Lets talk driveline angle for P.T cars - Chevelle Tech
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post #1 of 13 (permalink) Old Oct 21st, 11, 5:24 PM Thread Starter
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jason
 
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Lets talk driveline angle for P.T cars

So I have a 67 ss. its lowerd (springs) 3 inches. I have an auto gear m22 in it now. I have adjustable rear suspension and my current pinion angle is 1 deg blow zero. The drive shaft looks damn near strait from the rear diff to the trans. I wiped out a set of unoints in about 2k miles, the engine makes a fair amount of torque(619ftlbs) but I suspect driveline angle is at fault. How do i correct this for the front u joint. What should it be
Thanks in advance for any info you may have.

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post #2 of 13 (permalink) Old Oct 21st, 11, 7:19 PM
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Wayne
 
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Re: Lets talk driveline angle for P.T cars

It's actually the working angle between the rear diff and driveline (angle #1) and the working angle between the tranny and the driveline (angle #2)
From all I understand I either one of these working angles is 0* the needle bearings are not forced to roll around which causes them to remain in the grease. This will cause the u-joint to ride on one spot only and fail.
Ideally they will both have an equal but small working angle.

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post #3 of 13 (permalink) Old Oct 22nd, 11, 12:22 AM
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Doug
 
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Re: Lets talk driveline angle for P.T cars

When we had our driveline cut for a 700R4 conversion, the shop recommended a -3 degree angle at the rear diff. I'll have to measure where we are at the tranny.

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post #4 of 13 (permalink) Old Oct 22nd, 11, 3:31 PM
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Re: Lets talk driveline angle for P.T cars

Ideally you would want the same angle between the (trans to driveshaft) and (pinion to driveshaft).

Here's a good example of how to measure driveline angles.
http://www.wolferacecraft.com/images/tech/image004.gif


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post #5 of 13 (permalink) Old Oct 22nd, 11, 8:24 PM
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Re: Lets talk driveline angle for P.T cars

I agree with Cole, my main experience with drive-shafts is with trucks, but it is the same idea. You want the two angles to be within a degree of each other. If not the u-joints will be turning at different speeds and cause vibration at certain rpms. It also makes sense about what was stated earlier, how if there is no angle it can cause premature failure
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post #6 of 13 (permalink) Old Oct 23rd, 11, 8:23 PM
 
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Re: Lets talk driveline angle for P.T cars

In our asphalt late model, with 8500 rpm driveshaft speed, we put crankshaft/transmission angle up the same amount pinion angle was down. 2 degree for two degree and so on. As you generate more pinion angle in a drag car, you may run out of available space for the output shaft so I'd just go a reasonable distance up with the transmission.

I think things go wrong when the output shaft is down at the rear and pinion is down toward the front...

Oh, and jsand6769, Autogear M22's are awesome.

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post #7 of 13 (permalink) Old Oct 24th, 11, 6:51 PM
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Re: Lets talk driveline angle for P.T cars

Jason – U-joint angles are important for the life of the U-joints and also performance. Are you autocrossing or driving on road courses?

We have this really cool PDF document /instruction sheet that accompanies our adjustable upper control arms

http://www.hotchkis.net/_uploaded_files/1203AA.pdf


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post #8 of 13 (permalink) Old Oct 24th, 11, 10:30 PM
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Re: Lets talk driveline angle for P.T cars

Quote:
Originally Posted by Hotchkis View Post
Jason – U-joint angles are important for the life of the U-joints and also performance. Are you autocrossing or driving on road courses?

We have this really cool PDF document /instruction sheet that accompanies our adjustable upper control arms

http://www.hotchkis.net/_uploaded_files/1203AA.pdf


That's a good document, except when A-bodies are lowered, the rear end starts to ride higher up in the chassis. In fact, it rides so high that the driveshaft points up from the transmission to the rear end. This causes a situation where rear adjustable arms are not enough to correct the problem. Here is a pdf that I made to demonstrate what I am describing:

http://www.pro-touring.com/%7Eandrew.../driveline.pdf


The solution is to raise the back of the transmission to reduce the front working angle. However, there is a limit to how the transmission can be raised before the slip yoke will hit the floor pan. If the body mounts are old, this problem is even worse.

Some people have gone as far as replacing the whole transmission and driveshaft tunnel in order to get sufficient clearance for the transmission. This is a good solution but has its limits because the accessories can start to hit various other components in the engine bay and headers start to point up into the floor pan.

