Gears & Axles - Hey Joseph....? for Ya....

A tech at my local dealer who does a lot of gear installs told me that when he uses GM gears, they almost always set up perfect first time using all the original factory shims. What's your experience with this? <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />

Usually they get you pretty close, but not ideal. I've had probably 3-4 sets out of 40 that I've set up without adjustment. The factory shims do get you a pretty good baseline to start from.

2nd ?. When you are checking the pattern do you anticipate the concentration moves when there is load or do you just put it to the center ?

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by pekkaz:
<strong>2nd ?. When you are checking the pattern do you anticipate the concentration moves when there is load or do you just put it to the center ?</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Yes the gear pattern moves with load on it. While it is hard to duplicate a load pattern I usually simulate load using a long prybar while turning the pinion. I try to keep my patterns starting on the toe side of the gear. http://www.precisiongear.com/pgtech_contact.htm has some useful gear pattern pictures, I use the same chart at work for gear installs. <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />

Here's a quote from an old Chilton book I have:

Since you can only apply test load pressures to the gears, the contact pattern will be less distinct toward the tooth ends. But when the ring gear and pinion are under operating loads in the vehicle, the tooth contact area spreads out, especially towards the heel end of the tooth. For this reason, do not try to get by with a tooth contact pattern that is centered, but favors the heel end of the teeth. This will only lead to overloading at the heel ends of the gear teeth. On the other hand, a contact pattern that which is reasonably centered, but favors the toe end of the teeth is acceptable.