements in regards from center of wheel to fender well since the truck already had a 2" RC lift when I bought it.

 

[AlexCold]

Wait, so you still have stock shocks in the rear? Or RC shocks in the rear? That would definitely contribute to a rougher ride if the shocks are fighting each other.



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[pappawheely]

How much preload are you running?

 

[Carolina82]

Talked to a guy at King, he is saying I've got too much preload on the shocks. I turned the spanner nut back, now i'm only showing about 3 threads from top of coil body to top of spanner nut (was showing 6). He also said the coilovers I am running come factory with about 300 PSI, he said I could back them down to 200-250 PSI if I needed to and still not have to worry about cavitation. After backing the adjuster up and driving it some the truck seems ALOT smoother. I think I can still back it up a turn and be close to level. Not wanting to drop the PSI if I don't have to. Again, thanks for all the replies.

Wait, so you still have stock shocks in the rear? Or RC shocks in the rear? That would definitely contribute to a rougher ride if the shocks are fighting each other.



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Rear is 100% factory including shocks. Plan was to buy King rear shocks a few months after I got the fronts, but once I felt how stiff the front was there was no way I was spending that amount of cash on the rears.

How much preload are you running?

I had about 6-7 threads showing between top of spanner nut and top of shock body.

 

[Big Ern]

Spend the money and get the rear done so your system is working in sync

 

[Carolina82]

Spend the money and get the rear done so your system is working in sync

I plan to now that I've got this figured out.

 

[pappawheely]

Jack your truck up in front until it's fully drooped. Then loosen the coil spring seat until the coil is loose. Now thread it back down until it just makes contact with the spring and holds it in place. Measure the length of the coil at this point. If you have 700lb springs it means that the coils will take 700lbs to compress one inch. If you preload the coil one inch, you have 700 lbs of preload on the coil. If you went 2 inches, that's 1400lbs of preload. Getting the spring rate right is the first thing that needs to happen. If it's not right, the shock will not work right. The spring rate needs to match the weight of your vehicle. Go down to the truck scales and have it weighed, then get the correct spring for that weight. One of the benefits of your high-end shocks is that you can swap the coils.