Every now and again I pull my AWD project out of the dust of my brain and take another look at it.
I'm trying to come up with a way to make an AWD car/rod. Haven't decided yet on the vehicle as that might be driven by the packaging.
Anyhow, I've settled on independent front and rear suspensions which will essentially fix all the drivetrain components in the chassis so I don't have to worry about accomodating the drivetrain moving as a live rear axle would move up and down with the suspension.
One of the things I'm seriously considering then, is mounting the transfer case in front of the rear differential, instead of directly behind the transmission. That way, the packaging that large assembly will most likely affect the rear seat area instead of the front seat area.
A real problem I've been wrestling with is how to get the front driveshaft up to the front differential from the transfer case.
I have a Sierra pickup with 4wd. I'm assuming that any AWD transfer case I'll be using will have roughly the same dimensions. In the pickup, the front driveshaft runs roughly right under the accelerator pedal. I'd really hate to have to expand the driveshaft hump that far over to encroach on the driver (or front seat passenger, if I reversed it) footwell.
So, one thing I thought about is perhaps using a system of driveshafts, universals and bearing carriers.
I figured I could have one driveshaft that angled inward from the rear transfer case towards the main driveshaft off the transmission. That would lead to a straight driveshaft, parallel to the main, and held in place by carrier bearings front and back. That would run right up to where the main driveshaft enters the transmission, where another driveshaft would angle off to the front differential.
The intermediate driveshaft would always be parallel with the main. However, the front and back sections of the multi-section driveshaft going to the front diff would have two sections that would always be angled.
Just from experience, it seems most driveshafts with universals are set up so they are straight at ride hight, and only operate at angles when the suspension moves.
So, I'm wondering if it is feasible to have driveshafts that operate at a fixed angle all the time?
Is there some maximum recommended angle that can be used without problems?
Would CV joints be better than universal joints in this sort of setup?
CV joints will transfer power over a larger angle than Ujoints and they'll do it without vibes. I think the complexity of the system will give you fits though.
I often gave consideration to using a solid drive shaft instead of a hollow tube. That would add a little weight, but sure would save some room. You could use a series of ujoints and carrier bearings, but the straighter the better.
The complexity bugs me, although with the driveshafts all aligned on the same plane, it is probably less of a problem than if any of the components were moving relative to each other (although there would likely be some movement as the frame torques).
I'll have to play with some ideas and get measurements. Perhaps I can locate the transfer case right under the driver seat - that would lessen the clearance issue, depending on the seat I use, but that still doesn't help me with the actual driveshaft.
Luckily, I'm not too tall. I may be able to get away with raising the seat up a bit and then I could raise the floor as well without having to raise the entire body to clear.
I have mentioned this before when you posted about your AWD project. You should try to find a first gen Bravada/Syclone/Typhoon and take a look under it. The "transfer case" is not very big, I do not know how it compares to late model cases, but I know it is considerably smaller than the cases of the early 80's. It might be possible to rotate the case to make it more parallel with the ground. The drive shaft is not a large diameter shaft, I would have to look under mine again to check the size, it is much smaller than the rear shaft. The front diff. is mounted to the frame so it doesn't move except for vibration. The front shaft is located very close to the engine, there is no room for the oil filter it is remotely mounted. If needed I should be able to take some pics with the digital cam and post them.
Thanks OneownerT. I haven't been able to find a vehicle with the BW4472 under it to see what the dimensions are like. From what I've seen on the web, it would be a lot easier to fit. Even better, they're relatively plentiful and inexpensive compared to other cases. I haven't ruled it out.
However, I've also been thinking about the larger 4473 or NVG 149 which are used on the FS truck chassis with AWD. They have presumably a higher torque capacity than the 4472.
I haven't been able to find ratings for the 4472, but its been superceded by the NVG 126/136 on Bravadas and Astros which have torque ratings of around 1500 ft-lb. The NVG 149 has a 2200 ft-lb rating and a magnesium case. The 149 is largely in trucks while the 4473 is largely in vans. Problem is the shafts are spaced much wider apart than the 4472 - between 50% and 100% the distance from what I can gather.
I figure if I'm going to go through the work, it would be better to try to make the heavier, although larger, case work, if possible.
One thing I've noticed though, the 149 has mostly empty space in between the shafts - possibly to use the same space as a standard FS truck 4X4 xfer case. Perhaps it would be possible to swap the higher capacity parts from the 149 into the 4472 with a smaller diameter belt. I suspect the viscous clutch is the main failure component, probably followed by the belt.
Check out what some of the offroad "moon buggies" do. They use a 2-piece driveshaft. Many of them have their driveshafts made at: www.highangledriveline.com
I have thought long and hard about this same problem...
Here are a few sites that might help. Many of the transfer cases can be clocked to whatever position you want, provided they don't require sump oiling. Adapters are sold to go from just about any tranny to any Tcase, and a divorced Tcase solves almost any clocking or adapter issue.
