ok, i hear ya,but it would be benificial if you had somthing to stuff in the spider gears so that no molten aluminum gets into the splines. good luck on your project, and lets see some pics luanching at the starting line !
My friend Bill who supplies me wth most of my general use aluminum from his shop discards is the one I spoke of with the busted mini spools. We decided to pour one of these since it is no good as is anyway, not too big to pour and since he supplies all my general use (non piston aluminum. ) why not? If all goes well I will pour it tomorrow. It is no good anyway so we cant hurt it and if it works he has a usable piece. Don
Somebody used to make toothed plates (that's the best description i can think of) that locked the spider gears in a '57 Chevy drop-out rearend, but I've never heard of them for any other rearend. Speedway Motors still had them in the '90's, as I almost ordered a set to replace the '57 Chevy posi unit in my rail, but I upgraded to a 9" Ford instead.
Ansen used to make them . I didnt realize they were still available. Anyway this is not something I personally need as I have the stuff forboth my rails already but just an idea I had. Since my pal who supplies me with most of my melt down aluminnum has a diff that is giving him fits or was I will do it for him. Also his is a normal car so no one will be sitting on top of it. However given the amont of trouble he had with mini spools if this works then I will know it is a good idea. His car often eats diffs and driveshaft etc so this will be the untimate test. Anyway I am off to get some propane for the melt Don
It turned out the diff Bill sent was his first broken posi unit and it was badly busted. Spider greas were gone , spidershaft broken. Posi unit chewed up . I popped it out and i used two of the springs to hold the side gear innner axle splines in place. I lined the splines up and also tacked a piece of sheet metal over most of the open side hole. I also welded the broken stubs of spidershaft in their respective holes. The slight depression is where I poured and that is where the last shrink always occurs. I removed the sheet metal I had tacked on to cover the open hole and gave it a quick cleanup. I dug out and shook out the sand from the splines. You can see the aluminum at the end of the hole. The inner section is completely full . I personaly find it hard to imagine this could come lose. A open diff would be a better candate but this is what we have . Fomerly good for nothing. Now a solid spool. Cost? I figured it out. $2.47(Propane 20 minutes)Anyway it was an idea I had and there it is as promised. Don
Don, your projects never cease to amaze me! I would have never thought of this, but you did, and now you have a very cheap spool. Kudos!
Thanks for the encouragement.This aluminum casting thing has opened up a whole new world to me. While i poured this I also made a two slot adapter from my 318 poly manifold. To go from the old WCFB four hole to to large modern Holley slots. Like you would find on any modern dual plane intake. I have to clean it up a bit but I did shake it out. It seems so interesting. You want something , you glue it up in blue styrofoam, pack it in sand and 15 to 20 minutes later it appears. No shipping, no duty, no brokerage fees and no waiting. Also you never get the wrong part. I think I may have created a monster. This idea for the spool came while I was waiting for a melt. Anyway for what it is there it is. Anyone else want to try pouring aluminum I will gladly give details on how I melt and how to make it. Very simple , No funny materials to find or buy like on the internet sites or foundry books. Don
That is CRAZY cool!!! My only concern, and you may already have this covered, is sometimes the splined axle ends protrude through the side gears in the carrier - so they may not seat fully in the housing ends. I forgot - what kind of rearend is this? Hopefully not a C-clip style, as you now have no way to retain the axles. I'm anxious to see how well this works! My great-grandfather used to make some of his own castings in the '30's & '40's - mostly for engines for the different class hydroplanes he raced. He cast his own cylinder blocks, pistons, lower units, and even his own carbs. He even machined his own cranks & rods. In the '60's he started casting his own tail housings for the ClutchFlites he & Dad were building. Nobody else seems to do their own casting anymore, so a big Salute to you, Sir!
