2 Speed rearends

[pengyou]

I have looked at some 2 speed rear ends. so far, all have stated that they were not designed to be shifted while the vehicle is in motion. Is this true for all 2 speeds?

[Ronnie]

I have a two speed in my bus, and all my medium duty trucks including my Dad's have had two speed rear and all are intended to be shifted while moving. They are used like an auxilary trans to "split" gears.

So with a heavy load you would start in first gear, low range on axle, then shift to high while still in first; shift to second gear but before letting out the clutch shift rear back to low, next shift would be rear to high while still in second, etc so as you can see the it 4 speeds so far. A 5 speed with 2 speed rear gives you 10 speeds forward and two reverse.

Normally the read end shift knob is a red button on the gearshift. For whatever reason it is on the dash on my bus.

[ol trunt]

I could see not shifting a 2 speed transfer case on the fly but a 2 speed rear axle would be absolutely useless if it could only be shifted while stationary as best I can see. What "brand" axle comes with this directive?
Jack

[pengyou]

I haven't paid attention to name brands yet...was looking at a page that had lots of used rear ends for sale. Does it make any different with the shifting if the tranny is automatic? There is no clutch to put in the remove the pressure from the system.


I know that 2 speed rear ends usually come with tall gears. I have seen a few shops that specialize in changing gears in rearends and trannies. Would it be possible to put a 5.1 and a 3.5 in a rear end. The 3.5 would be used for flat land cruising - I think greyhounds use that ratio??? and the 5.1 ( or there abouts would be useful for climbing mountains, hills, etc

[Ronnie]

Most two speed rears that I have used have used like the one in my bus have around 5:1 high and 7:1 low. To change gears a large amount would normally require a different carrier, so in a two speed rear a large change may not be reasonable to do. I have Eaton shop manuals and sales info for two speed rears.

What bus do you have?

As far as shifting with an automatic it can be done, and I have done it.

[cadillackid]

im familiar with using 2 speed rears in a stick shift environment.. I guess with an auto you would place the auto in neutral first.. i dont think you can split gears with it in an auto scenerio like you can with a manual...

[EastCoastCB]

Originally Posted by pengyou

I haven't paid attention to name brands yet...was looking at a page that had lots of used rear ends for sale. Does it make any different with the shifting if the tranny is automatic? There is no clutch to put in the remove the pressure from the system.


I know that 2 speed rear ends usually come with tall gears. I have seen a few shops that specialize in changing gears in rearends and trannies. Would it be possible to put a 5.1 and a 3.5 in a rear end. The 3.5 would be used for flat land cruising - I think greyhounds use that ratio??? and the 5.1 ( or there abouts would be useful for climbing mountains, hills, etc

They usually come with low gears, not tall.

[cadillackid]

Originally Posted by EastCoastCB

They usually come with low gears, not tall.

tall / short is relative.. i agree most people using 2 speeds are doing it for work trucks where the objective is a low range for off-road / construction type use.. but you could say buy a 5.13 / 4.10 2 speed that gives you in town and highway gears...

[Sleddgracer]

Originally Posted by cadillackid

tall / short is relative.. i agree most people using 2 speeds are doing it for work trucks where the objective is a low range for off-road / construction type use.. but you could say buy a 5.13 / 4.10 2 speed that gives you in town and highway gears...

my old 56 Mercury 2 1/2 ton had highway gearing and a lower geared split - loved that old truck - it was good on the highway and the steep hills - it had been an in-city beer delivery truck, so it looked sharp with it's professionally built stake sides and nice paint job - I put a lot of miles on it before eventually trading it for a pony and a small flock of sheep (the pony wound up winning dozens of trophies at the gymkhanas my family and I used to compete in ) that was long enough ago that I can't remember what we eventually did with the sheep

[Booyah45828]

Originally Posted by Ronnie

I have a two speed in my bus, and all my medium duty trucks including my Dad's have had two speed rear and all are intended to be shifted while moving. They are used like an auxilary trans to "split" gears.

So with a heavy load you would start in first gear, low range on axle, then shift to high while still in first; shift to second gear but before letting out the clutch shift rear back to low, next shift would be rear to high while still in second, etc so as you can see the it 4 speeds so far. A 5 speed with 2 speed rear gives you 10 speeds forward and two reverse.

