AT545 good or bad?
03-13-2009, 12:43 AM
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AT545 good or bad?
I have access to this allison AT545 and was considering putting it behind the cummins i'm building.
I'm going to be putting out 6-700hp to start with the engine I'm building, would i be able to make this trans handle this? Would I just be better off building a th400?
I guess I'd be better off with something like a th400 as theres endless aftermarket parts and there easy to get, but its so tempting because theres a 545 right in my buddies junkyard. I'd cryo a lot of the internals but are there options for HD torque conveters? I've heard there junk, I've heard they can be good.
A lot of the trucks use will be play in dirt and mud so thats a little less stress than something getting hard 4x lanches on the strip every weekend, but when this truck is done im sure that it will thrashed and abused without reason and pulling whatever i can, so would this be a better option or worse?
I'm going to be putting out 6-700hp to start with the engine I'm building, would i be able to make this trans handle this? Would I just be better off building a th400?
I guess I'd be better off with something like a th400 as theres endless aftermarket parts and there easy to get, but its so tempting because theres a 545 right in my buddies junkyard. I'd cryo a lot of the internals but are there options for HD torque conveters? I've heard there junk, I've heard they can be good.
A lot of the trucks use will be play in dirt and mud so thats a little less stress than something getting hard 4x lanches on the strip every weekend, but when this truck is done im sure that it will thrashed and abused without reason and pulling whatever i can, so would this be a better option or worse?
03-13-2009, 11:36 AM
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IIRC, the 545 is a T400 with granny low, which eliminated the PARK range : R-N-D-3-2-L - even looks like a T400 - no aftermarket stuff is available, so you might wanna stay away from it - next one up is a really big unit, external oil filter right on top, for the 8.2's, 8.3's in the 4500-5500 range chassis
03-16-2009, 07:44 AM
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a 545 would be the biggest trans i'd want to use but i guess it's not even worth it so i'll just go with a built 400....would love to go with a stick but ya just can't beat auto shifts with gobs of power...
03-16-2009, 09:03 AM
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Why not build the 3sp version of the 47RH, pre overdrive and lockup TCC - came behind the Cummins in '88-'90, then got the TCC in '91, bcame the 3sp\od 47 RH in '94, 47RE in '96, 48RE in '03 - can be upgraded with off-the-shelf parts just like the 47\48 - take a cruise thru PATC website, check out the hi-perf parts that go into their Ramzilla 47\48, all available for home buildups - might do you better than the T400 (my favorite for GM products, but I had to blend the GM D4 t\c with the Dodge\Cummins D4 t\c to lower the stall speed, due to no TCC available for the T400 - caused the same overheating problems as the Dodge\Cummins were having - used it with Brown-lite aux overdrive box in my GMC over-the-road rig for 6years, went to the 4L80E to get TCC and overdrive)
03-17-2009, 04:44 PM
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I'm not too big of a fan of dodge transmissions, i'm still throwing around some ideas, if i could get a beefy torque converter to work with the at545 that would get rid of what seems to be the weak point of the 545 to me. I'm not sure if the truck itself is going to end up being street legal or not yet so i'm kind of waiting to see how radical i end up making it, if it ends up too crazy for the street, i was thinking a powerglide would be interesting. I'm leaning towards making it a rear engine truck so if that happens than a streetable trans is definately not neccesary.
03-17-2009, 05:12 PM
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The Allison AT 545 is a good transmission for its designed purpose. The problem with using it in a streetable light truck with the B series engine is that the Allison hydraulic system is designed to be operated at a minimum of 2400 rpm engine input shaft speed to hold proper line pressure.
You will burn out the clutches if you try to put the power to the transmission at any point the input speed is below that minimum level because it will not have enough pressure built up to clamp down on those clutch packs before they go spinning away.
The maximum engine operating speed is 4000 rpm on this transmission, so you will find you have to idle at slightly less than 2400, then get on it to go. Most of the B series Cummins are getting right down the highway at a good clip by the time they are at 2400 rpm, and will tear themselves up in about 15 minutes of extended unloaded idling at anything close to 2400 rpm.
The Allison pressure can be modified to handle the torque and rpm range of the B series, but the cost to do so will be close to $2500. Not really worth it with the other options available.
If it were me, and I had any budgetary concerns, I would stick with an automatic with a broad usable rpm range that matches that of the B series Cummins. A old modified GM Turbohydro 400 with the cast iron case will do the job, but will cost around $6000 by the time the necessary mods are completed; any of the Dodge transmissions will do the job, and the cost can be reasonable if you sit down and chat with your performance transmission shop before launching into spending money; some of the Ford automatics can be made to work, but they are for the most part junk. One of the Allison T1000 series can be easily modified for around $4500 to handle power from a B series Cummins up to about 650 real horses, after that they will not handle the torque and experience case distortion problems.
There are a series of Allison 6 speed units that were made for motorhomes that can handle the torque, but they are a nightmare to keep maintained and are not happy with rpm above 3200.
You will burn out the clutches if you try to put the power to the transmission at any point the input speed is below that minimum level because it will not have enough pressure built up to clamp down on those clutch packs before they go spinning away.
The maximum engine operating speed is 4000 rpm on this transmission, so you will find you have to idle at slightly less than 2400, then get on it to go. Most of the B series Cummins are getting right down the highway at a good clip by the time they are at 2400 rpm, and will tear themselves up in about 15 minutes of extended unloaded idling at anything close to 2400 rpm.
The Allison pressure can be modified to handle the torque and rpm range of the B series, but the cost to do so will be close to $2500. Not really worth it with the other options available.
