Driveshaft angles

Does anyone have an opinion on the optimum driveshaft angle?

I've been told that anything less than dead level saps power & accelerates wear.

However, some owners have lowered the engine & box in the chassis & this would mean driveshafts at an angle... Is it a case of weigh up the pro's & cons??

FWIW My lotus' driveshafts are angled 'back' at about 5-10 deg...

Does anyone have any suggestions?
 

Peter Delaney

GT40s Supporter
I'm not sure that it is a real problem at all. There must be millions of 4WD's & trucks running around with quite severe angles in their prop-shafts & these do hundreds of thousands of km's without trouble. Intuitively, I guess that a "straight-through" setup would be optimal, but I suspect that the losses through a well arranged angled set of uni-joints would be in the order of fractions of a horsepower.

The most critical thing is to try to have the input & output shafts parallel, & to ensure that the 2 uni-joints are 180deg out of phase (this allows the cyclic variation in rotational speed through 1 angled uni to be exactly cancelled by the variation through the 2nd uni - assuming that the angles through each uni are the same).

My DRB has a Porsche G-50 box & the driveshafts are angled down about 10deg & forward about 5deg. Some of the early versions of this car have now done some serious mileage, & none (to my knowledge) have had any problems with the drive-shafts.

I hope that the above helps a bit.

Kind Regards,

Peter D.
 
G

Guest

Guest
"Does anyone have an opinion on the optimum driveshaft angle?"

5 to 10 degrees is correct, you don't want zero degrees because then the bearings ride in just one place and wear out quicker.

true zero does eat less HP but only slightly

"Do most GT40's use CV joints, U-joints, or the flex couplings like the originals?"

CV's is the only way to go, more expensive though, have seen real cars retrofitted to CV's
 
Thanks Kalun,

So presumably that's 5-10 deg in any direction? IE the g'box outpu c/l lower than the wheel c/l is not a problem?

In this instance, under hard acceleration the drvshaft angle would increase. Presumably as long as it is not possible to exceed the maximum angle in any circumastances (hard acceleration whilst hard cornering) this wpould be a satisfactory set-up?
 
G

Guest

Guest
Julian, While the actual travel of a GT40 suspension is quite small in normal use. The ideal would be to have the resting position such that the outboard end is lower so that normal travel of the suspension takes the 1/2 shaft through the neutral position at which the shaft would be at its shortest. Also keep in mind that while the two ends should not be in the same plane either vertically or horizontally, they should be parallel to each other in both again in the normal resting position. (It is hoped that the suspension geometry maintains this parallelism throughout its travel as much as possible.)
 
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