Reply
 
Thread Tools Display Modes
 
Old 05-26-2015, 03:07 PM   #11
New Member
 
Join Date: May 2015
Posts: 6
Quote:
Originally Posted by Tango View Post
Howdy again --- the biggest obstacle to highway speeds will be the gearing on the rear end and tranny. Both can be modified, it's just a matter of how far you want to go. Your engine compartment would easily handle a Cummins 5.9 but a properly rebuilt, a 6 cylinder gas Chevy would pull higher gears as well.

As I recall, your rear axle is very likely either a 5.43 (rare) or a 6.17 (most common) and finding anything taller is next to impossible. You can determine the rear axle gearing one of two ways...

1. Jack up the driver side rear wheel...put marks on both the wheel and the driveshaft...then, while in neutral, rotate the wheel while counting the number of turns the driveshaft makes. That number will be your ratio (i.e., 6.17 turns of the shaft to one of the wheel = 6.17:1 or what ever)

2. The other involves removing the inspection plate on the back of the axle. Chevy stamped the ratio directly onto the flat side of their ring gears.

Either way, it is a good idea to know just what your gearing might be. From there, you can plug numbers into an online speed/RPM calculator such as the one below to determine what speeds at various RPM's you can achieve.

Engine RPM Calculator

Most of these buses top out about 45 to 50 which makes highway traveling dangerous these days thanks to the lamewits who are incapable of judging speed or distance while texting on their cell phones.

Also worth noting in this regard is tire diameter. I've seen a number of people swap out their 20" rims & tires for smaller ones to get a lower profile and hot rod look. Going smaller in diameter makes a huge reduction in top gear/speed at any given RPM. Here again, the calculator above can show the effect of different diameter tires. Handy tool.

Best of luck and please do keep the pix coming.
Thanks for the info, Tango. According to the seller it is a 4 speed with a 2 speed rear axle. I'm not really sure what that means but he says it drives comfortable at 90km/h on the highway but can be pushed to 100km/h.
15416 is offline   Reply With Quote
Old 05-26-2015, 04:05 PM   #12
Bus Geek
 
Tango's Avatar
 
Join Date: Mar 2011
Location: Houston, Texas
Posts: 6,174
Year: 1946
Coachwork: Chevrolet/Wayne
Chassis: 1- 1/2 ton
Engine: Cummins 4BT
Rated Cap: 15
That translates to about 55-60 mph down here south of the border. A little better than many but still a bit too slow to avoid getting rear ended by a gasoline tanker headed for home. I would shoot for some engine/gearing combo that gets you up around 65 mph (about 105 km/h) at the engines' peak torque rpm so that you'll still have a little more pedal when needed.

Do you know yet what the final rear axle ratio might be?

Tango is offline   Reply With Quote
Old 05-26-2015, 04:09 PM   #13
New Member
 
Join Date: May 2015
Posts: 6
Not sure of the final rear axle ratio yet. We have a baby coming any day now so I feel it would be irresponsible for me to be on the road for 12 hours!

The idea of swapping an engine seems way beyond my abilities at this point. Maybe I'll get the courage once I start digging into the bus!
15416 is offline   Reply With Quote
Old 05-26-2015, 04:12 PM   #14
Bus Geek
 
Tango's Avatar
 
Join Date: Mar 2011
Location: Houston, Texas
Posts: 6,174
Year: 1946
Coachwork: Chevrolet/Wayne
Chassis: 1- 1/2 ton
Engine: Cummins 4BT
Rated Cap: 15
BTW...be sure to check out the GMC Heritage site. They have online manuals for a great many vintage vehicles. Yours being built on a truck chassis, you may be able to dig up some useful info there. It certainly helped me.

https://www.gmheritagecenter.com/doc...olet-Truck.pdf

And...best of luck on the baby watch!
Tango is offline   Reply With Quote
Old 05-26-2015, 05:04 PM   #15
New Member
 
Join Date: May 2015
Posts: 6
This is great! I'd like to switch to a 12 volt system before I get on the road with it. Mostly just to save me from having to buy a 6 volt battery just to get it home. I've seen a few kits available but I'd like to make sure I have everything I need. Is this a good resource for my purposes?

12 Volt Conversions for Classic Chevy and GMC Trucks | Advance Design Trucks
15416 is offline   Reply With Quote
Reply

Tags
1954, canada, gmc

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


» Virginia Campgrounds

Reviews provided by

Powered by vBadvanced CMPS v3.2.3

All times are GMT -5. The time now is 06:03 AM.


Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2017, vBulletin Solutions, Inc.