# [EVDL] Tranny/differential alignment (Drive shaft angles)



## EVDL List (Jul 27, 2007)

Years ago, when I was doing ICE engine swaps, as a "hot rodding" hobby, I
had to have drive shafts custom fabricated. The company that was building
the shafts warned me to be careful NOT to have the centerline from the
transmission output shaft line up perfectly straight with the centerline of
the differential input coupler. In other words, it should NOT be a zero
angle, straight line, from the transmission to the differential. The reason
stated was that the driveshaft U-joints REQUIRE a slight angle to prevent
whipping/wobbling. It was suggested that a 5-10 degree angle at BOTH ends of
the driveshaft would prevent the problem. (The centerlines of both the
transmission output and differential input would be parallel, but not
centered on each other.)

Check for yourself: Go look under any rear-wheel drive car and you'll see
what I'm talking about: There is a slight angle at both U-joints. I'm no
engineer, so this advise is offered with a "Caveat Emptor" warning.
Roger Daisley
Pullman, WA
www.96-volt.com

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## EVDL List (Jul 27, 2007)

I think the slight angle was to allow movement when torque is applied at
the axle. As torque is applied, the pinion gear will try and ride up
the ring gear. This causes the axle to rotate upwards. When torque is
applied at ride height the angles should be zero/zero. 

-----Original Message-----
From: [email protected] [mailto:[email protected]] On
Behalf Of Roger Daisley
Sent: Wednesday, September 05, 2007 10:40
To: [email protected]
Subject: [EVDL] Tranny/differential alignment (Drive shaft angles)

Years ago, when I was doing ICE engine swaps, as a "hot rodding" hobby,
I had to have drive shafts custom fabricated. The company that was
building the shafts warned me to be careful NOT to have the centerline
from the transmission output shaft line up perfectly straight with the
centerline of the differential input coupler. In other words, it should
NOT be a zero angle, straight line, from the transmission to the
differential. The reason stated was that the driveshaft U-joints REQUIRE
a slight angle to prevent whipping/wobbling. It was suggested that a
5-10 degree angle at BOTH ends of the driveshaft would prevent the
problem. (The centerlines of both the transmission output and
differential input would be parallel, but not centered on each other.)

Check for yourself: Go look under any rear-wheel drive car and you'll
see what I'm talking about: There is a slight angle at both U-joints.
I'm no engineer, so this advise is offered with a "Caveat Emptor"
warning.
Roger Daisley
Pullman, WA
www.96-volt.com

_______________________________________________
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_______________________________________________
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## EVDL List (Jul 27, 2007)

I talk to a master mechanic about this a while back, and he said that while 
the motor and transmission is parallel with the differential, the drive line 
must be had a angle of not less than 1.5 degrees while the vehicle is on 
grade and the maximum angle has to be determine by just laying out the drive 
line on a surface and see where the U-joints start to interfere with each 
other.

If the maximum angle exceeds this while the vehicle bounces, than a stop is 
design in the suspension arms, and a stop is place above the differential 
for the minimum angle. When I lower my EV 4 inches, I had to adjust these 
stops to maintain the driveline angles.

Roland

The main reason why the drive line has to be angle, is that if the drive 
line was at 0 degree, the needle bearings in the U joints would not rotated 
and will cause a flat spot in the needle bearing cups. He has see some of 
these units produce this wear pattern and fail when the drive lines were 
install at 0 degrees.

Roland


----- Original Message ----- 
From: "Dewey, Jody R ATC COMNAVAIRLANT, N422G5G" <[email protected]>
To: <[email protected]>; "Electric Vehicle Discussion List" 
<[email protected]>
Sent: Thursday, September 06, 2007 9:56 AM
Subject: Re: [EVDL] Tranny/differential alignment (Drive shaft angles)


> I think the slight angle was to allow movement when torque is applied at
> the axle. As torque is applied, the pinion gear will try and ride up
> the ring gear. This causes the axle to rotate upwards. When torque is
> applied at ride height the angles should be zero/zero.
>
> -----Original Message-----
> From: [email protected] [mailto:[email protected]] On
> Behalf Of Roger Daisley
> Sent: Wednesday, September 05, 2007 10:40
> To: [email protected]
> Subject: [EVDL] Tranny/differential alignment (Drive shaft angles)
>
> Years ago, when I was doing ICE engine swaps, as a "hot rodding" hobby,
> I had to have drive shafts custom fabricated. The company that was
> building the shafts warned me to be careful NOT to have the centerline
> from the transmission output shaft line up perfectly straight with the
> centerline of the differential input coupler. In other words, it should
> NOT be a zero angle, straight line, from the transmission to the
> differential. The reason stated was that the driveshaft U-joints REQUIRE
> a slight angle to prevent whipping/wobbling. It was suggested that a
> 5-10 degree angle at BOTH ends of the driveshaft would prevent the
> problem. (The centerlines of both the transmission output and
> differential input would be parallel, but not centered on each other.)
>
> Check for yourself: Go look under any rear-wheel drive car and you'll
> see what I'm talking about: There is a slight angle at both U-joints.
> I'm no engineer, so this advise is offered with a "Caveat Emptor"
> warning.
> Roger Daisley
> Pullman, WA
> www.96-volt.com
>
> _______________________________________________
> For subscription options, see
> http://lists.sjsu.edu/mailman/listinfo/ev
>
> _______________________________________________
> For subscription options, see
> http://lists.sjsu.edu/mailman/listinfo/ev
> 

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