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5eat center diffrential bulletproofing how to


frank_ster

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I thought this could be done for 100? Do we need 4 of them?

 

You need all 4, there are four planet gears, so four bushings. One set = four bushings.

 

to clarify, it is $200 for one set of bushings. you got the $200 quote for purchasing 4 sets (so 4 people), correct? More people (sets), cheaper price?

 

$200 is for a set delivered to your door. If you want to take time off of work and pick them up at his shop and pay him cash for your set (assuming he would take that risk of being a collection agent), it would be a little less for a set, then divide by 4 for your per/bearing price.

 

If I were to need this installed by a shop, what am I looking at for labor costs? And if I'm the type of person who needs this installed by a shop, do you think I even need a set? I'm guessing the whole center diff needs to be taken apart and then reassembled...

 

Call a shop or Paul and ask what the time/labor cost would be for replacing a center diff, plus 30 minutes for center diff disassembly (requires a snap ring plyers, every shop has them), swapping out the bushings in the 4 gears, and re-assembly. For anyone who knows how to work on cars at a professional level, it shouldn't be any trouble.

 

Now that you mention it, I need to add a center diff housing metal gasket to the item list. One new gasket per center diff install. They can be ordered from FBP.

 

Do you need these? Well, people break their center diffs most commonly by launching the car aggressively. Frank_ster has not blown up his center diff since he did this mod himself. If you are going to launch your car, and you want to make the center diff more resistant to breaking, then this mod is a good idea. If you break your center diff, you're out a LOT more than $200.

[CENTER][B][I] Front Limited Slip Racing Differentials for the 5EAT now available for $1895 shipped, please inquire for details! [/I][/B][/CENTER]
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thanks. i wasn't looking for a per-bearing price, just trying to get the point across that $200 was for a full set per person, and if we got enough people it could potentially be cheaper.

 

guess i'll have to give paul a call. wasn't sure if you knew a ballpark figure. just trying to price the overall cost of this, is all.

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thanks. i wasn't looking for a per-bearing price, just trying to get the point across that $200 was for a full set per person, and if we got enough people it could potentially be cheaper.

 

guess i'll have to give paul a call. wasn't sure if you knew a ballpark figure. just trying to price the overall cost of this, is all.

 

Maybe 3 hours of labor if on a lift, but I don't know what the "book" says. Could be a lot more in the "book".

[CENTER][B][I] Front Limited Slip Racing Differentials for the 5EAT now available for $1895 shipped, please inquire for details! [/I][/B][/CENTER]
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im not an enginer, but for 50 years aircraft wrist pin bearings(brass bushings) and rocker arm bearings (brass bushings) have been reamed as per the TCM FSM and they LYC FSM, (FSM= factory service manual), now im not saying micro poslishing isnt better just that reaming is a tried and true method.

 

Frankster is right.

 

Also, a ten-thousandths interference doesn't require cooling and heating to press. A ten-thousandths will probably slide together by hand. If you want to do a proper shrink fit, you need an interference of several thousandths. For a gear-drive system I did a few years ago, I did a 0.007 interference fit that required heating of the gear and cooling of the shaft (accomplished by spraying the shaft with an air-duster turned upside down). Even then, a high level of precision is required when pressing. It's not just something you can throw together by hand.

 

For this application, a shrink-fit isn't necessary. A simple press-fit would be sufficient and would decrease unnecessary stress in the bushing.

 

As for "reaming" the bushing out, that's not typically good practice for a bearing surface. You want a micro-polished and true surface. Ideally, you'd order precision ID stock, turn the OD on a high-speed lathe, then polish the OD and press fit the bushing. Finish it off by trimming the excess and finishing the ends on a lathe.

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I'm just talking about good practice. I haven't really been following the thread much more than a casual glance. If relative rotation is low, then it'll probably be fine. But polishing doesn't take very much time with something as soft as brass. Typically, reaming of soft-metal bushings is to get a "rough fit" and then the bushing will wear-fit and deposit a bunch of shavings into the fluid. I figured it'd be best to avoid this if possible.
[URL="http://legacygt.com/forums/showthread.php/proper-flip-key-interesti-159894.html"]Flip Key Development Thread[/URL] "Genius may have its limitations, but stupidity is not thus handicapped." - E. Hubbard
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a polished surface is not desirable on some thing with a splash lubrication system , the rough surface is to keep oil trapped in. and to have some what of little ramps for the oil to roll up and lift the surface up. so there is actually no metal on metal. polished surface is intended for full pressure lubrication ie crank shaft.

Now that's thinking out of the boxer!:lol:

fyi all 05 + legacy's have built in code reader

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There should be directionality to any kind of ridge or surface condition, though. You can't just have a chopped up surface.

 

My transmission reference is first gear on the 5MT. It uses a polished surface on first gear, and a polished, but directionally cut mating surface on the output shaft..

 

You can't just have a randomly scored surface.

 

I don't know what kind of surface finish you get with reaming, but I'd think polishing to somewhere in the 10 micron range would be sufficient, and easy. It's nothing more than a cloth-wrapped dowel with some micron-range polishing compound spun at some reasonably moderate speed. Less than a minute of work, and you'll have taken down any big scores. 10 microns is about the diameter of an average hair.

