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Thats the place. I couldn't get a price until I sent them the axle.

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Miata UBJ: ES-2074R('70s maz pickup)
Ford IFS viewtopic.php?f=5&t=13225&p=134742
Simple Spring select viewtopic.php?f=5&t=11815
LxWxHt
360LA 442E: 134.5x46x15
Lotus7:115x39x7.25
Tiger Avon:114x40x13.3-12.6
Champion/Book:114x42x11
Gibbs/Haynes:122x42x14
VoDou:113x44x14
McSorley 442:122x46x14
Collins 241:127x46x12

Depends on how good the weld is. Ideally, you'd want it to be choice #2. If its choice #1, there wasn't good penetration - the welder either wasn't set up right or it isn't powerful enough for the task.

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-Andrew
Build Log
Youtube

Well I got scared by a couple of things.

Years ago in a very early Formula Ford, I noticed an odd pounding sensation when I would got a really fast shot thru this one turn. It was heavily banked and you could really load the car up, and it was slow so you where nearing red line in 2nd just after the apex. It was subtle, but I was curious and kept my eyes open. Later that day I noticed from a certain angle that the yokes on the left half shaft had a lightly polished area on it and showed it to someone.

I was just a newbie, but was fortunate in getting good advice those days. That car used those rubber doughnut joints and it had started failing. I was assured the drive shaft would take the wheel right off the car in a heartbeat.

I started making it a point to pay attention to whatever little signals I could get and to trust my instincts after that.

The second thing is in the same time period during one of those very late night conversations at a track, while camping. I remember being told, "don't build your rig with a (Censored) rear-end, because that's how so and so had died..."

These aren't what your doing but to me indicate caution in this area, that's all.

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Marcus Barrow - Car9 an open design community supported sports car for home builders!
SketchUp collection for LocostUSA: "Dream it, Build it, Drive it!"
Car9 Roadster information - models, drawings, resources etc.

160'# times the gear ratio is a lot of shock torque when you slide your foot sideways off the clutch.

That machine took an awful amount of abuse. I was running 9.15x15 tires that had pretty good grip. I could climb a 100' high pile of dried clay with about a 20' head start at the bottom on a clean concrete portion of a road. The hill was formed when dump trucks were dumping the clay over the side of a plateau that washed out (so it was pretty steep).

I'd sit at the bottom and floor the gas pedal, when the engine wouldn't turn any faster I'd slide my foot off the clutch. I could clear the top but not many other cars/trucks could reach the top. Coming back down was worse than going up!!

There were tremendous shock pulses that hit the drive train. Of course the tires would pretty much light up at the start. Once you started up the hill the car was leaping like a horse so there were continuous torque spikes hitting the whole drive train. Low gear all the way.

That car was a good example of "They don't build them like that anymore." (thank goodness!).

P.S. the thing handled terrible since I didn't change the Ackermann. Once you got it in a power slide on dirt you had NO steering control with the throttle. The car would just as well slide sideways as go straight ahead. All you could do is let off the gas and wait till you had some steering affect.

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"My junk is organized. At least is was when I put it wherever it is." -olrowdy
Completed building GSXR1000 CMC7, "Locouki"
Website: http://projekt.com/locouki/

I've had a set of custom CV axles made by Mark Williams for a ~700hp application using Porsche 930 CV joints. From what I recall the center shafts and CVs were not terribly expensive, but the custom forged stub shafts to mate them to the differential and wheel bearings were over $2000. If you just need the custom length splined center shafts they should be under $200 for the pair for a low power application.

Also check out The Driveshaft Shop. http://www.driveshaftshop.com/
I have not used them, but I am planning to try them for one of my current projects.

I have heard of shortning axle shafts that way but they were in solid axles so failure would probably be less dramatic, just the thought scared me. DSS shortens Tbird halfshafts for FFR guys all the time.

