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How much lift before needing longer shocks?


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Hey guys, what are your thoughts about needing longer shocks or shock extensions? I cranked my stock keys 7 turns, which raised the front 1.5". There's still about 5/8" of clearance between the UCA and bump stop. I can easily fit my index finger between them. However, when I go over big bumps, I can hear a thumping sound in the front end. I wonder if it's the shocks bottoming out. I really thought I'd be fine with only 1.5" of lift. What do you think? Thanks in advance for your responses!

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It isn't the same truck, but on my '08 HD I cranked the same as you and wondered the same thing. I ended up biting the bullet and put +2 Bistein 5100's on it and it rode much better. Shock extensions are fairly cheap, my recommendation would be to pick up some of those and try them out for a short time. If your symptoms go away and it seems to ride a bit better then maybe consider longer shocks.

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We usually recommend that anytime ride height is altered that you look into changing your shock length. The reason being, when you change anything suspension wise (other that a basic drop/lift spindle) to alter the height it will decrease the amount of rebound or compression travel on the shock

In the case of a lifted truck, when the distance between the two shock mounting points changes, the stock length shock is stretched out limiting your rebound travel. Its the opposite on lowered trucks, they lose compression travel.

In an ideal world, we like to see about 60% compression travel and 40% rebound but a nice 50/50 mix is ok.

As an example..if the measurement from center of eye at the bottom to center of eye at the top (at ride height) is 12 inches you would need a shock with at least a 4in stroke. Fully compressed that shock would be about 10in, extended would be about 14.

Hope that helps. I imagine the "thump" you hear is probably your shock topping out. Factory style twin-tube shocks have a hard time with that kind of impact. Too much of that and the shock will eventually destroy itself.

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Might not be the case here, but when I installed my BDS lift, it changed the angle in which my torsion bars passed through that cross member. They ended up fairly close to the sides of the hole they pass through, so when I have an abrupt hit, the torsion bar ends up bowing into one of the sides causing a thud. I'm assuming that cranking the torsion bars up more wouldn't really change the angle, so they shouldn't be any closer to the hole they pass through in the cross member. You could always take a look though to see if it's close. I feel it directly underneath my feet.

 

Do to feel it in the floor board or in the steering wheel?

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We usually recommend that anytime ride height is altered that you look into changing your shock length. The reason being, when you change anything suspension wise (other that a basic drop/lift spindle) to alter the height it will decrease the amount of rebound or compression travel on the shock

In the case of a lifted truck, when the distance between the two shock mounting points changes, the stock length shock is stretched out limiting your rebound travel. Its the opposite on lowered trucks, they lose compression travel.

In an ideal world, we like to see about 60% compression travel and 40% rebound but a nice 50/50 mix is ok.

As an example..if the measurement from center of eye at the bottom to center of eye at the top (at ride height) is 12 inches you would need a shock with at least a 4in stroke. Fully compressed that shock would be about 10in, extended would be about 14.

Hope that helps. I imagine the "thump" you hear is probably your shock topping out. Factory style twin-tube shocks have a hard time with that kind of impact. Too much of that and the shock will eventually destroy itself.

 

I like useful info from folks that do it for a living. Thanks!!

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It isn't the same truck, but on my '08 HD I cranked the same as you and wondered the same thing. I ended up biting the bullet and put +2 Bistein 5100's on it and it rode much better. Shock extensions are fairly cheap, my recommendation would be to pick up some of those and try them out for a short time. If your symptoms go away and it seems to ride a bit better then maybe consider longer shocks.

Thanks, bud. That's a good idea. That would be a pretty cheap way to narrow things down.

 

We usually recommend that anytime ride height is altered that you look into changing your shock length. The reason being, when you change anything suspension wise (other that a basic drop/lift spindle) to alter the height it will decrease the amount of rebound or compression travel on the shock

In the case of a lifted truck, when the distance between the two shock mounting points changes, the stock length shock is stretched out limiting your rebound travel. Its the opposite on lowered trucks, they lose compression travel.

In an ideal world, we like to see about 60% compression travel and 40% rebound but a nice 50/50 mix is ok.

As an example..if the measurement from center of eye at the bottom to center of eye at the top (at ride height) is 12 inches you would need a shock with at least a 4in stroke. Fully compressed that shock would be about 10in, extended would be about 14.

