Ring and Pinion break in.

[Mark42]

Getting closer to having the R&P installed (got the sensor ring today, they sent the wrong one, so things will be delayed another few days). Was wondering if regular gear oil should be used during the break in, or synthetic. The rear takes synthetic, but it gets dumped after 500 miles. So I was wondering if regular gear lube should be used or not.

[WildBillyT]

Any special instructions in the R+P box? If not, run what the rear calls for and dump it.

Clarification: Run what the differential calls for, not the original 10 bolt spec.

[Mark42]

Any special instructions in the R+P box? If not, run what the rear calls for and dump it.

Yeah, that sounds like the best plan. If I remember right, it takes a synthetic gear lube. Only a few quarts, so its fairly cheap and easy to do.

[BonzoHansen]

check with the R&P maker and the dif makers. I'd break in on dino, esp since you are gonna drain it after a few hundred miles or so.

[Mark42]

check with the R&P maker and the dif makers. I'd break in on dino, esp since you are gonna drain it after a few hundred miles or so.

I'm pretty sure the shop doesn't have a dino. But if I went to a shop with a dino, how much do you think they would charge?

[BonzoHansen]

For oil? $10? Dino=regular oil, not synth.

Remember to check with the R&P maker and the dif makers to find out what they recommend. That is all that matters.

[Tru2Chevy]

I'm pretty sure the shop doesn't have a dino. But if I went to a shop with a dino, how much do you think they would charge?

Dino = dinosaur = regular petroleum based gear oil, as opposed to synthetic.

Not a Dyno, used for measuring horsepower and torque.

- Justin

[WildBillyT]

Oh, and just an FYI:

http://www.4x4now.com/gt0999.htm

[Mark42]

Dino = dinosaur = regular petroleum based gear oil, as opposed to synthetic.

Not a Dyno, used for measuring horsepower and torque.

- Justin

Oh, I am such a dufus some times! LOL!

[Mike]

check with the company that made the POSI, the rear may have took synthetic before but the housing is all thats staying and i assure you it doesnt care what oil is in it. the gears care a little more but not the most. its the posi you need to put the right lube in for

btw, in my moser with that posi they say NEVER use synthetic

[sweetbmxrider]

and its a few pints, not a few quarts.

[Slow-V6]

The rear take regular oil not synthetic and if it is a LSD you need a bottle of the LSD additive. You want to drive around town to break in. Daily drive in traffic. Dont just get on the highway and cruise you want to constantly speed up and slow down.

Good time to do a T/A cover for stability and you can hold more oil. Make sure there is a magnet somewere in the pumkin so it can catch the metal shavings. 300-500 miles is a good amount to break in.

I know some people who drive about 50 miles then start hammering there car to break in the gears. I always just drove around normal trying not to stay at a set MPH for a extended period of time. In the end it doesnt matter because 10 bolts suck and I broke 4 in my v6 and 1 so far in my 02.

[alamantia]

I bought my 2002 Z28 brand new, it came with synthetic and I never changed the fluid until about 20k thats about 80k before the manufacturer suggests that I change it and guess what. The rear is fine.

[Mike]

I bought my 2002 Z28 brand new, it came with synthetic and I never changed the fluid until about 20k thats about 80k before the manufacturer suggests that I change it and guess what. The rear is fine.

like i said, the stock rear with the stock differential likes that, he is putting in an aftermarket differential as well as his gears

[alamantia]

whats the difference? The gears dont need break in, they are ran at the factory and are heat treated to 50+ rockwell, there is nothing that wears off of them. Perhaps minimal clutch dust from the posi if its even a clutch style and there is a magnet for metal debris on the stock cover, if you upgrade to a TA cover its worse for the rear because if there is any debris its nit being collected by teh magnet, its floating around the assy. Clutch and cone stuyle posis like eaton and auburn usualy require mineral oil with friction midifier, worm gear posis work well in synthetic or mineral. Either way no break in is necessary. There is nothing you can do to upset the gemotery of heat treated hypoid gears. The only possible factor is if you use new bearings the preload is a few inch lbs higher so that when the rollers seat in the races the preload drops. New bearings may give off a little more heat until they seat. Thats about it.

[Mike]

ok, im purely referring to the use of standard oil in that diff, not to proper gear break in

[Pampered-Z]

With my rebuilds the posi was what we used for the type of lube = Dino/syn and the weight, not the gears. And I always added a bottle of GM posi lube. Drive the car easy and if you have the clutch/cone type posi ( unlike a locker )you want to go into a parking lot and do some easy circles to break in the posi 1/2 dozen right circles, the the same to the left to break in the clutch.

