There is a wealth of knowledge on this site, more then I could ever amass through years in a library or through google. I have a bit of a issue and like many of my things looking back at the fearless innovation years may hold the key. What I am trying to do is rotate a driveshaft between 8,000 and 12,000 rpm on almost each shift. Yes I know about rotational losses and have factored in for that. I will not go into the non h.a.m.b. related details. Now yes I could spend a huge amount and have a one off typical driveshaft built kind of deal. But I was wondering more along the lines of combining a torque tube with a collapsible driveshaft. A collapsible torque tube with a two piece rotating shaft that has a coupler in between the two shafts allowing the rearmost shaft to slide into the coupler during suspension travel seems like it would work. More importantly it seems like it is something I could fabricate easily enough. 4 bearings holding coupler 4 on the 1st shaft and 4 to 6 on the rearmost shaft is the plan. In my head less rotational mass(towards the outside) of the actual rotating part could potentially lend it self to higher rpm's. Anything like this been done before? Or am I on my own with engineering this thing in an attempt to save several grand vs a crazy expensive driveshaft. I am not saying it is a great idea. I just imagine someone has done it at some point and I would like to see how they did it any why they did what they did. Any help is greatly appreciated.
We use splined driveshafts to transfer power east west from central diffs to drive a planetary gearset inside the wheel hub. Allows for full drive through full articulation of the suspension system on 8x8 system, though it is not enclosed inside a torque tube.
8,000+ r.p.m. I would get a driveshaft made. There is a lot of potential for pieces flying at those speeds. You need something well made, not something that is "just good enough"
Gas pumper that was exactly what I was looking for. I need to do more digging to see how those years allows for suspension travel. But it is a great start. http://www.curbsideclassic.com/curb...classic-1952-buick-super-decisions-decisions/ Guys the rotating part is inside a non rotating tube. Placement of bearings will be the key but I am confident that if it breaks it will be at the joints not the shaft.
not so. the torque tube resists the axle housing's tendency to rotate around the axis of the differential/axle shafts. a torque tube whose length varies a bit due to suspension movement will still perform that task. Ray
Hey, cerial; There's always Ryans' Dogfight site. I'm guessing it'd fit in real well over there. Just let folks know... FWIW. Marcus...
I am going to answer this vaguely doing my best to stay within the guidelines still trying to use the design concept of the 50's as a basis here. If it helps in furthering the development through the insight of members on here all the better. This is for a gas engine making 950hp/900ft/lbs at 5800rpm. Off the engine I have a case that reduces the torque by 25%. This lets me run a wider variety of transmissions and less exotic clutches. It also packages everything tighter allowing for a wheelbase around 135". After the transmission I have a aux box to split each gear between direct and .72/1. This gives me the following ratios with the 4.56 rear I plan on running. Gear RPM % drop Final ratio 4.56 1D 4.92 -- 22.43 1H 3.54 39.0% 16.14 2D 2.68 24.2% 12.22 2H 1.93 28.0% 8.80 3D 1.275 34.0% 5.81 3H 0.92 27.8% 4.19 4D 0.75 18.5% 3.42 4H 0.54 28.0% 2.46 The engine is at full torque around 4300 rpm so I am trying to stay in that upper rpm range. I have 25.7 tires on it now(the smallest setting) and have room to go up to a 35" tire. Suspension travel is leaf sprung 0-4"and a bump at 6" under hard conditions. This was originally designed for a diesel. But, after doing research I can replace the gas long block of this engine for around $1000 and run 8psi through it with no internal mods to make that power. The 950/900 numbers are very street friendly. They can be increased if I feel like risking internal parts breaking. But, the long block not costing a ton means that it may be worth replacing the block then building one up for several times that amount and hoping it does not find a weak link somewhere else. It is hard to touch the internals of a "lightweight" 800ft/lb diesel for less then 3k let alone find a good complete long block. This engine also weighs in at a few hundred pounds lighter then the light weight diesel. This is idea is echoed through the rest of the drive train. The transmission is cheap and easy to replace/rebuild. The rear axle is also extremely easy to replace or completely swap out. I have a few overbuilt specialty parts to make this possible being machined currently. This allows the cheap parts to wear out and avoids the condition of needing to replace a stage 3 $6000 transmission having it be down for 6 months kind of deal. By running a 4.56 ratio in the rear and a high revving engine I can actually produce more torque at the wheels then I ever could with a diesel. But the driveshaft needs to spin increasingly fast. To further add to this once things get rolling I want to increase that ratio into the mid 5's and have a quick change specialty part that will increase that 5 ratio up to the mid 6's. If these ratios sound a bit extreme look up at the transmission ratios above and think 2 speed, 3 speed drag transmission ratios and you will get the idea. I have been drooling over the current fwd axle tech coming out over the recent years. Who would have thought that cv shafts could support 1000hp pulling a car down the track in the 7's. If they can do that with those diameter axle shafts hafts why can't I do something similar? The idea behind the collapsible torque tube is that I want to use axle shafts as the driving force. Once again keeping replacement parts cheap and easy to replace. The shafts I plan on are 1.367 at the smallest part diameter, are 30 spline, and support 17,000 ft/lbs run through them from the factory with some living into the 300k range. Of course that number can easily be increased with different materials. These axle shafts have been used for over 30 years(want to say 50) and there are several million throughout the country. They also come in two lengths(offset diff) 37 5/8 and 31 5/8 giving me flexibility in the driveshaft design. I plan on broaching a coupler for the 1.59" diameter splines of the shaft to slide into. This coupler will sit in the first fixed shaft held in place by clips to prevent it from moving while replacing the shafts. The axles halfs have 2" of splines per side so 4" of engagement will ensure the splines do not become the weak link. These are full float axle shafts and I plan on simply inserting both splined ends into the coupler and using companion flanges drilled/bolted to the axle shaft flange faces as a means of making replacement that much easier. At this point I believe I will need to extend the second shaft splines to allow the shaft to cycle into the coupler further during suspension compression. They are not cut all the way to the neck down point and I need them to be. That should add another half an inch to the splines and is the only machine work I see needing to be done. As for the tube itself I am thinking .120 wall D.O.M two pieces the same diameter(need to look into bearings) around 3.5" diameter. I will have two 3.5'(ish) pieces with a roller bearing center piece that is larger letting the tubes easily be pulled apart for inspection and maintenance. For checking how this thing is going to work and balancing I have a interesting idea. Basically I have a Motorcycle engine out back that I will use to spin the thing to the higher rpm's Everything will be enclosed in a stand and case kind of deal and operated remotely in case something goes wrong. The parts of this being under a grand means if it breaks replacing it will not be a huge undertaking. I will sprocket the motorcycle engine so it spins the driveshaft at rpm's and using a few tools(mostly cameras and vibration recorders) I will fine tune the collapsible torque tube. On the output side of the tube I will have a air bag to allow for angle changes remotely. I also plan on installing a brake at the output end of the stand to check and see the shaft flexes under a load at a point. This will allow me to further fine tune bearing placement. It will not be no where near what the final thing will see load wise. That will take a few months of trial and error. But, it will help fine tune it initially. If it sounds cheap and very backwoods your dead on. That's the point of the entire build. I won't go into the body. I just say it is lighter then carbon fiber and will not dent like aluminum. I want something that is fun to drive like I am mad at it when I want. But, when parts break I do not want to be out for 6 months while the thing gets rebuilt. I have made many compromises to get it to where it is. If anyone has ever had a built drive train component fail and get to that point where you are spending more time saving up then rebuilding the parts then you do actually do driving the thing you may get where I am coming from.
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