Planetary when to upgrade

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montser633

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Nov 30, 2012
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Looking at different planetarys how durable are the 47rh/re front and rear planetarys. At what point do they fail? Looking like 5 pinion steel front and 6 pinion rear aluminum. So basically when to replace as needed. Also I have read you can add a bearing in the rear planetary anyone have info on the mod?
 
Here is the simple answer.

If in doubt, change it out!!!

Few ever have issues with the rear one as I understand it. Most are doing boost launches.

Steel is stronger than aluminum.

I did go 6 pinion rear--aluminum in mine for comfort.
 
Didn't they switch to the aluminum in the 48re's? And as I understand it, most take the steel's because they have slightly less issues with big power. I don't think that either of them fail very often though.
 
If you have a steel front then your fine. I personally haven't seen an issue with any of the aluminum rear planets in transmissions ive pulled apart, but most are under 700hp to.
 
Broke when shifting into 2nd with the converter locked, 12 valve truck running a 75/96/1.32 t6 single charger and alot of nitrous... just went back with all 48 internals
 
Aluminum, it was a stock 47rh piece. That thing held up to many many passes in the 800-900 hp range
 
mathews8pt said:
I have seen one strip at 550hp. That would be a good upgrade for 500hp and over trucks for sure.
Click to expand...

They swapped to steel for the 47re's right? Then wasn't there another update to the design for the 48's? I thought they went back to aluminum?
 
5 pinion steel in the 47re's and 6 pinion steel in the 48s for the front planets. All 47s had an aluminum rear and they went to steel in the 48s I believe.
 
I just bought a 5 pinion steel planetary and it didn't come with anything but the planetary is there a special thrust plate or specialty plate need?
 
Thanks, I can just reuse oem what I have now or best off replacing? Are these truly a wear item? Service life?
 
the aluminum front RH planets have always been known to only hold around 500, I have multiple just like toby posted. Ive seen an aluminum rear pounded to **** but not actually broken. I ran 48RE front/rear with a stock straight cut steel RH OD planet and that held 1980Ftlbs of tq. for a ~500hp truck focus on the front.
 
Well my planetary just showed up with the thrust washer and plastic ring as a bonus! All set thanks for everyone help! Trans is almost out of the truck and will start a trans tread.
 
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