[sweetbmxrider]

iirc, some gear oils come with the posi additive already in it. might be some of the synthetics. a knowledgeable parts counter guy should be able to tell you.

[Slow-V6]

Its your car so you decide. Do the gears need break in? I hear both yes and no. I broke them in just to be safe. Dont want to dump 500.00 on gears and a diff just for them to break or really start to whine because I didnt break them in right. Thats just me.

[BonzoHansen]

I really don't get all this. Just check with the R&P maker and the dif makers to find out what they recommend. 5 minute phone call, problem solved.

[Mark42]

Ok...
The Owners Manual for 1998 bird says the rear takes 1.75 quarts of SYNTHETIC oil (75w90), and if the OEM posi is installed, use 4 oz less and add 4 oz of posi fluid.

The differential that is being installed is the Eaton Truetrac. Eaton says to use what the automobile manufacturer says to use. Posi additive not needed.

The gear install doc says to use what the automobile manufacturer says to use. The also say to drive for 15 -20 minutes, then let cool fully. The important part is not to over heat the gear lube so it fails during breaking. Gear instructions say the first 15-20 minutes of break in cause high oil temps as the gears are wear hardened from use. Then keep speed under 60 mph for the next 500 miles.


The reason I asked if regular lube or synthetic lube should be used is in the past I have read where synthetic is not good for break in, because its just too darn slippery and doesn't let the parts wear in properly. But if no one has info saying regular lube should be used during break in, then synthetic will be used.

[Mark42]

whats the difference? The gears dont need break in,
Yes, they do need break in. Its part of the wear hardening process specified by the popular gear manufacturers.

they are ran at the factory and are heat treated to 50+ rockwell, there is nothing that wears off of them.

Most gears have a dark grey coating on them. Its a phosphorus compound designed to assist with the wear hardening. It wears off and contaminates the oil. That's part of the reason the oil is dumped after the first 500 miles.

Perhaps minimal clutch dust from the posi if its even a clutch style and there is a magnet for metal debris on the stock cover, if you upgrade to a TA cover its worse for the rear because if there is any debris its nit being collected by teh magnet, its floating around the assy. Clutch and cone stuyle posis like eaton and auburn usualy require mineral oil with friction midifier, worm gear posis work well in synthetic or mineral. Either way no break in is necessary.

The Eaton Truetrac indicates that there is a break in period and the vehicle should be driven lightly avoiding shock loads for the first 500 miles.

There is nothing you can do to upset the gemotery of heat treated hypoid gears. The only possible factor is if you use new bearings the preload is a few inch lbs higher so that when the rollers seat in the races the preload drops. New bearings may give off a little more heat until they seat. Thats about it.

Just added a few comments to your post that needed clarifying.

Regards,

Mark

[alamantia]

A couple questions because I am in the middle of a rear swap and in doing so desided to reread this post to find that you sited what I said and I have considered what you mentioned.

I see we agree on posi clutches and bearing requiring time to seat but what exactly is wear hardening? Is it a force that changes geometry after a part has been heat treated?

Also, if the gears have phosphorus lapping compound applied to them and gear lube is made from phosphorous how will the oil get contaminated?

I ask these questions because I am a degreed mechainical engineer whos first job was designing gear reducers. Ive never heard of either wear hardening or contamination of lube. I want to know if these are indeed factual because it got me thinking perhaps I should switch lubes in my cars.

I work in an industry now where we manufacture medical devices and have technical writing to support the usage and handeling of our products. Id say 10% of the writing is valuable and 90% is BS precautionary instructions that was only placed in the handbooks to serve as rebuttle if a product fails in the field and we were held liable we could use this literature in our defence saying the product want taken care of properly. This is why I find a lot of manufacturers suggestions a waist of time. I also was fortunate enough to grow up working in my fathers dealership. When rear ends came in that were broken or worn one of 3 things were done. It was under warrenty and the axle was taken out and a new one delivered. If it was out of warrenty the tech replaced either the bad gears or bearings or we got a used one delivered from hunts point. The very few times I have seen gear sets replaced the Techs followed GM proccedure and I dont recall them ever test driving cars for 10min clips or running them on jackstands or anything. They just drove them around the block, checked for leaks and called the customer to come pick up their cars and drive away. If someone has all-data and finds the gear installation proccedure and it calls for break in then I stand corrected. All-data proccedure reccomends every possible precaution, it tells you to remove the negitive batter cable for replacing spark plugs in some cases, im sure if break heat cycles are supposed to happen it would say. My owners manual in my car doesnt even suggest changing the rear fluid, just checking the level. So when people ask for gear break in advise. I offer my opinion and personal experiance. I personally find a lot of what manufactures suggest to be overkill and I hate to see people waist time and money on someting that isnt necessary. I like to think about why they suggest it and see if it makes sence and weigh that on what I know and decide for my self. But now you got me thinking.