Don, Not to argue with you, because you are usually right..And you and I see eye to eye on almost everything...But.... Your statement that aluminum is stronger than steel (by weight) is true.. BUT...That plug is approxamatly 6"x6"x6" (or 1/2 cubic foot)> aluminum is 12 lbs (or so) per cubic foot.. So the plug is 6 lbs (estimated) Steel is 40 lbs per cubic foot, so 6x6x6 is 20 lbs (est.) So...you would need to double the weight of the aluminum plug ( aprox.) to get close to the strength of a steel plug....12lbs x 1.27(27 %) = 15.24 lbs To simplify ( and in round figures ) 30 lbs of aluminum is just slightly stronger than 40 lbs of steel.... OK , my brain hurts.. Dave
But Dave we dont need 6x6x6 inches of steel . Lets us say just for the sake of argument we made a thick wall splined steel sleeve to join the two axles. Say 1/2 inch thick just to be on the safe side . No one would worry about it breaking. That would be about 8.1 cubic inches of steel. (outside measurements minus the hole) Instead we have 6x6 X6 = 216 cu inches approximately of aluminum. I think we are well covered here. We are ususaly riding on Alminum wheels too and several trannnys like the 727 often have aluminum mounted planet gears, aluminum sprags in the converter too. It is pretty rare to see them borken in normal racing use and they are none even close to this thickness. . Yes this is a C clip diff but will use C clip eliminators and if the axles bump the aluminum we will relieve that with with a big drill or a small slice off the unused portion of the splines. Certainly an easy fix of a little thought and a few minutes work. And will not deter performance in anyway shape or form. It would also be no big problem to make the hole deeper past the splines with a bit of a sand core. I dont think it is necessay but so be it. Anyway. It was just an idea I had. I think it is workable and safe. I said I would pour it and show you . I have. I think it will stand a lot more then we realize but I agree that the proof is in doing it. Bill will have it back this week. My part is done. Don Also the fact that this aluminum is for the most part trapped and encased in steel must account for something as well. In the back of my mind way back in my early days as a BMC mechanic there was at least one car i worked on that had an aluminum carrier. i think it was the Austin Heally 3000 but i might be wrong. I can see it though in my minds eye. And then there is aluminum driveshafts. Hollow thin (relatively) tubes of this stuff handling hundreds of HP and sometimes over 1000 . How does that work?
If you're sure there won't be a balance issue, then why not spin that new "spool" on your lathe at 1500 rpm and see how it balances out...my guess is that the floor will shake, but I could be wrong...
Don, now that I am awake... I think you are missing the point of my post. I am in agreement with you in that I think it will work, just fine..... However....Given that the 27% stronger figure is based on weight, not volume,, I think that you would need a larger amount of aluminum to equal the strength of steel. Anyway, let us know how it works. Dave
So long as the void he filled is pretty symmetrical, there shouldn't be a balance issue. It's takes a pretty good volume of aluminum to make an ounce.
However....Given that the 27% stronger figure is based on weight, not volume,, I think that you would need a larger amount of aluminum to equal the strength of steel. Dave the axle itself is less than 1 1/2 inches in diameter of steel. This is like you said 6 inches of diameter and cast completley into two side gears of 3 inches diameter sealed in a steel housing with two sections of spider shaft sticking into it at least an inch plus stuck with an odd shaped opening which it is also cast into. if the sidegears go around in that Ill be a monkeys uncle. The axle will break long before this will. Before i did this five springs pushing against two side gears stopped it from spinning. Larry i wondered when you would jump in. Yeah I am definatley keeping warm doing this. I get even warmer trying to justify it. I suggested this but like i said I dont need it as I have all my diff stuff already. I did this for a friend so I could keep my commitment to try it and show you. I did. End of story. If no one wants to try it OK. I have satisfied my curiosity that it is doable . I think it is safe and S T R O N G! I am returning it to Bill. I have other fish to fry. (Aluminum fish of course!) Don
It does take quite a bit of aluminum to make an ounce, but in a world where grams of imbalance will destroy parts (like bearings, gear sets, crush sleeves and seals), an ounce is overkill...how many grams do you think are missing in that sinkhole where the aluminum was poured?...1500 rpm isn't much in relation to a 6500 rpm motor, but that 1500 rpm of unbalanced added weight is added stress on components designed to work best within a few thousandths of an inch of clearance...I'm not saying it's a gaurantee that it's now imbalanced, I'm just saying to test it out at 1500 rpm or put the assembly on a surface grinding wheel balancing fixture to KNOW that it's not imbalanced so it doesn't bite you in the ass later...you know what they say, an ounce of prevention...
I think this balance issue is totally made up. When guys stick their MIG in there and weld up their spiders, is anything balanced? Of course not. My prediction is no balance issue at all. I'll spring for a box of donuts if I'm wrong.
