Why does it tow so well?

[jsms264]

I picked up our new Sunline yesterday, and we very happy with the towing experience.

My previous TT was 28'3" long, weighed approx. 5,500 pounds with about 650 pounds of hitch weight. It was very high, I believe over 12' and over 2' off the ground. I use a Reese dual cam anti sway hitch set-up, with 600 pound bars. I know the bars were under weight. But all in all it was an OK towing experience.

My new TT is a 2005 264, 27'7" long, 6477 pounds, 845 pounds of hitch weight. The Sunline is less of a profile in height and not as high off the ground in comparsion to the previous. I kept the same hitch set-up but upgraded to 1200# bars.

The towing experience with the Sunline was ALOT more stable. Even tough the weight is greater. Why??? Is it the upgrade to the 1200# bars? I also noticed the position of the wheels on the Sunline are further towards the back of the Sunline in relationship to the previous TT, could that make a difference with stability? Could it be the lower profile?

I had an 1999 Ford F350 crew cab, 8' box, dually, 7.3 turbo diesel, totally overkill that I towed the previous TT with for 2 years. I wont compare the TV power difference, you can imagine that for yourself, but the stability with the Sunlne/1500HD is comparable. Why??

Is this real, or am I experiencing the new TT warm and fuzzy rush?

[sunnyseagull]

Hi and congradulations on your new Sunline ,and to answer your question I would say that the bars probly made a big difference and the way a floor plan is laid out and how balanced a coach is designed can make a big difference in the way that it tows. You didnt mention wheather or not your other camper had the same type of lay out as your sunline but that could add to the way it towed , I am glad that you had a pleasant towing expericence and happy camping and good luck with the new T 264 I really like my except for no bunks. Dan

[Sunline Fan]

Originally Posted by jsms264

Is this real, or am I experiencing the new TT warm and fuzzy rush?

I think it's some of both.

I know I swear mine hasn't towed as good as it did coming home, that is once the cams were set correctly and the trailer was no longer going down the Garden State Parkway sideways.

I think the bars have a lot to do with it. The 600's probably didn't do much for you before. Now, you've got plenty of bar and no stuff inside. They seemed to be balanced best when empty.

Just be very careful what all you put in and that you can have an even balance of your stuff before and aft of the axles...some more to the front if you have to, but NOT more to the back. Shouldn't be a problem with a front bedroom though.

Jon

[henryj]

jsms, you don't say if you also towed the old trailer with the 4ws 1500HD. If we believe GM's advertising, that is a particularly good tv that is very stable in lane changes as well as generally being more responsive. Too bad they dropped that option, but the price was prohibitive and they just didn't sell enough.

The heavier wd bars will definitely make some improvement. The 600 lb. bars would not be able to transfer enough weight; they would just flex and the tv would be tail heavy with a light skittish front end. In addition, it is possible, although not likely in your case, for light bars to leave too much weight on the hitch and make it more of a weight carrying rather than weight distributing hitch. Receivers and hitches have much higher ratings for wd than for wc so it is possible to overload a hitch with wd bars that are too light for the tongue.

Finally, Sunline did get it right with this aspect of frame design. Having the axles well aft creates an inherently more stable tt as well as putting more weight on the tongue. Although 10% tw is considered acceptable by many, 15% is better. Even so, the location of the axles is a design compromise. The further back, the more stable the tt, but the less maneuverable. So a 5 ft. longer tt will not likely have the axles 5 ft. further back as it would be too hard to get into campsites and too easy to run over curbs. The result is that poorly designed longer tt's often have axles that appear to be in the middle of the tt and tw that is lighter than that of a mid-size 25 footer.

In the end, your better towing tt is a combination of all these factors--plus the lower profile--with each one contributing cumulatively to an excellent towing experience. Enjoy--sometimes everything comes together like that.

