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?
Any other ideas?
Just loose the driveshafts and go to Hydraulics :thumbup:
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.
Not all transfer cases have the front shaft on the drivers side. Check out Subaru for a compact one
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:
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.
That's some amazing hardware they're selling.
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:
Multi Section Driveshaft & AWD
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!
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.
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.
Now, an open wheel car would look a bit goofy with the stock Chevy setup out front but a full bodied car would hide it a bit.
Me? I'm going the 4x4 route for a Studebaker Conestoga wagon SUV and am looking for a longbed s-10 chassis to match my car's wheelbase. :drool:
Good luck with your project!
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