Suspension enhancements for trailer towing

[HappyCamper]

I'm new to this forum and Yukon ownership, I've found this forum to be extremely helpful. As I've been searching the posts, I have not found this exact topic, but there is a lot to go through here. So apologies in advance if I am asking something that has already been discussed.

I recently picked up a 2013 Yukon xlt with hd towing package, we absolutely love it. Now that we have a vehicle capable of towing, we want to get a travel trailer. Looking at an unloaded weight of 5000 to 5500, to keep total loaded weight under 7000. The book says my yukon with HD towing package is 8200 max. I don't have the trailer yet, but I am expecting that it will sag the back end and I am researching suspension enhancements. The 2 items I am considering are the Firestone coil-rite air helper springs and the sumo springs solo custom helper springs (jounce sytle, not the one that goes on the coil spring). Obviously, I will also get a WD hitch when we get the trailer.

First of all, if anyone has experience with any of these products, or others, I would love to hear your thoughts. What I would really like to know is, is it wise to combine these 2 products together?

I am thinking that the air bags would provide most of the extra support, and the sumo spring would only engage when the air bag gets stressed. Also, the sumo spring would act as a backup if the air bag loses air. Is there any danger of having both products on the vehicle? Just looking to provide the safest and most stress free ride when pulling the trailer as I'll have my most precious cargo (my wife and 3 boys) in the yukon when we travel. Am I over thinking this and either one of these products individually will be sufficient and its just a matter of preference?

Thanks!

 

[HappyCamper]

Bonus question, how is the transmission cooler included with the K5L HD towing package. It looks a little small, should I replace it with a bigger one?

 

[SunlitComet]

I use Firestone bags for leaf springs and they are totally worth it. 8 years in they never leaked or failed and they support the entire rear weight. Your coil type kit would be great but if you can buy a compressor and self leveling kit to control them as well. And the compressorhas other pros as well. Just make sure you invest in a weight distribution hitch system first before getting the extras like a compressor of self leveling kit. Otherwise you will not be disappointed by the Firestone air bags.

 

[intheburbs]

You're probably overthinking this a little.

1) The stock transmission cooler is fine.
2) If you have a properly-sized and set up weight distribution system, the Yukon should be completely level, as if the trailer wasn't even attached.
3) 7,000 is starting to push it for a half-ton truck. I'd look for "half-ton towable" trailers, with a dry weight in the 4500-5000 range. That would put your loaded weight around 5500-6000, which, IMHO, is about the sweet spot for these trucks.
4) If it was me (and I used to tow a LOT with my '01 half-ton Burb), I'd do three things to the truck:
a) upgrade to LT tires, so I can air them up to 40-50 to firm things up when towing. The stiffer sidewalls will also help make for a better tow.
b) Get new shocks; probably Bilstein 4600s. This will better control the ride and minimize porpoising.
c) get a new rear diff cover with cooling fins. The rear axle is more worrisome/troublesome than the transmission, and the most likely item to break from heat/towing.


I've been towing for over 10 years, have had 5 different trailers and have used three different tow vehicles. We vacationed all over the US, and I've logged at least 25,000 miles of towing, and I've also broken stuff. Also have three kids, they're all in college now.

ETA: Our first rig, zero modifications to the Suburban other than E load tires, notice sitting perfectly level.

 

[kbuskill]

Check your RPO codes in your glove box for Z55 Autoride suspension.

If you have this option then you will already have the auto leveling rear suspension which consists of air shocks and a compressor in the rear with level sensors. The Air lift bags inside the coil springs make for a nice upgrade to the overall setup. Air you helper bags up before hooking up to the trailer and then check the pressure again afterwards to be sure your not exceeding the pressure rating of the bags.

I would also upgrade the transmission cooler to something like the Tru-cool max 40K.

I don't think you can have "too much" transmission cooling while towing. They also make transmission pans with cooling tubes. They are a deeper pan so they hold more fluid which, again, is a good thing.

 

[HappyCamper]

You're probably overthinking this a little.

