|
|
|
|
#1
25-12-11, 02:44
|
||||
|
||||
Gear ratios & highway speed
Ok - I know I'm going to get crucified for this but here goes!
 I'm planning a massive road trip in my C8AX in 2013. A trip of some 15,000 klm around Australia fund raising for Legacy. To that end, can anyone suggest a change in either gear or diff ratios that will give us better highway cruising speed, something more suitable in todays world? Of course I will keep all original equipment so I can to return to original specs once the trip is over. Any information greatly appreciated.  Cheers Pete
__________________
Peter Solomon '43 Chev C8AX Collector of all things Allied from WW1 & 2 Avid Military historian & traveller From Gallipoli and the Somme, Tobruk and Kakoda, through to Timor, the Gulf and now into Afghanistan remember the supreme sacrifice made by other so we can live our lives in peace and freedom, be proud of those who serve. Lest We Forget. 
|
|
#2
25-12-11, 03:59
|
|||
|
|||
|
Easy and complicated way......
Fabricate some wheel adaptors to use modern large diametre tires.....
.... or replace both front and rear axles with modern axles, tires, brakes, etc.... I hope you have medicare insurance or some coverage for chiropractor services ..... 15,000 km in that cab could cripple you for life...... Good luck on your venture...... don't forget to take photos and psot them o n MLU.... some of us can't read.... Bob
__________________
Bob Carriere....B.T.B C15a Cab 11 Hammond, Ontario Canada
|
|
#3
25-12-11, 08:12
|
||||
|
||||
|
Fit a GMC 5 speed gear box,and im sure that there are diferent diff ratios to be had.
20" wheels would be worth looking at as well,just thoughts really,but there is a C8AX here with a 5 speed GMC box fitted,worth looking into. Your trip will be interesting to follow,merry christmas.
__________________
kenney
|
|
#4
25-12-11, 09:16
|
|||
|
|||
|
If you took out the front axles (should not need 4WD on this trip) it will improve things tremendously in the fuel consumption/noise/vibration/steering departments. Just disconnecting the drive shaft still leaves you turning over all the axle/diff machinery. If you want to go one step further you could drop out the transfer case for another 50% reduction in gear noise and get a prop shop to make a straight drive shaft.
Not a big job to change diff ratios and probably easier and cheaper than fitting other gear boxes. Half a day at the diff shop and drive away. If you are going to fit a 5 speed gear box you would be better off with a Toyota Dyna box instead of a big clunky agricultural GMC box. Changing a gear box sounds simple but once started you chase your tail because the new box needs new mounts, gear stick hole has to be changed (and sometimes floor humped), tail shaft length may need to be altered etc. Lang
|
|
#5
25-12-11, 10:19
|
|||
|
|||
|
Peter,
Good luck with the the Legacy trip. I think that is wonderful. If your passing my way there will be a bed available if needed. We could also join your trip for a few Km in our area to help promote the cause.Maybe all Australian MLUers can join for a while along the way as well. An axle set from a C15A fitted with 20" wheels will be the easiest way to up speed the C8AX. The C15A has 8 stud wheels against the 6 of the C8AX. If you had a spare set of 6 stud centres you could also weld 20 inchers onto them but I guess they are pretty scarce on the ground. Good Luck and safe trip. Regards Rick
__________________
1916 Albion A10 1942 White Scoutcar 1940 Chev Staff Car 1940 F30S Cab11 1940 Chev WA LRDG "Te Hai" 1941 F60L Cab12 1943 Ford Lynx 1942 Bren Gun Carrier VR no.2250 Humber FV1601A Saracen Mk1(?) 25pdr. 1940 Weir No.266 25pdr. Australian Short No.185 (?) KVE Member.
|
|
#6
25-12-11, 16:30
|
||||
|
||||
|
Older truck type 5 speeds usually aren't overdrives so won't help. Some newer small ones like the T10 would take a lot of work to make them fit but could be done.
The C8A uses one ton rear ends so different ratios might be available. Modern 16" tires are available in quite a few sizes and it shouldn't be too hard to find some bigger diameter tires. They fit the rims and as a bonus you'll get a lot quieter and smoother ride. 4 inches more diameter cuts engine RPMs by 20 %.
__________________
1940 Cab 11 C8 Wireless with 1A2 box & 11 set 1940 Cab 11 C8 cab and chassis 1940 Cab 11 C15 with 2A1 & Motley mount & Lewis gun 1940 Cab 11 F15A w/ Chev rear ends 1941 Cab 12 F15A 1942-44 Cab 13 F15A x 5 1942 cab 13 F15A with 2B1 box 1943 cab 13 F15A with 2H1 box 1943 Cab 13 C8A HUP 1944 Cab 13 C15A with 2C1 box 1943 Cletrac M2 High Speed Tractor MkII Bren gun carrier chassis x 2
|
 |
|
|
Hybrid Mode
