Towing with XT

16506 Views 45 Replies 8 Participants Last post by OCRentAPopo, Oct 21, 2012

OCRentAPopo

Discussion Starter · Oct 4, 2012

I'm hoping to tow a Spec3 racecar (spec weight w/ driver 2900lbs) on an aluminum double axle trailer with brakes (1300 lbs) with a 2005-2009 Outback XT manual. So, I'm looking at 4200lbs loaded trailer weight with a corresponding tongue weight of roughly 420lbs (10%).

The US towing specs are 2700lbs gross trailer weight and 200lbs tongue. Apparently, European models (self-leveling suspension?) are rated at nearly 4000lbs though I haven't found tongue weight.

I figure I can stiffen up the suspension and get that at least as good as Euro spec with King Springs, maybe stiffer struts of some kind, and upgraded swaybars. I'm not sure how to increase max tongue weight, though.

Long story short, any thoughts on how to increase the max tongue weight? What's the weak link?

I've done tons of searching on this forum, legacygt and subaruforester etc. with no luck. I'm aware that this might be dangerous. Please don't respond with safety first, buy a truck, think of the children etc. Thanks for any responses.

21 - 40 of 46 Posts

OCRentAPopo

Discussion Starter · #21 · Oct 5, 2012

Alright my craziness presented itself again last night. I started thinking about tongue weight and how it's similar to cargo weight, so long as the cargo is located rear of the rear axle. People put whole replacement engines and loads of gravel in the back of Outbacks no problem. I wouldn't think twice about putting 400lbs of crap in my rear cargo area so why not tow w/ 400lbs of tongue weight?

Counterargument: When you brake the tongue-weight increases due to negative acceleration and weight shift. So, if the tongue weight at a standstill is 400lbs, the max tongue weight while braking could easily double. There are also lots of variables like wind, incline and potholes to consider.

I dunno, maybe an extended towing subframe and weight distributing hitch isn't such a terrible idea. Also, anything rated to tow 4000lbs is not fun to drive and definitely not available in a manual transmission.

Seabass

· #22 · Oct 5, 2012

Problem is where that 400 lbs is located. Directly above the rear axle is no problem. Behind the car is the problem. The rear springs will help slightly, but all of the struts are way underdamped to deal with those forces. You'll end up with the trailer telling the car where to go.

OCRentAPopo

Discussion Starter · #23 · Oct 5, 2012

Seabass said:
all of the struts are way underdamped to deal with those forces. You'll end up with the trailer telling the car where to go.

The suspension is easy to modify. I'm already planning stiffer springs, thicker swaybars and, if need be, firmer struts. I'm not aware of any off-the-shelf struts that would work for the Outback, but I'd guess I can get some Koni inserts to work just fine.

It's really the unibody I'm concerned about. If that won't buckle, the rest can be modified to work.

subiesailor

· #24 · Oct 5, 2012

OCRentAPopo said:
The suspension is easy to modify. I'm already planning stiffer springs, thicker swaybars and, if need be, firmer struts. I'm not aware of any off-the-shelf struts that would work for the Outback, but I'd guess I can get some Koni inserts to work just fine.

It's really the unibody I'm concerned about. If that won't buckle, the rest can be modified to work.

#1 issue is the unibody you can always find a spring that will support weight what that spring and suspension is mounted to might have a different opinion on what it is willing to support.

Anything mounted to the car behind the rear suspension assembly is in effect levered off the main structure of the car which is rear wheels to front wheels everything beyond those is simply window dressing.

Regardless of weight you won't be doing MT towing with the XT for very long in DC given your clutch will go up in a cloud of smoke.

OCRentAPopo

Discussion Starter · #25 · Oct 5, 2012

Towing with XT v2:

Spec3 Racecar: 2900lbs
Towing Dolly: 500lbs
Tongue Weight: 195lbs (((2900lbs / 2) + 500lbs) x 10%)

This seems more reasonable. Also the tongue weight calculation is a random guess and probably inflated; thoughts on the math there? I just have to hope I don't wreck/break the racecar such that it requires a flatbed. Even so, the risk of occasionally paying a tow company is better than owning a big dumb automatic SUV. Bonus: tow dolly will take up less room than trailer.

subiesailor

· #26 · Oct 5, 2012

OCRentAPopo said:
Towing with XT v2:

Spec3 Racecar: 2900lbs
Towing Dolly: 500lbs
Tongue Weight: 195lbs (((2900lbs / 2) + 500lbs) x 10%)

This seems more reasonable. Also the tongue weight calculation is a random guess and probably inflated; thoughts on the math there? I just have to hope I don't wreck/break the racecar such that it requires a flatbed. Even so, the risk of occasionally paying a tow company is better than owning a big dumb automatic SUV. Bonus: tow dolly will take up less room than trailer.

