Bought my First school bus and it broke down half way home

[BarnYardCamp]

google "Allison 643 for sale" I did a quick search and found a rebuilt for $1250 and a used one for $750.
So they are out there for less than the cost of fixing your current tranny...

[TomA]

Fortunately for you, it has been done and documented:

https://tatumskoolie.wordpress.com/2...allison-mt643/

2 notes:

1. Any old junkyard MT643 won't do- you need one that originally came behind a DT466 so that the valve body and shift points are optimized to your engine's power curve.

2. Making more power won't be the same for you as the mechanical DT466 in the link above. Your motor can most likely be rerated by the dealer or shop by reflashing the ECM software to a higher power level within the same configuration of hard parts in your engine. Search rerating on YouTube and get smart on it before you ask a dealer about it.

[Gambler936]

Ok will do thanks for the help

[EastCoastCB]

Your bus will run more efficiently and won't run as hot with a 643. The 643 will also allow engine braking which really helps going down grades.

[Gambler936]

Yea if the tranny needs to be replaced I think I’ll make it happen some how to get the 643 in there

[EastCoastCB]

Yeah. I've got a 545 in my bus. Its a fairly fresh reman unit so I'm adding a cooler to it and hoping for the the best. When it does go I'll be swapping a 643 in its place.
Best of luck to you with the bus. Keep us updated!

[SlimTim]

If you are interested I have a good used 3rd GEN Allison 3000 I would make you a deal on. It’s a six speed with a locking converter. PM me if you are interested.

[AutumnB]

Sadly when your on the road, your at the mercy of vultures. $450 for a u joint, when the tow guy broke it is sickening. It shouldn't have cost nearly that much and you could of did it yourself in less than 30 mins.

[EastCoastCB]

Originally Posted by AutumnB

Sadly when your on the road, your at the mercy of vultures. $450 for a u joint, when the tow guy broke it is sickening. It shouldn't have cost nearly that much and you could of did it yourself in less than 30 mins.

For parts and labor I could see a u-joint costing something in that ballpark.
IIRC my u-joint was $180 and I gave Ronnie some cash to hammer it on while I watched. Hell of a mechanic, that Ronnie.

Next time I need one I'll pull the driveshaft and take it to a driveline shop with a press and pay them to put em on the shaft.

[AutumnB]

Originally Posted by EastCoastCB

For parts and labor I could see a u-joint costing something in that ballpark.
IIRC my u-joint was $180 and I gave Ronnie some cash to hammer it on while I watched. Hell of a mechanic, that Ronnie.

Next time I need one I'll pull the driveshaft and take it to a driveline shop with a press and pay them to put em on the shaft.

I have replaced a few on my back. Not a bad job. They have a removal tool that is slick. No need to remove the shaft. Just strap it up and go at it. I've never paid labour prices so for me it was a choker price.

[Gambler936]

Yea the u joint costing that much was because of the labor the part was only like 80

[Gambler936]

Originally Posted by SlimTim

If you are interested I have a good used 3rd GEN Allison 3000 I would make you a deal on. It’s a six speed with a locking converter. PM me if you are interested.

Thanks I’ll keep it in mind

[AutumnB]

Originally Posted by Gambler936

Yea the u joint costing that much was because of the labor the part was only like 80

Yeahhhh I'm sorry. I figured so. I hate shops like that. I figured their other charges were BS too. Why didnt the wrecker pull it from the other end or was it locked into the transmission and you couldn't get it into neutral?

[jerry s.]

We had a couple of truck with automatic trans and they would go into limp mode. Wasn’t anything wrong with tranny, check with another mechanic

[Gambler936]

Why were they in limp mode

[BusT]

Hey man I had a similar situation happen to me ... from California to Texas I had to drive about 400 miles stuck going tops 40mph.
Felt like it was stuck in 2nd or 1st and that’s it...
I thought well if it’s already screwed might as well be closer to the house when it actually dies....

It started when I began climbing some steep grades....
Odly enough after about 400 miles and 10 hours later it worked itself out and I was able to reach highway speeds again ... then even was going 75 and back down to 1st and back to 75 ....
At the same time i had intermittent gauges going crazy and I think it was something eletrical going to the trans ....
i started my build exterior and roof raise and stuff and once I get this fuel tank on I well drive it around and see what happens ....
it’s been about 8 months since it’s been driven....
I wish you the best man

[Gambler936]

Originally Posted by BusT

Hey man I had a similar situation happen to me ... from California to Texas I had to drive about 400 miles stuck going tops 40mph.
Felt like it was stuck in 2nd or 1st and that’s it...
I thought well if it’s already screwed might as well be closer to the house when it actually dies....

It started when I began climbing some steep grades....
Odly enough after about 400 miles and 10 hours later it worked itself out and I was able to reach highway speeds again ... then even was going 75 and back down to 1st and back to 75 ....
At the same time i had intermittent gauges going crazy and I think it was something eletrical going to the trans ....
i started my build exterior and roof raise and stuff and once I get this fuel tank on I well drive it around and see what happens ....
it’s been about 8 months since it’s been driven....
I wish you the best man

Thanks I appreciate it I should hear back in the next few days from the mechanic I’ll let you guys know

[ralats]

the problem is not the torque converter the torque has no bearing on up or downshifts i dont know extent of problem but no upshift is a transmission problem not converter. 540s have a governor to help in upshift and downshift of unit also valvebody has trimmer springs that break and could also create no upshift also check modulator and engine vacuum to operate it

[EastCoastCB]

Originally Posted by jerry s.

We had a couple of truck with automatic trans and they would go into limp mode. Wasn’t anything wrong with tranny, check with another mechanic

A 545 doesn't have limp mode.

[cadillackid]

you can still buy a reman MT643 for about $650.. LKQ in missouri still has a few.. i know of someone who just got one.. im a year-in now with the 643 swap on my DEV bus.. one of the best things i ever did (other than add A/C) to that bus..

-Christopher