Gear ratios & highway speed
 

Ok - I know I'm going to get crucified for this but here goes! :giveup

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. :teach:

Cheers

Pete

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

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.

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

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

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 %.

Some thoughts on more speed with CMP
 

Hi Peter

This issue of more highway speed has been touched on before here is a link to some of them https://www.google.com/search?q=%22H...i&cr=&safe=off

Now on to some of the points that I have experienced in 33 years of driving a 101wb HUP and some 20 years of driving 134wb C60S.

The 20" wheels with 1100x20 tire sould definitely get you up to highway speeds of 60 MPH on the flat with the 216 engine. But I'm not sure the 216 will be happy with sustained driving at that speed for 15,000 Kilometers or nearly 10,000 miles. Remember that your distance target is over the rebuild distance for the engine, though your miles should be cleaner and mostly highway.

Reason I say the C8AX will do 60 MPH is that my C60S with its original 216 engine would pull down the interstate at indicated 50 MPH and corrected road speed of about 60 MPH (rubber overdrive) suspect that if you run military tires you will be replacing them about halfway through your trip.

Once drove my C60S leading a convoy with my foot planted on the floor, never shifting, for an entire morning top speed 65 MPH running away from the JEEPs on the down grades and down to 35 MPH on the hills. On other long convoys the CMP didn't seem to mind it as much as the CCKWs. You could always touch the transmission and transfer case of the CMP with your hand and not get burned, you could not say the same for the CCKWs.

When I up engined the C60S to a 261 it will pull away from most convoys if I want has more speed than I can use. Which brings us to another speed issue with CMPs particularly the 101 and 134 wheelbase they get very lively at speed, think you will find that 60MPH is about tops.

Next noise and vibration, good noise canceling headset with an intercom to talk with anybody riding with you will be essential. Drive train vibration will be something that you will discover for your particular vehicle there will be speeds that everything vibrates and speeds that things seem happier.

I did drive my HUP for an entire year with both of the front inner axles removed. Which did improve fuel economy and reduced the noise. With the axles out the front end is not turning the differential or front drive shaft.

If you go this route I would have your rear axle shafts magnafluxed to look for a problem right at the end of the spines.

One more suggestion get a infrared thermometer and make yourself a temp chart for all the critical points. Then check the temps at the end of the days run. May really help spot a problem in the making before it becomes a trip stopping break down.

Something else to think about, and I don't think has been mentioned, is raising the gearing with bigger wheels is fine for top speed, but it will mean higher ratios in low gears, and any hills may be more difficult, as the 216 is not blessed with a lot of power, I run a 28hp Bedford (72bhp) and is the British version of a 216, so know what this is like.

Richard,

First gear on the small CMP's is so low many people do not use it in everyday driving, I think that would not be a problem with upgraded final drive ratios. With any raising of gear ratios you certainly will have to change back earlier on hills but if Peter does not get too greedy and have to change down on the flat into a headwind he can drive normally.

Pete,

As for putting 20inch wheels on the vehicle in question it would dramatically change its appearance and make it look hotrodded. I have upsized the tyres and wheels on a lot of military and non-military vehicles over the years mainly to run on sand and without exception, on good roads they reduced road vibration but ALL handled and steered like c..p!

Taller 16 inch tyres are available but ANY of the above gearbox/diff suggestions would be cheaper than buying these in Australia. I have been trying to source some for my 4WD Mitsibishi Canter and find the very few brands available all add up to $2-3,000 for a set.

The modern Michelin radial equivilent of 9.00x16 which will fit your wheels are between $500 and $700 each depending on your source! The cheap and readily available MRF 9.00x16 non-directional that I have on my Dodge WC53 have done nearly 10,000km (much of it flat out on the highway going to and from Corowa) and all have over 80% tread remaining. A new set will get you around Australia easily. You might do some sums on getting tyres from Coker and others in USA but I doubt it will be an economic success.

