Motorhome towing an 80...update (1 Viewer)

[Tuner]

My first post here was to inquire about flat towing my '96 80 behind my motorhome and received numerous opinions....from you'll toast your TC or VC to no problemo. This week I finally found some time to weld up a bracket on the brush bar for the test I described a few months ago.

This morning I hooked to 80 to my dually with the basic towing rig and some beefy chains in case I overestimated the strenght of my welds. After a couple of trips around the block to make sure everything was copacetic, we hit the highway at 60mph for five miles....tranny and every part of the TC were still ice cold. (Ambient air temp: 74 degrees)

We increased the speed to 70 and ran another 20 miles....still no detectable heat from the running gear. After the 25 miles home at 70 mph, there was no heat generated in the running gear whatsoever and no visible overflow from any of the pieces holding fluid. The vehicle tracked perfectly, started instantly and shifted smoothly after the tow.

I have donned an asbestos suit for challenging absolute restriction against doing this in the FSM. If you were wondering if it was possible, it is.

My makeshift bracket is going to be replaced with a ARB bumper and a custom built bracket welded/bolted to it.

 

[CJF]

Tranny and T-case both in neutral, driveshafts not removed?

Just curious,

Curtis

 

[-Spike-]

Did you notice the drag?

I'm just guessing that with the t-case in neutral you wouldn't have any mechanical issues, unless it has to do with the diffs running with no load, did anyone express concern on this? I thought people avoided dragging around a FT4WD because of the increased drag.

-Spike

 

[NorCalDoug]

Glad to hear everything's okay.

Personally, I'd just load her up on a flatbed trailer/car hauler and not worry about it...but what do I know about pulling stuff behind motor homes...
:shrug:

 

[Tuner]

TC in neutral, tranny in park, nothing removed or otherwise altered...great question and an important one that I forgot to mention. The tranny has to be in park or it will generate some rotation and heat....possibly enough to damage it on longer trips.

I stop every 200 miles in the motorhome for fuel and to stretch and crank the toad's engine just to make sure.

Although it was a breeze to pull, the 80 is a real load. My truck could tell it was back there when it came time to apply the brakes. I doubt the motorhome will be able to tell.

 

[Waggoner5]

I am glad someone had the cahunas to actually try it. Everyone has alsways said NO, Don't do it, it will burn up the VC. I have always pulled my junk on a trailer behind my motorhome mostly because of the possibility of a fatal break, but now owning an 80 hybrid thingy, I was thinking of flat towing it. I have the 2wd kit installed with hubs up front so it shouldn't be an issue.
Does your truck have the CDL installed? Are you locking it when you flat tow? Inquiring minds want to know.
Gary

 

[Tuner]

I am glad someone had the cahunas to actually try it. Everyone has alsways said NO, Don't do it, it will burn up the VC. I have always pulled my junk on a trailer behind my motorhome mostly because of the possibility of a fatal break, but now owning an 80 hybrid thingy, I was thinking of flat towing it. I have the 2wd kit installed with hubs up front so it shouldn't be an issue.
Does your truck have the CDL installed? Are you locking it when you flat tow? Inquiring minds want to know.
Gary

I took the exploded view of the TC from the FSM and couldn't find anything that resembles a true VC so I changed the front, center and rear diffs to full synthetic fluid. The only wear points I can find are the bearing surfaces where the shafts enter the TC and a film of synthetic is enough to prevent any harm to them. I don't have a CDL but don't think it would have any effect.

If I was towing this thing with my dually to a rock crawling meet, a trailer would make sense. My 80 is an everyday driver and I don't head offroad unless bird hunting. A trailer/dolly is a real PITA when you travel each day and need the vehicle quickly plus there's no where to store one at RV camps. Flat towing is the only way to go for my purposes.

BTW, an old friend was visiting this weekend. He's the GM of a big Toyota store, helped me hook everything up and went along for the ride. He was very interested in the results.

I'll post some photos once I finalize the bumper/baseplate rig.

 

[IdahoDoug]

The much ballyhooed "VC" in the 80's TC does not exist, many people's opinions to the contrary. Ironically, I just posted this to another thread. It's not a viscous coupling, it's a device designed to allow minute amounts of slippage to eliminate axle windup when turning. Big difference.

I myself am guilty of calling it a VC more than once, I'm sure.