Most of these sites have adapters listed for 4x4 applications, so the tranny listings won't correspond to many of the trannys you would find in a performance car, but by carefully cross referencing the Tcase applications versus the transmissions they were used behind, and you might come up with some powerful info.
These are links I happened to come across while working on a 65 Scout project.
Thank you for those links. I didn't know much about what the off-roading guys were doing. Looks like they've already solved a lot of the same problems, although for different reasons.
I did not read all the responces to your multi drive shaft deal but did you think about using ,, i think it is a didge 4x4 set up or an older chevy full size truck .. but one i have seen dumps out on th epassenger side of the vehicle which might give you more clearance.. dont know what kind of body your going to use.. also the jimmy blazer uses a small transfer case as well as the bronco two. just remember this the more complicated the plumbing the easier it is to stop up lolol :thumbup:
Thanks to innovators like yourself that we have the most advanced Nation in the world. Just don't let that stop you from looking at some of the most successful AWD vehicles on the market today.They are either German or Japanese. AMC with the Eagle was a pioneer in production AWD but AUDI really pioneered and used the concept. Seriously, the Japanese have not been much for initial development, but they have excelled at polishing out the rough spots in what others have designed.
How are the AWD high performance German cars doing it??
Have fun & hope your pockets are deep!
jwvonl
You'll need an IRS to mount the transfer case at the back, but that's not a big problem. Instead of having so many u-joints for a minimum of room saved, angle the driveshaft from the t-case to where it needs to come from under the floor. Then put in a carrier bearing and another u-joint to swing it where it needs to go.
As for a hot rod instead of under another car, there's an easier way that looks feasible. Take a look at C-boy's project page. He has a "rat rod" with a Ford truck Twin-I Beam front suspension. Using a frame similar to that with a live axle in front, with the radiator in front of the axle (like C-boy's, only really have the radiator in front!), there wouldn't be many problems. Use a passenger side transfer case to solve some clearance issues, and use a straight six or four for more room. Most have nothing but the fuel pump hanging out the right side, and that can be replaced iwth an electric if it's in the way -- no exhaust or steering over there!
Use parallel leaf springs like an American Undersprung or use coil overs and hairpins/four links. Keeping the transfer case on the driver's side is doable, just have a raised floor. Driver would be sitting nearly straight legged on the floor though. To keep movement under the floor to a minimum having a two piece shaft going to the front with a u-joint at the bottom of the firewall/front of floor would work well. Get a Jeep Cherokee with 4.0L EFI six and you'd have all the parts needed!
I have to admit, passenger side transfer case would be a LOT easier. Not because of room under the floor, but because the exhaust and steering gear is on the left side too. CJs used a passenger side front shaft transfer case (through 86) -- it's even gear driven! Drawback: it's full cast iron -- a little heavy but bullet proof. Early full size Jeeps used passenger side transfer cases, later ones don't (not sure which years). A straight six FSJ would provide most of the needed parts or a CJ. The six lug wheels would be an issue though. Toyota pickups have a passenger side T-case, so one of those would be a good base for a light weight roadster. Forget using the frame -- a custom frame Z'd on both ends is needed.
You'll need an IRS to mount the transfer case at the back, but that's not a big problem. Instead of having so many u-joints for a minimum of room saved, angle the driveshaft from the t-case to where it needs to come from under the floor. Then put in a carrier bearing and another u-joint to swing it where it needs to go.
That's sort of where I'm currently leaning. IRS was where I wanted to go anyhow. I just wasn't sure if you could have a driveshaft that was always at an angle. Looks like its doable, although it might require a double cardon u-joint. No biggie there.
farna said:
I have to admit, passenger side transfer case would be a LOT easier. Not because of room under the floor, but because the exhaust and steering gear is on the left side too.
I don't think this would be a problem. Can't speak to the standard 4x4 cases, but for AWD it appears that the case can be pretty easily "clocked" as long as the input and output shafts are mostly side-by-side (to keep oil on both halves of the mechanism). The two shaft assemblies are belt connected - nothing's really in between, and on the FT AWD boxes, there is no real mechanism to worry about. Any planetary gears are surrounding the shaft which doesn't care which side is up. Flipping the case shouldn't be a problem. The only issue would be if the oil fill hole isn't far enough down to work as a drain, but that's easily addresed.
The car I have in mind as my first choice is going to probably weigh around 4000 lbs.
The Syclone/Typhoon weighed in at 3600 and 3800 respectively. They were both running 360 ft-lbs of torque out of the turbo'd V6. So, I think if I don't power it with anything too radical, the 4472 transfer case should hold up OK. I'm thinking around 400 ft-lbs max should be doable for a driver. That's mild smallblock torque territory, which should be reasonably fun.
Here's a link to a Stude on a S-10 chassis w/ 4 link rear end creating an all wheel drive and 4 wheel independant suspension and a Caddy mill pushing thru a 4L80 into a jag rear end.
Thanks for the info on Darius (UtahTorque). I've come across a bunch of his posts on other forums. We seem to have been researching a lot of the same issues.
