PD4104 from Highway traveler to Highway Hauler

[johns4104]

I changed out the final drive in my 4104 and picked up 10 Mph at 2100 rpm.
So if my calculations are right I should have a top speed of 97mph, if there is enough motor.

Well I could install a turbo and change to countersunk shave rivets, and 24.5 tires might get me over 100mph.
Lets see maybe a trip to Bonneville will be in order. LOL


What about Stopping, I think I need to install my Jakes!

Does anyone know where I can find a tall 6-71 valve cover.

Thanks,
John

[scanzel]

If you do Bonneville you better at three parachutes to the back of the bus.

[5B Steve]

   For extra power, awhile back there was a thread about the poor mans turbo, someone mentioned about

   changing the blower drive gear. I haven't a clue to what it is or what the results would be.  Might want to

   check into it for "EXTRA POWER"   Maybe someone will clue in!


   Steve 5B......

[Rick59-4104]

 I have seen different 4104 top speeds posted here and there, I ran I-40 Little Rock to Fort Smith a while back with my new Firestone 24.5's my GPS told me top speed was 74 MPH. Guess I cannot run with John

Rick

[johns4104]

If I can't find a tall Valve cover, I think I will start working on the parachutes!
I don't know if changing the blower gears will help or not. seems like there was a debate as the extra horsepower needed to run the blower if it would help?

Rick, it also depends on what the gov. is set at.
anyone?

[seaton@mta]

I had a TDH 5106 (GM Old Look Transit with two-speed auto) that would top out at 75.  The previous owner had used it as a charter bus and swapped out the original rear-end for one from a PD 4103.  So, I guess a 90 mph 4104 shouldn't be out of the question.

-- Seaton

[wg4t50]

100+ mph, no problem with MCI-7 with either 12V-71 or 8V-92, 3.73 rear, 12R24.5R tires & RTO910 @ 2500 rpm.   

[johns4104]

Dave,
Sounds like a fun Mci-7!

[artvonne]

  You could have got away doing 100 in a Bus 20 or 30 years ago, today they would likely imprison you for a very long time.

  I looked at a 4106 in Minnesota once that JD had for sale. It had a speeding ticket framed above the driver for 86 mph. And yes, I checked and it had the correct plate number on the ticket that matched the Bus. Hate to blow a front tire at that speed, might be quite a thrill.

  No idea how my -5 is geared or how accurate the speedo is, but bringing her home the old girl would roll if I wasnt paying attention, several times seen the needle over 80.

  Guess you could always turn up the governor, lol. Crazy crazy people, I tell ya.
 

[gus]

Taller diff gears with a Spicer 4sp will give you fits starting on any incline!!

[wg4t50]

Johns3104,, Yes, best toy I ever had, 12V-71 is magic and class, the 8V-92 is just power, no class, Have had a lot of fun preventing cars from passing on the inside, I tend to run with traffic in left lane in those days, I-95 North bound from Arcadia event, in Ga, some yankees would try pass on right as I kept a comfy distance from traffic ahead, when I saw them start inside, I could take the hole away from them, guess it made some hot headed, but I laughed, from 75 to 85&90 is quicker than the car could get past me.  Lots of fun.
After a few go rounds, I would get in right lane for a while then get back in the fast lane.  Boys & Toys
If you  see a MCI7 with a large radiator across the rear, good chance it is the one.
Maybe the guy who owns it now will chime in one day and tell of his amazement with the power.  (Troy are you listening?)

[RJ]

John -

The stock rear axle in a 4104 was 4.125:1 with 1:1 bevel gears.  If the very rare "HydraShift" option was chosen, then there was a 3.55:1 ratio that went along with it, same bevel gear ratio.

So what did you find and install?

Am also curious to know what size wheels (22.5 or 24.5) you're running.

Have you made a run yet with an accurate tach and a GPS to sync rpm to speed?  Would be interested in your findings.

FWIW & HTH. . .

[johns4104]

Gus,
I thought about that, (starting on an incline)
Here was my BUS NUT logic:
I make a trip across the country at least 1 time a year.
I try to minimize taking off on an incline.
My bus weighs less than 22k loaded with water, fuel, fuel(gen), gear and 6 passengers.
The factory set up was designed for about 32k gvwr
The 3.555... to 1 ratio was an option on the 4104, in fact I took it out of my parts bus.
Also the bus came with 11-20's (12-22.5) from the factory and I am running 11r-22.5's.
So that is just a tad lower than the set-up I took the gear out of.
Also the 4106 runs an effective 3.33 to 1 after angle drive and the 4.125 rear end with the 11-20's (12-22.5's).
So again my clutch should hold up ok.

RJ, I made a run and I am turning 2100 rpm at 70Mph With GPS.
I don't shift out of 3rd gear until I hit 55 mph.
My Detroit's gov. is set at about 2500 rpm, HN70 injectors, (advanced timing maybe) that is where I get the theoretical top speed!
Now it feels like I am going 80 MPH backing out of my shop! LOL!!!

[RnMAdventures]

It seems like my ole 4104 would run about 65 and it had the 11-20's on the rear. I don't remember what the rear end ratio was.

John, The small pic of your 4104 looks nice. Do you have any pics on the web we can see?

[johns4104]

Mike,
Sounds like you had the 4.13 final drive in your 4104. That's what
I had in my 4104 to start with.

I have a couple of pictures in the post your bus section.
I may have to put build a project bus thread.

John