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driveshaft angle
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beersngars
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Joined: 04 Feb 2006
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13369.80 points


1948 Chevrolet Coupe

PostPosted: Tue May 01, 2007 2:34 pm    Post subject: Reply with quote

af2 wrote:
10sec.et wrote:
good to see you back. how was the vacation? at least thats where i assume you went.

oh, back on topic, i found this article....http://www.carcraft.com/howto/91758/. af2, i understood what youre saying and its the "straight line" part that makes me believe i need to get the diff a bit lower because the way it is now, if i raise the pinion angle opposite of the trans, theres no way possible it could make a straight line through the drivetrain with the pinion pointing up.



That bottom picture on that page is what I was saying.

Vacation was great! All of us stayed out of the Mexican jail and caught some big Dorado and Marlin. Nothing like the Caribbean in April!


You beat me AF2. Welcome back.
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Knarley Darley
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PostPosted: Tue May 01, 2007 3:08 pm    Post subject: Reply with quote

Somtimes it is not possible to achieve the pinion below the trans output hight and get the ride hight you want. What I do is put the trans as high as possible by shiming the trans mount, and if possible lower the engine (even a small amount helps the problem a great deal) which tips the tail housing up. I usually dont worry as much about parallel as having the rear pinion angle pointed slightly down, and then get the trans as high as possible and see what happens.
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af2
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1933 Willys Coupe

PostPosted: Tue May 01, 2007 3:15 pm    Post subject: Reply with quote

Knarley is correct about the motor/trans position. I would be thinking on that 1st then deal with the pinion.
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86GN
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1990 Chevrolet Corvette

PostPosted: Tue May 01, 2007 9:46 pm    Post subject: Reply with quote

Ideally, you want the transmission output shaft and the pinion shaft to be parallel under load. The closer to the same plane you can get them the better. At rest that puts the pinion down a couple of degrees compared to the trans.

Like Knarley was saying - on a big rear tired car you actually want the transmission to be pointing up towards the rear with the pinion pointing down at it. Same deal happens as you set a car up with lower and lower ride height.
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10sec.et
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1969 Oldsmobile Cutlass

PostPosted: Tue May 01, 2007 10:32 pm    Post subject: Reply with quote

well i just crawled underneath and spent some quality time measuring and aligning. looks like it will work if i raise the trans about an inch. may have to raise ride height an inch also but ill wait until its all together to worry about that. thanks for all the help.
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af2 wrote:
It seems we can look at our magical Balls and come up with a fix?

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Big Dave
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PostPosted: Wed May 02, 2007 6:21 am    Post subject: Reply with quote

I do not think it makes any difference if the driveshaft runs up hill or down (angle of slope being positive or negative is a mathematical concept) the forces should be the same either way. Don't let ride height suffer because we "think" it has to point down because that is the way it has always been on production cars.

I see heavy duty construction trucks with twin screw rear axles and transfer cases for front wheel drive on cement trucks that have the drive shafts running at all manner of strange angles. But always with the universal joints forming equal but opposite angles with the shaft.


Big Dave
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beersngars
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1948 Chevrolet Coupe

PostPosted: Sat May 05, 2007 11:05 am    Post subject: Reply with quote

Just came across this: http://www.rosslertrans.com/Pinion%20Angle.htm

This should help explain the parallel theory.
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Paul P
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1971 Chevrolet Chevelle

PostPosted: Sat May 05, 2007 11:41 am    Post subject: Reply with quote

I was wondering who was going to post a picture(Diagram) for him to go by. It speaks a 1000 words and looks like about 15posts. Could have been your one and done! Cheers

Last edited by Paul P on Sat May 05, 2007 11:33 pm; edited 1 time in total
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af2
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1933 Willys Coupe

PostPosted: Sat May 05, 2007 5:54 pm    Post subject: Reply with quote

All the links posted had pictures. 10 is in the same ballpark as me and I can't get a good side picture without removing the body, floor panels and tires. I have the pinion 1" higher than the transmission and run the reverse as if it were 1" lower. The 2 degree negative I disagree with but that is my opinion.
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Big Dave
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PostPosted: Sat May 05, 2007 7:13 pm    Post subject: Reply with quote

It all depends upon how stiff the chassis is. If the chassis doesn't deflect much and the bars holding the four link are stout enough the rear end will not rotate that extra degree or two to make it opposite but equal under load.

But by definition in terms of engineering an applied force will result in deformation of something by definition. The reason we know how much horse power a Top Fuel dragster makes isnít on a dynamometer but by strain gauges mounted to the rear axle.


Big Dave
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10sec.et
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1969 Oldsmobile Cutlass

PostPosted: Sat May 05, 2007 8:18 pm    Post subject: Reply with quote

Paul P wrote:
I was wondering who was going to post a picture for him to go by. It speaks a 1000 words and looks like about 15posts. Could have been your one and done! Cheers


i wasnt that i needed a picture. i was concerned as to how critical it is that it be exactly like the pictures.


beersngars wrote:
Just came across this: http://www.rosslertrans.com/Pinion%20Angle.htm

This should help explain the parallel theory.


good info to have. thanks. im going to save that site for future reference.


Big Dave wrote:
I do not think it makes any difference if the driveshaft runs up hill or down (angle of slope being positive or negative is a mathematical concept) the forces should be the same either way. Don't let ride height suffer because we "think" it has to point down because that is the way it has always been on production cars.

I see heavy duty construction trucks with twin screw rear axles and transfer cases for front wheel drive on cement trucks that have the drive shafts running at all manner of strange angles. But always with the universal joints forming equal but opposite angles with the shaft


this is why i posted the question. i know what its
supposed to be like but im curious about "what if". im not 100% sure i can get the perfect angle but if not, im sure the car will let me know. im going to try to get it as close as possible and "see what happens". thanks for your help guys Cool

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af2 wrote:
It seems we can look at our magical Balls and come up with a fix?

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Paul P
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1971 Chevrolet Chevelle

PostPosted: Sat May 05, 2007 11:40 pm    Post subject: Reply with quote

Ok a diagram and maybe an explanation of how critical these settings are. I stand corrected. It really depends how much power and how the rear end is mounted as to how much extra pinion angle you use.

This car IMO would have been better off if you left the stock setup in the car but we have been there I know. It's too late to turn back now.
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10sec.et
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1969 Oldsmobile Cutlass

PostPosted: Sat May 05, 2007 11:57 pm    Post subject: Reply with quote

Paul P wrote:
This car IMO would have been better off if you left the stock setup in the car but we have been there I know. It's too late to turn back now.


yeah, the rear suspension was a total mess. the factory brackets were extensively modified for a different rearend and welded with a small 135 amp MIG (had that discussion before Rolling Eyes ).

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af2 wrote:
It seems we can look at our magical Balls and come up with a fix?

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K5runner
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1979 Chevrolet Blazer

PostPosted: Tue May 08, 2007 12:43 am    Post subject: Reply with quote

From what I've experienced you need to have both ends of your driveshaft (trans/axle) to be parallel. You also have the option of going to a CV (constant villosity joint). But what crazy angle would your engne be at if your trans is pointed to the ground.
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af2
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1933 Willys Coupe

PostPosted: Tue May 08, 2007 6:35 pm    Post subject: Reply with quote

K5runner wrote:
From what I've experienced you need to have both ends of your driveshaft (trans/axle) to be parallel. You also have the option of going to a CV (constant villosity joint). But what crazy angle would your engne be at if your trans is pointed to the ground.



I think the point was missed as far as angles.

The point is stated without the use of CV joints that pose more problem than the correct angle.
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