Info needed: Building a repro LRDG 1940 Chev.

[Bob Carriere]

Hi Bob.... Hi everyone....

Finally found a picture of the tubular axle....... tell me if that is the same.

The width of the axle...tracking width....according to reference manual matches other CMP tracks standardized at 70 to 71 inches..... and since I may have to use a CMP C15a rear axle to facilitate using existing CMP rims it may ntobe an issue.

If need be removing and re-fabricating the spring perches is not impossible.... in my days we torched them off and rewelded new one made from thick wall square tubing..... a lot will depend on how standard the 1940 frame width is?

Bigger issue raise by Tony....... the current axle has a 6 inch drop the ambulance axle is straight..... which would raise the nose unless I fabricate spacers for the rear axle......

Too early for that..... I need to get rid of the snow and get my hands dirty touching and measuring.

Still working on a wooden mock up adapter to allow using CMP rims with the existing 1940 axle........ but rather fascinated with the tubular axle.

Bob do you have one axle and possibly a second one???? will "parlez" a price or a donation to MLU upkeep on your behalf...... not sure I need to consider the Ford beam front axle at this point but will look them up in Grant's bibles-s-s-s-s.

Found a wheel fabricator, of all places Canada South of Montreal and not in California, who also has some interesting options for a modern any width and diam rim with a solid flat steel center drilled to the GM 10 bolts.

...and it gets complicated.... got a parts book for the 1940 Chevrolet and another for the Maple Leaf 1940....... and they show 4 different Beam axles and 4 different wheel/rim offset which creates a multitude of front axle width.

Bob....look for a PM.....

Cheers

[Bob Phillips]

Hi Bob see my PM
photos are the heavy version of the axle- was just thinking there is a Maple Leaf GM truck at my local yard with a drop front axle- hubs from the CMP straight axle may fit right on....can investigate if it ever warms up
BP

[Bob Carriere]

Would appreciate you looking into the Maple Leaf front axle.... it may fit..... I know for a fact that many CMP were converted to dual rear wheel by simply removing the CMP brake drum/bearing and sliding in place the late GM/Chev dual wheel drum and all.... everything was a bolt on.....

Will see you at the OMVA show.

Thanks for your help.

[Bob Carriere]

....well we palyed with our MDF wooden adapter that allows bolting a regualr 16 in. CMP rim to the 10 bolt Chev front I beam axle........

...it fits quite nicely but gives the wheel a full 5 inch outboard offset and would explain why the LRDG trucks had the front fenders extended/widened by 4 inches.

We also removed the front bearing for inspection ..... and has appropriately nicknamed by Australian/New Zealanders..... "bicycle wheel" bearing of real punny size............

It seems that only the HD 3 ton trucks, COE and C15 had the sturdier roller bearings.

...and the search continues.... still considering all options...

[Tony Smith]

But looking at the color pic in post #9, the wheel is bolted directly to the brake drum without the 4 1/2" spacer. Where would that put you? Will the rim clear the brake drum?

[Hanno Spoelstra]

Bob,

Good to see you experimenting with the wheel/brake drum setup!
That offset will put quite some leverage on the axle stub and put a large load on the bearings. As long as you don’t go lugging around the desert packed to the rafters you’ll probably be fine.

Originally Posted by Tony Smith

But looking at the color pic in post #9, the wheel is bolted directly to the brake drum without the 4 1/2" spacer. Where would that put you? Will the rim clear the brake drum?

Like I said, looking at the WB model, I wonder if they could be civilians rims, possibly widened and mounted inside out? One can clearly see the rivets so this is not a split rim.

http://www.mapleleafup.net/forums/sh...439#post258439

[Bob Carriere]

Hi Tony

On posting #9 that rim when enlarged shows signs of being a rim with an outside ring........ I have no doubt the rim has been modified and possibly mounted backwards....... if it is mounted on 10 bolts then they have to be mounted to a hub/adapter of unknown size as the actual adapter mounts to the brake drum with only five bolts of different diameter to the 7 1/4 diam 10 bolt pattern............ it is unusual and would not be surprised if it was 18 inches....and here is why I think so

If you look at my mock up posting the brake drum is fully cleared of the CMP rim. The inside diameter of the CMP rim is 15 + inches as it is slopped a few degrees as you get closer to the center....and we measured the stock brake drum which measure a hair over 14 iinches....leaving less than a half inch clearance between rim and drum....The other is that the front picture fo Rick Cove's repro shows clearly the front brake drums outside the front rms and his brake drums are ribbed/fins....... which is a variety of brake drums used on those vehicles by GM.

Another factoid...... just got a hold of two new 1940 Chevrolet and Maple Leaf parts book and in the listings.....although only one size hub/adapter of 4 1/4 inch is listed they have four different offset rims sizes ranging from 4 1/8 to 5 1/4 offsets on the rim center parts....all in 20 inches. My spare rim and spare axle has the inside part of the rim even with the brake plate ...this to me implies that it is the smallest offset......... Philippe in Florida has the opposite on his 1939 Chev and his rim clears the brake drum completely. so GM played with the track width by varying the offset of the wheels and the greater offset seems to be on the larger truck axles....series 15 to 18 had the wide offset....... they were not to concerned with the overloading of the bearings. Honestly I am concerned with the old technology and will search to see if I can find roller bearing that fits that particular hub/adapter....... too much unsprung weight to far outboard for my taste.

Hanno.... I agree they are not split rim as far as I can tell.....but have a closer look at the rim/ring edge........looks to me to be a 2 or 3 part rim of that period with the tire pressure locking the rim bead....

The tight fit of the GM brake drum and the split CMP rim may partly explain the reason for using a two part 18 inch rim......18 inches rim where popular in that period and Ford trucks did use them as well.

It would seem possible that a regular 16 in. CMP rim would fit by reversing the location of my adapter plate and mount the rim backwards.... in any event I will play with the mockup to see if I can have the wheel mounted with less overhang..... yet not quite overlap the brake drum...... might be able to gain an inch or so......

Thanks for the interest and questions in this challenging project.

Now looking at finding mid to late 40s production Chev/Maple Leaf 3 ton front axle...... and Ford also had 3 ton I beam front axles...... but only after this snow cover finally melts.......

Bob C