The other solution is to get a driveshaft made that has a CV joint at the front. That is the solution that I came up with. It is not for everyone, but it works very well.

https://www.chevelles.com/forums/showthread.php?t=353010

Andrew


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post #9 of 13 (permalink) Old Oct 24th, 11, 10:56 PM Thread Starter
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Re: Lets talk driveline angle for P.T cars

Quote:
Originally Posted by Hotchkis View Post
Jason – U-joint angles are important for the life of the U-joints and also performance. Are you autocrossing or driving on road courses?

We have this really cool PDF document /instruction sheet that accompanies our adjustable upper control arms

http://www.hotchkis.net/_uploaded_files/1203AA.pdf



Thanks for the info I have a full adjustable rear suspension (art morrison) The car is street driven. I am in the market for your sway bars however

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post #10 of 13 (permalink) Old Oct 24th, 11, 10:59 PM Thread Starter
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jason
 
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Re: Lets talk driveline angle for P.T cars

Quote:
Originally Posted by andrewb70 View Post
That's a good document, except when A-bodies are lowered, the rear end starts to ride higher up in the chassis. In fact, it rides so high that the driveshaft points up from the transmission to the rear end. This causes a situation where rear adjustable arms are not enough to correct the problem. Here is a pdf that I made to demonstrate what I am describing:

http://www.pro-touring.com/%7Eandrew.../driveline.pdf


The solution is to raise the back of the transmission to reduce the front working angle. However, there is a limit to how the transmission can be raised before the slip yoke will hit the floor pan. If the body mounts are old, this problem is even worse.

Some people have gone as far as replacing the whole transmission and driveshaft tunnel in order to get sufficient clearance for the transmission. This is a good solution but has its limits because the accessories can start to hit various other components in the engine bay and headers start to point up into the floor pan.

The other solution is to get a driveshaft made that has a CV joint at the front. That is the solution that I came up with. It is not for everyone, but it works very well.

https://www.chevelles.com/forums/showthread.php?t=353010

Andrew

Andrew how does the cv joint handle the torque. I am very interested in this fix

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post #11 of 13 (permalink) Old Oct 24th, 11, 11:19 PM
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Re: Lets talk driveline angle for P.T cars

Quote:
Originally Posted by jsand6769 View Post
Andrew how does the cv joint handle the torque. I am very interested in this fix
The following is taken directly from the Driveshaft Shop website:

"The 108mm CV is one of the coolest, most innovative designs in CV’s. It was originally introduced in the early Porsche’s (some refer to it as the Porsche 930 CV joint or size 15) and has become synonymous with high powered CV axles, but most are not aware that the CV in its standard trim is not as bullet proof as you would think. GKN is the manufacturer behind the original joint and if you look at their specs it is only rated at 3700 Meter-Newtons = 2,726.60 Foot-Pounds of torque. The cage is made from a brittle material and is Carburized. But when the inner race and cage is changed to our 4340 cage and 300M race, it will handle over 7000ft-lbs of torque (that’s a higher torque rating then the much larger size-21 CV which is rated at 6000 Meter-Newtons = 4,421.51 Foot-Pounds). Its a great CV joint but can only move in and out safely about .750 of an inch so its generally used for Rear wheel drive applications or only the inner CV of a front wheel drive axle."

The reason that the CVs need to handle that much torque is because they experience all of the torque multiplication in the driveline. So just do the math for your particular combination. If the engine makes 600lb/ft multiply that by the first gear ratio and you will have the maximum torque that is applied to the driveshaft, thus CV.

Andrew


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post #12 of 13 (permalink) Old Oct 24th, 11, 11:50 PM
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Re: Lets talk driveline angle for P.T cars

Andrew, to add to what you say, for those with automatic transmissions you must take into account the maximum stall torque multiplication of the converter. This is only for a very short moment but is a higher torque output.

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post #13 of 13 (permalink) Old Oct 25th, 11, 12:02 AM
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Re: Lets talk driveline angle for P.T cars

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Originally Posted by pist0lpete View Post
Andrew, to add to what you say, for those with automatic transmissions you must take into account the maximum stall torque multiplication of the converter. This is only for a very short moment but is a higher torque output.
Yes, very true, but also keep in mind that an automatic is generally more gentle on driveline components, compared to a clutch, assuming there is no trans brake. In any case, the calculations are a guideline and personally I'd want a 20% cushion above whatever number I come up with. For my car, it makes 400lb/ft of torque and has a 2.77 first gear. That's about 1100lb/ft to the slip yoke. I'm way, below what that CV can handle.

Andrew


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