Henry

[Tweety]

Sunline WAS fussy about the location of the axles and the balance of their coaches. For example, when we went to the factory to look at the QUE we noticed that the axle wasn't in the same place in the brochure as on the actual unit. Larue explained to us that their engineers made them move the axle to correct the tongue wieight.

[jsms264]

sunnyseagull...the previous TT was a rear bunkhouse, rear bath, mid-kitchen slide out design (Trail-Bay 26BHS). Funny you mention you like your 264 but no bunks. I have 2 children, and they wouldn’t use the bunks, it was a waste of space, they were the torpedo style.

Sunline Fan....yeah I was a little excited so it’s probably some of that as well, I thought so.

henryj.....I towed with the 1500HD for a full camping season, about 4,000 miles last year. The quadrasteer is absolutely fantastic, towing and daily driving! The wider stance of the rear tires helps with the stability and the maneuverability with the 4ws is wild. I am a huge fan of it, GM got it right except for the price. I have been in search of the perfect truck for a few years, started with a GMC 1/2 ton...too wimpy, moved to F350 dually diesel....to large needed a city block to turn it around but man could it tow, now the 1500HD is almost perfect, but really sucks bad on fuel consumption...I average under 8 mpg towing and 10 not towing, that hurts oh so bad!! It's my wifes daily driver, thank god we are only 3 miles from where she works.

[Mooney]

I get between 12.5 and 15.3 mpg reliably out of the 6.0 L with the addition of an AEM air filter and Hypertech program. This doesn't account for the extra time warming the truck up this winter. I just got the programmer, so I don't have towing or non-winter (warmup and defroster) numbers yet. It's a matter of keeping the right foot off the silly pedal... your rear axle may be a limiting factor though, with the added weight and rolling resistance with the 4ws. I used to get more mpg without the adders, but it took me too long to get anywhere. I am waiting to see what I can get out of her once gas prices go back up- until then, I am too impatient to putt along.

I got the Hypertech off fleabay for $170 and it's already paid for itself (plus it's fun to dust a Beemer or Mustang off the line...esp. when they "obviously" think they're the cat's meow...). I think the air filter cost $35 or so.

As a big rig driver, I can tell you that center of gravity and tongue weight are everything.

Enjoy!

[jsms264]

Mooney...

I heard and read a little about the add-on technology available. It scares the heck out of me though, I've heard the programmers can really mess up your truck of not installed properly? Can you really program it run that much more efficiently to get 3-4 mpg better? In my case a gain like that would be HUGE! Also, the 4ws is "fly by wire" technology and I would really be scared to mess with the trucks computer.

Is it difficult to install?

Any other opinions/experience on this out there?

Maybe I'll start a post on this subject...

[nasa42a]

Joe....

Mooney, Tweety, John B and the others can put you on the right technical trail.

I'm not so quick with technical/mechanical performance improvements....

But let me offer you a non-technical massive gas mileage improver. Keeping your average speed at or about 3-5 MPH under the posted speed limit on Interstates will increase your gas mileage ABOUT 10 PERCENT as compared with sticking with the average traffic flow. Average traffic flow, I think, is at least 5-7 MPH over the posted limit on interstates. An amazing and money-saving difference. The major effort here is in adjusting necessary travel time.

A fringe benefit of doing this is that traffic is so busy zooming past than nobody can cut in sharply enough in front of you to cut you off!

Frank

[Viking]

Frank,

Good advice, especially since I am sure I read in a post on tires, that trailer tires (=ST rated) are only rated for 65 mph.
I did not know that until I read it here.
I keep reading and learning!

Roar

[kanyonkitty]

Because it's a SUNLINE



sorry couldn't resist saying that

[Mooney]

The Hypertech and others are easy to use- they plug right into the OBDII port under the dash, answer some yes/ no questions, and it does it itself.

