Lowered Dually guys step inside....

[TerryH]

Few questions for those of you that have done a 5/8 on a dually.....

I've looked through the shock thread but not sure which shocks are right for the dually. I had already replaced all 4 on my dually before lowering. Will they work or do I need shorter?

The rear sits virtually on the bump stop with no air in the bags. Is there a shorter bump stop or can I cut some off the Bell Tech bumpers or???

I bought Air Lift Slam Air bags. They only pick up the rear of the truck an inch or so even with 100lbs of air. Looks like I can get some more lift from the bags by turning the upper brackets up side down. I see no mention of this in the instructions. Anybody tried this or have any other suggestions? I'm concerned that I'm not going to have enough lift in the back when I pull my trailer.

Any other tricks or such that any of you want to share with me would be very much welcomed!!

TIA,

Terry

Sure does look sweet though.....

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[TerryH]

Problem solved with the bags. Air Lift says that I need a 2" spacer kit for the C300 with the Bell Tech flip kit. I made my own from 2x3 tubing and it worked fine. Still confused on which shocks to run though. Anyone done this that would share what they are running?

 

[sewlow]

You'll definitely need shorter shocks.
Some guys are running '70's(?) Impala shocks in the rear of their lowered trucks, but with what you're doing with you're truck, I'd say that you need something a bit more substantial.
If you've got $$$ to burn, go with the Steeda QA1's. They come in 2 styles. Single adjustable (Rebound) & Double adjustable (rebound & compression)
Last I checked, the dble. adj. ones were in the $375.00 range. EACH!!! Yea! $1500.00 for 4 shocks! Ouch!
But, they're guaranteed for life, with free rebuild services at any of their approved dealers. If you go with these, I have a chart to help you dial them in. There's something like 571 different combinations for the dble. adj. ones!
Next in line would be the Belltech Street Performers. Considerably more substantial in every way than the Nitro-Slammers or Nitro-drops. Better valving & stronger, larger dia. shafts. Nitro-whatever shocks are just re-branded Doestch's, & mimic the stock shock ride characteristics. Certainly not a 'performance' shock. The 'nitro' is for nitrogen which is used to prevent the oil inside from foaming. Nothing special, though. They're just a short version of 'stock'.
The Belltech's will make the truck ride firmer, though.
At 8" down in the rear, those shocks are pretty layed out. A lot! They're working as levers as opposed to absorbing. The geometry is all wrong. Relocating the upper mounts makes a huge dif. in the shock's performance! Got pix if you'd like.
The bumpstops on the rear of my truck don't look like the others that are stepped for progressive cushioning. They're about 2.5" across & maybe 1/2" thick. They're red (Oooh! Lol) & were part of a complete urethane body & suspension bushing kit. They can be bought separately. Cheap!
Yes. You can cut those ones you have now.

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[TerryH]

You'll definitely need shorter shocks.
Some guys are running '70's(?) Impala shocks in the rear of their lowered trucks, but with what you're doing with you're truck, I'd say that you need something a bit more substantial.
If you've got $$$ to burn, go with the Steeda QA1's. They come in 2 styles. Single adjustable (Rebound) & Double adjustable (rebound & compression)
Last I checked, the dble. adj. ones were in the $375.00 range. EACH!!! Yea! $1500.00 for 4 shocks! Ouch!
But, they're guaranteed for life, with free rebuild services at any of their approved dealers. If you go with these, I have a chart to help you dial them in. There's something like 571 different combinations for the dble. adj. ones!
Next in line would be the Belltech Street Performers. Considerably more substantial in every way than the Nitro-Slammers or Nitro-drops. Better valving & stronger, larger dia. shafts. Nitro-whatever shocks are just re-branded Doestch's, & mimic the stock shock ride characteristics. Certainly not a 'performance' shock. The 'nitro' is for nitrogen which is used to prevent the oil inside from foaming. Nothing special, though. They're just a short version of 'stock'.
The Belltech's will make the truck ride firmer, though.
At 8" down in the rear, those shocks are pretty layed out. A lot! They're working as levers as opposed to absorbing. The geometry is all wrong. Relocating the upper mounts makes a huge dif. in the shock's performance! Got pix if you'd like.
The bumpstops on the rear of my truck don't look like the others that are stepped for progressive cushioning. They're about 2.5" across & maybe 1/2" thick. They're red (Oooh! Lol) & were part of a complete urethane body & suspension bushing kit. They can be bought separately. Cheap!
Yes. You can cut those ones you have now.

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Thank you!!! Great info. I definitely do not have money to burn so $1500 for shocks will not be the one. I was hoping to be able to find something that would work at my local parts store but looks like the Bell Tech Street Performance might be the route to go. I'm pretty sure the fronts are bottoming out and as you stated, the rears are not doing what they need to do. I would like the link to those bumpers and to see how you relocated the rear shock mounts!

 

[sewlow]

Link to lotsa bump stops!
http://www.energysuspension.com/universal-products/bump-stops-shock-strut.html

Now this is 1/2 ton stuff, but I'm pretty sure that this should be applicable to you're 1 ton, At least as far as the shock relocation goes, anyhow.