I knew he was on this board, but I couldn't remember his screen name.
Oddly, he's going with the same engine in his Studillac that I've been working towards with my project - a Cadillac 425. Its essentially the same block as the popular 472/500s, but was significantly lightened (by around 75lbs) making it lighter than an iron SBC. Torque is around 300ftlbs stock which should be about perfect for what I'm trying to pull off, assuming I can fit it in. Also, 300 ftlbs is a reasonable torque level for most manual transmissions to accomdate without scattering.
I'm trying to build a driver - once I get it together, I want it to stay together so I can actually drive it. I think I've found a combination of parts that will work well together, and won't break apart at a stoplight.
JUST in case someone passes this way again. I would like to know if a sucesssful project was completed and how. Years ago you could plan on ford on the left, every body else on the right. I don't have a clue if something has become a general rule, JAG in the rear, what ever in the front. Dana 44 was a standard in jag for a number of years. Eventually they could not afford the quality control jag wanted, so they say. You could find a cast iron carrier and jag stubs for a hundred bucks. If you pass this way just something else to consider, I was looking for something else, but read this line. mark
Have you ever taken a close look at the HMMWV. In order to accomplish a complex drive line the originators of this vehicle. ( I think it was originally a crew of rodders in Utah/Nevada back in the mid/late '60s, these guys were using the original MOPAR full time transfer) the entire drive assembly is in a tunnel, with the seats off to the side of the tunnel. Makes for great ground clearance & almost unlimited power transfer to all 4 wheels. Good luck & have fun! BTW Happy Easter!
I passed through again, what happened to the project. There are several vehicles that have drive shafts on the passenger side. I also noted you mentioned using solid shaft instead of tubing. Bad idea. Something else first though, Universal joints usually are prelloaded, I think up to about 4 degrees. Check the engineering specs of the joint manufacturer. The hard part. PSSSS! Do you really want me to explain the tube driveshaft. Lets consider a flat piece of metal - a leaf spring-just1 the two ends are on something. Push down in the middle of the spring. You are trying to stretch the bottom of the spring and compressing the top of the spring. Most of the middle is doing nothing. Its the surfaces. Thats why you have more than one piece in a leaf spring. The drive shafts are the same way. I can't believe I missed that. Like the man said universal joints can only be bent so far. I don't remember what you were doing I sorry its late, but this is a bad idea particuarly if you are going to add high impulse torque. Like 300 hp,6000 rpm, and pop the clutch. stand back. You would have to do the numbers, but at some point, things really would start to break. Let us know. good luck mark
If you do it right I believe a smaller shaft would be better. It would be nice to have it gun drilled for weight reduction but that is not necessary. What you would end up with would be a long solid shaft that is splined on both ends. Something similar to a half-shaft (which sees more torque than a drive shaft because of gear reduction). It would act like a torsion spring helping to absorb things like clutch drops (that a tubular drive shaft would not). The key is that it would have to be made right and that doesn't come cheap.
you got it right. I really like torsion bar suspensions- very clean. But you have to do it right. Besides that you are going to get a harmonic flex at some point that shaft is going to bend in these lengths. Drill it out. I am guessing but at about 3 feet, put the pressure on it and it's going to bow. Put a bearing in the middle and it.s going to shear-twist in two. If you are going to do this find somebody to do the numbers. I haven't been a design engineer in years. I think you can do it, If you don't run the numbers trial and error could be very expensive, as you know. I have a example,.keep it simple. Somebody I know built a piece of machinery with a 5 in shaft. the drive chain sprocket was mounted close to a bearing-he kept breaking the shaft. The set up should have acted like a torsion bar.the sprocket was so close to the bearing he had no torsion flex-He kept shearing a 5 inch shaft, 5in--A foot long 2 in shaft worked fine.I certainly know the book never replace expierence,B I have a math major,a physics major, and a mechanical engineering major, and taught 3 years in college, And I have been out too long to do this.I hope you do it, The other thing is safty-that thing can come out of there with terrible results. Do racing rules still restrainers, certainly scatter shields I considered a while before I posted this , being winded even for me, and pushy. I don't want to be bearer of bad news, so I apologize for my negative attitude,but I don't want to see anybody get hurt either. I may well be that I am out of the ball park, but till you do the numbers, you won't know.I will give my assistance any way I can.good luck. Mark A. Adams P.E.
Agreed. I have been thinking- I would say go look at a large dump truck. They are frequently 3 or 4 sectiond. The fact that are used under high stress situations means they are sucessful, and you can guess as opposed to running numbers.I had a college proff that could guess closer than I could calculate, that's what 40 years of expierence does. My specialty is processing light weight paper, lots more interesting than it sounds. But thats why I PREFER not to do this.I am pretty good with gas dynamics-turbos and like. .Thanks, Good observation. m PS If you want the torsion spring effect, you can put one section say 24 inches in. I keep thinking about dodge pickup front bars, I don't think they are big enough. How many ftpds, are you putting out-any body?
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