The only thing is that it is sensitive to OnStar, and aftermarket electronics- it only wants to work with a stock (or less) electrical system. I was having an issue with mine until I unplugged the "dinger" attached to my aftermarket stereo- it just wouldn't go until it was disconnected. I pulled the fuses out of my subwoofer amp, hd radio, stereo, "dinger", cap interior and brake lights, and pulled the plug for my brake control. This added about 5 minutes (I know where all my stuff is and how to get at it) to the process each way (5 to unhook it all, 5 to hook it all back up).

The performance gain is huge, you can really feel it (they say it's about 30hp and 35 ft/ lbs. at the rear wheels with regular gas tuning)- and you can run either regular or premium gas. I have mine set for regular gas, and so far I really like it.

The thing that kills us 6 liters is the gearing- the 4.10 gears really keep the engine ready to rock and roll. I wish I had the extra $$ to get the Gear Vendors Over/ Underdrive kit- it's a transmission add-on that splits the gear ratio, so it would be like having an 8 speed, with a 2 stage overdrive. Supposedly drops the rpm at 65 by 500-800. Truck would just float along real smooth-like then... My mechanic said he put one on Mo Vaughn's (formerly of the Boston Red Sox for anyone who doesn't remember him) Chevy Impala SS and it got near 28 mpg highway, at 450+ hp. That's just silly! :P

[JohnB]

Hi Joe (jsms264)

In your post your asked "why does it tow so well" and you said
"The towing experience with the Sunline was ALOT more stable."

Are you refering to "pulling" easier or "towing more stable" feeling in the truck or both?

Try and explain some of what you felt and I'll try to fill what is going on with the TV and TT to maybe match up with it.

Thanks

John

[jsms264]

Hey John,

OK, let me give it a shot...

1st power....Very simular to the previous TT, the rpm's at 60-65 mph range was the same, no additional shifting, and acceration almost the same. Even the gas mileage was just as bad, 7.6 both ways. All in all power was not much different, but I could tell I had an additional 1000#'s or so back there.

2nd stability....This is where I experienced the biggest difference. Overall, the Sunline stayed very straight and level behind me. No bouncing on highway imperfections, very little "push/pull" from semi's passing me. This is a stretch, but it almost felt like the TT was part of the truck, an extension, as compared to dragging something behind the truck. With my previous TT (which towed fairly well) it was consistently in a state of movement, when I would look down the side of the TT in tow while moving at highway speed I could see the movement. When i towed the Sunline and watched down the side it was like a rock, almost no movement. I dont want to paint a picture of my previous TT being a two hands on the wheel white knuckler, but even tiny movements are felt....do you know what I mean?

Here's a breakdown of my total guess as to why it so much more stable,
40% psychological because it's a new Sunline (thats for kanyonkitty) and being excited,
30% for the 1200# bars,
20% TT design as to placement of axles in relation to weight distrubition of unit,
10% for a lower profile, less air drag.

The one unknown is how much of a variable was my toolbox add-on off the rear bumper? It added 18" to the overall length and about 100#'s for the frame extension/box/contents back there....but could that really make that much difference?

[JohnB]

Originally Posted by jsms264

Hey John,

OK, let me give it a shot...

1st power....Very simular to the previous TT, the rpm's at 60-65 mph range was the same, no additional shifting, and acceration almost the same. Even the gas mileage was just as bad, 7.6 both ways. All in all power was not much different, but I could tell I had an additional 1000#'s or so back there.

2nd stability....This is where I experienced the biggest difference. Overall, the Sunline stayed very straight and level behind me. No bouncing on highway imperfections, very little "push/pull" from semi's passing me. This is a stretch, but it almost felt like the TT was part of the truck, an extension, as compared to dragging something behind the truck. With my previous TT (which towed fairly well) it was consistently in a state of movement, when I would look down the side of the TT in tow while moving at highway speed I could see the movement. When i towed the Sunline and watched down the side it was like a rock, almost no movement. I dont want to paint a picture of my previous TT being a two hands on the wheel white knuckler, but even tiny movements are felt....do you know what I mean?

