The RedByrd TRANSformation.

[Tango]

ECCB...great numbers! --- I wanted to hit this point because so many folks seem to jump in and buy a bus with no idea what it is like on the interstate. And they are later stunned to learn it may only have a top speed of 50 mph or that they have to run at or beyond redline to
maintain anything like reasonable highway speeds.

NOTE to Newbies:

Running the numbers before making a buy will help inform you of what to expect if you plan on spending much time traveling.

Find out...

The rear axle ratio
The transmission final drive ratio
The tire diameter
The engines RPM "Sweet Spot" and Redline

From there, you can use any online gearing/speed calculator to see where you stand. If you go in well informed (like Mr. ECCB), you can find a rig that will give you excellent performance and durability for your intended purpose right from the get-go.

Otherwise...figure on spending a fair amount of money to make it right.

At least I went in fully informed and understood what it was going to cost to make a 45 mph Skoolie roadworthy. For some, the fix can cost far more than the original purchase price and be a back breaker.

It is best to know in advance.

[cadillackid]

what tango said! alas the swap for Kubla and I if we can puill it off (what a TRUE SWAP). would be fantastic, my 3.54 gears that worked fine with my AT545. gave me 65-70 MPH highway crusing at the top of my RPM range.. he has 3.90 now so im guessing he tops at 55 max.. a 3.90 rear with my 6 speed would put my RPMs in 5th gear just a couple hundred below the max power band. and in 6th gear right in the sweet spot..

for those unlocking 6th gear... pay attention to a thread Rameses has open about this too.. the trick for these may be to ship the TCM module off somewhere as opposed to going through the hastle of a dealer network.. playing it up that your allison is in some custom project as opposed to stating its in a school bus...

-Christopher

[cadillackid]

Originally Posted by Tango

ECCB...great numbers! --- I wanted to hit this point because so many folks seem to jump in and buy a bus with no idea what it is like on the interstate. And they are later stunned to learn it may only have a top speed of 50 mph or that they have to run at or beyond redline to
maintain anything like reasonable highway speeds.

NOTE to Newbies:

Running the numbers before making a buy will help inform you of what to expect if you plan on spending much time traveling.

Find out...

The rear axle ratio
The transmission final drive ratio
The tire diameter
The engines RPM "Sweet Spot" and Redline

From there, you can use any online gearing/speed calculator to see where you stand. If you go in well informed (like Mr. ECCB), you can find a rig that will give you excellent performance and durability for your intended purpose right from the get-go.

Otherwise...figure on spending a fair amount of money to make it right.

At least I went in fully informed and understood what it was going to cost to make a 45 mph Skoolie roadworthy. For some, the fix can cost far more than the original purchase price and be a back breaker.

It is best to know in advance.

another piece too is.. "is the bus you desire even manufactured?" in my case there were very few pre 2005 busses built with overdrive transmissions.. the T-444E was thought to be a budget engine so many schools ordfered AT545's with them.. the DT-466E is a sought after engine and thus commands very high prices right off the gate for one with overdrive..

in my case I had it in the back of my mind if my AT545 ever blew up id be upgrading... granted im sure with what my 545 was doing it couldve been fixed fairly easily.. it was a valve sticking. or a clogged internal filter.. neverthless I chose to Build what I want rather than try and find it..

Tango didnt have much a choice.. but in the end is going to have a near perferct combo.. the folks at CAC have been running 4BT's with allison 1000s for years in their own personal trucks and their customers..

the 1000 and the 2000 are generally the same.. though the 2000 can be bouight with a wider gear ratio set.. a lower first.. the same 6th and a slightly lower 5th.. wider ratio helps a bit for faster starts in heavy vehicles..

GM used the 1000 in their pickups and their medium duty trucks up through the C-8500, International used the 1000 in their lighter 3000 series (aka the IC BE school bus platform)..

