Need Advice on Rear Sagging When Towing

[teksavy]

Hi:

My rear end sags when towing. (No, not that rear-end!) 

I'd like your advice on how best to deal with the rear end sagging when loaded. I've seen some entries about air bags, but I don't know much about them and would like to install them prior to towing a toy hauler next weekend.

Any suggestions are welcome.

BTW, this is on a 2003 1500 4x4 with 6" RCD lift.

-Ed

 

[m02redl]

some info here

 

[Alaska_AV.]

I don't think stock airbags will work for you. Your rcd coil is taller. I'd contact the manufacture to see if they make taller ones for you.....Firestone and rcd

you may beable to get a custom coilspring made for you , stronger same height

Best bet may be Air shocks

good luck

 

[teksavy]

Actually the RCD setup uses factory springs. RCD uses a perch to extend the stock springs. So the airbags might work. Any recommendations on brand and where to buy?

I don't think stock airbags will work for you. Your rcd coil is taller. I'd contact the manufacture to see if they make taller ones for you.....Firestone and rcd

you may beable to get a custom coilspring made for you , stronger same height

Best bet may be Air shocks

good luck

 

[BUDMAN]

If I were you, I would run the Air Lift and possibly add the remote compressor.  I have heard nothing but good things about Air Lift.  I just wish they made bags long enough for my application.  I need 15", and I think you need somewhere around 10".

 

[Brianster]

Hi:

My rear end sags when towing. (No, not that rear-end!)?


BTW, this is on a 2003 1500 4x4 with 6" RCD lift.

-Ed

Darn!  I was going to recommend a butt-lift.

 

[Alaska_AV.]

if the perch is solid but with a hole in the center for an air tube, you should beable to use an air bag sys.

I have the coil rite bags on mine and love em. Firestone bags
I sugest geting the full kit. compressure, dual guages,

 

[Chopped_Burban]

I went with the Air-Lift bags because they were easier for me to get but also went with the compressor and gauge/switch like Alaska_Av suggests. They work great on my toy hauler. Really helps to keep the back end from bouncing around too. Two pieces of advice:
1) attaching the air line to the air spring before sticking it in the coil spring really helps. I would have no idea how to get to it after like the instructions said to do.
2)Shooting the air spring and coil down with diluted dish soap help them slide in easier.

Happy trailering

Fair warning, with stock size tires and 4:10's I was really pushing her, but she did good. I don't know how the 35's are going to affect you.

 

[Snoball]

I just finished the installation of the Air Lift bags on my 2004. It took about 1 hour with my son helping me. The hardest part was getting the Air Lift bag rolled up and then back to shape inside the coil spring. If you get that done, everything else is just nuts and bolts?no surprises. The instructions with the Air Lift bags instruct you to just install the bags into the coil springs with the springs still in place?I know some have done it, but it is not worth the hassle trying to get them into the coil springs while they are in the vehicle.  Here is what I think will get anyone through the process:

Air Lift Bag Installation on Avalanche 1500?s with Rear Coil Springs
Air Lift 1000 Air Spring KitPart # ARL-60769 for 2001-2004 Chevrolet Avalanche
Order  at: http://www.centuryperformance.com  -- Sales Price: $69.99 ; or by phone @  775-746-4887
Tools Required:
? ?? ratchet
? 13mm, 18mm, 21mm sockets
? Drill and 5/16? bit
? Pliers
? Floor jack & jack stands (and wheel chocks)
? Lug wrench or socket for wheels
? Torque wrench
? 1? hole saw or exacto knife
? Air pressure gauge and compressor
? Ty-wraps

Installation:

1. Loosen rear lug nuts and jack the rear of the Avalanche & install jack stands under the frame rails.
2. Remove tires & wheels.
3. Support rear axle housing with a floor jack under the differential (it must go low enough to remove coil springs without prying).
4. Remove upper sway bar nuts on frame (18mm) and push lower arms clear; leave lower mounts in place.
5. Remove lower 21mm bolts from shocks - each side; leave uppers attached to frame.
6. Caution: There is a hydraulic brake line and an emergency brake line! You can snap the rubber hydraulic line right off the distribution block on top of the differential!  You MUST remove the 13mm bolt on the differential cover holding the distribution block down. The Chilton manual says to disconnect the brake lines and plug them which also means bleeding them?.it is not necessary if you are careful when lowering the axle.
7. Remove the 13mm bolt holding the emergency brake line's hanger on the passenger side (next to exhaust hanger) , in order to get both springs out safely
8. Unbolt the track bar (21mm bolt/nut) at the axle housing on the left side- leave connected to frame on right side.
9. Detach the rear axle vent hose?.just pull off
10. Very slowly lower rear differential until the springs are fully extended then remove springs & top rubber insulators.
11. Cut out top coil rubber to 1" diameter- to enlarge the hole in the top of the spring mount to an inch. You can use a hole saw or an exacto knife?.. the rubber is very soft.
12. Push air bag (draw air out- remove plastic cap from barbed stem on end of cylinder. Exhaust the air from the cylinder by rolling it up toward barbed stem. Replace cap on stem to hold flat shape.) It might help to spray the bag with a soapy solution to make it slide in the coils easier. Place air bag in coil with air fitting connection to top. When the bag is in place remove the cap and let the bag assume its molded shape. Install the round provided protector on the top of the air bag inside the coil before it is installed.
13. Slide the clamps onto the air lines before placing them on the barbs at the bag and fittings. Install air hose and place spring in cradle with air hose out top and clear of exhaust or any potential chafing.  DO NOT FORGET: Be sure to install the round provided protector on the top of the air bag inside the coil before it is installed. Pre-run your air lines and cut them to size. Leave enough slack to permit full suspension travel. Before you put the coil springs back in hook up the lines to the air bags. It is a lot easier then trying to hook them up while they are back on the rear-end. The air lines must be pushed over the barbs and then with pliers, slide the clamp over the connection.
14. Jack differential up to install sway bar & shocks.
15. Route both air lines to the ?T? fitting and outlet Drill a 5/16" hole by the gas cap or rear bumper and hook up the lines. Tie-wrap air lines.
16. The Avalanche requires a heat shield to protect the bag from the exhaust. The heat shield is installed on the exhaust pipe at the closest point to the air bag. Bend the heat shield tabs at a 90 degree angle to form an ?L? to enable you to attach to exhaust. Bend the heat shield to form it around the pipe. Use the hose clamps and install heat shields ? be sure to maintain ?? ? 1? clearance between the shield and exhaust.
17. Raise the axle with the floor jack until you can attach the rear shocks. (Torque lower shock bolt to 70 ft-lbs. for 2002-2004 Avalanches and 59 ft-lbs. for 2005.)
18. Connect the track bar (torque to 77 ft-lbs.), the emergency brake line hanger, the distribution block for the brakes and the vent hose. Reinstall the upper sway bar nuts on frame (torque to 48 ft-lbs.)
19. Install tires & wheels (torque to 140 ft-lbs.)
20. Remove jack and test per Air Lift (for lower pressure I used an ATV air gauge Air up the bags to 35 psi and test for leaks.



NOTES:
? It is best to remove the rear wheels to give you more room to work around.
? If your Avalanche has an optional suspension system (i.e. Real Time Damping, etc.) remove the sensors.
? Always maintain a minimum pressure of  5 psi to prevent coil pinch.  Place 35psi in bags before placing a load on the Avalanche?then lower pressure to ride height required. DO NOT add load or trailer and then add pressure
? Test for leaks by applying a solution of dish soap and water to all fittings.
? Recheck pressure after 24 hours. A 2-4 p.s.i. drop is normal after initial installation. If more than 5 lbs. retest with soapy water.

 

[Bad Dad]

Snoball... great write-up! I've got mine and will be doing the install next weekend -- thanks to everyone for the tips!
My Avy is lowered 2/2.5, so I got part # 60742 listed for the 97 to 04 Infinity QX4 with are 6" bags instead of the 10" bags in part #60769. I had to call Air Lift for the protector plates that come with 60769, which cost me an additional $11.00 plus shipping. I'll let you know how it turns out...

Bad Dad

 

[ygmn]

What are you towing?
Weight?
Tongue Weight?
Trailer ball height when level?
Truck Hitch height when unloaded?
Drop/Raise hitch bar?