Here's a breakdown of my total guess as to why it so much more stable,
40% psychological because it's a new Sunline (thats for kanyonkitty) and being excited,
30% for the 1200# bars,
20% TT design as to placement of axles in relation to weight distrubition of unit,
10% for a lower profile, less air drag.

The one unknown is how much of a variable was my toolbox add-on off the rear bumper? It added 18" to the overall length and about 100#'s for the frame extension/box/contents back there....but could that really make that much difference?

Hi Joe

Sorry this took so long to respond back but I wanted to give you some things that can contribute to what you felt. Work has been on overlaod here lately and affecting my Sunline Club habit...

HenryJ hit a lot on this. I’ll add some more. I had a similar drive train K2500 Suburban (6.0 with 4.10 rear axle) complete with Quadrasteer that I used a lot to tow my T2499 and a limited time on my T310SR. Towing the T2499 around I learned a lot about the hitch and the specific GM truck. Your hitch is the same as I use, Reese HP trunnion bar hitch with the DC.

Now to what you felt. The pulling department. The Sunline has a better wind profile on the front then your older TT. This helps but still pulling the brick thru the air we tug around has it effects on the pulling performance of the truck. So here since the T264SR is already a slide camper and up higher, there most likely is not that much shift between your old and new camper.

In comparison, wind drag difference between a Sunline Non slide and a Sunline Slide is a lot bigger. The non slide camper has a lower profile to the ground and the front top of the TT is tapered more. The newer slide models while still low in profile to many other brands, is still higher. And the front top of the trailer is not as tapered as. As a point of reference on my K2500 Burb, it pulled the T2499 filly loaded, about 6,800# with water about the same as my unloaded T310SR, about 7,300# . And the gas mileage was about the same. 7.5 to 9.0 on the T2499 pending on the wind doing 60 MPH in 3rd gear. The T310 was 8.0 or lower. You seemed to have validated this as well.

Now to the stability feeling. This is where Sunline shines and then there is the truck part. As others have said Sunline worked hard at making sure the TT balanced out well giving good tongue weight. 13% to 15% in many cases. That % Tongue weight all by itself creates a stable towing TT.

Next comes the truck and the WD hitch. Here is the biggest feeling where setup can change things. On your old camper you had 600# WD bars. Those are very light and very likely too light for your old trailer in order to obtain proper WD on the Chevy.

Next is, what is optimum WD on a Chevy? Let’s take yours as most all GM SUV’s or PU’s have the same requirements. (Ford too for that matter) Your truck by the age of it I’m almost sure has torsion bar front end suspension. Does it? And you have the 1500HD which is for all practical purposes a 3/4 ton truck. That front end rides best with the WD hitch set to return the front end back to unhitched height and weight. Going over unhitched, meaning adding more weight to the front end does not do the torsion bar suspension a lot of good. There are lower control arm jounce bumper stops in it that will likely get cracked and beat up if you lower the front end a lot beyond normal Z trim height. (Normal ride height)

And if you go a lot less then unhitched weight/height then the front end of the truck can sort of float around.

So for the WD it needs to be set up to return the front end to unhitched height and weight. This puts the front end back where it is most optimum. If you need help with how to do the WD setup, ask away. We have several here that can help and I too can type some more.

By upgrading to the 1,200# WD bars you can now transfer the weight properly to the front end. Using 600# bars on a 800# tongue will have issues and most times just cannot get the weight back up front like it needs too. To optimize WD setup you need a few things. Actual loaded and scaled tongue weight. And is that in the 13% or more of the TT GVW, again loaded. Then how much weight is in the back of the PU bed aft of the rear axle? The WD bars are lifting this too. Meaning if you have 800# of tongue weight and 200# of fire wood, bikes, BBQ grill aft of the rear axle in the truck bed that is 1,000# the WD bars need to work on.

Towing stability also deals with tire pressure. Each brand tire has different effects of towing sway/sogginess. I’m assuming you have LT’s, And I’m assuming the driver door side sticker might say, 50 psi front and 75 or 80 psi rear for full load. Is this correct or what is it? And what brand tire/size?

Even if you have LT’s tires in the size you are talking about, 16” I’m thinking, the rear should be at max side wall pressure when towing. This stiffens up the rear of the trucks from shifting left to right. The front pending brand can be an experiment. The door stick is the place to start. Again I’m assuming 50 psi is the pressure for full axle loading on the front. On my Burb I started with the Steel Tex stock GM tires. For towing they worked great at 50 psi. Very stable. Then I changed to Michlean LTX LT’s and they where great non towing. But towing on the Burb, 50 psi gave me instability that never existed before. I finally figured it out and 60 psi I saw a global shift back to close to where I was. I tried 65, 70 and 75. And ended up on 65psi as the best option. 75 and up I had front end bounce from road bumps which created a non desirable pounding and wander. So I went back to 65 which was 5 psi over the global shift area and still did not have the hard bounce from concrete road joints.

Now you mentioned the truck and TT where like one together. This comes from 3 things. Proper WD on the TV, the right tire pressure with stiffness and the DC set spot on centered.

The only way to dial in the DC to being perfect is with a tracking test. Have to find a level parking lot and one where you can drive exactly straight for about 100 feet. The truck and trailer now are tracking in natural rhythm. Then you have to get out and look to see that the DC is exactly centered over the cam. If not then an adjustment needs to be made. And then from there after, mark the WD bars left and right and always use them on the same side. The bars are not machined and as such they are different slightly in length. They will then wear into being a perfect match to the cams. If you never did the tracking test, then when you added the new WD bars it may have been better to being centered. I know between 800 and 1,200# WD bars the bar length in some case was like 3/8" different.

So in recapping if you want to optimize the towing setup need these things to fall in place.

1. TT has proper tongue weight and balance, loaded with camping gear. Shoot for 13% to 15% of total TT loaded GVW. To do this you have to weigh the trailer.
2. Load the TV with all camping gear and air tire pressure to max side wall on rear and front to at least door sticker. TT tires should be at max side wall cold pressure.
3. Adjust the WD hitched to return the front end of the truck to unhitched height as close as you can get. This may be at unhitched or 1/8” high. ¼” high is OK but you are now approaching the limit where you can do better.
4. Once the WD is set right, raise lower the hitch head on the hitch shank to level out the TT. If you cannot get right on level, then go slight nose down verse nose up.
5. Recheck WD settings again when the TT is leveled out. Front should be at unhitched height tolerance, rear of TV will most likely be 1” to 1 ½” on your setup down from unhitched.
6. Set the DC and mark the WD bars.
7. After a few rides around the block check the fender heights again. The springs settle in the numbers will change slightly. If you where ¼” high on the front you could now be 3/8” to 7/16” high which is time to tweak if you want this as good as it can get.
8. When all done, take entire rig to the truck scales and get 3 sets of weights.
a. TV and TT hitched and WD engaged.
b.TV and TT hitched and No Wd bars on. Just stay on the scale and get a reading with the WD bars off.
c.Drive off scale and unhitch. Then weight just the truck
d.All above 3 weight fully loaded to go camping and all axle by axle.
9.Then compare all TT and TV axles and truck GCWR and GVWR and TT GCW to the GVWR. See that all ratings are at or under the specs.

Once you do those 9 steps you will have the truck and camper as optimum as it can get with what you have. Along the setup and investigation trail you may find a few problems that need to be fixed, like a hitch shank that will not level out the TT, or low tongue weight, or very high tongue weight and the rear of the truck is over the axle ratings. Those you fix as you go.

The 1st time thru setting up a tow rig to be optimum may seem like a lot. And the 1st time it is as you are learning along the way. If you have a life line to someone that has done this before and can explain it to you, it cuts down the learning curve drastically. There are a number of us here on Sunline club that are willing to help just for asking. Once you have been thru this, making changes then gets a lot easier and faster. Why, because you now understand it.

