Projects 1917/1928/1938 American Lafrance Plymouth V12 Speedster

Way cool. I will be following as many others. I get a kick out of that 100 yr old speedster stuff. Did you have todo any math on rear diff gearing as opposed to sprockets, tire hieght? Im sure it matters somehow?

 

Yup i'll have to sit down and do some math to figure out exactly which sprocket ill go with.
It's kind of a bitch to figure out because there isnt an engine RPM to transmission gear to rear diff ratio to sprockets to rear wheel rpm/speed calculator lol

 

Yea thats what i was thinking too lol

 

The math shouldn't be too difficult, just take it a step at a time. Sketching the components and locations helps alot.
If you need a sprocket outline designed, I might be able to do it and save it as a dxf.
(I've done large non-commercial #40 i.g 216; the principles are the same for other tooth profiles)
You could then have it water-jet cut out of whatever material.

But, it would be more economical to buy commercial sprockets.

BTW, your chain(s) will be flopping a bit due to the front spring perch not being coincident with the rear axle shaft center........ you probably already knew that.

 

I did not know that. I dont know what you mean by coincident. Please explain more.

 

By "rear axle shaft" I mean the shortened differential that is bolted into the notched frame so that you don't have to put a drive shaft in there; as you've explained.
The issue is that the distance A, (chain) in this crude sketch will shorten when the driven axle pivots about the forward spring perch bolt.
C is constant as built. Length of C is what I was referring to when I said "the front spring perch not being coincident with the rear axle shaft center"

B lengthens slightly as the spring is subjected to more load, as it has a tendency to straighten the curve of the spring, however this will not be the same amount as what happens to A.

If the chain length is made to fit when the vehicle is at rest,
it will slacken because of a change in A to A1 as a load is applied or the drive axle is displaced vertically.
You can check this easily by taking out the spring shackles at the rear (differential supported)
and measure A as you move the differential up/down.

It may be that it's not enough to worry about, but the change in A to A1 will def be there.

 

I had a Ruttman Mini Bike as a kid. Hot Rod West Bend engine. Was cruising at about 35 mph when the chain broke. Still have the scar. Just saying.

 

So the chain drives used on Mack Bulldogs and similar age vehicles (1920s and earlier, at least) had slack in them, but they were also using springs with a relatively high load rating. Maybe 1-2" of slack? Anyways, if the chain would break under load, they would usually just lay down in the road after going over the drive sprocket. Similar to a tank tread coming off. And because of the slack, they aren't under the tension that a bicycle (or mini bike) chain might be under.

I don't think a chain "snapping" and causing injury is of much concern here, but I reserve the right to be wrong.

 

Thanks for the explanation Gatz.
If it's to much for my liking I'll put sprung idler in.

 

Just don't lose your head.

 

This is a similar concept to ladder bars/rear trailing arms needing to be mounted as close as possible to trans output yoke correct? Except the obvious difference of this case the chain gets slack or tighter, and the ladder bar example the driveshaft would slide in or out on the slip yoke.

Just trying to understand the science in my head.

-Adam

Sent from my rotary phone using The H.A.M.B. mobile app

 

The Mack Bulldog trucks that used the chain drive had an adjustable strut with a circular mount that pivoted about the primary drive axle, so slack could be kept to a minimum, This eliminated the C factor as well as any change in B in the sketch posted. "A" then being the constant once this adjustment was made.




I remember assembling a Bulldog model kit as a youngster and giving it to my Grand-dad.
Also gave him a Bulldog hood ornament, which I inherited and still have.
The chain drive was an interesting, but non-functioning detail of the kit's design.

I would suggest that the OP still consider the effect as mentioned in previous post.
A sprung idler on the slack (lower) side may work.

Check out this type of tensioner....

https://www.lovejoy-inc.com/products/runright-rubber-suspension/

there are other brands of the same.

gatz

 

Cool project, it's fun to build something that uses nothing from a catalog, huh?
I have my dad's big old pre war Jeager cement mixer. The bowl is driven with a big roller chain that has about an inch and a quarter between pins. When the original chain tensioner sprocket bearings failed during a pour he quick like cut a chunk of oak 2 x 4 about 6 inches long, cut a curve on the side that rides on the chain with a chainsaw and drilled a hole for the shaft to go through. We were back to work in about 20 minutes and that oak block has been in there doing it's job for 50 years. No wear is evident except a couple little grooves where the side rails of the chain wore in. Once the rollers hit the wood it hasn't changed.
I said all that to plant the idea in your head that hardwood is period correct and would (wood) look cool in my opinion. Easy to build a short swinging arm with a hood spring for tensioning on the bottom/slack side.
Subscribed.

 

Just thought I'd add an opinion (even though nobody gives a damn), I really do prefer your choice of body less speedster like old 999 to the boat tails.

 

Thats bad ass Fabber McGee.

 

I decided to test fire the engineyesterday for shits and giggles and it seemed to only be running on the left bank of cylinders. TodayI investigated more and discovered some stuck Valves the old school way.
WITH GREAT BALLS OF FIRE!!
I started working them back and forth andhope they free up. Ifnot it's OFFWITH HER HEAD!

 

This is a really awesome car. I had the same engine stored in my shop for a few years for a friend, it finally sold 2 months ago. If I had seen your build before that, I'd most likely be working on something similar.

If you want to get fancy, design the sprockets in halves so you can change them without pulling the wheels etc.. You could change ratios quicker that way. Look at shifter karts for examples.

 

Animal, back a ways I think you said you looked at sprockets. Have you looked in McMaster Carr for them? They have quite a few in flat sprockets fairly cheap. They could be split and bolted to a hub as, I THINK, Mcgyver was suggesting. I have seen this in use on big equipment and it works. I am sure other places have them too, but I like Mc Carr.

 

What'd ya geet for it Mcgyver?

I got the valve semi freed up but the guides are crumbling so she'll need a valve job atleast.

 

I havnt been able to dig into the head yet but I finished up the battery box, and upper rad support. Also used my CAD software to create floor templates.

 

Hi Animal.
I like where this build is going ,looks really nice.
What kind of welding machine do you have?

I think I have the same CAD

 

Really great build !

 

Currently I have the Prime weld Tig 225. It's a great machine.

 

Wow, what a great build. You going to add any kind of shock absorbers? May get to much bounce without. Watching closely.

 

Thank you. I will add shock absorbers when I find a set I like. Probably just some simple friction shocks

 

You might look at the friction shocks that Gui @Drmalacarne made for his V-12 speedster
https://www.jalopyjournal.com/forum/threads/seagrave-531-v12-special-build-up-in-brazil.1163715/

 

That's a badass build. Love his rear suspension. I may have to join thd short list of hambers that have built their own friction shocks lol

 

Late to the party but enjoying this build.
As a youth I spent many hours at the Ford museum staring at the 999. What a beast that must have been to drive. And on the ice no less.
It scared the crap out of me just sitting there with it's exposed fly wheel. LOL
Old Henry and Barney Oldfield would be proud of you.
Torchie

 

This is the one that I stared at as a youngster. It's referred to as the "Red One" , I believe.
He had 2 racers by that name.
Torchie

 

One of my great inspirations for this build Torchie.