Rear suspension upgrades for towing

earleyksig · March 30, 2017

I just bought a used 2015 Sierra 1500 Crew cab with the 5.3 and 2wd. I'm new to lift/leveling kits, suspension upgrades, etc. and am looking for some advice. First off, I noticed the truck looked level if not a little lower in the rear. I have the stock 20's and measured my fenders tonight and front is sitting at 37.5" and rear is at 37.25". My guess is the previous owner installed a leveling kit, is there anyway I can easily check to see? I don't believe the rear was lowered, it appears to still have the factory blocks. I actually prefer a slight rake but more importantly, my guess is once I hook my boat up, the lower rear end is going to be that much more exaggerated. I have a 21" Sea Ray which is around 4700 lbs with trailer and should be 3-400 at the tongue. What I'd like to do is bump up the rear 1-2" and add some strength. Since I only tow the boat in the summer and the truck is my daily driver, I want to keep ride quality in mind. I've scoured the forums and am currently thinking Zone AAL and Bilstein 5100's. However, will the lift of the Zone's be too much lift for the 5100s? Another option I've considered is swapping out the stock block with maybe a 3" and adding a set of Hellwig helper springs and 5100s. I know a lot of guys recommend airbags but not sure they'd help my lower rear end unless I kept them inflated, correct?

O_J_Simpson · March 30, 2017

Do you want show or go?

silveradosid · March 30, 2017

you could take leveling block out and put one in that only lifts the front 1.5 inches, which will give you some rake back and then put helper spring in the back

Andy Seibel · March 30, 2017

I would have made the dealer remove the leveling kit before I bough it. lol.

But for your boat, are you only concerned with how your truck will look with the rear end 1" lower while towing? you definitely don't need any add-ons just for that amount of weight.

I do have hellwig helper springs, they barely raise the rear end above stock.

Seriously, I would just leave the rear end alone and adjust the front back closer to stock. leveling kits lower your fuel mileage as well, if that matters to you.

FreeAmerican · March 30, 2017

I'm towing a 7000 lb camper with a 650-700 hitch weight. I also wanted to stiffen up the rear so I went with Timbrens. They are hollow rubber springs that replace your snubbers. No air lines to run, no pumps nada.

I've been please with them. The only issue is this.... they leave a space of an inch or so between the rubber spring and the axle. This lets the truck ride over normal bumps and cracks without hitting the Timbrens. If you hit a big pothole it will contact the Tembren, which is stiff so it will be a little harsher on really rough terrain. Its well worth it to me, but if you want Caddy quality ride, maybe its not for you. In short it will ride like a truck.

I would undo the level job on your truck. Even with a weight dist hitch you are going to be set up funky.

Andy Seibel · March 30, 2017

I also wanted to stiffen up the rear so I went with Timbrens.

The only issue is this.... they leave a space of an inch or so between the rubber spring and the axle. This lets the truck ride over normal bumps and cracks without hitting the Timbrens. If you hit a big pothole it will contact the Tembren, which is stiff so it will be a little harsher on really rough terrain.

Bingo. I tried rear timbrens and was disappointed by the ride when unloaded. partly the problem is there is a bridge I drive over every time I leave my house and it would always "bottom out". It was just annoying. I sold them about 6 months after i installed them.

If you aren't hauling serious weight very often, I wouldn't recommend rear timbrens. For the OP, 300 lbs on the rear a few weekends is not worth changing the suspension or ride.

Now I am a big fan of the front ones however. But that is mostly for my snow plow. I don't know why you would want them otherwise.

Donstar · March 30, 2017

Are your tires the same size as specified in the door? If they are stock height or close to it, I would pay for an hour of labor and an alignment to have your truck returned to stock. Hold on to the spacers that are removed because you may choose to use them at a later date! It will also give you peace of mind to have a professional give your suspension a thorough look. Welcome to this forum!

earleyksig · March 30, 2017

Should be, truck only has 18k miles and has 275/55R20 Continental LX20's which I beleive are the OEMs.