How often do wheel bearings suddenly seize up when confronted with a wheel that is one ounce out of balance? Not very. And that's with a much larger rotational moment of inertia, because the diameter is so much larger. With the size of bearing you have on most carriers and the diameter of said carrier, you'd have to be several ounces out of balance for it to make any difference. Every bit of what I'm talking about is calculable, it's just (as my Dad would say) Chinese 'Rithmatic, and not worth the trouble for this discussion. Operating RPM makes a big difference as well. At 8,000 rpm, quarter gram imbalances count big. At 1,500 rpm, I'd wager that an ounce won't matter a bit (especially since the mass on this thing is symmetric about the axis of rotation). Again, it can be calculated, but I don't care enough to crawl through the math. I would not be afraid to run it a couple of times and see what happens. If your ass detects a driveline vibration, you've already got a pretty good idea what it might be, pull it out and balance it. You can remove mass with a drill or die grinder quite easily, so if there's a problem it shouldn't be a big deal to put it between bench centers and find the heavy spot.
Wright bros.,Chuck Yeager,Tucker,Delorean,Dolmetsch. You guys always trying crap that people clearly tell you that you shoudn't or couldn't be trying really crack me up.
Seems to me that when you look at the average carrier there hasn't been much effort put into balancing them. When you look at the diameter of the assembly, I doubt there will be any problem. Wouldn't be that hard to balance it if it worries you.
Don once again you have hit a good one like the idea and looks like an easy to get a spool for early rears that are shot...............
Balance should not be an issue. I'm anxious to hear how well this works, but I think the aluminum will eventually crack & break off around the side gear teeth. Aluminum has no true endurance limit - it eventually fatigues from alternating stresses. It might never fail in a dirt track car though.
Do you ever sleep Don ? haha. Its so cool the way you are always thinking,and taking ACTION,need more guys like you.Good idea too,i like the preheat also.Ive never casted any thing but want to ,sooo maybe one day........................YG
Yes, definitely KUDOS for at least TRYING something! If every trial worked perfectly the 1st time, cancer & AIDS would be wiped out by now. Now, for that snow plow idea I've had for awhile...
This is very true, aluminum has no infinite endurance limit, so anything made from aluminum will eventually fail when exposed to cyclic loads. However, the "eventually" part is where we can find our wiggle room. As you say, the aluminum surrounding the side gear teeth will eventually shear at the gear tip (or the root of the alum "gear" if you prefer), allowing the gear to spin more or less free. But so what? In the event of an alum fatigue failure, the carrier reverts back to an open diff. That's a non-catastrophic failure mode IMO, which is why I thought this was the perfect situation for Don to prove his theory out with. If he's wrong, all he's out is some time and a plan. Remember, aeroplanes are mostly made from aluminum too, but the wings don't just fall off randomly in mid-air (or at least not real often ). Because aviation mechanics and inspectors are hard core about structural inspection for fatigue. You've got to inspect your alum structure every so often so that you're out ahead of failure (by detecting fatigue cracks before they become fatigue ruptures). Such is the nature of the beast.
""But so what? In the event of an alum fatigue failure, the carrier reverts back to an open diff."" I picture a wedge factor if the alum gives up which would destroy the carrier, it would be really open then !
You picture incorrectly then. When the alum fails, it will fail at the root of the alum tooth (or the crown of the steel tooth), in plain shear. Think about it. For the alum tooth to ride the wedge upwards, the entire thickness of the material above it would have to first fail in shear if it just pushes up a bulge on the surface, or straight tension (in several places) if it were going to crack open like you suggest. For the alum to just shear from the root of one tooth to the next, it would only have to fail the width of the root of each tooth in shear. We can run the numbers if you like, but the answers you get will be the same as intuition will point you. The path of least required cracking for fatigue failure is from tooth to tooth, AND the path of least required force for outright overstress failure is from tooth to tooth. The only way it cracks open like a melon is if there is a freeze line someplace or bigass voids that line up to make a weaker line than the one connecting all the stress risers at the root of the cast in place gear teeth. You're right about the volume of alum though. 6"x6"x6" = 216 cu in = 1/8th cu ft
https://www.coperacingtrans.com/product_info.php?products_id=359 on up the other end we usually run something like this. I personally have never broken one even doing stuff like this. Not quite the same I know but the power must go through this to get to the diff or quick spool. Still with a transbrake etc it has got to be taking at least a simlar beating. Then there is the sprag in the converter also aluminum in 85% of cases. Also the rear spargue in the 727. Just a toothed deal pressed into a not all that thick aluminum housing. These planets are also splined to the shaft by the way. Don
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