1) The stock transmission cooler is fine.
2) If you have a properly-sized and set up weight distribution system, the Yukon should be completely level, as if the trailer wasn't even attached.
3) 7,000 is starting to push it for a half-ton truck. I'd look for "half-ton towable" trailers, with a dry weight in the 4500-5000 range. That would put your loaded weight around 5500-6000, which, IMHO, is about the sweet spot for these trucks.
4) If it was me (and I used to tow a LOT with my '01 half-ton Burb), I'd do three things to the truck:
a) upgrade to LT tires, so I can air them up to 40-50 to firm things up when towing. The stiffer sidewalls will also help make for a better tow.
b) Get new shocks; probably Bilstein 4600s. This will better control the ride and minimize porpoising.
c) get a new rear diff cover with cooling fins. The rear axle is more worrisome/troublesome than the transmission, and the most likely item to break from heat/towing.


I've been towing for over 10 years, have had 5 different trailers and have used three different tow vehicles. We vacationed all over the US, and I've logged at least 25,000 miles of towing, and I've also broken stuff. Also have three kids, they're all in college now.

ETA: Our first rig, zero modifications to the Suburban other than E load tires, notice sitting perfectly level.

@intheburbs Thanks for the reply. As I got the Yukon pre-owned from a dealer, they put new brakes and nice new LT tires (Nitto Ridgegrappler LT285/70R17) on it. The rear shocks look new too, but the salesman didn't mention them. Question: What will Billstein 4600s do that the air bags wont? Also, thanks for the tip on the diff cover, I didn't even think of that. Seeing as I don't have the trailer yet, should I wait till I see how the trailer rides before I consider any modifications to the suspension? From my research, I am reading that most people who tow close to the top end of the towing capacity have done something to help the suspension so I was figuring I'd have to do something, just trying to decide which direction to go.

 

[HappyCamper]

Check your RPO codes in your glove box for Z55 Autoride suspension.

If you have this option then you will already have the auto leveling rear suspension which consists of air shocks and a compressor in the rear with level sensors. The Air lift bags inside the coil springs make for a nice upgrade to the overall setup. Air you helper bags up before hooking up to the trailer and then check the pressure again afterwards to be sure your not exceeding the pressure rating of the bags.

I would also upgrade the transmission cooler to something like the Tru-cool max 40K.

I don't think you can have "too much" transmission cooling while towing. They also make transmission pans with cooling tubes. They are a deeper pan so they hold more fluid which, again, is a good thing.

@kbuskill I don't have the Z55 auto ride, As I understand that was standard on the Denalis, and an option on the SLT(which I have) I was able to obtain the PDF of the RPO codes from the GM support website. It was super easy, just start an online chat and ask for it. They ask for your address and vin number and 5 minutes later you have it in email. I didn't know the codes were also in the glove box, thanks for the tip on that.

As for when to put air in the airbags, I have also read that some people put the tongue weight on the hitch, THEN inflate the bags until it just starts to lift the back end. Any idea if that way is better or worse then pre-inflating the bags?

I think I will look into beefing up the trans cooler. A few weeks ago I was towing a pop up camper (2500 lbs) up a steep windy mountain road and the trans got up to 220 for a very short period of time, which made me nervous. I was probably pushing it too fast, and I don't anticipate taking the travel trail in situations like that, but it got me thinking about doing something with the cooler. Question: Should I leave the existing cooler in place and daisy chain another on to it, or replace the existing one completely. I also like the pan with the cooling tubes.

Back to the original question: Is combining airbags and jounce springs a good idea, bad idea, or just overkill?

 

[kbuskill]

@kbuskill I don't have the Z55 auto ride, As I understand that was standard on the Denalis, and an option on the SLT(which I have) I was able to obtain the PDF of the RPO codes from the GM support website. It was super easy, just start an online chat and ask for it. They ask for your address and vin number and 5 minutes later you have it in email. I didn't know the codes were also in the glove box, thanks for the tip on that.