Glad to be here, have already learned a ton!

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earleyksig · March 30, 2017

I would have made the dealer remove the leveling kit before I bough it. lol.

But for your boat, are you only concerned with how your truck will look with the rear end 1" lower while towing? you definitely don't need any add-ons just for that amount of weight.

I do have hellwig helper springs, they barely raise the rear end above stock.

Seriously, I would just leave the rear end alone and adjust the front back closer to stock. leveling kits lower your fuel mileage as well, if that matters to you.

I'm still not 100% sure it has one but based on the front sitting a 1/4" higher than the rear, that's my best guess. Do you know the size of the front OEM block? I'm going to crawl under it this evening to see if I can tell it's been modified.

Interesting on gas mileage, I've only had the truck a couple of weeks but have done quite a bit of highway driving and milage has been a disappointment so far.

I like how the front end looks now, leveling kit or not. However, I'd be willing to sacrifice the front height if it helps with MPGs and gets some of my rake back. For the helper spring, I didn't realize they give you some lift, good to know.

Also, I failed to mention I do have a damaged shock, looks like prior owner hit it on something and put a pretty good dent in it. I figured I'd take the opportunity to upgrade those since I need to swap them anyways. If I left rear stock and just went with a helper spring, I take it the Bilstein 4600s would be the recommended shock?

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earleyksig · March 30, 2017

Bingo. I tried rear timbrens and was disappointed by the ride when unloaded. partly the problem is there is a bridge I drive over every time I leave my house and it would always "bottom out". It was just annoying. I sold them about 6 months after i installed them.

If you aren't hauling serious weight very often, I wouldn't recommend rear timbrens. For the OP, 300 lbs on the rear a few weekends is not worth changing the suspension or ride.

Now I am a big fan of the front ones however. But that is mostly for my snow plow. I don't know why you would want them otherwise.

I work downtown and roads are pretty terrible, I definitely want to avoid worsening the ride if possible. My biggest concern is with the rear already being lower than the front, the boat is going to make it that much worse. I'm also not a fan of how it currently sits unloaded, I personally like a bit of rake.

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earleyksig · March 30, 2017

you could take leveling block out and put one in that only lifts the front 1.5 inches, which will give you some rake back and then put helper spring in the back

Pending it does have a leveling kit, any issues swapping out the block but leaving all other parts in place?

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Andy Seibel · March 30, 2017

So, since you are not sure what mods your truck has, that is the first thing you need to figure out. If you say the front is 1/4" higher than the rear, something was definitely changed because the rear should be noticeably higher (especially since you have 2WD)

I'm not an expert in this area because I have never done a lift/level. Post a couples pics of your front suspension and rear blocks and someone should easily be able to identify what you have going on.

Helwig helper springs might raise your rear up to 1" IF you crank the bolts all the way down. I only have mine tight enough to remove all slack when unloaded.

Lastly, it seems that bilstein 5100 is the replacement shock of choice on this forum.

earleyksig · March 30, 2017

So, since you are not sure what mods your truck has, that is the first thing you need to figure out. If you say the front is 1/4" higher than the rear, something was definitely changed because the rear should be noticeably higher (especially since you have 2WD)

I'm not an expert in this area because I have never done a lift/level. Post a couples pics of your front suspension and rear blocks and someone should easily be able to identify what you have going on.

Lastly, it seems that bilstein 5100 is the replacement shock of choice.

Agree, and thanks for confirming rear end should definitely be quite a bit higher. I'll post some pics this evening.

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Smoore8691 · March 30, 2017

I love my load lifter 5000 ultimate bags by Airlift. Helps me level the truck when i pull the camper.

earleyksig · March 30, 2017

I was able to snap a few pictures.

Rear

I'm not sure what the stock setup looks like for comparison. However, from looking at different kits it appears like it may have a basic 2" leveling kit. Can anyone confirm if this is stock?

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