Unibody and tongue weight no longer an issue - weight behind car pushing car without contributing much weight ie traction to the rear of the OB - would be your primary problem the tail wagging the dog effect. However 2900lbs if your being very conservative ie heavy on your numbers is FAR FAR FAR better than the duel axle flat bed trailer + race car wagging the dog.

However! Can you trailer brakes on a dolly? I'm Asking given I have no idea but I would assume you can put brakes on anything with an axle and wheel on it. Which case with a good trailer brake set up on the dolly your only major issue is the tail wagging the dog due to reduced tongue weight from the dolly. Fixable by packing your 200lb track tool box in the back of the OB. So this might be workable however if your doing fairly long trips in traffic on a regular basis I predict your replacing the XT with a Yukon shortly given you would much rather go race than not.

OCRentAPopo

Discussion Starter · #27 · Oct 5, 2012

subiesailor said:
Can you get trailer brakes on a dolly?

Yes. A quick search found at least one place that sells dollies with electric brakes. Many others with surge brakes. I'd go electric.

2006 OBXT has a curb weight of 3500 + tools/fuel + people. Dolly + Racecar = 3400. Tail wagging the dog seems like a concern but not a horrendously stupid deathwish.

I'm sticking with the manual. Don't care about traffic or replacing clutches. The clutch in my '97 Outback (which does not tow anything but does get thrashed) has 94k on it with no slippage. I figure I can deal with half that lifespan and still be fine with it.

Seabass

· #28 · Oct 6, 2012

You'll probably be ok with that setup as long as the dolly has brakes.

The issue with the underdamped struts will still be a problem though. It is also the fronts that will cause problems. There aren't a lot of aftermarket shock options for the xt. But if you're willing to drop the height to legacy height, you'll have more options. The tail wagging is not fun, but you'll figure out what conditions cause it and it can be avoided. When i was towing, it only happened above 55. It got scary at 60!

aftCG

· #29 · Oct 6, 2012

I just got done towing my son's Toyota Camry (broken timing belt) using a dolly behind my '05 XT.

I didn't feel like it was dangerous but I won't be doing it again. XT brakes are not exactly capable of stopping that much rolling mass. My overload springs did a phenomenal job of keeping the car level but as Seabass points out the underdampened struts amplified the back and forth weight shifting.

In the past I've pondered getting a sailboat on a trailer and using my car to tow it. I now know what line I wouldn't cross even for short haul work

ScoobyRu

· #30 · Oct 10, 2012

I don't endorse this, but I think the best way to strengthen the unibody would be to use the Australian tow hitch. They aren't that expensive to buy used, but the shipping is going to be expensive (400+ dollars). It's a class 3 and should allow to use a weight distributing ball mount. I don't know for sure if it will mount to a US car, but I think it will. I looked into getting one, and it seemed like all the mounting points were there. Be warned though, your car will no longer meet US bumper specs.

Contrary to popular belief, a "weight distributing" hitch doesn't put any extra load on the car. It's the extra mass of the trailer that requires the beefier hitch. The ball mount is what handles the spring-compression force of the weight distributing hitch. If you have a 1,000 pound tongue weight trailer, and a (2) 500# weight distributing springs, the net down force ("tongue weight") on the hitch is 0. The "weight distributing" factor is in reality, the lack of weight on the back of the vehicle that normally pitches the vehicle up, robbing weight off the front wheels. Keeping the normal amount of weight above the front wheels is why "weight distributing" systems handle so much better than conventional hitches. Note that this doesn't reduce the physical "tongue weight" (read: Center of Gravity) of the trailer, which is important for handling properties. Of course this is a simplified, ideal situation, but the basic principles apply.

EDIT: These numbers are wrong, it's not quiet that simple, but the principle holds.

That said, if you can't afford a $3,000 80's 3/4 ton pickup, you are in the wrong hobby. Racing is expensive.

See less See more

rasterman

· #31 · Oct 10, 2012

OCRentAPoPo-

I'm quietly rooting for you over here... would love to see you find a fun-to-drive car with a lot of towing capacity. What about something like a late 90s Impala SS? I don't know if they ever made it with a manual trans, but it's a big full-framed car that would be pretty easy to modify for towing load. Same goes for the Ford panthers, the crown vics & marauders. I'd think that they have the platform strength and space to allow all of the performance & towing mods you'd need for track haul & DD duty.

I agree with others, it would be just too much for an outback unless you switched to say... motorcycle racing.

I've also been a bit concerned that I don't see any weight allowances for extra tires, parts, pit tools, fuel, tents etc. I don't race but I've seen it enough to know that a significant amount of stuff gets hauled out there along with the driver and the car.

I bring this up because even if you solve the problem of an outback as car hauler... aren't you soon going to want to haul more?

I wish you luck!

See less See more

OCRentAPopo

Discussion Starter · #32 · Oct 10, 2012

st3mpy said:
The best way to strengthen the unibody would be to use the Australian tow hitch.