[WildBillyT]

A couple questions because I am in the middle of a rear swap and in doing so desided to reread this post to find that you sited what I said and I have considered what you mentioned.

I see we agree on posi clutches and bearing requiring time to seat but what exactly is wear hardening? Is it a force that changes geometry after a part has been heat treated?

Also, if the gears have phosphorus lapping compound applied to them and gear lube is made from phosphorous how will the oil get contaminated?

I ask these questions because I am a degreed mechainical engineer whos first job was designing gear reducers. Ive never heard of either wear hardening or contamination of lube. I want to know if these are indeed factual because it got me thinking perhaps I should switch lubes in my cars.

I work in an industry now where we manufacture medical devices and have technical writing to support the usage and handeling of our products. Id say 10% of the writing is valuable and 90% is BS precautionary instructions that was only placed in the handbooks to serve as rebuttle if a product fails in the field and we were held liable we could use this literature in our defence saying the product want taken care of properly. This is why I find a lot of manufacturers suggestions a waist of time. I also was fortunate enough to grow up working in my fathers dealership. When rear ends came in that were broken or worn one of 3 things were done. It was under warrenty and the axle was taken out and a new one delivered. If it was out of warrenty the tech replaced either the bad gears or bearings or we got a used one delivered from hunts point. The very few times I have seen gear sets replaced the Techs followed GM proccedure and I dont recall them ever test driving cars for 10min clips or running them on jackstands or anything. They just drove them around the block, checked for leaks and called the customer to come pick up their cars and drive away. If someone has all-data and finds the gear installation proccedure and it calls for break in then I stand corrected. All-data proccedure reccomends every possible precaution, it tells you to remove the negitive batter cable for replacing spark plugs in some cases, im sure if break heat cycles are supposed to happen it would say. My owners manual in my car doesnt even suggest changing the rear fluid, just checking the level. So when people ask for gear break in advise. I offer my opinion and personal experiance. I personally find a lot of what manufactures suggest to be overkill and I hate to see people waist time and money on someting that isnt necessary. I like to think about why they suggest it and see if it makes sence and weigh that on what I know and decide for my self. But now you got me thinking.

Work hardening is what the gear companies recommend because the gears are manufactured under different conditions that that which they run in. I posted a link above that Randy from Randy's Ring and Pinion wrote. And I can say with confidence that Richmond, Randy's, Motive, and Yukon Gear all say to break them in. I don't think jack stands would work as there would be little load being transferred and too little heat in the rear.

Edit:


Work hardening is similar to forging in the way that it compresses the metal molecules into a very compact and hard formation. This can only be accomplished if the metal surfaces are lubricated and the gear temperature stays cool enough that the molecular structure does not change. If the temperature of the metal gets hot enough to change the molecular structure, it will soften the surface instead of hardening it.

[alamantia]

Wear hardening the same as work hardening?

[alamantia]

I rember learning that work hardening can not be perfomed post heat treating and does not require heat. Thats why I am asking. When we cut bevel gears at my old job (gear cutters are cool) we had them sent to alferd heller in patterson for heat treating and oil quench to 50-60 rockwell so that their physical proberties could not be altered in use. Its tough to learn and be personaly involved in certain things and see and hear statements that dont make sence and question them. But if I am missing something I do want to learn. I never change the oil in my differentials but after reading what mark said I am curious. Until i see evidance of gawled gear sets due to lack of so called break in I hate to offer advise suporting the proccedure. In the end its really a moot point i suppose, it only takes a few bucks and an hour of time for peace of mind. I just feel it to be a waist unless i learn otherwise.

[sweetbmxrider]

i didn't see anything in all data for you but it did say lubricate everything in gear oil before installing.

[WildBillyT]

Just got off of the phone with a metallurgist/mechanical engineer. Here's what he said:


When you are breaking it in you are setting the right balance of hardness on the outer surface of the gear. There is no real geometry changing.

When the gears are manufactured there's a hobb setting which defines the exact environment that they were manufactured under. This is what is inscribed on the gear in tenths of thousands. At GM they probably have this setting and can spec the rear setup to minimize the need for a break in. In a shop you don't have their type of setup and a break in is needed to make up for the lack of industrial environment. Street gears for non high performance cars are harder than high performance gears and aren't as sensitive to the lack of a break in period.

He mentioned the cross sections of the gears and their associated Rockwell hardness however I do not recall enough of that to post it completely. Something along the lines of the whole gear set being hard enough but the alignment of molecules being key for wear protection.