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Stock gear question

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Old Jan 30, 2010 | 10:36 AM
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Default Stock gear question

I'm just wondering about stock gears
I recently contacted rockland gears for a quote on a transmission rebuild and was told the following:

"WE BUILD A PERFECT TRANSMISSION RATED AT 750FTLBS. WE TAKE YOUR TRANSMISSION AND REPLACE ALL YOUR GEAR TRAIN WITH CORVETTE GEARS AND SYNCHRO'S ALL NEW. THE VETTE GEAR TRAIN USES TRIPLE AND DOUBLE CONE SYNCHRO'S 100% BETTER SHIFTS AT HIGH RPM'S. WE OFFER TWO MAIN SHAFTS 27spl. OR 32spl. (750FTLBS RATING)
2) RATIO'S TO CHOOSE FROM
2.97 2.07 1.43 1.00 .84 .56 OR 2.66 1.78 1.30 1.00 .74 .50
YOUR COST IS 2595.00 27spl. 2795.00 32spl."

I see they want to completely change the gears to corvette spec ones. I'm wondering at approximately what power do our stock gears tend to fail at? I see that tick-performance level 3 viper rebuild says its good for 600+ ft/lb without changing gears, but when would the gears actually fail in this rebuild?

So basically, when do the stock gears themselves become the weak point in an f-body t-56?


(I won't be seeing these power levels any time soon, so I'm just doing it for inquisitive sake)
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Old Jan 30, 2010 | 10:56 AM
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Nothing magic about this conversion, I've done about a dozen of them. You end up with either a GTO clone with MN12 ratios or MM6 ratios if they use a standard C5 MM6 gearset. The upgraded synchros are nice for smoother/firmer shifting. The 32-spline upgrade is the same gear sets on the SSR mainshaft.. I'm working on one of those right now.

http://www.eecis.udel.edu/~davis/z28...SSR-mainshaft/

I'm using an LS7/Z06 MM6 donor for mine since it has the stronger 1pc countershaft also. There are a few engineering issues to keep it from being a direct DIY swap, but nothing impossible.

So the stock gears in all the units are good for 750lb-ft+, but the mainshafts start to be a limiting factor, as do the common synchro parts (fork pads, keys, 3/4 fork) which all get upgraded in these packages also.
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Old Jan 30, 2010 | 11:00 AM
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Originally Posted by 85MikeTPI
Nothing magic about this conversion, I've done about a dozen of them. You end up with either a GTO clone with MN12 ratios or MM6 ratios if they use a standard C5 MM6 gearset. The upgraded synchros are nice for smoother/firmer shifting. The 32-spline upgrade is the same gear sets on the SSR mainshaft.. I'm working on one of those right now.

http://www.eecis.udel.edu/~davis/z28...SSR-mainshaft/

I'm using an LS7/Z06 MM6 donor for mine since it has the stronger 1pc countershaft also. There are a few engineering issues to keep it from being a direct DIY swap, but nothing impossible.

So the stock gears in all the units are good for 750lb-ft+, but the mainshafts start to be a limiting factor, as do the common synchro parts (fork pads, keys, 3/4 fork) which all get upgraded in these packages also.

Thanks! Although, I heard they use their own custom made billet gears.

So, the stock fbody gears are still good for 750?
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Old Jan 30, 2010 | 11:03 AM
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Their custom gears are in the Tranzilla, and it will cost close to $8,000(?) for one of them.. Notice that the gear ratios are the same as the MN12 and MM6 ratios, and they mention using Corvette gears..

If you can source a C5 core, a GTO mainshaft, and any/all upgrade/repair parts for the C5 core, you can build one yourself.
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Old Jan 30, 2010 | 11:06 AM
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Originally Posted by 85MikeTPI
Their custom gears are in the Tranzilla, and it will cost close to $8,000(?) for one of them.. Notice that the gear ratios are the same as the MN12 and MM6 ratios, and they mention using Corvette gears..

If you can source a C5 core, a GTO mainshaft, and any/all upgrade/repair parts for the C5 core, you can build one yourself.
Ahhhh, okay, thanks! I probably won't reach that power level anytime soon(if ever), and was just wondering when I would have to fear my stock gears failing. Thanks for the information though!
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