Many if not all of us would love to do the trip
 

Hi Peter

You started your thread "Ok - I know I'm going to get crucified for this but here goes!". But not to worry, most if not all of us have wanted to take a really long trip in our CMPs and are either envious or doubt your sanity (my kind of crazy) for undertaking a trip of that length.

I'd love to do the Alcan tour in 2012 but the distance to and from the start is to long to consider for my old bones. I suspect the C60S would make the trip fine.

Hope that you can workout all the details, carry a good video camera and still camera so that you can share the trip.

Hope you will keep asking questions and bouncing ideas of the rest of us.

Cheers Phil

Five speed over-drive
 

I operated my Lease-Lend Chev for many years with a Five speed OD box from a CCKW. I found that it was not a success with the 216 as that engine just didn't have enough grunt to pull 5th gear except under favourable conditions. The 235 engine (still a splash feed) made all the difference but even then I could have used a few more cubes.

David

Motto,

Didn't you upgrade your Dodge Weapons Carrier too 20" wheels as well? How did you do it and how did it go?

Regards Rick.

Hi Rick. Seasons Greetings to you and Jill.

Yes I had a set of White M3A1 Scout Car wheels modified by Austral Wheel Works to go on my 3/4 ton Dodge WC and used 9.00-20 ND bar tread tyres. I still have them but don't look upon them as being a success. I thought it an easy and easily reverse able way to increase road speed.

Where they weren't satisfactory was as Lang commented in relation to the C8AX, 20 inch wheels just looked wrong and added to that the 230 cu in engine is barely adequate anyhow so I was back to 3rd earlier. Another negative affect was the degredation of off-road performance that the single speed transfer case couldn't help with.

I currently have a Dodge 3/4 ton Command Car on the build in which I have installed 4.89 diff's and a two speed transfer case as against the 5.83 and single speed originals. We'll see.

David

transfer case
 

This is just rambling thoughts . You can buy a aftermarket gear set for the series Land Rover transfer case . The ratios are such that the high range road speed is better but the low ratios for off road use are hardly affected . At the Traf swap a few years ago, a guy had a land Rover FS with that aftermarket gear set fitted ...the complete car was $600 ..... cheap when you consider the special gear set is about $900 to buy . :teach: All that doesn't mean much for a C8AX ..but there were two diff ratios fitted on the C8A series ...

Mike,
Do you know if it is possibe to adapt a Fairey overdrive to a Blitz transfer case? If you could do this by even getting a new gear cut it would be the answer to Peter's prayers. Those Landrover overdrives are not too hard to find and probably the perfect upgrading for the Blitz which certainly has more power in reserve to pull a higher gear than the Landrover 4's. A Dodge or any of several other (Nissan, Suzuki, International 1200, F150 etc) remote transfer cases might take the overdrive and be easily fitted in place of the original.

Lang

fairy
 

lang

The Standard 2 and 1/4 litre Land Rover 4 engine puts out about 70 bhp.

Mike,

The 216 Chev puts out 90hp so should handle the Landrover overdrive ratios quite OK.

Lang

Thanks every one for your input - I certainly have a few options to consider. Probably the simplest is dropping the front drive shaft, axles and transfer case and getting a longer rear shaft made. That way everything original can be kept and ref-fitted after the trip.

I have considered an intercom and headsets - they are on the wish list, as is a whole pile of camping gear, generator etc etc. This trip is something I am not undertaking lightly - I have sent letters to Legacy for official sanction and will be seeking sponsorship and assistance from the Australian Army any one of the fuel suppliers that wants to get on board, hotel chains, equipment suppliers etc etc - the list is endless.

Im doing this because not because it will be fun, ( ok - a bit) but because it will be so hard - I really want to re-focus Australia's attention on Legacy - in my mind the most important charity orgaisation we have - it seems to be over shadowed by red nose day, daffodil day and pink day and all the others. I also want to try an make our young people understand the sacrifice the diggers (my grandad - your dads and perhaps even some of you - I dont know) and allied soldiers made - they drove these things across Africa in the blazing sun, through the snow of Europe, all over the Pacific for 6 years - getting shot at. I can sit in one with my mate for 4 months Im sure!