Rockcrawl, I just got off the phone with Mark Williams Co. They did not respond to my e-mail request. They would need the halfshaft sent to them as you mentioned to reverse engineer them and they would need the CV joints to test for fit. However they shot me a ballpark price of ~$900 for the pair. Not very Locost. I mentioned your $200 figure and he said they "could" make it out of thinner material and maybe get down 100 less. That is still $800. Way too rich for my project. I'll give driveshaftshop a ring. Anybody else have any suggestions?

Make a guy wanna go "huh?"

Sorry about that. I must be getting old. Mark Williams broached the miata hubs to accept the thunderbird outer cv joints. Moser made the axles. How about $315/pair?


http://www.moserengineering.com/Pages/A ... alloy.html

Edit: Looking at this again, it shouldn't be $315/pair, since they are talking about a axles with a large flange on the end. It may still be around $200/pair.

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Miata UBJ: ES-2074R('70s maz pickup)
Ford IFS viewtopic.php?f=5&t=13225&p=134742
Simple Spring select viewtopic.php?f=5&t=11815
LxWxHt
360LA 442E: 134.5x46x15
Lotus7:115x39x7.25
Tiger Avon:114x40x13.3-12.6
Champion/Book:114x42x11
Gibbs/Haynes:122x42x14
VoDou:113x44x14
McSorley 442:122x46x14
Collins 241:127x46x12

I did have to send them (Mark Williams) some parts so they could measure and fit the splines etc. I don't know if there was a complete breakdown on the pricing and I didn't pay the bill, but I got the impression that the center shafts were relatively cheap. I guess my $200 estimate was wrong. It was a $50,000 build, so I guess even $900 would seem cheap.
Let us know how you make out with the Driveshaftshop.

But the driveshaft only sees engine torque X gearbox ratio.

The halfshaft sees the engine torque X gearbox ratio X axle ratio/2 (assuming both tires have equal traction) That torque multiplication in the diff can be a killer.

Very true. I once calculated that Miata diff mounting bolts see around 1200 lbs force due to that very issue. It has about the same torque as the engine above.

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Midlana book: Build this mid-engine Locost!, http://midlana.com/stuff/book/
Kimini book: Designing mid-engine cars using FWD drivetrains
Both available from https://www.lulu.com/

with regard adapting shafts where the shaft is generally agreed to be non weldable in a reliable manner.
One way to do this does not involve welding the shaft and so does not create any heat effected zone.
1] press or drive a sleeve over the axle
2] cut deep into the sleeve to form a longitudinal recess that extends through the sleeve and well into the shaft. One way to do this is with a hand held angle grinder with a small grinding wheel.
3] this leaves a woodruff key shaped recess that extends through the sleeve and into the shaft.
4] Hammer woodruff key[ use weldable steel keys easy to make] into the recess and then weld the key to the outer sleeve hammering the key while hot into the shaft in the process.
5] do say 3 of these equally spaced around the circumference of the job.

Now, you have a large sheer area created in the shaft which is done with some thought will sustain great loads and the axle steel itself has not been welded and so retains its original characteristics.
P.

Hey Phillip,

Haven't you then reduced the area of the shaft suddenly by a fair bit?
I just wonder if this would create a large stress raiser(s).

Cheers - Gavin.

hi Gavin, yes its not as good as a uniform intact shaft. But if the keyways are cut with a rounded profile in the corners , and the key material is peened into the keyway before , and after welding the key to the outer sleeve, and the axle is a press fit in the sleeve it " might be better" than direct welding the axle steel. Cheers P.

I'm not sold on making splines with an angle grinder. I can picture it acting as a shear pin as used in outboard motors to protect the engine. Or worse, wearing the keyway loose like the short-nose Miata engines do.

I should probably do a follow up here. I ended up cutting - welding - grinding - sleeving- and welding my axles. 4 years now going on 5 and I have had no issues. Would I have done this on a BBC engine? No! But JD did the same on his SBF engine. Yes he had some teething issues but ended up OK in the end. My process can be found here: viewtopic.php?f=35&t=4145&start=30

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Chuck.

“Any suspension will work if you don’t let it.” - Colin Chapman

Visit my ongoing MGB Rustoration log: over HERE

Or my Wankel powered Locost log : over HERE

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