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11 degree prop shaft angle

1K views 4 replies 3 participants last post by  cerial 
#1 ·
I have a case that is fixed to the frame going to a aux trans that is also fixed to the frame. The aux trans and box will have rubber bushings. But will be otherwise bolted to the frame.
I have a propshaft between the two at a 11 degree angle. 0 degrees vertical. This propshaft will see 5500 to 6000rpm constantly. The propshaft will never encounter more then 1500ft/lbs and is set up for 1410 joints currently. The propshaft will be 50 to 53 inches long.

Pictures of the current pile of parts being arranged before I begin building.
Aux trans:


Front(reverser) box:


Having both parts fixed is 11 degrees to much? Can I just expect less life or am I looking at vibration issues? Would a constant velocity driveshaft be a better option? I am thinking a constant velocity with a carrier in the center would work angle and strength wise but have no idea rpm wise.

That wooden box is the correct passenger seat location/height. The prop shaft will be enclosed of course.

I can run the 50-53" propshaft true(0 degrees). But this requires I run it under the passengers butt(loosing lots of leg room also) and I will need to increase the roof height 6". I also need to increase the wheelbase and vehicle length a minimum of 11" due to the smaller propshaft between the Main transmission and box being at a angle. With the current setup I am using a 7" slip yoke true between the reverser box and Main transmission output.

Thank you for any help.
 
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#2 ·
tech info

In the past I have posted links to drive line supplier engineering data charts but I couldn"t find them. A lot of jacked up 4 X 4 's run double joint cardon, or u joints that can run at steeper angles.
off road shops might be able to help with info. There are a couple around here that build sand dune vehicles.
 
#3 · (Edited)
search info

If you do a search here on hotrodders ( drive line angles) you will find lots of info here;s one link
http://www.hotrodders.com/forum/pinion-angles-driveline-setup-street-62742.html
billy shope was an engineer at chrysler. and part of the old racing team. an expert on lots of stuff.

more info


and the one I was looking for'
http://www.studebaker-info.org/tech/driveshafts/J3311-1-HVTSS.PDF
file:///C:/Documents%20and%20Settings/Tim/My%20Documents/Downloads/U-JOINT%20GUIDE%20(SPICER).pdf
 
#4 ·
Double Jointed - U-Joint Differences - 4-Wheel & Off-Road Magazine


perhaps those will help you gain some additional angle without ripping the joints out of the ends of the shafts..

i have always wondered about one of the transfer cases with the front chain section that could be moved to either side.. drop it almost straight down off the back of the transfer case.. to drive the rear driveshaft at reduced angle..

i wish i had access to a machine shop.. i would build the reverse for a removable pinion carrier like a 9" ford.. that uses an transfer case type of arm.. with it mounted to the pinion carrier studs.. the bottom yoke has either something like a transfer case sprocket or a TH425 sprocket and chain.. or even a supercharger sprocket. and gilmer belt.. the top would be a front wheel drive hub and bearing assembly.. bolted to the front plate.. so a splined shaft can slip thru. because of rear end wind up.. you may have to have a custom double slip joint driveshaft made that is spring loaded on both ends to keep it centered on the splines. or use a CV shaft with a tulip on one end.. so it can plunge in and out without a lot of friction..

these are just thoughts that have been floating in the my fertilized mind. and you know what fertilizer is. .
 
#5 ·
Actually, that is similar to how I am running my Aux transmission to the Rear axle pinion.
I am using a chain and sprockets from a 273 transfer case(rated at like 7,000lbs of input torque) Bolting the sprockets to a flange on the axle pinion. Then another flange on the output of the aux trans and have the chain connecting the two.

The aux pinion is fixed. But it is not. It will ride on a track sliding from the passenger to the driver and deflect no more then 1.5" as the suspension cycles(6" of max cycle and the pinion sits level with the aux output). In most instances it will not cycle more then a inch. I am using some 1.5" Dom with screw adjusters to keep chain tension tight at all times. I am using valve springs within the track(it will take some playing around to find the correct spring rate)to keep any of the suspension from binding. I am having the chain enclosed within a lightweight container(whatever I have laying around) that will hold the lubrication fluid. This movement lessens pinion angle slightly at full droop/compression and I was trying to avoid explaining why the chain so I just said it was fixed.

Why all this engineering?
Well, for starters it lets me run the common 4.56 FF 14 bolt out of dang near any one ton from the early 70's all the way up to late 90's without the need to offset the diff or buy expensive(custom) shafts. By leaving the rear stock. When I break a shaft(and I will). Replacement is a 10 minute job.

The second reason is that later on I want to change the sprockets from the 1/1 ratio to something like a 1.2/1 or 1.5/1 ratio. This requires I machine a sprocket(s). But the cost of me machining a sprocket is drastically less then what even a quick change empty housing would cost. I believe I can change out sprockets within 20 minutes with a inspector looking over my shoulder waiting for fluid to hit the track. If I do it right it should not drop a single drip.

The most important reason is gearing. You must remember that the reverse case has a .75/1 ratio and the aux has a overdrive of .72. This gives me a top gear with a .54 ratio. That being said during daily driving I plan on keeping the Aux in Low and shifting from 3rd to 4th on the main. This gives me ratios of 2.58, 1.52 with a straight pull for shifting and a max speed of 66mph@4500 engine speed. From there I can bump the throttle putting the aux in direct and bump the throttle again to put the aux in overdrive for a top speed of around 140 or a cruising rpm of 2415@75. The final ratio (12th gear with 4.56 rear)ends up being 2.46.

This is far to small though more gear=more torque=more power as long as the engine is happy and shifts are not to drastic. So back up to the quick change sprocket thing. When I install a 1.5/1 sprocket the aux left in direct for 3/4 shifts of 1.91, 1.12 the final ratio(12th gear with 4.56) ends up being 3.69. With the motor turning 4500(max) the prop turning 6000(max) I get 4500rpm at 67mph and almost identical shift points as with the 1/1 low gearing. But, this means the pinion will be spinning at 9,000 rpm at that 67mph point. Where I can shift into overdrive and it drops to 7290rpm@67.

I should note that all of the above numbers are with a 205/60/r16 tire. The smallest easily available tire I can mount on my rims. But, I can go up to a 30" tire without changing the much (by moving pins) and change the mph where I shift. But, this will have very little effect on pinion speed.

I am planning on rotating the engine/main trans/reverse case(all in line) towards the passenger |\| which lessens the prop shaft angle by 3 degrees. Then by using a 2 piece shaft with a 2 piece carrier bearing(actually 3 pieces) and having double cv u joints on front and rear of the carrier I end up 3-4 degrees. Still not great. But livable considering how tight everything is around this prop shaft.

Right now I am building a very overbuilt monocoque frame which leaves a good amount of room for moving things around and many different engine/trans combinations later on. ie There is room to fit a 24V cummins or 2 inline engines(both options to costly right now) later on(up to 1000 ft/lbs) with no chassis changes. The diesel options puts the transmission after the reverse case lessening the torque(to the transmission input shaft) and increasing the (engine) rpm by 25%. The diesel would be a perfect fit with enough torque and a rpm range that would drastically reduce the amount of stress the prop shaft would see. With the two inline engines I could disconnect one via clutch when I did not need the power to increase mileage/reduce stress. The Cadillac 500 which I am using can be found in stock form for around $500 easily while weighing less then the two above at 1/2 the power.

Thank you for all the help.
 
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