……
Corvair DiagramCorvair Photo
Corvair Center
home forum corvairs calendar links Corvair Podcast
California Corvairs
Clarks Corvair
Clarks Corvair
“CORSA"



Chevy Corvair License Plate
Chevy Corvair Chrome Wheel
Corvair Center Forum :  Corvair Center Phorum - presented by CORSA The fastest message board... ever.
Corvair Center 
u-joint trunnion stress-wear
Posted by: Saxon ()
Date: May 11, 2022 10:14PM

I saw these wear or stress marks on all my universal joint trunnions.

They are not evenly distributed across the circumference but rather concentrated on about half of it.

I am trying to picture how the shaft and joints rotate at non zero angles. My brain can only conceive of a shock during installation or a forceful load during operation. How did these scoring marks and pits get here?

And a question on checking for play after installation...
I will be replacing all 4 and the shop manual does not go into details regarding acceptable axial play.

These 7 part videos from Weber State University go into quite the nitty gritty from history to measuring axial play with a dial indicator. The educators premise is that axial play should be measured because amounts greater than .002 will contribute to run-out of the rotating shaft. That leading to premature wear and/or vibrations.

[www.youtube.com]

What is practice from you veteran mechanics?

Northern CA
66 Monza Coupe 4-spd 140



Edited 4 time(s). Last edit at 05/11/2022 10:21PM by Saxon.

Attachments:
Options: ReplyQuote
Re: u-joint trunnion stress-wear
Posted by: RobertC ()
Date: May 12, 2022 01:53AM

Interesting, but of no real importance.

By the time (60,000 - 70,000 miles) I have replaced mine, those marks cover the whole circumference.

Just need to use care not to crimp the needles on installation.

Grease zircs go towards the half shaft.

Options: ReplyQuote
Re: u-joint trunnion stress-wear
Posted by: vairmech ()
Date: May 12, 2022 05:06AM

Anymore I do not use any u-joint that has a grease zerk. I use the solid u-joints and install my own Amsoil grease.

As far as installation goes just put them together as all the design work has already been done.
You also said "all 4" so you must have a late model car. There will be a lot of axial play in the diff yoke but that is acceptable. I think you may have been referring to radial play. Like I said the design work has already been done, nothing to worry about.

The wear you show is normal for standard u-joints that don't get greased enough and even sometimes when they do!
As far as understanding the wear it comes in on the pressure side of how it is installed. Just think of the direction of travel, the diff is the driving force and the wheel is the resistance. What this means is you can see the wear pattern on one side because of the pressure.

Ken Hand
Handy Car Care
248 613 8586

Vairmech@aol.com

Options: ReplyQuote
Re: u-joint trunnion stress-wear
Posted by: JimBrandberg ()
Date: May 12, 2022 05:32AM

I've noticed that "premium" u-joints seem to have more needles of a smaller diameter.

Jim Brandberg
Isanti, MN
CorvairRepair.com



Options: ReplyQuote
Re: u-joint trunnion stress-wear
Posted by: RobertC ()
Date: May 12, 2022 09:20AM

vairmech Wrote:
-------------------------------------------------------
> Anymore I do not use any u-joint that has a grease zerk. I use the solid u-joints and install my own Amsoil grease.
>

I should add, in my experience, that greaseable u-joints did not last any longer than the original non-greaseable u-joints.

Options: ReplyQuote
Re: u-joint trunnion stress-wear
Posted by: dryenko ()
Date: May 12, 2022 07:33PM

Marks at a angle indicate a missing needle bearing.
Or too loose of a needle pack.

Bob C aka Dryenko
Dobson, NC 27017

Options: ReplyQuote
Re: u-joint trunnion stress-wear
Posted by: Saxon ()
Date: May 12, 2022 10:15PM

Ahh, if there is too much axial play, then it would allow some bearings to slant inside the cup.

Northern CA
66 Monza Coupe 4-spd 140

Options: ReplyQuote
Re: u-joint trunnion stress-wear
Posted by: joelsplace ()
Date: May 13, 2022 08:20AM

Once you start getting wear you will have excess clearance.

Joel
Northlake, TX
5 Ultravans, 138 Corvairs and counting...

Options: ReplyQuote
Re: u-joint trunnion stress-wear
Posted by: CoCoCo ()
Date: May 13, 2022 12:30PM

Is that wear called "brinelling"(sp?) or is that of a different nature?
Looks like it to me, equated with tired old (or not enough) grease, an overheated state at some point, or just too much load/impact for the part.
And was always considered a cause for replacement.

Glad you found that and are replacing yours Saxon. Do you know how long they were in service?

Paul

Options: ReplyQuote
Re: u-joint trunnion stress-wear
Posted by: CoCoCo ()
Date: May 13, 2022 12:40PM

Nevermind... Looked it up to make sure I was speeling it correctly and one of the first images to load up was this one:

Attachments:
Options: ReplyQuote
Re: u-joint trunnion stress-wear
Posted by: cnicol ()
Date: May 13, 2022 01:16PM

Saxon Wrote:
-------------------------------------------------------
> Ahh, if there is too much axial play, then it would allow some bearings to slant inside the cup.

Craig replies: Not really, the needles will tolerate quite a bit of axial play and still stay lined up. Most likely, someone took it apart at some time and lost a needle. A missing needle causes some of the needles to operate at an angle and it goes downhill from there.

Craig N. Coeur d'Alene ID.
66 Black Monza 4dr, 4.2L V8 49k
61 Seamist Jade Rampside 140 PG
65 Canadian Monza 4dr 110/PG 40k
66 Sprint Corsa convt - First car! Re-purchased 43 years later
2+2 gnatsuM 5691

+17 Tons of parts

Options: ReplyQuote


Sorry, only registered users may post in this forum.
This forum powered by Phorum.