Here's the pix of the upper shock mount relocation mods.
#1 shows the stock shock tower location. The hole in the frame in front of the tower is stock.
Check the bumpstop!

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#2. This is the driver side. The shock tower moved ahead and bolted into that stock hole. As you can see, we had to mod the lower part of the tower some, as the frame gets narrower in height as you move forward.

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#3. Passenger side. For some reason, GM didn't mount the towers an even amount away from the center line of the axle tubes. IIRC, they are farther forward on the pass. side. That ground-down spot with the hole in front of the relocated tower was the original location. The towers are now an even distance from the axle housing, front to back.

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#4. Modded Belltech shock extenders. Extended 3/8", welded in & ground down smooth. The extra length added was because we dropped the rear down another 1", to a 7" total, & we did all we could to correct the shock angle for that.

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#5 & #6. While we were at this, we ditched the Belltech flip kit spring/axle mounts and did this.
Actually, we ditched the bolt-in notch, too, as you can see in the previous pix. Just boxed the backsides of that ones we made. Wanted to do the whole frame from the rear cab mount to the last box mount, but time & $$$ was getting low at this point. Now that the box is off once again, one of the mods I have planned is to box the frame. I could see that also being a big help on the 1t's when towing.
(These trucks suffer from 'Beam Walk'. A lot of the vibrations that GMT400 owners complain about is due to that. GM's aware. Their solution is 500lbs. of 'ballast'! WTF?)
And some more suspension work! That'll be round #5 with that!
The bed cross member was also notched at this time. You don't have to do that on a long bed.

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#7 & #8. We also integrated some sway-bar mounts, instead of the 3" HD muffler clamps that I originally used to mount the bar. (You do have a rear sway-bar, don't you? Highly recommended, especially if your towing.)

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All done!

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Check the better shock angle!

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We also made these evil looking frame mounts for the sway-bar!

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The relocated shocks work so much better now!
But, if you'll notice in some of the pix, we removed the overload springs & had some other small, short springs made up to replace the O/L's.
The O/L's wouldn't fit by flipping them over & re-installing.
This was to get the truck down 1 more inch for that 7" total. But it's sooo wrong! Lost the progressive spring rate! Normal driving, they're fine. Push relatively hard in the corners, & the rear just blows right through the travel till it's on the bump stops!
So, the overloads are going back in & I'll get that 7" lowered height with a dropped shackle set at the first hole.

Hope this helps!

 

[88GMCtruck]

Now that the box is off once again, one of the mods I have planned is to box the frame. I could see that also being a big help on the 1t's when towing.
(These trucks suffer from 'Beam Walk'. A lot of the vibrations that GMT400 owners complain about is due to that. GM's aware. Their solution is 500lbs. of 'ballast'! WTF?)

I've also heard it referred to as "Frame Beaming". My dually does it bad. When I first bought the truck I thought the drivelines weren't balanced or i had a bent wheel. This is the only GMT400 I've ever felt it in, my 99 ECLB diesel didn't nor do any of my friend's trucks in any configuration... other than my dually.

Oh yeah, it doesn't do it with the camper in the bed (you know 5k in the bed would fix it, right?)

Terry, does your truck do it?

We also integrated some sway-bar mounts, instead of the 3" HD muffler clamps that I originally used to mount the bar. (You do have a rear sway-bar, don't you? Highly recommended, especially if your towing.)

I've been thinking about adding one myself, just unsure if I actually need one. It doesn't feel bad as is, with the bags + wider tires and it being a dually.

 

[TerryH]

Wow, sewlow!! Thanks for all the great info and pics. I do not have a rear sway bar and I've never heard of beam walk so I'm clueless about that. More projects. lol

 

[TerryH]

I've also heard it referred to as "Frame Beaming". My dually does it bad. When I first bought the truck I thought the drivelines weren't balanced or i had a bent wheel. This is the only GMT400 I've ever felt it in, my 99 ECLB diesel didn't nor do any of my friend's trucks in any configuration... other than my dually.

Oh yeah, it doesn't do it with the camper in the bed (you know 5k in the bed would fix it, right?)

Terry, does your truck do it?


I've been thinking about adding one myself, just unsure if I actually need one. It doesn't feel bad as is, with the bags + wider tires and it being a dually.

I've never even heard of frame beaming, Dave. Can you describe it a bit more? As far as the sway bar, I don't know about that either. I was pulling the trailer with my '11 Ram 1500 Hemi so the dually is SOOO much better that I guess I don't know if I need a sway bar or not.

 

[88GMCtruck]

Basically the frame beaming or beam walk is a frequency the frame basically vibrates due to the length from my understanding. At certain speeds the back of the truck vibrates. I first thought it was a bent wheel or bad u joint but after going through the drivelines and putting new wheels and tires on it definitely is the frame. I've came to terms with it now.

 

[TerryH]

Basically the frame beaming or beam walk is a frequency the frame basically vibrates due to the length from my understanding. At certain speeds the back of the truck vibrates. I first thought it was a bent wheel or bad u joint but after going through the drivelines and putting new wheels and tires on it definitely is the frame. I've came to terms with it now.

Hmmm. I'll be paying attention for it now. I don't think it's been an issue. I'm pretty **** about noises and vibrations and pretty much everything else.