 

[Snoball]

What are you towing?
I tow either a custom flatbed ATV trailer or a Qwest Baja by Jayco or both.
I added the air bags because of the Baja. It is customized and I added quite a bit of weight and the tail of the Z71 Avalanche really sagged with the coil springs. It usually dropped about 4? when I dropped the tongue on the hitch.  Now, with 30-35lbs of air in the bags, it does not drop at all. The height of the bags means that my truck does not really raise any when there is no load (at any pressure). The springs at rest are about the height of the bags?when the springs compress however, the bags prevent it and the truck stays level?.I really like them. We are getting ready to leave in two weeks for a week long trip with the trailer and I will see how it works on the road.
Weight?
It weighs about 4500 lbs when loaded with supplies, food, water, etc.
Tongue Weight?
The book says about 250 lbs. stock, however I added an Onan generator on the tongue along with an aluminum covered battery box....and the 5 gallon gen set gas tank. I would estimate tongue weight at 400 lbs.
Trailer ball height when level?
It all depends on if you have raised or drop hitch. I have a 6? rise hitch and it was 20-7/8? to the bottom of the hitch. It used to drop over 4? when I put on the load of the tongue.
Truck Hitch height when unloaded? N/A
Drop/Raise hitch bar?-6?

 

[Snoball]

And here is the triple tow set up.

 

[Chopped_Burban]

Snoball, nice write up and nice toys. I don't know if I feel secure enough pulling two trailers like that. It's got to be interesting. I wanted to drag around pretty much the same stuff but opted for the toy hauler outright.

 

[22off]

I'm interested to hear how are you backing up a triple setup like that. My rear visibilty when backing up my boat is almost zero so I wonder how do you see the second trailer?

 

[Didit]

I just finished the installation of the Air Lift bags on my 2004. It took about 1 hour with my son helping me. The hardest part was getting the Air Lift bag rolled up and then back to shape inside the coil spring. If you get that done, everything else is just nuts and bolts?no surprises. The instructions with the Air Lift bags instruct you to just install the bags into the coil springs with the springs still in place?I know some have done it, but it is not worth the hassle trying to get them into the coil springs while they are in the vehicle. Here is what I think will get anyone through the process:

Air Lift Bag Installation on Avalanche 1500?s with Rear Coil Springs
Air Lift 1000 Air Spring KitPart # ARL-60769 for 2001-2004 Chevrolet Avalanche
Order at: http://www.centuryperformance.com -- Sales Price: $69.99 ; or by phone @ 775-746-4887
Tools Required:
? ?? ratchet
? 13mm, 18mm, 21mm sockets
? Drill and 5/16? bit
? Pliers
? Floor jack & jack stands (and wheel chocks)
? Lug wrench or socket for wheels
? Torque wrench
? 1? hole saw or exacto knife
? Air pressure gauge and compressor
? Ty-wraps

Installation:

1. Loosen rear lug nuts and jack the rear of the Avalanche & install jack stands under the frame rails.
2. Remove tires & wheels.
3. Support rear axle housing with a floor jack under the differential (it must go low enough to remove coil springs without prying).
4. Remove upper sway bar nuts on frame (18mm) and push lower arms clear; leave lower mounts in place.
5. Remove lower 21mm bolts from shocks - each side; leave uppers attached to frame.
6. Caution: There is a hydraulic brake line and an emergency brake line! You can snap the rubber hydraulic line right off the distribution block on top of the differential! You MUST remove the 13mm bolt on the differential cover holding the distribution block down. The Chilton manual says to disconnect the brake lines and plug them which also means bleeding them?.it is not necessary if you are careful when lowering the axle.
7. Remove the 13mm bolt holding the emergency brake line's hanger on the passenger side (next to exhaust hanger) , in order to get both springs out safely
8. Unbolt the track bar (21mm bolt/nut) at the axle housing on the left side- leave connected to frame on right side.
9. Detach the rear axle vent hose?.just pull off
10. Very slowly lower rear differential until the springs are fully extended then remove springs & top rubber insulators.
11. Cut out top coil rubber to 1" diameter- to enlarge the hole in the top of the spring mount to an inch. You can use a hole saw or an exacto knife?.. the rubber is very soft.
12. Push air bag (draw air out- remove plastic cap from barbed stem on end of cylinder. Exhaust the air from the cylinder by rolling it up toward barbed stem. Replace cap on stem to hold flat shape.) It might help to spray the bag with a soapy solution to make it slide in the coils easier. Place air bag in coil with air fitting connection to top. When the bag is in place remove the cap and let the bag assume its molded shape. Install the round provided protector on the top of the air bag inside the coil before it is installed.
13. Slide the clamps onto the air lines before placing them on the barbs at the bag and fittings. Install air hose and place spring in cradle with air hose out top and clear of exhaust or any potential chafing. DO NOT FORGET: Be sure to install the round provided protector on the top of the air bag inside the coil before it is installed. Pre-run your air lines and cut them to size. Leave enough slack to permit full suspension travel. Before you put the coil springs back in hook up the lines to the air bags. It is a lot easier then trying to hook them up while they are back on the rear-end. The air lines must be pushed over the barbs and then with pliers, slide the clamp over the connection.
14. Jack differential up to install sway bar & shocks.
15. Route both air lines to the ?T? fitting and outlet Drill a 5/16" hole by the gas cap or rear bumper and hook up the lines. Tie-wrap air lines.
16. The Avalanche requires a heat shield to protect the bag from the exhaust. The heat shield is installed on the exhaust pipe at the closest point to the air bag. Bend the heat shield tabs at a 90 degree angle to form an ?L? to enable you to attach to exhaust. Bend the heat shield to form it around the pipe. Use the hose clamps and install heat shields ? be sure to maintain ?? ? 1? clearance between the shield and exhaust.
17. Raise the axle with the floor jack until you can attach the rear shocks. (Torque lower shock bolt to 70 ft-lbs. for 2002-2004 Avalanches and 59 ft-lbs. for 2005.)
18. Connect the track bar (torque to 77 ft-lbs.), the emergency brake line hanger, the distribution block for the brakes and the vent hose. Reinstall the upper sway bar nuts on frame (torque to 48 ft-lbs.)
19. Install tires & wheels (torque to 140 ft-lbs.)
20. Remove jack and test per Air Lift (for lower pressure I used an ATV air gauge Air up the bags to 35 psi and test for leaks.



NOTES:
? It is best to remove the rear wheels to give you more room to work around.
? If your Avalanche has an optional suspension system (i.e. Real Time Damping, etc.) remove the sensors.
? Always maintain a minimum pressure of 5 psi to prevent coil pinch. Place 35psi in bags before placing a load on the Avalanche?then lower pressure to ride height required. DO NOT add load or trailer and then add pressure
? Test for leaks by applying a solution of dish soap and water to all fittings.
? Recheck pressure after 24 hours. A 2-4 p.s.i. drop is normal after initial installation. If more than 5 lbs. retest with soapy water.

A whole lot of unnecessary work there snoball, just replaced mine, cause one developed a leak at the fitting, just raised the truck, scrunched the bag , pushed it into the spring and done, yea it takes a little maneuvering but it can be done, both sides, from start to finish and a pee break in the middle, 40 minutes.  No bolts to torque, no bolts to break loose.

Didit

 

[INresponse]

I'm interested to hear how are you backing up a triple setup like that. My rear visibilty when backing up my boat is almost zero so I wonder how do you see the second trailer?

You don't back up.  At least not much, and don't plan on turning.  You kind of have to plan your moves before you get there.  In a pinch you unhook the last trailer and move it aside until you get turned around.

Nice set up SnoBall.


Teksavy, have you considered a load distribution hitch with the equalizer bars?  I also recommend an anti-sway bar to help keep things straight at highway speeds.

 

[Snoball]

Hey Didit....congrats to you on replacing one without removing the spring. I tried to install it in the truck first. Not worth the hassle. But good to hear others are successful. 

It tows great with both trailers and tracks well. You really do not realize that it is pulling like that. A lot of people here in the southwest pull a 5th wheel trailer and a boat behind that, but that is a really long rig.
I considered a toy house, but we are able to keep both trailers inside the garage and we could not do that with a toy house.  The toy house is the best solution if you always take them along. 

 

[Didit]

Hey Didit....congrats to you on replacing one without removing the spring. I tried to install it in the truck first. Not worth the hassle. But good to hear others are successful.

 

hint to yourself and others that may try this mod, don't follow the directions, lol, just squeeze as much air out of the bag as you possibly can, THEN stick the little red stopper they give you, in the fill hole, at this point in time you can pretty much stick it where you want it and then reposition it up or down or sideways, whichever way you need to go to straighten it up inside the spring!

Didit

 

[Alaska_AV.]

