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Re: Finally a BB automatic overdrive tranny!
[Re: DaytonaTurbo]
#1702083
11/28/14 10:56 PM
11/28/14 10:56 PM
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Joined: Jan 2003
Posts: 28,067
Irving, TX
feets
Senior Management
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Senior Management
Joined: Jan 2003
Posts: 28,067
Irving, TX
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Quote:
And anyone who's owned one knows the ones even on stock unmodified Cummins are not known for their longevity. Not saying the 518s are bad, but they're not the holy grail either.
I'll strongly disagree with you on that.
The failures started happening when the lock up converters were used. The clutches in those converters would disintegrate. The trash would get into the system and the overdrive fluid passages would be the first to get plugged.
The failure wasn't in the transmission. It was in the converter.
Do these bits look like they have over 270,000 miles on them?
Last edited by feets; 11/28/14 10:58 PM.
We are brothers and sisters doing time on the planet for better or worse. I'll take the better, if you don't mind.
- Stu Harmon
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Re: Finally a BB automatic overdrive tranny!
[Re: DaveRS23]
#1702084
11/29/14 11:39 AM
11/29/14 11:39 AM
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Joined: Feb 2003
Posts: 21,318
Manitoba, Canada
DaytonaTurbo
Too Many Posts
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Too Many Posts
Joined: Feb 2003
Posts: 21,318
Manitoba, Canada
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Quote:
I don't know of a more durable tranny than a well built 727 for most of what we all do. So, as far as the first 3 gears, a 518 would be as tough as any comparably built 727.
Now I don't know the limits of a lock-up converter or the OD section, but do those really need to hold all of our power in normal driving?
I plan to use a non lock-up 518 in the Cuda next year. The main body will be built just like the 727 in there now which has proven to be nearly indestructible. The OD will be beefed up, but I do not plan to ask it to hold all of power the engine is capable of making.
Someone correct me if I'm wrong, but it's my understanding that ALL engine power is transmitted through the OD clutch pack, whether OD is engaged or not.
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Re: Finally a BB automatic overdrive tranny!
[Re: feets]
#1702085
11/29/14 11:41 AM
11/29/14 11:41 AM
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Joined: Feb 2003
Posts: 21,318
Manitoba, Canada
DaytonaTurbo
Too Many Posts
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Too Many Posts
Joined: Feb 2003
Posts: 21,318
Manitoba, Canada
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Quote:
Quote:
And anyone who's owned one knows the ones even on stock unmodified Cummins are not known for their longevity. Not saying the 518s are bad, but they're not the holy grail either.
I'll strongly disagree with you on that.
The failures started happening when the lock up converters were used. The clutches in those converters would disintegrate. The trash would get into the system and the overdrive fluid passages would be the first to get plugged.
The failure wasn't in the transmission. It was in the converter.
Do these bits look like they have over 270,000 miles on them?
I can't attest to that, having never owned and earlier year model. However when looking at the later year ones, especially once the 24v came out and they started making a little more power, finding one with a trans that was not already on it's way out was a tough task. Best you could ask for is one that already had the trans done. And even then I don't recall anyone doing converters.
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Re: Finally a BB automatic overdrive tranny!
[Re: DaytonaTurbo]
#1702086
11/29/14 05:00 PM
11/29/14 05:00 PM
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Joined: May 2005
Posts: 4,706
Florida
BDW
master
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master
Joined: May 2005
Posts: 4,706
Florida
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I sure hope it holds up, I'm not too hard on my rides. Took mine out for the initial test drive, a few bugs to work out, but it is awesome. Only 2800 rpm at 75mph, and no vibrations which was a concern. Now I can keep up with the rice burners on I-95 without rattling my teeth. Here's a shot at 60mph, only 1800rpm and I have 3.73 gears. Glad I got the LU converter, I can definitely feel it drop a few RPMs when it kicks on, it's like having a 4.5spd auto. 
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Re: Finally a BB automatic overdrive tranny!
[Re: DaytonaTurbo]
#1702087
11/29/14 06:52 PM
11/29/14 06:52 PM
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Joined: Jan 2003
Posts: 28,067
Irving, TX
feets
Senior Management
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Senior Management
Joined: Jan 2003
Posts: 28,067
Irving, TX
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Quote:
Someone correct me if I'm wrong, but it's my understanding that ALL engine power is transmitted through the OD clutch pack, whether OD is engaged or not.
That is incorrect.
There are two clutch backs inside the OD housing. One for direct and one for OD. The direct pack is inside the hub and has pressure applied by an 800 lb spring. The OD clutches surround the hub.
The second photo I posted shows the two sets of clutches in the OD housing.
Here's a shot of all four sets out of my 270,000 mile D250.
Last edited by feets; 11/29/14 06:56 PM.
We are brothers and sisters doing time on the planet for better or worse. I'll take the better, if you don't mind.
- Stu Harmon
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