I hope to get in contact with all the military vehicle clubs along the way and welcome people joining in where ever possible. The more attention we can make - the more media will get involved - the more money we raise. It's a big job, but with your help I will put it together and pull it off.

Thanks everyone. :)

Later 235 or 261 instead of the 216
 

Hi Peter

In considering how to make the vehicle and you happier at sustained 55-60 MPH don't forget to consider engine swap. I suggest this for a number of reasons with the gear you are mentioning carrying the 216 will be pulling hard.

A late 50's early 60's 235 or best yet 261Chevy is a reasonably simple bolt in conversion. When properly setup either of these engines has more use able RPMs and far more usable horsepower and torque.

In looking at 235s you want the later pressure crank version.

Just a thought.

Cheers Phil

Hi again guys,a while ago i used to drive my mates spare C8AX on club outings,it was fitted with a "Blue Flame" Chev engine.
Well it would pull away from my mates other C8AX no trouble at all,could sit on 50-55 MPH
and not be flogging it,it just made all the difference and was a pleasure to drive.
My mates Chev that he drives has the 216 original engine still in it,BUT he sold the Chev with the Blue Flame!!,now he has been scouring arond for another blue flame to replace the 216 in his C8AX.
I must say that the C8AX is faster on the open road than my F30 (as the Ford will do 38 MPH on the flat,)but different weight ratios between the two though.

What size wheels on the F30
 

Good point Ken, just out of curiosity what size wheels does the F30 have?

I ask because the C30 had 16in wheels running 7.16 to 1 gears which should give them some real low end grunt but would cut into the actual road speed. My `41 C60L had the 16" wheels and the 7.16 to 1 and it was impossible to drive on the road, was over revving engine just trying to drive on secondary roads. Changed over to 20" with 11:00x20 tires and it is a lot happier.

As to the Blue Flame engine which version pressure crank or splasher?

Cheers Phil

Peter,

How long do you expect to be on the road?

If you are looking at something like 6 weeks there really is no reason to do anything to the vehicle. Your current preference to take out the front axles and transfer case is more than adequate to give you the increased noise comfort and fuel consumption improvement. All the more complex changes are not only unnecessary but will cut in to the funds raised.

There is absolutely no reason why a standard CMP can not easily do that distance in 6 weeks with an average of 350km per day. At an average speed of say 65km/30mph you are on the road for less than 6 hours. Getting away at 0700 each morning gives heaps of time to stop in towns for your charity promotion along the way.

I have driven a C60 straight off the farm from Mareeba to Melbourne (4,000km) and a C15A also unrestored from Townsville to Brisbane (!,800km). It's just a matter of relaxing and watching the scenery go slowly by!

We averaged 300km per day a few years back in 100 year old cars Peking to Paris for 14,000km cruising at 40-50kmh and found it quite practical. On the Istanbul to Normandy trip a couple of years ago the guys in the CMP's had no problem keeping up and were no more fatigued than those driving Dodges, light Fords and Chevs etc.

Keep it simple.

Lang

Doing the math isn't fair
 

Hi Peter and Lang

Lang the simplicity of your approach is really to be commended. All of us were concentrating on the technical end and you hit the key elements of the question how long and whats a reasonable distance a day.

The comments on the other long distance antique vehicle tours are also on point.

Cheers Phil

Hi Phil, The F30 originaly had 10x50x16s fitted and the speed was the early 30s,bearing in mind the v8 is not fully run in.
I have now fitted 8x25x20s on military rims made by GM !! as the 16s were all cracking in the tire walls and treadand cant source local tires of 10x50x16.
The original 20s were 10x50x20,and the speedo drives were different in the number of teeth fitted(in parts manual).
With the 20s fitted it looks like the truck has grown up!.
The difference between an F30 and a F60S is the 60 has an extra leaf spring in the front springs, bigger stearing ends,although not allways.and air assisted breaking system and wheel size, oh and somtimes a bigger stearing box.