I did mine through the spring also. jacked up with the suspension hanging. not hard at all

 

[teksavy]

Snoball- Your writeup rocks! Really wish I had it when I installed mine the night before we left for the beach. They say it only takes an hour to install, but it ended up taking me about 3 hours. I couldn't get the rubber spring bushings out from under the springs. Since the instructions said you needed to enlarge the hole to  1", I needed to get them out. Perhaps it was my lift that complicated things, but I don't see how you could enlarge that hole without removing that bushing out.

I ended up dropping the rear driveshaft, popped out the spings, modified the bushings, and reinstalled the springs. A lot of work, but I think it was worth it.

Here are the results:

Note, hardly any rear end squat. Man, my ass would be dragging without those springs. Thanks for the tip BUDMAN!

Teksavy, have you considered a load distribution hitch with the equalizer bars?  I also recommend an anti-sway bar to help keep things straight at highway speeds.

Luckily the trailer from Cruise America included a weight-distributing hitch, and it was great.. no sway whatsoever. The only downside was the the hitch they supplied for the receiver did not accomodate my lift too well, but I didn't have any problems. Just that the trailer was a  little low in the rear.

Also, lemme tell you... a 5.3L, with 35" tires and a 3.73 axle is NOT a good setup for towing that 24' trailer. It constantly downshifted and could barely make it over Cuesta grade. Floored, I was at 30 MPH and the trans temp got up to 250!! Needless to say, time for a fluid change.

So, do I go with 4.10's or 4.56's?

-Ed

 

[INresponse]

to decide gear ratios you need to do some math first.

http://www.4lo.com/calc/gearratio.htm#ratios

What are your RPM's now, in 3rd and in OD at various speeds, IE 45, 55, 65, 75, etc.

What RPMs would you like to run at those speeds?

What gears will get you to those RPM's?

It might help if you knew what your stock RPM's were at those speeds, but the calculator at the top of the page in this link can help you answer all these questions.

 

[teksavy]

Cool calc.. That will really help. You know, I've been thinking that 4.56s are the way to go. The RPM at 70 with the 4.56 and a 0.75 4th gear is only 2300 vs. 1900 now. In 3rd, it goes from 2500 (3.73) to 3100 (4.56). And we all know that the 5.3L has a great upper end and shi*ty low end.

Also, because the thing is so huge, I need more street Umph, and I rarely go over 70 in this huge lifted beast... Just can't stop in time. The brakes are scary bad.

Brake upgrade recommendations? I have 18's, so I can replace the calipers. Who has a good value?

What about ABS with the 4.56s? Will that be a problem?

Thanks guys!

-Ed

 

[Chopped_Burban]

Cool calc.. That will really help. You know, I've been thinking that 4.56s are the way to go. The RPM at 70 with the 4.56 and a 0.75 4th gear is only 2300 vs. 1900 now. In 3rd, it goes from 2500 (3.73) to 3100 (4.56). And we all know that the 5.3L has a great upper end and shi*ty low end.

Also, because the thing is so huge, I need more street Umph, and I rarely go over 70 in this huge lifted beast... Just can't stop in time. The brakes are scary bad.

Brake upgrade recommendations? I have 18's, so I can replace the calipers. Who has a good value?

What about ABS with the 4.56s? Will that be a problem?

Thanks guys!

-Ed

I've been looking at the SSBC and the BEAR brakes myself. They both have various combinations of upgraded calipers and oversize kits. None of them are cheap. Since I'm still riding on 17"s and can't do the oversize upgrade yet I opted for those "Green Stuff" brake pads for now. Those have been working great. Much better than the stock stuff and the upgrade was less than $200. I'll get more of an upgrade when I can afford it.

When I was researching brakes, I looked at a whole bunch of different charts for the upgrades, and the major difference in braking didn't really start to show until repeated braking was brought in to play. Don't get me wrong, I'd love to get an oversize set with some slotted rotors, and the repeated braking thing will come in to play going down long hills with a trailer, but when you start looking, match it to your realistic application. I don't see you driving it around town like a sports car with that sweet lift. When I do get around to an upgrade, I'm looking at a kit with oversize rotors, brackets to move the stock calipers out, and new pads. Can or two of paint for the calipers. I actually like the dual piston calipers that are on the Av. Just my opinions since you asked for some. Hope it's a little helpful.