I think friehgtliner used it behind the MBE906 in the FL60's / 70's as well..

allison transmissions are work transmisisons.. they dont necessarily have the super smooth shift manners of a consumer trans like a 6L60E or the 4RL stuff.. they also dont take kindly to extreme high horsepower and torque thrown at them in overdrive.. (unless you build them with updates)... the Duramaxx guys know all about spinning the CLutches in 5th gear with the smoke turned way up...

the allison I have is updated and a mild performance build.. good to 500 HP.. more than ill ever throw at it in a school bus... medium duty long chassis arent designed to be ripped hard with extreme consumer-kid Horsepower.. esp with a school bus body.. (ever study the body mounts on a bus? they are simply clips that keep the body from, falling off.. they appear to provide NO rigidity to the frame...). so dropping huge amounts of power into a bus requires a lot of thought and fabriacting / stiffening of the frame to accomodate.. not to mention, motor mounts, rear, driveshaft, axles, you name it...

cruising at 65-70 is perfect for me..

-Christopher

[cowlitzcoach]

The body mount clips are made in such a way that in an accident the body will slide on the chassis. The sliding will thus absorb a huge amount of the force of the accident before transferring that energy into the passenger compartment.

You will discover that all of the Type 'A', 'B', and 'C' buses are built that way. Some Type 'D' buses are built in the same fashion.

All of which is to say you need to inspect the body hold downs occasionally to make sure none of the fasteners have loosened. If they should ever get loose you could conceivably drop the body off of the frame. It isn't likely but there is the possibility.

[Kubla]

My current top speed is 63 mph at 2700 rpm with 245/70R19.5 tires and a 3.90 rear

[cadillackid]

Originally Posted by Kubla

My current top speed is 63 mph at 2700 rpm with 245/70R19.5 tires and a 3.90 rear

with my 225/70R19.5 and the 3.54's. (and the 545 trans) I could run it up over 70. though with the 545 unlocked it would slow down on the larger hills running against the rev limiter.

I didnt realize it was so simple to yank the 3rd member out of one of these.

-Christopher

[cadillackid]

One piece im still working on is getting the transmission to recognize Throttle position when the cruise control is engaged..

so I found a circuit in the ECM that was to activate the modulator of the AT545.

I ran an ouitput test on it and found that yes I had found the right wires and the circuit worked.. so I connected al ight bulb to it and left it out on the hood while I drove around..

as I increased and decreased the throttle and engine load it worked perfectly... set out on the freeway, foot to the floor, circuit active.. i set the cruise and thought YES!! it works.. then the cruise decreased throttle need on a flat and the circuit deactivated...

except.. as I climbed the next hill the bus slowed down.. went to 100% engine load and the circuit just sat there.. hmmm. maybe thats why people hated the electronic AT545s as the ECM didnt do their job.. without that circuit active, the AT545 would not be modulated to downshift.. looks like someone only wrote half the code needed... Grrr..

oh when I pressed the pedal down the circuit activated like it was supposed to and stayed active till the engine load dropped..

of course all i have to do is press the pedal down and the trans downshifts or hit the tap shift button and it does.. but you know I want a fully automastic intuitive system..

so i believe its time to build a box that will read the engine loading and turbo data from the J1708 link and translate it to a TPS signal under heavy load.. a couple of ELM chips and a board and a few components.. the software shouldnt be too tough.. ill tie it together with a zbasic.net chip that generates analog out through a DAC...

-Christopher

[Tango]

There he goes talkin' that funny furin language agin.

[PNW_Steve]

Originally Posted by Tango

There he goes talkin' that funny furin language agin.

I understand exactly what he is saying.

I just wish I was smart enough to figure out how he figured it out......





Christopher,

I see commercial applications. You could make some $$ with this.

[cadillackid]

Originally Posted by PNW_Steve

I understand exactly what he is saying.

I just wish I was smart enough to figure out how he figured it out......





Christopher,

I see commercial applications. You could make some $$ with this.

possibly a few years ago.. but nowadays in the mosrt modern trucks the transmissions and engines talk directly.. in fact in the Maxxforce stuff they did.. there is a J1939 link between the ECM and the TCM.. its just on an older bus it didnt exist.. theres *possibly* a commercial application to add to something like CAC, defeo, rifraff and the others who build standalone kits to run allisons behind cummins electronic engines or the like.

the issue doesnt exist on mechanical engines as the throttle pedal is moved by the cruise control actuator... ( if there is a cruise at all).

-Christopher