Captain504
Active Member
Can you use a truck with a 4.56 gear ratio and 15 speed 3406B CAT for daily flatbed hauling?
4.56 ratio 3406B CAT with 15speed
- Thread starter Captain504
- Start date
389 Hood
Well-Known Member
Why not? A lot has to do with the final drive ratio and what the intended use is. If you are using a double OD, with a .65 final drive, you'll still be up in the RPM band at highway speeds, (65-70) but you'll have the 'grunt' the B is known for. Best engine ever made. They like to run all day at 1300-1400
Captain504
Active Member
Not sure why my other thread was cut regarding long legged on highway.
Defeats the purpose of trying to get information to just cut someone’s post.
Defeats the purpose of trying to get information to just cut someone’s post.
Sinister
pari animositate
It was redundant.
We only have like two music threads too.
And only one peanut butter thread.
Some of our members get an anxiety overload from too much stimulation and start freaking out and hitting themselves and doing things like driving a green Mack and listening to country music.
We only have like two music threads too.
And only one peanut butter thread.
Some of our members get an anxiety overload from too much stimulation and start freaking out and hitting themselves and doing things like driving a green Mack and listening to country music.
15 speed doesn't have a very tall Overdrive, and even running tall 24.5, that's going to be a very short geared truck. 1800 @ 63 mph.
Yes, those old cats will turn 2100, but engine life is much better if they're kept below 1800. Back in the 80's, Jewett Scott pulled their Fleet back to 1750, and saw a substantial reduction in bottom end failures and increased TBO.
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Captain504
Active Member
I am changing careers and just trying to get up to speed.
Does long legged simply mean the truck will be slow with 4,56 gears.
389 Hood
Well-Known Member
No. Long legged means that it has long legs and it will stroll. As in a 15 over with 3.08:1 rears.
Depending on the type of 15 that you have, go to your local trans guy and have him swap positions with the two top gears. That will give you an 'against the dash', over-drive. You'll be able to get down the road at 70-80 and the kitty won't be screaming.
Depending on the type of 15 that you have, go to your local trans guy and have him swap positions with the two top gears. That will give you an 'against the dash', over-drive. You'll be able to get down the road at 70-80 and the kitty won't be screaming.
389 Hood
Well-Known Member
The higher the rear gear numbers, the more low end grunt you will have. 4:56's are stump pullers. You'll get 200,000 pounds moving like it was nothing. However, you won't have a respectable top end without over-revving the engine. Plus the fuel usage will be ungodly and the wear and tear on the motor is significantly higher due to the high RPM's. 3:43's and 3:55's are a perfect combination for a direct drive transmission.
Captain504
Active Member
Thanks
is it a good idea to purchase a w900 with a 15 speed behind a 3406b and 4.56 gears?
Duck
Sarcastic remark goes here
No it's just the opposite.
Think of it as two guys walking, taking the same number of steps per minute.
One guy is 7 feet tall and the other guy is Danny Devito.
The 7 foot tall guy is going to have longer legs and therefore a longer stride. He's going to walk faster than Danny Devito because Danny Devito is going to have shorter legs and a shorter stride.
Your truck is Danny Devito in this comparison.
So it'll be slow.
But it'll have a shit ton of power.
Not a metric shit ton either. A real one.
Duck
Sarcastic remark goes here
Only if you're going to be doing some heavy haul or running local in a mountainous area with tons of steep hills.
389 Hood
Well-Known Member
Sure, providing that the unit is in good condition. You also have to consider what you will use the truck for. It it local work? All 48?
Just don't expect to try and run 70 mph with any efficiency. Those engines like to run 1400-1500 rpms. They still love to consume fuel, but if you are running the Rockies, you'll be passing the flat landers like they are backing up with 80 bushels on a 13% pull.
You will be able to listen to the engine and where it's comfortable.
Just don't expect to try and run 70 mph with any efficiency. Those engines like to run 1400-1500 rpms. They still love to consume fuel, but if you are running the Rockies, you'll be passing the flat landers like they are backing up with 80 bushels on a 13% pull.
You will be able to listen to the engine and where it's comfortable.
389 Hood
Well-Known Member
You countered yourself. Read what you posted again.No it's just the opposite.
Think of it as two guys walking, taking the same number of steps per minute.
One guy is 7 feet tall and the other guy is Danny Devito.
The 7 foot tall guy is going to have longer legs and therefore a longer stride. He's going to walk faster than Danny Devito because Danny Devito is going to have shorter legs and a shorter stride.
Your truck is Danny Devito in this comparison.
So it'll be slow.
But it'll have a shit ton of power.
Not a metric shit ton either. A real one.
Electric Chicken
Well-Known Member
I'd buy it if the truck was overall a good deal, and put taller rears in it.
My Ford has 4.44 rears and screams at 2100 RPM running 65. My Mack has 2.47 rears and barely turns 1100 running 65. The Ford pulls like a mule without downshifting most of the time and the Mack takes a little longer to get up there and needs to kick down more often.
The transmission gearing plays a role in that too. If you put my Ford transmission in the Mack it would probably turn different RPMs at those same speeds and vice versa.
If the 15 speed lets you run at adequate speeds (for you) in the 1400-1500 RPM range then you wouldn't even need to change the rears.
Sinister
pari animositate
That truck is not going to be new either. It could have all sorts of things lurking. They haven't made a blue button 15 speed in quite a while if I recall...
Pictures for this thread will help.
We are simple people and do well with pictures.
Electric Chicken
Well-Known Member
That's true. I was going to have a 13 double over put in the Ford for the same reason. Low HP engines like it has need gearing to help get them moving.
Electric Chicken
Well-Known Member
Yeah you have to take old trucks on an individual basis.
Could be a pristine example of someone's baby or it could have been pulled from weeds and spray bombed to look better.
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