Hope that helps. I imagine the "thump" you hear is probably your shock topping out. Factory style twin-tube shocks have a hard time with that kind of impact. Too much of that and the shock will eventually destroy itself.

Thanks for the reply! I figured that's what was going on. I think I'm going to pick up some shock extensions and see if the thumping goes away.

 

Might not be the case here, but when I installed my BDS lift, it changed the angle in which my torsion bars passed through that cross member. They ended up fairly close to the sides of the hole they pass through, so when I have an abrupt hit, the torsion bar ends up bowing into one of the sides causing a thud. I'm assuming that cranking the torsion bars up more wouldn't really change the angle, so they shouldn't be any closer to the hole they pass through in the cross member. You could always take a look though to see if it's close. I feel it directly underneath my feet.

 

Do to feel it in the floor board or in the steering wheel?

Nope, I can't really say that I "feel" it anywhere. I just notice the sound. If my radio was turned up pretty high, I'm not sure I'd even hear it.

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Hey guys, what are your thoughts about needing longer shocks or shock extensions? I cranked my stock keys 7 turns, which raised the front 1.5". There's still about 5/8" of clearance between the UCA and bump stop. I can easily fit my index finger between them. However, when I go over big bumps, I can hear a thumping sound in the front end. I wonder if it's the shocks bottoming out. I really thought I'd be fine with only 1.5" of lift. What do you think? Thanks in advance for your responses!

I did similar raised up front 2 inches drove a week. went with shock spacers drove a week

noticed some improvements. still control arm made contact with the stop. next added new ccm control

arms and aligned. seems to be better riding with control arms not just hitting bumpstop but smoother in

general. probably just my imagination but after putting out near 5 hundred for arms even if its just in my

mind I feel better.

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Hey guys, what are your thoughts about needing longer shocks or shock extensions? I cranked my stock keys 7 turns, which raised the front 1.5". There's still about 5/8" of clearance between the UCA and bump stop. I can easily fit my index finger between them. However, when I go over big bumps, I can hear a thumping sound in the front end. I wonder if it's the shocks bottoming out. I really thought I'd be fine with only 1.5" of lift. What do you think? Thanks in advance for your responses!

B Whiskey..... Im inclined to say that you're contacting the upper control arm stops. I get the same noise if I hit the speed bumps too fast

 

 

Sent from my STH100-1 using Tapatalk

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Clean the UCA where the bump stop would hit and the bumper. Smear some grease on the UCA. If it's contacting it will show on the bumper. If it isn't John is correct. Shock is topping out. Don't guess, Measure and mark.

 

My personal research is showing there is not allot of wiggle room on the shock length. Just say'n. :rolleyes:

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B Whiskey..... Im inclined to say that you're contacting the upper control arm stops. I get the same noise if I hit the speed bumps too fast

 

Clean the UCA where the bump stop would hit and the bumper. Smear some grease on the UCA. If it's contacting it will show on the bumper. If it isn't John is correct. Shock is topping out. Don't guess, Measure and mark.

 

My personal research is showing there is not allot of wiggle room on the shock length. Just say'n. :rolleyes:

Thanks, guys. I'm really hoping it's the shocks, rather than the UCA. The shocks are a much easier fix, haha. There aren't any marks on the bump stop that would indicate they've been hitting the UCA, but I'll mark them with chalk or grease to see for sure. I think I'll also throw some shock extensions on there too.

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If you haven't tried the spacers, contact Danny at CCM (Central Coast Motorsports in San Luis Obispo, Ca). He sells the full leveling kits with UCAs, keys, diff drop spacers, and shock extenders...but he will sell each part individually too. Like DirtFan stated above, it's a cheap way to troubleshoot your problem.

 

I am running their full leveling kit. I raised my front end up about 3". Every once in awhile, I'll still get the shock noise you are referring to. But, you gotta remember, I raised it up 3" and the shock extender is only about 1/2", so in no way does it bring the shock back to spec. The UCAs and diff spacers help to keep other angles happy and closer to factory spec, but they will never be perfect. If we wanted them perfect, we would have left them alone. Well, now that's not going to happen...

 

I too will soon replace the stock Rancho's with Bilstein's...and the fronts will be slightly taller than the stockers...

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