Highway speed question

musigenesis · 02-06-2020, 11:38 AM

I took my bus out on the highway today for the first time in about six months. The previous time I drove it I wasn't paying attention to the RPMs (too nervous) and I had it up to a max of about 62 or 63 mph. Today I noticed that when I got to 60 mph the RPMs were at about 2400 and I didn't take it any faster than that.

I have a 2000-series transmission (no circled D on the shifter) and 6.17 gearing - does this seem normal that this would be about my top speed, or is my tranny not shifting into another gear for some reason? The guy who delivered my bus to me from Syracuse last January said he did 65 mph the whole way down, but I guess that would mean he was cranking the engine the whole time?

Brad_SwiftFur · 02-06-2020, 11:50 AM

Yeah, he was likely running it wide open.

musigenesis · 02-06-2020, 11:54 AM

Is 60 a good top speed to limit myself to? Or should I go 55 if I'm driving a few hours somewhere? I haven't really paid any attention to this issue, since I stupidly assumed when I got the bus that the spoiler on the back and the cruise control meant it was a fast bus.

cofrari · 02-06-2020, 02:01 PM

Mine is a 2500 with the circle around the "D". On flat, I can go about 70 at 2500 RPM. I have been keeping it at about 62 which has me down to about 2100. It sounds like I am in about the same range as you.

PNW_Steve · 02-07-2020, 01:05 AM

Quote:

Originally Posted by musigenesis

I took my bus out on the highway today for the first time in about six months. The previous time I drove it I wasn't paying attention to the RPMs (too nervous) and I had it up to a max of about 62 or 63 mph. Today I noticed that when I got to 60 mph the RPMs were at about 2400 and I didn't take it any faster than that.

I have a 2000-series transmission (no circled D on the shifter) and 6.17 gearing - does this seem normal that this would be about my top speed, or is my tranny not shifting into another gear for some reason? The guy who delivered my bus to me from Syracuse last January said he did 65 mph the whole way down, but I guess that would mean he was cranking the engine the whole time?

I am not terribly sharp when it comes to Allison shifters. My understanding was that the 2000 series will have the circled D. MT-643 and AT-545 shifters have the D with no circle.

Mmink · 02-07-2020, 07:17 AM

My Allison 2000 shifter is 124DNR. There is others with the circle D. Allison 545 is 123DNR. That being said, you’ve got some low gears in the rear. It’ll be good mountain climber but yeah that’s probably it for top speed. I’m thinking you have a 2000. A 545 probably wouldn’t get to 63 with those gears. Just an educated guess, I didn’t do the math

EastCoastCB · 02-07-2020, 07:30 AM

Quote:

Originally Posted by Mmink

My Allison 2000 shifter is 124DNR. There is others with the circle D. Allison 545 is 123DNR. That being said, you’ve got some low gears in the rear. It’ll be good mountain climber but yeah that’s probably it for top speed. I’m thinking you have a 2000. A 545 probably wouldn’t get to 63 with those gears. Just an educated guess, I didn’t do the math

You're correct.

musigenesis · 02-07-2020, 07:33 AM

Quote:

Originally Posted by Mmink

My Allison 2000 shifter is 124DNR. There is others with the circle D. Allison 545 is 123DNR. That being said, you’ve got some low gears in the rear. It’ll be good mountain climber but yeah that’s probably it for top speed. I’m thinking you have a 2000. A 545 probably wouldn’t get to 63 with those gears. Just an educated guess, I didn’t do the math

Thanks for the shifter info. Where I live is actually pretty hilly in places and I have a couple of steep climbs between my storage lot and my house, bus does great on those. I want to take it down to Florida next winter, though, and I'm not sure I can psychologically handle a thousand miles at 55 mph. I think if I could swap the gearing for less than a grand I would do it (after my build is complete, anyway).

EastCoastCB · 02-07-2020, 07:39 AM

Quote:

Originally Posted by musigenesis

Thanks for the shifter info. Where I live is actually pretty hilly in places and I have a couple of steep climbs between my storage lot and my house, bus does great on those. I want to take it down to Florida next winter, though, and I'm not sure I can psychologically handle a thousand miles at 55 mph. I think if I could swap the gearing for less than a grand I would do it (after my build is complete, anyway).

If you do the work yourself its about $400-$600 to regear it.
Check out Vander Haag's.

If I were you I'd go for something in the 4.44-5.29 range.

musigenesis · 02-07-2020, 07:45 AM

Quote:

Originally Posted by EastCoastCB

If you do the work yourself its about $400-$600 to regear it.
Check out Vander Haag's.

If I were you I'd go for something in the 4.44-5.29 range.