To your rear boxes on the other TT, I too have done this but I had special problems I was going after to fix. And in my case it was 20% plus tongue weight and 1,200# was all my K2500 Suburban could hold up. So I moved things around and got it down to 14.5% no fresh water and 16% with fresh water. The rear living area campers we love, have the gear loading to the front problem. On your old TT, the rear box will lower the tongue weight. As long as it does not go below the 13% number then you can work with it. If it goes below this, then you have to move things around to get it back up.

Hope this helps and good camping to you and your family in your new Sunline

John

[jsms264]

John,

OMG, wow! Thank you, I am humbled by the amount of information, you are amazing! Did you say your an engineer! I never have put that much thought into the whole set-up, this post and your response in particular has been eye opening. You asked what tires I have on my TV, they are Goodyear Wrangler pro series load range E, 16".

One more question...I promise! Where do folks go to weight their set-up, in particular some place that will let you spend that much time getting all the weights?

[kanyonkitty]

Many quarries have their scales available 24/7, feed stores, truck stops, and I'm sure the guys will chime in with other places.

The trick is "which" one can you spent a lot of time at without being in their way.

Kitty

[PTHutch]

Originally Posted by jsms264

One more question...I promise! Where do folks go to weight their set-up, in particular some place that will let you spend that much time getting all the weights?

Hi Joe,

I've weighed my trailers at CAT scales and they've always been vary helpful and understanding. If there are no truckers waiting to be weighed they have no problem with you making multiple weightings. After all, they charge for each weighting

I’ve weight our current trailer at the CAT scale located at the Geneva Exit (Exit 42) of the NYS Thruway. They allowed me to weigh our setup both hitched and unhitched. If interested, here's a link to my Tow Vehicle and Trailer Measured Weight Results post where I posted the results of my weighting and how I did it.

Hope this helps and answers your question.
Hutch

[larry818]

There's a metals recycling place near me that's closed on the weekends. Their scale is out front and they leave it on. I've seen a few places like this, usually associated with factories and trucking.

[henryj]

John, thanks for taking the time to write such detailed posts. These are all timely reminders for us as we set out on a new camping season.

A couple of my own experiences with an Equal-i-zer hitch...
I gave up on our previous 1500 after getting weighed on our 2499 shakedown cruise. The hitch plus a light load for a 2 day trip added 1280 lb. to the tv putting it just over its GVWR. Interestingly, the rig fully loaded for a 4 wk. trip to FL added only 1180 lb. to our 1500HD. On the 1500 only 4 washers were used to get adequate tilt on the hitch head. On the 1500HD, with its high rear end, I'm using 7 washers. Equal-i-zer's instructions are to adjust the washers and height of the wd brackets until the front and rear suspension of the tv compresses by the same amount. I felt uneasy about this because of the significant nose down attitude on all HDs, but after consulting their tech support to verify for my exact situation, I did adjust for equal compression. I got stuck on the very next trip and switched back to slightly more compression on the rear end just to add more weight. I now have just slightly less weight on the front axle loaded than solo and am happy with that, but will do more tweaking this year especially with tire pressures. I replaced the OEM shocks all around with Bilsteins, but haven't towed with them yet, so that alone will no doubt require some psi adjustments.

So, John, my experience is also to return the loaded front height and weight to the unloaded, despite what Equal-i-zer says. I wasn't aware that this was better for a torsion bar front end so that is an added bonus.

Another thing I'm working on is the slight attraction a tt feels for passing semis. I think ours is stable enough--some semis don't affect it at all--but the shape, size and speed of the semi does make a difference. I think the presence or absence of cross winds also plays into this. Does anyone have a magic bullet here, or is this something we all live with to a certain extent when we drive 60 mph on just about any Interstate in the country?

Henry