If someone know which bearing Tracy use on prop shaft if yes
what brand,ball or roller and
 bearing number



 Jean Prudhomme

 I don't have it here but I think it is a 1.3875" ID and
 the OD is 3.350". It is .75 inches wide. Double sealed.
 Inch series. Probably a Chevy Pick up truck rear wheel bearing.

 Search the internet for ball bearing makers and give
 them the dimensions.

 Paul Lamar


Do you know if is a roller trust bearing or ball trust bearing??

When you have a chance could you send me the bearing number and brand

Jean Prudhomme


It is a ball bearing Jean. The Chevy Truck has a lot of
side load on the rear wheel while cornering so it must be
a combination of axial and radial load.

I am getting ready to go to Germany
so I may not get out to the hanger for a couple of weeks.
Try to find it on your own. Start with an auto parts store.
Just measure the bearing they bring out and if the dimensions
are correct that is the right one.

Ball bearings are ball bearings.

Paul Lamar


Paul
Your statement that ball bearings are ball bearings.
"It aint necessarily so".
It's over 40 years since as a design engineer I designed bearing systems but
if my memory serves me well there are deep groove ball bearings that have
greater axial load carrying capabilities than the standard type. If this
particular bearings is required to take high axial loads then I would be
surprised if it wasn't a deep groove type. Care needs to be taken in
selecting the correct bearing for this application
Bob Izett -Perth, WA

Well yes that is true and I totally agree but any rear axle bearing
THAT size will work. Tracy's prop shaft is an actual section of a GM rear
axle. The side loads on the rear axle are similar to the thrust loads on
a prop shaft. In fact the retainer for the ball bearing is the same
way GM retains the rear axle ball bearing. Namely it is pressed on.

Tracy has sold well over 100 gear boxes with many of
them flying for the past 10 years so it must be OK.

There is nothing seriously wrong with it but it could be designed
to be as strong yet lighter in weight. The bearing itself is very
heavy being over 3 pounds as I recall.

I should have said a rear axle ball bearing is a rear axle ball bearing.


Paul Lamar
Hi Jean,
Years ago when Tracy first started making PSRU's, I recall his website blog telling the story of
several bearing failures. The bearings were of similar physical size but were from different
manufacturers. This is a sealed bearing which means whatever lubricant the manufacturer
put in is there for the life of the bearing. So maybe he stumbled on a lube difference. Bearings are
manufactured to different tolerance classes. So maybe he stumbled on the wrong class of bearing
a few times. The bottom line is why should you remake his mistakes? Just buy the bearing from him.
If his axle supplier can get it and press it on, then he can get one for you. Sure he'll mark it up, but so will
the auto parts dealer. At least with Tracy, you'll get the correct bearing and the markup profit will
support someone who supports the rotary. Dave M


I don't recall that was the prop bearing. As I recall it was the helical
gear thrust bearing. Apples and oranges. I have the emails.

I challenge anybody to show me two bearings of that EXACT size double
sealed that have significant differences.

Paul Lamar


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