Would the job be any easier with the big opening in my floor like there is right now?

banman · 02-07-2020, 08:13 AM

Quote:

Originally Posted by musigenesis

Would the job be any easier with the big opening in my floor like there is right now?

Not really.
The major steps are pulling the axle shafts out enough that you can then remove the 'third member' (center section with the gears).
Since they're full-floating axles you may be able to do this without jacking up the rear end.
I would recommend a trolly jack and a helper to do this with so you don't crush yourself. It won't kill you -- it will just hurt and maim...

I suppose with the top of the axle exposed you could rig a hoist from above to do the removing and installing...

musigenesis · 02-07-2020, 08:28 AM

Quote:

Originally Posted by banman

Not really.
The major steps are pulling the axle shafts out enough that you can then remove the 'third member' (center section with the gears).
Since they're full-floating axles you may be able to do this without jacking up the rear end.
I would recommend a trolly jack and a helper to do this with so you don't crush yourself. It won't kill you -- it will just hurt and maim...

I suppose with the top of the axle exposed you could rig a hoist from above to do the removing and installing...

Yeah, this one is well outside of my DIY zone.

banman · 02-07-2020, 09:32 AM

Quote:

Originally Posted by musigenesis

Yeah, this one is well outside of my DIY zone.

You're currently functional --

maybe bide your time --
do more hwy driving so you really know what gear ratio would be optimal for your engine/rpm. (this might just be research on your part)
take your time finding the best deal on the third member you can get.
Change it out next summer (or later) at your convenience down in FL where you can plan to rent/borrow/trade, time/labor/money with some of the other knowledgeable Skoolie folk who seem to be like minded here.

Truthseeker4449 · 02-07-2020, 10:29 AM

Quote:

Originally Posted by EastCoastCB

If you do the work yourself its about $400-$600 to regear it.
Check out Vander Haag's.

If I were you I'd go for something in the 4.44-5.29 range.

This is a nice site, but how to know if I'm looking at the correct third member?

My cab data plate says Dana J230

sportyrick · 02-07-2020, 12:39 PM

There should be a tag on your 3rd member and a tag on the front left side of the housing, those are the numbers you want to re-gear a third member, specifically the third member numbers. They are not that bad to pull but weigh about 350# so it's no job for a weakling. Drop driveshaft, take the nuts off the axles, pull them out a foot or so, pull nuts off differential and pry it out. Be ready for the weight, rent a transmission jack or use your available top access. You can get it rebuilt with a new ring and pinion or buy a used one from a semi wrecking yard. I paid $500 for a whole rearend out of a semi with 4.44 ratio. Silicone the rebuilt rearend and put it back in, silicone or gasket the axles back in, put some oil in the hubs (some hubs have a way to fill through a bolt hole in them) oil in the diff, drive it a little and check the level, back in business. You don't even have to jack it up (but that may make it hard to get diff out from under bus), with full floating hubs the weight is on the hubs not the axles. I just went through this a month ago........ twice.

FamilyCircus · 02-10-2020, 10:28 AM

In looking for gear sets for my N190 I learned that the gear sets will fit various diff's. In my case the gears set i purchase for my N190 would fit the N175, N190, N230, N310, and N420. It is the diff carrier that changes to accommodate the different axle splines, 36, 39, and 41.

Brad_SwiftFur · 02-10-2020, 04:12 PM

What flavor (gear ratio) are you looking for?

I have a 5.38 in my N175 I want to swap for something (numerically) lower.

FamilyCircus · 02-10-2020, 06:36 PM

Ive got a ring and pinion gear set that are 3.91 Ive been trying to sell for ever. this requires installation.

Ive got 4.44 and an MD3060 with a current 5th gear .75 ratio and it cruises at 65 mph around 1800 rpm, it got me 10.3 mpg

Ive also got an TCM with the 6th gear enabled but the power side is dead and wont turn on, I found a place to fix it, now Im not too sure I wan it. From reading the 6th gear unlock thread it looks like the fuel mileage gain is minimal. I might do it anyway, I can always gear down on the shifter if I dont like it.

gdaddy · 02-12-2020, 03:48 PM

how much for the ring and pinion ? shipping to nw fl.

JodyandRenee · 02-13-2020, 06:41 AM

Quote:

Originally Posted by banman

You're currently functional --

maybe bide your time --
do more hwy driving so you really know what gear ratio would be optimal for your engine/rpm. (this might just be research on your part)
take your time finding the best deal on the third member you can get.
Change it out next summer (or later) at your convenience down in FL where you can plan to rent/borrow/trade, time/labor/money with some of the other knowledgeable Skoolie folk who seem to be like minded here.

Wouldnt it be easier to find another bus or a parts supplier and get another third member that has the lower gears already installed? Thats the beauty of removable third members is the ability to swap easily. Then its literally plug and play.

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