Now this is a set of gears...

[Steve1968LS2]

My new lightened and polished 3.90 gears came in.. man, they are almost too nice to hide in the differential. lol

Thanks to Tom for the advice. Cost was $240 for the lightening and $99 for the polishing.

https://static1.pt-content.com/images/noimg.gif

[cheapthrillz]

WOW.... maybe you sould hang them from the rear view instead? lol

They are pretty, and i bet the polishing does reduce a ton of friction.

Are those going in Penny?

[Steve1968LS2]

WOW.... maybe you sould hang them from the rear view instead? lol

They are pretty, and i bet the polishing does reduce a ton of friction.

Are those going in Penny?

Yep, inside the new aluminum case suggested by Tom.. :naughty:

[CarlC]

Yeah, Tom's very good at spending my money as well.

[Hoot]

Hey Steve,

I forgot if you said in the other thread if you are going to put a differential fluid pump in the 9" housing or not. I saw a nice internal one in one of the circle track mags, but I can't remember the brand name. I think penny needs a diff cooler. Whaddya think about a little B&M polished stacked plate cooler under there?

[Steve1968LS2]

Hey Steve,

I forgot if you said in the other thread if you are going to put a differential fluid pump in the 9" housing or not. I saw a nice internal one in one of the circle track mags, but I can't remember the brand name. I think penny needs a diff cooler. Whaddya think about a little B&M polished stacked plate cooler under there?

I like the idea of a cooler, I just need to research it some to see what is best for a street car that visits the track as opposed to a race car that visits the street.

I am designing a new vent system like Parson's deal.

[megaladon6]

i did see a clear diff cover around somewhere...

[slowcamaro]

i did see a clear diff cover around somewhere...

...heh...for a 9"?

[Hoot]

found the circle track article...

http://www.circletrack.com/techarticles/ctrp_0709_keeping_youre_rear_gears_cool/index.html

[pdq67]

I gotta wonder if they are lightened too much and may be too thin behind the gear tooth root which may lead to strength issues??

pdq67 (BSME)

[chicane67]

https://static1.pt-content.com/images/pt/2005/09/paranoid-1.gif You guys are too kind...

...Is that why I never talk to you guys on the phone anymore ?? Hell... I cant even afford my own ideas, so I gotta guinea pig some body to weed out the issues.

[Steve1968LS2]

I gotta wonder if they are lightened too much and may be too thin behind the gear tooth root which may lead to strength issues??

pdq67 (BSME)

Shouldn't be.. there's still quite a bit of material left. You should see when they REALLY lighten a ring gear.. lol

What's your thoughts Tom?

[chicane67]

At our power and traction level's... I would'nt be concerned.

Metallurgically the 8620 material, with proper heat treat, has enough modulus of elasticity and if it is not too hard (< Rockwell 60C) its plasticity will yield the same strength no matter if the ring gear is of a full or reduced profile. The more plasticity... the more forgiving the material before a shear polycrystalline lattice failure.

Proper heat treat is the real key to it's overall durability in this example.

The majority of the tooth load is within the second and third quarters of the tooth itself. If the load pattern was further out towards the heel... then yes, there would most certainly be an issue. From there... the load deflection of the tooth doesnt go very deep into the ring gear itself. The ductility of the material when properly heat treated should be more than enough for a ring gear even if it were trimmed the same amount across the entire flange surface.

The reason I say this is that the typical quick change differential ring gear... is even thinner under and across the tooth than what Steve's picture displays without issue.

[4MuscleMachines]

At our power and traction level's... I would'nt be concerned.

Metallurgically the 8620 material, with proper heat treat, has enough modulus of elasticity and if it is not too hard (< Rockwell 60C) its plasticity will yield the same strength no matter if the ring gear is of a full or reduced profile. The more plasticity... the more forgiving the material before a shear polycrystalline lattice failure.

Proper heat treat is the real key to it's overall durability in this example.

The majority of the tooth load is within the second and third quarters of the tooth itself. If the load pattern was further out towards the heel... then yes, there would most certainly be an issue. From there... the load deflection of the tooth doesnt go very deep into the ring gear itself. The ductility of the material when properly heat treated should be more than enough for a ring gear even if it were trimmed the same amount across the entire flange surface.

The reason I say this is that the typical quick change differential ring gear... is even thinner under and across the tooth than what Steve's picture displays without issue.

https://static1.pt-content.com/images/pt/2008/04/10h9655-1.jpg -> :banghead:

[Vegas69]

Them perks:2nd:

[Damn True]

At our power and traction level's... I would'nt be concerned.

Metallurgically the 8620 material, with proper heat treat, has enough modulus of elasticity and if it is not too hard (< Rockwell 60C) its plasticity will yield the same strength no matter if the ring gear is of a full or reduced profile. The more plasticity... the more forgiving the material before a shear polycrystalline lattice failure.

Proper heat treat is the real key to it's overall durability in this example.

The majority of the tooth load is within the second and third quarters of the tooth itself. If the load pattern was further out towards the heel... then yes, there would most certainly be an issue. From there... the load deflection of the tooth doesnt go very deep into the ring gear itself. The ductility of the material when properly heat treated should be more than enough for a ring gear even if it were trimmed the same amount across the entire flange surface.

The reason I say this is that the typical quick change differential ring gear... is even thinner under and across the tooth than what Steve's picture displays without issue.


Ok. Everyone think back to Jr. High.

Remember the kid that barked out in algebra, "Nobody's ever gonna use this......this is stupid!!!!"

Tom wasn't that kid.

....and for those who think "spellin dont mattur" - I ask you this: How credibly would that ring, if it were not spelled and punctuated properly?

[megaladon6]

chicane: :hail: the phrase that got me was "modulus of elasticity"

i can't find it right now, but i know i've seen a 9" housing that actually had a rear cover.

[Steve1968LS2]

chicane: :hail: the phrase that got me was "modulus of elasticity"

i can't find it right now, but i know i've seen a 9" housing that actually had a rear cover.

A 9-inch rear doesn't have a cover. What you saw was a GM 12-bolt with a clear cover. Good for show, bad in a practical way since the cover helps add to the rigidity of the housing and the clear one flexes too much.

Now clear valve covers, that's cool :)

[David Pozzi]

Steve, FYI, we haven't had any problems at all with Mary's 73 Camaro rear axle. we have no cooler or temp gage. I tried to install one, but got out voted, - she didn't want another gage in the dash...

We have seen no signs of the rear axle overheating. One thing though, only Mary drives the car. If we were to do back to back runs with two or more drivers, things would heat up much more, especially with more power and your car will have 125hp more than ours. Plus the 9" will generate more heat than a 10 bolt.

I'd install a gage and monitor the temps, hook up a cooler as needed. Jabsco makes a small electric pump that can be thermally switched.
David

[megaladon6]

no offense but i knew i'd seen a ford nine with a rear cover. http://www.currieenterprises.com/CESTORE/productsRE.aspx?id=1532

[chicane67]

A 9-inch rear doesn't have a cover. What you saw was a GM 12-bolt with a clear cover. Good for show, bad in a practical way since the cover helps add to the rigidity of the housing and the clear one flexes too much.

Now clear valve covers, that's cool :)

Back in the day... some (Smokey Yunick for sure) used to run the banjo with a cover, not only for use as an inspection cover... but to run thru bolts thru the banjo to the third member for a strength increase. Its an interesting idea but not very practicle for most. Not to mention that the newly available housings (the HD and/or the motorsport kit housing) are pretty darn good. They incorporate billet flanges and seamed case half's that allow full seam welds to the tubes.

Clear differential and valve covers have been tried... and clear polymers have been utilized for various covers over the years, but the same problem always rears its ugly head... no matter what the material... it always discolors. I am thinking that is the reason they really didnt make it to the mainstream market.



I have to agree with David... it would be much eaiser to just install a simple temperature sender first, to see if you actually require any additional cooling. If you do... great, it will give you time to plan your attack. If not... its money in the bank.

I dont think that you will have much of a problem with cooling, considering your usage... especially if you stepped up to a better differential fluid. Obviously... my recommendation would be for a straight weight 140, Schaffers #209 (with the suspended moly) or TORCO's RGO 85-140wt.

[Steve1968LS2]

Back in the day... some (Smokey Yunick for sure) used to run the banjo with a cover, not only for use as an inspection cover... but to run thru bolts thru the banjo to the third member for a strength increase. Its an interesting idea but not very practile for most. Not to mention that the newly available housings (the HD and/or the motorsport kit housing) are pretty darn good. They incorporate billet flanges and seamed case half's that allow full seam welds to the tubes.

Clear differential and valve covers have been tried... and clear polymers have been utilized for various covers over the years, but the same problem always rears its ugly head... no matter what the material... it always discolors. I am thinking that is the reason they really didnt make it to the mainstream market.



I have to agree with David... it would be much eaiser to just install a simple temperature sender first, to see if you actually require any additional cooling. If you do... great, it will give you time to plan your attack. If not... its money in the bank.

I dont think that you will have much of a problem with cooling, considering your usage... especially if you stepped up to a better differential fluid. Obviously... my recommendation would be for a straight weight 140, Schaffers #209 (with the suspended moly) or TORCO's RGO 85-140wt.

I didn't know they made 9s with a cover like that. hmm.. live and learn.

I have a case of the Torco stuff here for the rear and I just switched Penny to thier 10-30 syn oil. They make killer oils.

So, what is an OK temp for the rear to run at? I also have an oil temp gauge and what is a "too hot" temp for it? After driving my oil is around 200 degrees.

[eville]

With the torko, which additive should I use with a true trac differential?

[CarlC]

Heh, heh heh. He said shear polycrystalline lattice failure.

I am a geek.

[chicane67]

With the torko, which additive should I use with a true trac differential?

Nadda. Zip. Zero. Ziltch... its not required with a True Trac.

[David Pozzi]

For engine oil, I think 220 is pretty normal, below 200 you are probably losing power. I've run the Lola engine a lot at 240 before going dry sump. If it's getting to 250 or a little more, I'd change it after running the event. Synthetics can take more I guess but I'd say it's risky territory. I've had eng oil temps at 275 - 300F when I had water cooling problems, it survived, but I wouldn't recommend running anywhere near that hot. It freaked me out and I just couldn't put my foot down with readings that hot. I read that engine oil life can be counted in MINUTES around 275 degrees and higher. When I had high coolant temps, the oil was crazy hot too, even with oil coolers. When I got the coolant temps down, the oil temps came down too, went to dry sump and now it's almost too cool on both water and oil!

I don't have a good number for rear axle temps, but I'd like to see below 250 there too.

The difference a dry sump makes in water and oil temps has to be seen to be believed! :bananna2:

I'd like to hear from Tom or anyone else about rear axle temps.

[chicane67]

Oils and lubricants... another subject of great debate.

As I understand it, the base oil product have additives introduced that make up the composed lubricant. Those additives have certain properties that change within a range of specific conditions. The predominant condition is that of temperature. When the additive reaches it's "working" temperature it does its job for the reasons it was added to the composition.

Most lubricants being used in the engine, a manual transmission and/or transfer case or that in a differential all share the same primary functions. (Notice that steering and automatic transmissions are not included in this, as they run a 'fluid' that is more hydraulic in nature than that of an actual lubricant.) Out of those primary functions, the first is to provide a protective film between to working surfaces. The second, and most important in my opinion, is to extract the heat created by those working surfaces. The additives are to improve upon anti-corrosion, anti-oxidization and anti-wear of the base oil product, because there is no oil or lubricant that is perfect for any specific application, this side of something synthesized by man. They are also added for other specific properties like that of a detergent, a friction modifier, anti-foaming... etc, etc... and even to modify the lubricants pour point.

Well... now back to the basis of this reply... about temperature. Operating temperature is thought of as being between two points. When you are below the low side of that scale... the oil and additives might not do their job as intended because of their specific properties. When you are above the high side of that scale... the oil and additives start to brake down because they are outside of their working properties or conditions. Most observed base oil products and their respective additives are designed to work their magic from around 215-220, all the way to their point of initial brake down. The point of brake down is determined by the base product and any additional additives. I would say crude and parrifin based lubricants have operational safe limits near 260*F and some of the newer technology synthetics are nearing the 285-300*F mark... which is quite impressive... before they start showing brake down. So... I believe the idea would be to keep the oil at or above 215*F and below 260*F. Optimally I like to keep it between 220*F and 240*F. I was impressioned long ago by a few engine builders I had the pleasure of hanging out with, that it is considered to be perfect when you can maintain engine oil temperature at 20*F above of the engine coolant temperature. Since you get your best engine volumetric efficiency between 195 to 205*F... that would put the engine oil right in at 215 to 225*F.

Alright... enough of my rambling.

Differentials, in my opinion, follow the same principals. Somewhere between 200 to 240*F. The reason that I lowered the intial temperature is that the differential doesnt have any help from any other liquid cooling like that of the engine... but keeping it around 220*F would be ideal.

[CarlC]

I'll add a few other things to Tom's treatise to consider as well.

As Tom mentions manufacturers provide additive packages to suit a general application. EP (Extreme Pressure) additive packages, usually something along the lines of a molybdenum disulfide, have an affinity for water. It is important that these types of lubricants get hot enough to vaporize the water from condensation out so that the lubricant is not contaminated. Water and oil don't mix.

Though many may say "look at that industrial gearbox temperature" that never gets over 120*F. Yeah, but there's no practical way to work in an industrial environment with gearboxes/general lubricant systems that are 215+ degrees. Imagine trying to work near one of those on an August day....

Vizard has in one of his books that he would like to see the oil very hot, and the coolant very cool. Hot oil to let the oil do it's job and to reduce heat-related friction, and cool water to keep the intake charge cool. From a practical standpoint, and from a wear perspective, most engines are very happy with a 180* coolant and a 210-220* oil temperature.

The temperature rules do not apply to greases, even though they are 90% oil. After about 150*F, for every 10* increase in grease temperature the life of the grease will decrease by 1/2. In other words, if it lasts for two years at 150*, it will only last about one month at 200*F if you are lucky.

[Steve1968LS2]

I seem to run, around town and on the highway at 190 coolant and 200ish on the oil.

I need to see what those numbers do when I pound on it. I just switched from Mobil 1 (they screwed it up some more) to Torco.

[chicane67]

They screwed it up ?? Do tell...

[matty b]

https://static1.pt-content.com/images/noimg.gif
currie track 9 housing, may actually be able to trick some one into thinking its a 10 bolt lol

[Steve1968LS2]

They screwed it up ?? Do tell...

Rumor has it that to please the govt they pulled even more additives out of oil (ie, Mobil 1). This effected all oils that are on the market.

The exception are oils labeled as "racing" oils. They are allowed to keep thier "earth killing" additives at an effective level since theoretically they aren't oils for mass consumption.

I get it all for free so I figured why chance it so I grabbed a case of 10-30 Torco for Penny and used the Mobil 1 for my truck.

It's supposedly not a huge deal for a roller motor, but still... why risk it.

Again, just what I heard. I haven't had time to research it.

[sharp67]

Who did you use to do the polish and lightening on the ring and pinion?

[Steve1968LS2]

Who did you use to do the polish and lightening on the ring and pinion?

Currie farmed it out... I doubt they would want to give up thier source, but I will ask on Monday when we install the unit in Penny.