 

But then again, my knowledge of the 5EAT is... none really.

[URL="http://legacygt.com/forums/showthread.php/proper-flip-key-interesti-159894.html"]Flip Key Development Thread[/URL] "Genius may have its limitations, but stupidity is not thus handicapped." - E. Hubbard
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well the lay or direction or roughness does make a difference. but i don't think its going to matter in this application.

Now that's thinking out of the boxer!:lol:

fyi all 05 + legacy's have built in code reader

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Probably not. I was just pointing out. I definitely wouldn't "ream to fit" though. But I also don't have a 5EAT.
[URL="http://legacygt.com/forums/showthread.php/proper-flip-key-interesti-159894.html"]Flip Key Development Thread[/URL] "Genius may have its limitations, but stupidity is not thus handicapped." - E. Hubbard
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  • 7 months later...
well bronze is pretty damm ling life .. and snce they are running in oil .. and the fact that the gears are not actualy turning 99 % of the time its will last forever..

those gears only turn when your turning with the car..

and or if you tow the car .. witch your not suposto do anyways

 

Excuse my ignorance as I know very little about transmissions.

If these gears only turn when the car is turning, why do the bearings break when launching?

 

Also, why would Subaru go with a bearing when a bushing is much cheaper and stronger? Shouldn't we be worried about more friction with using a bearing?

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Excuse my ignorance as I know very little about transmissions.

If these gears only turn when the car is turning, why do the bearings break when launching?

 

Also, why would Subaru go with a bearing when a bushing is much cheaper and stronger? Shouldn't we be worried about more friction with using a bearing?

 

doublepost

 

The Subaru center diff bearings are great for stock power. Increased friction appears to not be a problem, though high mileage will be required to know for sure.

[CENTER][B][I] Front Limited Slip Racing Differentials for the 5EAT now available for $1895 shipped, please inquire for details! [/I][/B][/CENTER]
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  • 2 months later...
  • 1 year later...

so to bring life back to this thread.

 

My center diff broke Friday :mad:

 

the bushings were installed in september 2009 so its been approximately 3.5 years and 70 000 km of hard beatings frequent awd burn outs and the last 2.5 years behind the 3.8 buick v6 turbo engine.

 

this time other than the last two times i have had the brass bushings installed witch i attribute to the life span lasting more than a week.

 

the bushings prevented the pins for the planet gears from breaking as i expected. however the teeth on the intermediate shaft still bit the dust with fatigue. and damaged the planet gears slightly.

 

we were worried about wear on the bushings and i can easily say there is none. I can still seam the reamer marks on the inside of them.

 

i'll post some pictures tonight.

Now that's thinking out of the boxer!:lol:

fyi all 05 + legacy's have built in code reader

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  • 4 weeks later...
Thanks for the update on this. I have your bushings in my garage but still waiting to get some free time to make the upgrade, but I've been wondering how they will last in the long run. This puts my mind more at ease. Now I gotta just get to it.
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^ yea the bushings life is the life of your car. but there is a maximum torque that the gears can deal with.

Now that's thinking out of the boxer!:lol:

fyi all 05 + legacy's have built in code reader

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^ yea the bushings life is the life of your car. but there is a maximum torque that the gears can deal with.

 

Hey frank

 

Putting my bushings in next week with my acme pinnacle kit

 

Great to see them holding up ! :)

 

Question for you - once the centre diff breaks like that, is the rest of the transmission generally cactus or can you replace the centre diff planetaries in isolation?

 

Reason I ask is if I have the same problem in future, I'm hopeful of still retaining the rest of my built up 5eat. I'm assuming as long as no metal paricles find their way to the remainder of the servo pump assembly and front half then it should be ok???

 

When my centre diff broke on my old box (car was completely stock at the time), we ended up replacing the whole box (due to my ignorance at the time of 5eat's and the lack of knowledge on these boxes here in Australia, which thankfully I am having an influence on changing now).

 

 

Mick

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Hey frank

 

Putting my bushings in next week with my acme pinnacle kit

 

Great to see them holding up ! :)

 

Question for you - once the centre diff breaks like that, is the rest of the transmission generally cactus or can you replace the centre diff planetaries in isolation?

 

Reason I ask is if I have the same problem in future, I'm hopeful of still retaining the rest of my built up 5eat. I'm assuming as long as no metal paricles find their way to the remainder of the servo pump assembly and front half then it should be ok???

 

When my centre diff broke on my old box (car was completely stock at the time), we ended up replacing the whole box (due to my ignorance at the time of 5eat's and the lack of knowledge on these boxes here in Australia, which thankfully I am having an influence on changing now).

 

 

Mick

 

well i'm on my 3rd center diff of this tranny.

the only thing that got me the first time was a peice of metal some how flung up and took out the front output speed sensor inside the tranny.

so if your center diff breaks trailer the car and take it apart dont drive it other wise it may damage some other components.

 

but just changing the intermediate shaft and the planets and possibly the pins is what is necessary. the intermediate shaft from subaru is about 700$ cad and each planet is about 80$

Now that's thinking out of the boxer!:lol:

fyi all 05 + legacy's have built in code reader

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