Normally the read end shift knob is a red button on the gearshift. For whatever reason it is on the dash on my bus.

You wouldn't happen to have make or model of the rear end that you're talking about.

All the 2 speeds I've seen, although they could be shifted on the fly, weren't really supposed to be. More of a shift it to low, crawl out of the yard with it, then shift back to high and go down the road. I've actually read online of certain motor coaches that had a 2 speed rear axle that was designed for shifting on the fly. But that was from the 60's and I'm not sure how common they were.

[Sleddgracer]

Originally Posted by Booyah45828

You wouldn't happen to have make or model of the rear end that you're talking about.

All the 2 speeds I've seen, although they could be shifted on the fly, weren't really supposed to be. More of a shift it to low, crawl out of the yard with it, then shift back to high and go down the road. I've actually read online of certain motor coaches that had a 2 speed rear axle that was designed for shifting on the fly. But that was from the 60's and I'm not sure how common they were.

if I remember correctly, the split in the old Mercury 2 1/2 ton, you let off the gas momentarily to up-shift into high, and depressed the clutch when downshifting into low, all done on the fly - when hill climbing, if you couldn't shift on the fly, there would be little advantage to having a split rear end

[Ronnie]

Originally Posted by Sleddgracer

if I remember correctly, the split in the old Mercury 2 1/2 ton, you let off the gas momentarily to up-shift into high, and depressed the clutch when downshifting into low, all done on the fly - when hill climbing, if you couldn't shift on the fly, there would be little advantage to having a split rear end

Yes this is how mine works and all the trucks(including an 68 International dump truck I owned) I have driven that had two speeds work like this as well. On my Internationals it is electrically shifted, and on GMC/ Chevy they were vacuum shifted, on the fly.

On my bus before I took the automatic out going from low to high was easy just let off the gas a little let it shift then re apply gas. To go from high to low, set rear to low(note it will not shift just because you moved the shift button) let off gas then hit it pretty good, but not enough the tranny will downshift too. Must say with the 6 speed Allison there was no real need, as shifting the tranny down to 5th gave about the same speed. Although I did do it a few times to find out. So splitting on the 6 speed did not gain much. In most of the trucks they have had 4 speed trans with two speed rear, great combo in the mountains.

Mine is 5.14 in high, low I do not know, but is a bit lower then ideal, however with it in low and the trans in granny gear it can just crawl nicely.

You know unless you are in the mountains a lot or tow heavy loads I am not so sure I would bother with a two speed for a bus.

[Ronnie]

It might be hard to read but I can take a photo of the shift instructions on the glove box on my bus if anyone wants to see it.

[Sleddgracer]

Originally Posted by Ronnie

Yes this is how mine works and all the trucks(including an 68 International dump truck I owned) I have driven that had two speeds work like this as well. On my Internationals it is electrically shifted, and on GMC/ Chevy they were vacuum shifted, on the fly.

On my bus before I took the automatic out going from low to high was easy just let off the gas a little let it shift then re apply gas. To go from high to low, set rear to low(note it will not shift just because you moved the shift button) let off gas then hit it pretty good, but not enough the tranny will downshift too. Must say with the 6 speed Allison there was no real need, as shifting the tranny down to 5th gave about the same speed. Although I did do it a few times to find out. So splitting on the 6 speed did not gain much. In most of the trucks they have had 4 speed trans with two speed rear, great combo in the mountains.

Mine is 5.14 in high, low I do not know, but is a bit lower then ideal, however with it in low and the trans in granny gear it can just crawl nicely.

You know unless you are in the mountains a lot or tow heavy loads I am not so sure I would bother with a two speed for a bus.

I live in a mountain valley surrounded by mountains and valleys - I'm hoping to find a bus with a split

[Ronnie]

Originally Posted by Sleddgracer

I live in a mountain valley surrounded by mountains and valleys - I'm hoping to find a bus with a split

Must say it would be neat to meet you one day, we seem to think alike. I do come out to Washington from time to time.

[Sleddgracer]

Originally Posted by Ronnie

Must say it would be neat to meet you one day, we seem to think alike. I do come out to Washington from time to time.

I'm just across the border, 2 - 2 1/2 hours due north of Spokane - be glad to show you around and swap some stories with you if you get up this way