Need to tow 100 behind motorhome (1 Viewer)

[Trunk Monkey]

I know how the center diff works, I've just never heard "unloading" with regards to differentials. I think of unloading like leaf springs, stored potential energy that goes kinetic quickly. The diff doesn't store energy, it sends it to the path of least resistance. And it can do it for much longer than a few seconds, it can do it indefinitely, that's its design (as long as it's lubricated).

I really think this just comes down to that it would be possible (if you had a dolly that could take the weight of the 100) if done correctly. But, the average person isn't going to know how to do this correctly and cook their transmission and/or t-case. So, better to just say don't do it ever.

 

[Sandroad]

Even with a class 5 hitch, a 100 is a lot of weight if there are no brakes on the towed vehicle. Might be illegal towing weight w/o brakes in some states.

Factory service manual for an '04 reiterates the owners manual that the 100 can't be towed with a dolly (without disconnecting the driveshaft going to the wheels on the ground). "There is a danger of the drivetrain heating up and causing breakdown...."

 

[NMuzj100]

Even with a class 5 hitch, a 100 is a lot of weight if there are no brakes on the towed vehicle. Might be illegal towing weight w/o brakes in some states.

True, most vehicles flat towed behind a motorhome are using a brake system of some kind.

 

[sleeoffroad]

Toyota does not recommend flat towing but it can be done. The issue is that there is a mechanical oil pump in the transfer case that is driver by the input gear. It pumps oil through the center of the output shaft with oil passages going to the bearings. When the truck is in neutral the pump is not working. However that said, the output shaft is in bathed in oil when it is turning and the gears has no load on them, thus not creating friction. There could be a long term effect, but we have tested it and took temp measurements of the transfer case while flat towing it and did not see any temp increases.

That was on a 07 with a part time kit installed. The part time kit is not necessary, but it does eliminate all the front end parts from turning as well. So in effect halving the amount of parts that can be effected.

We also investigated the housing and one can install a pump and then draw oil from the drain plug and then pump it into the passage for the output shaft. One has to drill and tap the housing and use a 12v pump to circulate the oil.

I have also spoken to people that have done this for 1000's of miles with no ill effects.

The braking is an issue and in some states it would be illegal to pull without supplemental brakes. The 100 has a electronic brake assist and you would have to speak to the people that make the brake buddies to see if they can do one for you. Not sure those systems that apply the brakes via the pedals will work.

This might be a good place to start
Unified Tow Brake

 

[sleeoffroad]

Putting the 100 on a dolly will have the same effect, but through different means. The input side and one of the outputs spin, but the other output is not allowed to spin.....not ideal in my opinion since it was never intended to that for more than maybe a few seconds.

This will work, but you will be spinning the spider gears in the center diff. That would be way worse than flat towing it.

FWIW, I am going to set up my truck for flat towing. Dolly or trailer sucks to deal with.

 

[sleeoffroad]

I thought I would update this thread. I hooked my wife's LX470 behind the motorhome and towed it from Denver to Salida. Probably 200 miles or so. Transfercase in neutral, tranny in park, key in lock so wheel is free to move.

I measured the temp on the transfer case with a IR temp gun. When we stopped in Salida, the temps if the transfer case center section, front and rear output areas we all in the 100 F to 110F range. Simmilar to the rear and front diffs. If there was an issue in the tx case, it would have shown up as excessive heat. So for now, I am happy to tow this way.

Here is a pic for reference.

 

[pman]

How many 100s do you own? BTW props to you, thats a bold experiment.

 

[sleeoffroad]

How many 100s do you own?

Right now only one. The other LX was sold.

BTW props to you, thats a bold experiment.

it was more of a educated guess. We did some smaller tests first before we did it for a longer trip, we also did it with Gary's truck. I just wanted to update the thread with some real data.

 

[hoser]

Or, how many white LX's have you owned?

Thanks for the update. This will come in handy one day.

 

[sleeoffroad]

Or, how many white LX's have you owned?

Only three , one I owned twice, one Joe (our technician) now owns and htis one I bought recently with 275k miles on it.

 

[bkgee]

Transfercase in neutral, tranny in park, key in lock so wheel is free to move.

Maybe exposing my ignorance here, but why tranny in park?

 

[arbetrader]

How many bolts is it to simply remove the rear DS and be worry free with a dolly?

 

[sleeoffroad]

If the transfercase is in neutral, it does not matter what the tranny is in. I guess one could put that in Neutral as well, but you don't have to.

As for dolly, yes you can pull the rear driveshaft, only 8 bolts, but I don't want to get under the truck everytime I have to use it and put a driveshaft in. I have zero worries doing it this way.

 

[Skidoo]

If Christo has checked it out, pretty sure it is a good solution. If you are concerned do some short trips and check temperatures of T-case like he did. The big question in the past was, will enough oil circulate to lube the T-case output shaft bearings, based on his readings sounds like it does.

As for dollies, has anyone come up with one that can safely handle 6000+ pounds of Cruiser.

Christo, what are you doing for brakeing on the Cruiser when towed?

Think this thread should go in the FAQ, has the most real world info on the topic.

 

[mint400]

Just reading this thread, has me concerned... I'm sure it is a stupid question but.. can a tow truck tow a 100 safely?

 

[1loudLX]

Only three , one I owned twice, one Joe (our technician) now owns and htis one I bought recently with 275k miles on it.

should have put lockers in the one Joe has before you sold it ;p

 

[sleeoffroad]

If Christo has checked it out, pretty sure it is a good solution. If you are concerned do some short trips and check temperatures of T-case like he did. The big question in the past was, will enough oil circulate to lube the T-case output shaft bearings, based on his readings sounds like it does.

FWIW, on Ulitmate Adventure a couple of years ago we had issues with overheating on our crawler box on the Shortbus. We had a gauge on it and we pegged a 300 degree gauge and actually smoked the oil in the crawler box. We had no choice to continue. We did and completed the 2000 mile trip and the box was ok. So I am ok with it running at 110F. What is more, 100 transfer cases are not expensive used.

Christo, what are you doing for brakeing on the Cruiser when towed?

Still investigating that part, but honestly that motorhome does not really feel it back there for braking. Much better than when I had it on a trailer with trailer brakes. The 2k lbs of the trailer makes a difference. The convenience of flat towing far outweigh the concern about the transfer case.

 

[sleeoffroad]

Just reading this thread, has me concerned... I'm sure it is a stupid question but.. can a tow truck tow a 100 safely?

Why are you concerned? The shaft in the transfer case that has the oiling passages that get oiled by the input shaft pump is actually below the oil level. So it is oil bathed while towing. Also there is no load on the gears when spinning. OK a little, but not nearly the same as the engine applying torque to the case.

 

[sleeoffroad]

Just reading this thread, has me concerned... I'm sure it is a stupid question but.. can a tow truck tow a 100 safely?

Why are you concerned? The shaft in the transfer case that has the oiling passages that get oiled by the input shaft pump is actually below the oil level. So it is oil bathed while towing. Also there is no load on the gears when spinning. OK a little, but not nearly the same as the engine applying torque to the case.

I would say if a tow truck tows the truck with 4 down it is OK. However two wheels on a dolly, no, since the spider gears in the transfer case is then spinning. That wuill create a whole lot more heat.

 

[DWSD]

I thought I would update this thread. I hooked my wife's LX470 behind the motorhome and towed it from Denver to Salida. Probably 200 miles or so. Transfercase in neutral, tranny in park, key in lock so wheel is free to move.

I measured the temp on the transfer case with a IR temp gun. When we stopped in Salida, the temps if the transfer case center section, front and rear output areas we all in the 100 F to 110F range. Simmilar to the rear and front diffs. If there was an issue in the tx case, it would have shown up as excessive heat. So for now, I am happy to tow this way.

Here is a pic for reference.

How much was your tow yoke? Can you share a link to the setup?
Did you do something for adapting the braking?

Thank you,

Doug