MTFCA Forum

Hello All,

I am in the process of rebuilding my Ruckstell axle. The last time I had it apart was 20 years ago when I was 15 years old. Now I’ve got a little more experience (and a little more $$) to do things better this around.

Here are photos of my ring (40 tooth) and pinion gear (11 tooth). I do not have a better photo of the ring gear as we haven’t split the axle halves yet. No chips, fractures, or missing teeth. But as you can see, lots of pitting on both. The ring gear has some wear and burrs along the top edge.

As you have probably guessed, I’m looking for some opinions from the gear doctors in the house on the current condition and long term viability of these gears.

The car runs great and I am happy with the combo of Ford standard gearing with the Ruckstell. I am open to considering new gears, and would like also like to hear about any recent experience with the quality of new gears that are available from Chaffins and others.

I’ll be making a separate post about what I found while disassembling the driveshaft. It was NOT good.

Ring gear pictures.

Dan

you did great as a 15 year old, but being older and wiser plus better endowed with $$, spring for another gearset and be a little more careful about mesh.

I read somewhere that gears with pits can cause the oil to diesel causing excessive noise and pressure inside the housing, I don't know it this is true but it seems plausible.

David, Can you tell me what dieseling means? It's a new one on me.

Allan from down under.

Look up cavitation, and micro-dieseling

cavitation causes pitting really, not the other way around (although with respect to rotating parts in fluid, pitted surfaces will increase cavitation...sort of a chicken/egg thing).

Cavitation is what does the cleaning in an ultrasonic cleaner.

Stop reading now if you don't want non-T info: If you want to know what cavitation can do, you can look for "hot-spots" in your ultrasonic cleaner using thin aluminum foil. A good cleaner will dimple and shred aluminum foil like you would not believe. It is a standard test for certifying or replacing cleaners in industry. Strips are treated, and the area in the tank most active is where the parts are concentrated. Samples are kept and analysed over the course of the machine's lifetime and finally retired when the damage to the foil coupon no longer like it was when new. And believe me, while all new ultrasonic cleaners "buzz", some will absolutely destroy the coupon and others will barely dent them. That's why you can buy no-name ultrasonics off of Amazon for $100, and with a known brand, you can't touch one with any useful capacity for less than $1200.

In the last photo it looks to me like the ring gear teeth are rather pointed on the outside edge indicating improper gear mesh. There appears to be heavier damage in that area. That pitting (fretting) is probably caused by high tooth loads; due to improper gear mesh. Fretting occurs with repeated high loads in an area over time.

Dieseling is where the oil is compressed in the small pitted holes and ignites (micro dieseling) Diesel oil can be ignited by compression A. by the oil itself or B. by super heated air and the oil injected in to it. Some large pile drivers are operated by injecting fuel oil under the hammer where it is ignited (exploded) and forces the hammer back up. This action in a micro form can happen inside the differential with pitted gears where the oil is compressed in the pitted cavities.

I understand cavitation, caused by reduced pressure at points and material being "sucked" out, as in boat propellers. Does the micro dieseling require a small pit, like a rust pit to be able to progress?

Allan from down under.

Altair and Allan.
I can say that if you don't learn something every day on this Forum then you are not trying.
Thanks for your time and knowledge.
Thanks to the MTFCA and the ADMIN for making it possible. ...N.

It looks like Hertzian fatigue/macropitting on the crownwheel.

The pinion looks like corrosion. Could it have been like that when you assembled the axle 20 years ago?

I would replace both.

Micro Dieseling (MD) is a problem anytime a petroleum oil is recovered in an oil pump as well. I have made many baffles in engines just to slow down the recovery flow to allow air bubbles to raise/escape and not reach the pump. Air when compressed creates a lot of unnecessary heat. The another problem with either MD or Cavitation is an out of balance event by lack of equal density. Plays hell on shafts, gears, and support housings. Glad this topic has been addressed, most doubt this theory. Windage trays in high RPM race engines take a lot out. I even put one in a high performance T engine once with excellent results, lowering the oil temperature by 20 degrees.

Hope this Helps Others,

Hank