As for when to put air in the airbags, I have also read that some people put the tongue weight on the hitch, THEN inflate the bags until it just starts to lift the back end. Any idea if that way is better or worse then pre-inflating the bags?

I think I will look into beefing up the trans cooler. A few weeks ago I was towing a pop up camper (2500 lbs) up a steep windy mountain road and the trans got up to 220 for a very short period of time, which made me nervous. I was probably pushing it too fast, and I don't anticipate taking the travel trail in situations like that, but it got me thinking about doing something with the cooler. Question: Should I leave the existing cooler in place and daisy chain another on to it, or replace the existing one completely. I also like the pan with the cooling tubes.

Back to the original question: Is combining airbags and jounce springs a good idea, bad idea, or just overkill?

First of all let's get some terminology straight.

Air bags are a bellows style bag like this...


Air helper springs look like this...


And installed...


As far as when to inflate the helper bags... I guess it's personal preference.


True (bellows style) air bags don't care when they are inflated because they provide the actual lift. You could take the coil spring out entirely and the bellows will still lift the truck.

Helper springs, on the other hand, don't really provide lift. What they do is "fill in" the gaps between the coils of the springs making it harder for the coil spring to compress (stiffer).

By inflating before compressing the spring the air bladder has a chance to bulge out between the coils.

Inflating after means it has to try to push it's self between coils that are already compressed and spread them out. Seems like it would be harder on the bladders to me but that is just my way of thinking.

As far as daisy chaining the coolers... again personal preference but it also depends on the size cooler you are trying to add. If you get the big 40k then you probably won't have room without rearranging some things. I guess it depends on what you want to spend as well. The down side to daisy chaining them is it adds more potential for problems i.e. more connections to leak, more hoses to fail, etc.

I would probably just get the 40k and install it by itself and forget about it.

As far as "Air bags" (helper bladders) and jounce springs... i dont see why they would interfere with each other or cause any problems if used together since they install in different locations.

I cannot speak to how well the jounce springs will function as I have never used them but they seem like they would be ok. I think if you were ever in the situation where you needed both then you would be far exceeding the weight limits for towing with your Yukon and perhaps it would be time to look at the 3/4 ton (2500) Suburbans.

 

[intheburbs]

@intheburbs Thanks for the reply. As I got the Yukon pre-owned from a dealer, they put new brakes and nice new LT tires (Nitto Ridgegrappler LT285/70R17) on it. The rear shocks look new too, but the salesman didn't mention them. Question: What will Billstein 4600s do that the air bags wont? Also, thanks for the tip on the diff cover, I didn't even think of that. Seeing as I don't have the trailer yet, should I wait till I see how the trailer rides before I consider any modifications to the suspension? From my research, I am reading that most people who tow close to the top end of the towing capacity have done something to help the suspension so I was figuring I'd have to do something, just trying to decide which direction to go.

Airbags and shocks are doing two different things. Airbags will (theoretically) help carry the load. Shocks, like the 4600s, will better control bouncing/porpoising. When I started towing with my 2500 Burb, the bouncing was pretty bad on certain roads, and the 4600s were just about universally recommended on RV boards, so I got them. Made a night and day difference in the ride.

Be careful about making suspension mods. It may make you more prone to overloading the truck. The most important number is your rear axle weight. That's the one you'll most likely exceed first, and the rear axle is the weakest part of the powertrain. I had the self-leveling shocks on my '01 Suburban, so regardless of the tongue weight/load, it never sagged.

 

[swathdiver]

...and the trans got up to 220 for a very short period of time, which made me nervous.

220 is fine with Dexron VI. The warnings don't start until around 260. Keep clean fluid in it.

See Post #290 here:

https://www.tahoeyukonforum.com/threads/useless-information.97483/page-29

Some food for thought. At the beginning of summer a couple of fellas replaced their stock coolers with those 40K coolers that were so large as to restrict airflow across their radiators. The solution for them was to lower them down some below the bumper to get more air across the radiator. I do not remember what kind of temps they are seeing with them now. Personally, I think the stock one is fine. I read somewhere that these trucks were designed to tow through Death Valley.