Go With Lang
 

Hi Pete - I have been following this thread with interest but I think it is a matter of not seeing the wood for the trees. You would incur a lot of time and expense modifying a perfectly adequate vehicle. It might be a slower and rougher drive but military trucks were made for that purpose. Lang is the adventurer and I concur with what he says.

As you get closer to the departure time you must let us know the route and approximate timings. There will be numerous MLUers on the route so accommodation would not be a problem and we can promote this fund raiser in our areas. Many of us are in the RSL so they would be greatly interested. You may even be able to get a grant from Veteran Affairs.

Bob

Help 'round
 

Absolutley! Let us know the details when you have them and/or feel free to make a visit to us a part of your itinerary!
H :salute:

Once again thanks to all for your input.

Once I have got official sanction from Legacy I will start another thread devoted specifically to the trip. Havent worked out the exact route yet but am thinking 5th of May 2013 as a departure date as that makes it 70 years to the day the C8AX was built. This would also work in relation to weather in the top end and across the Nullabor as it will be cooler & more truck friendly. My copilot will be visiting in the next few weeks so we will nut out more details then but we will have at least 9 weeks - maybe as many as 12 depending on our leave (both emergency service personnel)

Lang is of course right - we can do the trip in the vehicle in its original configuration with out any modifications with no dramas - My main concern was about the safety aspect of being on major highways at 70 kph or so as for some legs we will not have a support vehicle.

Watch this space! :salute:

Pete,

We have run the Postie Bike Challenge for 10 years now (40-60 riders on Honda 110cc stepthroughs) 3,000km through the outback. They travel at 70kph and we have never had a bike run down. A CMP is a heck of a lot bigger target so you will have no problem. You must spend $150 and get a UHF radio so you can talk to the road trains and other trucks. You will find they are some of your best salesmen and will spread the word.

We had great support from them on our prostate cancer trip in the 1915 Willys Overland www.willys.com.au Feel free to use any ideas from our trip to plan yours.

Lang

Once again with his vast experience at conning slow moving machinery across the face of the planet Lang's opinion is worth listening to. Travel times are not a real consideration. What I point out to people who query that aspect of a vehicle with a low cruising speed is that ships sail around the world at 25 or 30 MPH and it's quite an adequate rate of travel.

Having said that, some images/incidents flash to mind. One is of a DUKW (NOT a small vehicle) upside down on top of the Armco railing alongside an English motorway as the result of a semi-trailer changing lanes a fraction too late.

I also remember talking to the owner of a Leyland Hippo in Normandy 2009 who was run into from behind on the motorway on his way down to the docks. (Again, NOT a small vehicle) The amusing part of this incident was the wry observation from the owner that he glanced at the speedo at the moment of impact and it was showing 33 MPH instead of the usual top of 28. He said that's the fastest she'd ever gone. Damage to Hippo=bent mudguard, damage to VW impacting vehicle= total write-off, driver=multiple injuries inc two broken legs.

Another, more recent incident was the death of a well know and greatly liked British MV identity in his Jeep when hit from behind. He had taken part in a tour to Italy and was only a few miles from his English home.

Like it or not, low speed is a safety issue if only because of the blind bastards out there and luck plays a huge part in the outcome of any time spent on the road. I painted the rear bolster on my 3 ton Chev vivid white and seriously considered putting an amber rotating beacon on the vehicle. I have it in the shed yet and it won't take much prompting to use it.

Consider.

David

Motto,

Sobering thoughts in relation to rear impacts. Believe me - 10 years as a front line Paramedic has shown me the stupidity of a lot of road users!

I already have purchased a magnetic flashing amber beacon for the back of the truck & it will be used on all trips except the run down the street to the post office!

I will also be fitting a 6v-12v converter so I can run a UHF radio as I agree that the truckers are a wealth of knowledge on road conditions and also great source of early warning and information. :thup2: