Can my 5.9 and AT545 pull a 9k van?

[natedlee]

Ok - so we're on our maiden voyage with the SkooLee. Travelled from MD to CO and currently staying in Grand Lake. I can't stop thinking about how fun it'd be to pull our 4x4 van out to do some trails. But realistically - is that even possible with this setup?

We have a 28' Blue Bird TC2000 with the 5.9 12v and AT545 - ~150k miles. On the big mountain passes (6%-7% grade) she can maintain 35-45 mph uphill in 3rd gear. She's also got highway gears the previous owner upgrade to.

Funny thing is my van has a 7.3L turbo diesel, which seems better suited for the towing task. I'm over estimating the weight - but let's say it's 9k with the wheelchair lift and crap we throw in it. It's probably more around 8-9k though.

Here we are in CO:




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[turf]

i tow about 4k lbs with a similar set up. i;ve added a transmission cooler and turned up the power a bit.

towing up long hills is tough. you'll be pushing the limits of the 545. your bus and truck will be 30k lbs combined weight. and higway gears are the opposite of towing gears. speed or power is a trade off.

[Kubla]

You are going to need a transmission cooler. To get a close guess of the weight of the van, look at the GVW on the plate on the drivers door frame and subtract 1000 pounds from it

[LectricLance]

The 12 valve doesnt have nearly the power of 24 valve but your bus should be able to tow more than a full length, i have 2 tcfe 2000's, a '97 with the 12v and 4.44 rear end ratio and a '04 with 24v and 5.29 ratio. both 72 passenger, both AT-545 trans, 13 window. i would take rigs to weigh station and get axle weights and make sure its within specs on placard in bus. transmission cooler sounds like a good plan, trans temp gauge too.

[cadillackid]

awesome bus!! most certainly a transmission cooler... for one thing the 545 will add lots of heat to your radiator not to mention heating it up wit hthe weight.. you'll likely drop to second gear on the uphills.. you need to keep the revs up on a 545 under heavy load or you will pull the clutches loose,slip and glaze.... they need at least 2000 RPM to run at full pressure..
-Christopher

[EastCoastCB]

The exporters pull a bus with another bus. You should be fine pulling a van.

[natedlee]

Originally Posted by cadillackid

awesome bus!! most certainly a transmission cooler... for one thing the 545 will add lots of heat to your radiator not to mention heating it up wit hthe weight.. you'll likely drop to second gear on the uphills.. you need to keep the revs up on a 545 under heavy load or you will pull the clutches loose,slip and glaze.... they need at least 2000 RPM to run at full pressure..
-Christopher

I just did the Rocky Mtn. National Park pass (12,173' !!) and had to stop several times in the steepest grade for the entire 50 miles for 1-way roadwork traffic. I was so nervous it wouldn't get going. It was slow but once the turbo kicked in we got moving. I was making good use of 1st and 2nd on that pass




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[cadillackid]

using 1st and 2nd is wise! that kept your RPMs up so you have full line pressure in the transmission, keeps the fluid in motion through the cooler and the clutches held tight! its when people leave them in D or 3 and the RPMs go way down because the engine is bogging (AT545s take a long while to downshift).. that gets people in trouble. as the line presure drops
-Christopher

[natedlee]

Originally Posted by cadillackid

using 1st and 2nd is wise! that kept your RPMs up so you have full line pressure in the transmission, keeps the fluid in motion through the cooler and the clutches held tight! its when people leave them in D or 3 and the RPMs go way down because the engine is bogging (AT545s take a long while to downshift).. that gets people in trouble. as the line presure drops
-Christopher

I am having some coolant leaking problems I'll post in another thread. But otherwise the bus is doing great!


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[natedlee]

Oh and here's the van I also have to get a quick disconnect driveshaft to flat tow and that seems to be a complicated endeavour.

Honestly I've wondered if buying another bus, a pusher, with 7.3 equivalent (DT444??) would be more appropriate.




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[turf]

can it pull 9k and will it do it everyday are 2 different things.

the 545 slipomatic isnt going to last long the way you are planning. get a dt466 with a MT643 or MD3060 trans.

its cheaper to start with something that works than to modify something that doesnt.

[natedlee]

Originally Posted by turf

can it pull 9k and will it do it everyday are 2 different things.



the 545 slipomatic isnt going to last long the way you are planning. get a dt466 with a MT643 or MD3060 trans.



its cheaper to start with something that works than to modify something that doesnt.

Ah - right. The 466. So that was my plan in the beginning but I wasn't finding one with a wheelchair lift - or at least one in the middle of the bus. The mid-body lift made for a way better pseudo-accessible space to maneuver my daughter's chair and stuff. I may jump on a chance to get that engine with the configuration I need.


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[chev49]

If used correctly a 545 will last a long time. With my saf t liner, I pulled a 7k weight trailer back n forth across the usa with no problems on the interstate, however the hills had to have close temp management ....
Besides, they are simple n cheap to rebuild...

combined length is not an issue either, so your short bus n van will go most anywhere. however, truck stops n waysides r best places to stop.

[natedlee]

So a couple of things about my question:

1) I forgot to mention that the previous owner pulled a 12k camper up and down the East Coast. Bus came with a 20k lb hitch and brake control.

2) I also just figured out that it already has a transmission cooler. Not sure how to tell how effective it is, but if he pulled a trailer that heavy I guess it's working. Any way to track the temp?





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[turf]

that trans cooler is standard on all buses. you'll need an additional one.

the biggest short coming of the 545 for towing is the fact that it doesn't have a locking torque converter.

what does that mean?? when you go up and down hills, you go faster and slower.
a non locking transmission (at545) keeps a constant rpm and slows down. the difference (slipping) is lost as heat in the transmission.
a locking torque converter doesnt slip. if you slow down the rpms go down.

long uphills with the non locking transmission will create tons of heat and will be the death of the 545.

i am a huge fan of the 545, i have one on my bus, i tow 3k lbs, and abuse the **** out of my transmission dragging my trailer up and down the rockies.

towing has probably indirectly cost me a few thousand in repairs already. i have replace my manifold (cracked by heat), rebuilt turbo, added gauges, overheated, new fan cltuch, new water pump, new thermostat....and now a new transmission.

i'm in the process of replacing my 545 with a 1545, a locking version of the same transmission.

thats a fluid to fluid trans cooler, so your water temp and trans temp will be real similar.

check out my thread when i added the cooler.
http://www.skoolie.net/forums/f33/ad...545-14363.html

[natedlee]

So, if anyone was curious - some more info on my setup.

According to this site the AT545 on a school bus is rated at 30k lb.

My van weighs 8,300lb with just me and 3/8 tank of fuel.

My bus currently weighs in at 18,200lb (with out water tanks)

So at a combined 26,500lb, before water weight and so on, I'd be pushing the limits of the transmission application in the bus, but not exceeding them. Add water and I may very well be getting up there towards the limit.

[turf]

thats a nice info sheet about the 545.

if you look at any other bus with any other transmission spec, they will be higher. the 545 is the bottom of the barrel as far as common school bus transmissions/ conversion buses.

the MT643 is rated 60K lbs
the MD3060 is also rated at 60k lbs capacity.

the 545 is a great tranny for in town large vehicle use. as far as a highway cruiser/tow platform its the least robust choice we skoolie owners have.

30K may be the capacity, i'm am at 80% of capacity around 24k and have had my share of problems.

[natedlee]

Originally Posted by turf

thats a nice info sheet about the 545.



if you look at any other bus with any other transmission spec, they will be higher. the 545 is the bottom of the barrel as far as common school bus transmissions/ conversion buses.



the MT643 is rated 60K lbs

the MD3060 is also rated at 60k lbs capacity.



the 545 is a great tranny for in town large vehicle use. as far as a highway cruiser/tow platform its the least robust choice we skoolie owners have.



30K may be the capacity, i'm am at 80% of capacity around 24k and have had my share of problems.

Yeah i was looking at the MT643 as a next option.


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[turf]

capacity of the trans is both weight and hp.

even though you are at the weight limit, you're still under the hp limit with a stock 5.9. you can probably add 40 ponies and still be under your limit.

i'd try to turn up the afc on your fuel pump a bit first before swapping into a 643, but eventually you'll want something different.

i've run my 545 for 5-6 years now and i'm swapping in a locking transmission now.

[cadillackid]

I never thought a locking transmission made much difference.. then I changed out to one and wow!! its like a whole different bus.
-Christopher