I don't understand how a hitch can strengthen the unibody. Do you mean distribute weight across a larger section of the unibody? Also what is different or special about the Australian hitch that isn't offered in an aftermarket class 3 hitch?

st3mpy said:
That said, if you can't afford a $3,000 80's 3/4 ton pickup, you are in the wrong hobby. Racing is expensive.

I agree. It's not so much the cost of a tow vehicle as the room to keep it. Tow vehicle + trailer + racecar + DD = four parking spots. I'm trying to reduce that number. If I can tow with my DD and use a dolly, I reduce that number to 2.5 parking spots.

I plan on using a class 3 hitch w/ weight distribution. Coupled with stiffer springs, some to-be-determined added damping, and stiffer swaybars, the suspension should be up to the job.

OCRentAPopo

Discussion Starter · #33 · Oct 10, 2012

rasterman,

Thanks for the support. I don't think Chevy or Ford ever made their big sedans with a manual tranny. While I enjoy modifications, I think an auto to manual tranny swap in a car that never came with one is a bit more than I can handle. Also, I need a wagon for storage and moving the dog around. If they made the Dodge Magnum in a manual I'd probably be looking at those. I used to have a 1984 Chevy Caprice Wagon with a 305 that could probably handle towing but it was an automatic and not exactly fun to drive.

Extra stuff will be in the Outback, not on the dolly/racecar. Obviously this contributes to suspension load, braking performance (4pot/2pot upgrade?), and drivetrain wear. I plan on loading the heaviest stuff forward of the rear axles. It has the benefit of adding weight to the tow vehicle so the tail is less likely to wag the dog.

ScoobyRu

· #34 · Oct 10, 2012

I don't understand how a hitch can strengthen the unibody. Do you mean distribute weight across a larger section of the unibody? Also what is different or special about the Australian hitch that isn't offered in an aftermarket class 3 hitch?

A picture is worth a thousand words.

I found one on eBay AU a few months ago, but the shipping was too much.

rasterman

· #35 · Oct 10, 2012

That picture does a great job of illustrating how beefy that hitch is- and how insubstantial the back of the wagon was before the reinforcement plates went in.

Those plates look like they do a much better job of mating with a larger surface area than the aftermarket USA hitches I've seen.

subiesailor

· #36 · Oct 10, 2012

rasterman said:
That picture does a great job of illustrating how beefy that hitch is- and how insubstantial the back of the wagon was before the reinforcement plates went in.

Those plates look like they do a much better job of mating with a larger surface area than the aftermarket USA hitches I've seen.

The bent unibody cars I've seen all bend just behind the back door ie at the end of the safety cage / primary frame of the car. I have no idea what that hitch would do other than add weight to the back of the car. LOL

Seabass

· #37 · Oct 10, 2012

You'll be fine with the dolly. Just make sure it has brakes. Also you'll want front struts with a bit more control. You'll want to replace the rear struts whether you're towing or not. Problem is there are no decent ob strut options. You'd have to switch to LGT suspension to get konis. But you could go with the 04 kyb front and rear struts. It will at least be better than the stockers. You might want to switch to legacy gt brakes as well. It's a simple swap and worth it. OB brakes are not made for towing duty. Even though mine did ok, they smoked if you breathed on them a bit too hard while towing.

OCRentAPopo

Discussion Starter · #38 · Oct 10, 2012

St3mpy,

Thanks for the link. That hitch looks hardcore. I wonder if I could adapt one of the aftermarket class 3 hitches to use the same mounting points.

subiesailor said:
The bent unibody cars I've seen all bend just behind the back door ie at the end of the safety cage / primary frame of the car.

Can you describe the area of failure more? Do you mean just behind where the Aussie HD hitch mounts exit the frame rails? Do you mean further forward where the rear frame rails meet the main frame?

subiesailor

· #39 · Oct 10, 2012

OCRentAPopo said:
St3mpy,

Thanks for the link. That hitch looks hardcore. I wonder if I could adapt one of the aftermarket class 3 hitches to use the same mounting points.

Can you describe the area of failure more? Do you mean just behind where the Aussie HD hitch mounts exit the frame rails? Do you mean further forward where the rear frame rails meet the main frame?

If you sit in the back seat your butt is the bend point beefing up the over hang behind the rear wheels doesn't do a thing to address where the unibody bends at the back of the passenger cage.

OCRentAPopo

Discussion Starter · #40 · Oct 10, 2012

subiesailor said:
If you sit in the back seat your butt is the bend point beefing up the over hang behind the rear wheels doesn't do a thing to address where the unibody bends at the back of the passenger cage.

I see. So much further forward than the Aussie hitch goes. Still, unibody failure shouldn't be an issue if I keep my tongue weight down by using a dolly instead of a full trailer. I think the aftermarket class 3 hitches should be fine for dolly towing.

21 - 40 of 46 Posts

This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.