Anyhow, doing what you are doing would not stress the viscous device in the TC at all, so I'm surprised there was much concern. The real concern would be internal bushings and bearings in the tranny that are not being properly cooled because there's not enough tranny oil flow around them. Picture an internal bearing that's supposed to have cooling tranny oil flowing past it whizzing around and around in an increasingly hot puddle.

Unfortunately, you did not eliminate that as a concern because these bearings could be hot as hades inside that huge assembly and by the time they radiate heat to the tranny housing you would not even perceive it (tranny holds several gallons). For the record, you may be stressing the heck out of a few parts in there and have no way of outwardly knowing it until a few thousand miles of towing later things are no longer copacetic.

I honestly don't know enough about the tranny's innards to take a position on it, other than Toyota's recommendation. I've personally met a guy who towed a Lexus RX around and was told it was OK to do so by the dealer. After about 4 months of this, the tranny up and died with no warning (he's highly mechanical). Lexus put a new tranny in under warranty. Another 4 months, another tranny.

So, just want to point out you're not out of the woods yet and may be rolling the dice on this one. Obviously, we'd all like for this to be a good outcome, but I would be remiss in not pointing that out.

DougM

 

[Tuner]

Anyhow, doing what you are doing would not stress the viscous device in the TC at all, so I'm surprised there was much concern. The real concern would be internal bushings and bearings in the tranny that are not being properly cooled because there's not enough tranny oil flow around them. Picture an internal bearing that's supposed to have cooling tranny oil flowing past it whizzing around and around in an increasingly hot puddle.

Unfortunately, you did not eliminate that as a concern because these bearings could be hot as hades inside that huge assembly and by the time they radiate heat to the tranny housing you would not even perceive it (tranny holds several gallons). For the record, you may be stressing the heck out of a few parts in there and have no way of outwardly knowing it until a few thousand miles of towing later things are no longer copacetic.

I honestly don't know enough about the tranny's innards to take a position on it, other than Toyota's recommendation. I've personally met a guy who towed a Lexus RX around and was told it was OK to do so by the dealer. After about 4 months of this, the tranny up and died with no warning (he's highly mechanical). Lexus put a new tranny in under warranty. Another 4 months, another tranny.

So, just want to point out you're not out of the woods yet and may be rolling the dice on this one. Obviously, we'd all like for this to be a good outcome, but I would be remiss in not pointing that out.

DougM

I appreciate all input and I have a question: the tranny has an input shaft from the engine and an output shaft to the TC. In my situation, the engine is not spinning the input, the tranny is in Park and the TC is in neutral thus allowing no rotation to reach the tranny through the output shaft....where is the heat coming from?

BTW, Toyota has the same restriction on a 4Runner. I towed one of those over 10,000 miles with no problem. If the 4Runner was half the truck an 80 is, I'd still have it.

My 80 has 186k on the odometer so if something is going to go wrong, it should show up rapidly and I'll be back to report it and admit failure.

 

[Rich]

I'd guess any concerns around towing and the viscous coupler would be related to towing with the front wheels up and the rear wheels down as doing this would heat up the coupler.

For what its worth, the 97 service manual labels the viscous coupler as "Center Differential Control Coupring Assembly". The proof reader must have been slacking off. Other Toyota docs label the VC as "Viscous Coupling".

 

[alia176]

I'm a bit confused....the driveshafts are turning but the Tcase is not letting that go any further than that. Isn't the tranny totally free and clear at this point and wouldn't throwing it in Park take care of the rest?

 

[CJF]

I'm starting to think this mysterious, seldom seen VC is just something to keep you later guys from having such a clunky drivetrain like us 91-92 guys do...

Curtis

 

[lahar50]

My owners manual says you can pull it with all 4 wheel on the ground but not just 2 wheels.Glad to know its ok to do it.

 

[Waggoner5]

When I pulled my 96 tcase apart to do the 2wd conversion the VC did not look like what a VC should look like. I removed it anyway for the conversion anyway, but my question is if the VC only allows a minute amount of slip, whats the big deal with the CDL? I will be flat towing mine as well, so I appreciate the facts.

 

[SHREG]

Any updates on this?

 

[FXJ 96]

I'm going to set my 80 up for flat towing - sounds like others have had success

How to Flat tow your 80 series... safely.
Motorhome towing an 80