Rear end ID on Prevost

[robertglines1]

I have a 98 XLE with a 4:56 gear set installed. Without tearing it apart(taking out) How would I know what kind of gear set to buy to replace it? Id number location external on case?  I'm changing to a Eaton 10sp Autoshift .75 overdrive top gear. Now is the time. Engine is ready to sit in.  Have decided at this point it would be foolish to just be satisfied with 4;56 and waste fuel. Also need to find out how high I can go.  I'm lost here!!! Jim and others have sent me the charts and looks like mid 3:50 would be perfect. I like to run around 70mph. 60 series Detroit  aprox 500hp(with/mods) around 42,000 lbs  315 80r 22.5 tire  491 rev per mile.  Any insight will help!!! I lost 9 months due to health(back surgery) and am back to work now and want to do it rite the first time.  Bob   

[luvrbus]

Bob,the ratio ID, is all on the very end of the pinion shaft you may need to remove the nut,if the pinion is not centered in the housing it will be a RT or RS Rockwell series,I have saw 3:42 and 3:28 in those but never a a 3:50

[B_K]

Bob if the center chunk is the same as what's in my '86 MCI 102A3 that we parted out because of the busted frame. I have a 3:33 I'd let ya have reasonable!
  BK 

And might even have a 3:73 in one of the others I'd have to check!

[Brian Diehl]

Bob,
Do you have the close or wide spaced autoshift (B or C model)?
In my 96A3 I have the 3:33 rearend with a 400hp ISM and the wide range autoshift.  My bus weighs about 31k right now and I often tow my 5k lb Jeep.  I love the 3:33 rearend.  I hardly turn any rpms at 60mph and this helps for good fuel efficiency.  I only wish I had the close range autoshift as I have about a 400 - 500 rpm drop between every gear.  The close range would be better and allow for tighter control of engine speed to the load.  If you can get the 3:33 from Bryce in your Prevost it would work well.  I would personally not want the 3:73 since I would end up down in 10th gear around 50 instead of around 58.  The 3:73 will also make you slower off the line than I am.  There are a LOT of gear changes before you get over 30mph with the autoshift and this slows things down a lot.  Each gear change is pretty quick, but they all add up.  At your weight you will be starting out in 3rd gear most of the time.  5th gear tops out around 26 mph (I think that is what I remember).

I built a little calculator in Excel for estimating gears speeds and rpms for all gears.  Let me know if you would like a copy.
Brian

[rusty]

Bob With my Autoshift and 60 series I am going with a 3.53.With 495 RPM tires At 75 I will be at 1616 rpms, At 70 I will be at 1508, at 65- 1400 and 60- 1293. Not tested except on paper.

Wayne

[robertglines1]

#on hog head 3200-N-770  Has a - J - direct under N.  Has a sensor antilock brake(need to research) on curb side.  12 bolts hold hogs head in.  The Eaton Autoshift is a RTA016710-CAS      I understand 10th is .75.     Been awhile since I looked at spread but understand first three are about useless in a bus. Have Drive line all in hand so now is time to make gear change while it is still easy. Next step was to slide engine trans last 40 inches in place and do final bolt up. It will just have to wait! Have plenty else to do till I get correct set-up. Just need to figure out what will fit in the housing I have or what ring and pinion I can change out and fit my hogs head. Will probably have to take it out and count bolts in ring gear and do some measuring.  I'm lost here as I don't know how common they are to each other.Like MCI to Prevost etc. Any one comment on this?   Bob

[luvrbus]

You will need something different Bob lol the .75 OD is almost the same as 5th in the B500 which ran the 4:56,this is what was offered for your housing

3.07
3.21
4.30
4.56
4.88
the 1st 2 are for 6 and 7 speed manual transmissions a MCI center will not work in your housing,oops sorry about that 3:07 and 3:21 will not work in your housing

[robertglines1]

Just how bad would the 3:21 be at 42,000lb? Would it be a dog?  I do know I have the 4:56 now for sure and would have to crank  hard to run 70mph---  should pull stumps though.  Bob

[robertglines1]

I think it be time to visit my local drive line/rear end big truck guy and see what magic he has for me.      4:30 would save me some $ on fuel and give me a little more speed but not ideal.  Keep Ideas coming and I will keep up search also. Having a hard time getting use to the lower RPM of the 4 stroke power curve.   Bob

[Boomer]

Just request a copy of the final record from Prevost.  Give them your VIN and you don't even have to get your hands dirty to get the specs.

[robertglines1]

I have build sheet from Prevost and verified rear end. Just changed engine and trans combo. Actually bought bus without them. Now have to decide to slow down-- change whole housing and all. Apparently 4:30 is the highest that will fit in that housing. change trans in or just go. Need to talk to Hard Headed Ken  and see what he did. He had suggested under 3:50--- Still thinking.  

[robertglines1]

What I probably need is someone parting out a 2 stroke Prevost with a standard shift rear end in it.  Any Idea what other rear end will fit in my coach and bolt up with out much modification.  Need some direction as where to start looking for solution as this is one that for some reason got put on back shelf for later solution ---later is here.   Lesson to self   Don't get distracted!    Bob

[luvrbus]

You having anti lock brakes will limit your search Bob that will be a whole can of new worms a B500 Allison would be looking good to me lol but anything is doable like you said the 1st 3 or 4 gears are no value to you with the 10 speed 

[robertglines1]

Would be a  bigggg chunk of change !  A big oversight by my self.  experience cost $$$  Thinking outside box cost more$$$$$   Checking out Eaton final overdrive sets now to see if they offer a .64... haven't given up just..  down a notch or two in thinking and need to regroup..... Could just be happy with 70mph at 1900rpm and keep looking for answer.  Bob

[robertglines1]

What if I do away with anti lock feature?  I have never driven a bus with it.  Have done just fine with out it.  The manual says it will default to regular brakes if something in system fails (sensor etc)      So let the  neg fly--- I understand.  But in all honesty what would be the differance between the 89 I am use to without anti lock and the 98 with or without.  I understand from research it would still work on the tags and steering according to the manual.  What would be the actual differance?    Wish we could forget legal but actual facts.  Would it effect anything at all or be equal to my 89 coach performance?     Bob