Gear marking compound

[pmbrunelle]

Not really a Fiero-specific question, but more of a general automotive maintenance question.

Thursday I tried to buy the stuff at my local auto parts store, and the clerk directed me to the spray-paint section.
Today (Friday) my dad went to another parts store, and he had no luck there either.

Is there any sort of home-brew recipe, paint, grease, or whatever easily-obtained concoction that can act as a functional substitute?

I'm changing the pinion bearings on my Ford Ranger's diff, so I need to make sure the contact pattern is good before closing things up.

[Honest Don]

Try the dealer? Or maybe a gear & axle specialty shop?

https://www.amazon.com/ACDelco-10-5055- ... B007Q10TES

[pmbrunelle]

Yeah, it may end up like that, with some place that's only open during my working hours Monday-Friday...

[Honest Don]

I wonder if greasepaint or something from a craft store would work? The real stuff has a paste-like consistency.

[pmbrunelle]

I tried white lithium grease, applied with a paintbrush. It worked, sort of...

It didn't leave a very clear pattern. From what I could see, it looked OK, but my level of confidence in that inspection is low. The real test will be on the road.

For next time: buy the AC Delco stuff...

[The Dark Side of Will]

What pimped out ride is this?

Doing that on the bench is bad enough... doing it under the car must suck more.

[pmbrunelle]

This is on my "daily driver" 2007 Ford Ranger, 3.0 Vulcan, 2WD, extended cab. The truck is almost as bare-bones as I would like it to be, but not quite.

Since this is nominally a DD, I have resisted the urge to go full project mode on this. I've kept it stock. Since it's stock, and I only do Cheeseburger Palace work on it, I didn't think it was interesting enough to merit a forum thread.

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The truck has 290 megametres on the odometer. It recently started to exhibit a whining noise, seemingly related to road speed only (no variation with driveline torque).

4th "gear" in the M5OD-R1 is 1:1 direct drive. A transmission-related problem could be expected to show different symptoms in direct drive where the power flow bypasses the layshaft. In this instance, the whine didn't depend on gear selection, so I turned my attention to the rear end.

The diff pinion had two failing bearings, one of which was very bad!

With axle supported on wood blocks, and the spare tire removed, I'm actually able to sit upright (well, slouched over) on the floor, facing the diff.

[Honest Don]

How do they sound?

[pmbrunelle]

I reassembled the truck on the weekend, and I didn't hear any gear sound.

Just silence!

[CaptainHindsight]

Permatex® Prussian Blue is usually available at most auto part stores if they don't have the yellow gear marking grease.

https://www.permatex.com/products/speci ... cale=en_us

[The Dark Side of Will]

Here's a Dana 30 Eagle front that I did: http://www.realfierotech.com/viewtopic. ... 47#p152347

[pmbrunelle]

I ordered the Permatex 80038 and the AC Delco 10-5055 for checking power steering gears and tapered fits (ball joint stud). Both were available on amazon.

The Delco may be preferable (at least for the gears), as inspection departments don't necessarily like Prussian blue. Apparently it stains everything, and when employees go home, it's not hard to end up with smurf fingers. Not fun if you have to do this inspection regularly.

[pmbrunelle]

The AC Delco yellow grease is good stuff. You paint on a thin layer with a paintbrush (as indicated on the tube). I painted the large gear, but left the small mating gear bare.

I then spun the gearset once, back and forth with a small amount of torque (provided by my hands). The idea was to have enough normal force to displace the yellow grease.

Delco Pattern.JPG (161.18 KiB) Viewed 2685 times

In real life, the pattern is quite easy to see. The contrast is less good in the photo.

I would recommend it! Definately going to use it next time I have a diff job to do. Eventually I think I want to change the truck's axle ratio from 4.10 to 4.56 or 4.88; it lacks gusto (easy to stall) when leaving from a stop.

[The Dark Side of Will]

In real life, the pattern is quite easy to see. The contrast is less good in the photo.

Gear patterns are a weird thing... you can look at every photo on the internet and still have no idea, then look at it in person and think "oh... duh".

What gear are you showing us?

[The Dark Side of Will]

Eventually I think I want to change the truck's axle ratio from 4.10 to 4.56 or 4.88; it lacks gusto (easy to stall) when leaving from a stop.

Sounds like a Coyote swap would be more along the lines of what you're looking for.

[pmbrunelle]

That's a plastic gear for a column-mount electric power steering (work-related). The spur gear shape is preferred because it is easily injection-molded.

A multi-start worm gear mates with it. The axis of the worm gear is inclined such that its helix angle is tangent to the spur gear.

The contact patch looks like it's touching the addendum circle. That may be normal, considering that I spun these gears around by hand.

Under load, I suspect that the plastic gear tooth might be pushed over, and the contact might move towards the middle of the tooth face. I'll probably redo the contact pattern inspection, but with a more typical working torque going through the gearbox.

Today was the first time I ever checked power steering gears with gear marking compound, so I'm still a noob at interpreting these patterns.

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Technically yes, an engine swap on the truck might be more exciting, but for now I am busy enough with my Fiero and house.

I don't really want to go down the rabbit hole of too many unfinished projects at once...