If it were me, and I had any budgetary concerns, I would stick with an automatic with a broad usable rpm range that matches that of the B series Cummins. A old modified GM Turbohydro 400 with the cast iron case will do the job, but will cost around $6000 by the time the necessary mods are completed; any of the Dodge transmissions will do the job, and the cost can be reasonable if you sit down and chat with your performance transmission shop before launching into spending money; some of the Ford automatics can be made to work, but they are for the most part junk. One of the Allison T1000 series can be easily modified for around $4500 to handle power from a B series Cummins up to about 650 real horses, after that they will not handle the torque and experience case distortion problems.
There are a series of Allison 6 speed units that were made for motorhomes that can handle the torque, but they are a nightmare to keep maintained and are not happy with rpm above 3200.
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07-18-2017, 01:51 PM
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The Allison AT 545 is a good transmission for its designed purpose. The problem with using it in a streetable light truck with the B series engine is that the Allison hydraulic system is designed to be operated at a minimum of 2400 rpm engine input shaft speed to hold proper line pressure.
You will burn out the clutches if you try to put the power to the transmission at any point the input speed is below that minimum level because it will not have enough pressure built up to clamp down on those clutch packs before they go spinning away.
The maximum engine operating speed is 4000 rpm on this transmission, so you will find you have to idle at slightly less than 2400, then get on it to go. Most of the B series Cummins are getting right down the highway at a good clip by the time they are at 2400 rpm, and will tear themselves up in about 15 minutes of extended unloaded idling at anything close to 2400 rpm.
The Allison pressure can be modified to handle the torque and rpm range of the B series, but the cost to do so will be close to $2500. Not really worth it with the other options available.
If it were me, and I had any budgetary concerns, I would stick with an automatic with a broad usable rpm range that matches that of the B series Cummins. A old modified GM Turbohydro 400 with the cast iron case will do the job, but will cost around $6000 by the time the necessary mods are completed; any of the Dodge transmissions will do the job, and the cost can be reasonable if you sit down and chat with your performance transmission shop before launching into spending money; some of the Ford automatics can be made to work, but they are for the most part junk. One of the Allison T1000 series can be easily modified for around $4500 to handle power from a B series Cummins up to about 650 real horses, after that they will not handle the torque and experience case distortion problems.
There are a series of Allison 6 speed units that were made for motorhomes that can handle the torque, but they are a nightmare to keep maintained and are not happy with rpm above 3200.
You will burn out the clutches if you try to put the power to the transmission at any point the input speed is below that minimum level because it will not have enough pressure built up to clamp down on those clutch packs before they go spinning away.
The maximum engine operating speed is 4000 rpm on this transmission, so you will find you have to idle at slightly less than 2400, then get on it to go. Most of the B series Cummins are getting right down the highway at a good clip by the time they are at 2400 rpm, and will tear themselves up in about 15 minutes of extended unloaded idling at anything close to 2400 rpm.
The Allison pressure can be modified to handle the torque and rpm range of the B series, but the cost to do so will be close to $2500. Not really worth it with the other options available.
If it were me, and I had any budgetary concerns, I would stick with an automatic with a broad usable rpm range that matches that of the B series Cummins. A old modified GM Turbohydro 400 with the cast iron case will do the job, but will cost around $6000 by the time the necessary mods are completed; any of the Dodge transmissions will do the job, and the cost can be reasonable if you sit down and chat with your performance transmission shop before launching into spending money; some of the Ford automatics can be made to work, but they are for the most part junk. One of the Allison T1000 series can be easily modified for around $4500 to handle power from a B series Cummins up to about 650 real horses, after that they will not handle the torque and experience case distortion problems.
There are a series of Allison 6 speed units that were made for motorhomes that can handle the torque, but they are a nightmare to keep maintained and are not happy with rpm above 3200.
The logic used above is, quite simply...horse poop.
I am not saying the 545 Allison is any good...nor am I saying it is "bad."
If you listen to the advice in the previous post, however, you just excluded the THOUSANDS of school buses made stock with Cummins 6B's and Allison 545's from ever running.
(They do not "idle" @ 2400RPM.)
Not really sure what the heck the guy meant, but ignore it. It isn't true at all.
08-06-2017, 02:57 AM
#9
I know this is an ancient thread...but I found it through Google, so others might also.
The logic used above is, quite simply...horse poop.
I am not saying the 545 Allison is any good...nor am I saying it is "bad."
If you listen to the advice in the previous post, however, you just excluded the THOUSANDS of school buses made stock with Cummins 6B's and Allison 545's from ever running.
(They do not "idle" @ 2400RPM.)
Not really sure what the heck the guy meant, but ignore it. It isn't true at all.
The logic used above is, quite simply...horse poop.
I am not saying the 545 Allison is any good...nor am I saying it is "bad."
If you listen to the advice in the previous post, however, you just excluded the THOUSANDS of school buses made stock with Cummins 6B's and Allison 545's from ever running.
(They do not "idle" @ 2400RPM.)
Not really sure what the heck the guy meant, but ignore it. It isn't true at all.
11-12-2018, 10:11 AM
#11
Registered User
1997 P1000 w/5.9 and 545
For my 1st gen (ve 5.9/rh46)I have found a fed ex delivery truck downer P-1000 with a p-pump(215hp?) and Allison model# at545nrm, ref#10-182, PN29537831.
what should I expect??
what should I expect??
11-12-2018, 10:42 AM
#12
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Slow top end speeds with no overdrive, as I believe that is a NON O/D transmission.
What to expect in one word?....Problems.
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oliver foster (11-14-2018)
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