Manual Transmission T56 | T5 | MN12 | Clutches | Hydraulics | Shifters

Weird problem!

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Old 05-11-2014, 04:16 PM
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Default Weird problem!

I am in the process of fixing the 5/6 gear whine in my t56. I'm looking at the old gear and the new one, and am seeing some differences.

Whiney gear: inside is grooved from top to bottom except for one small spot in the middle. Slides onto shaft with almost no force.

New gear: Grooved for the first 2 inches, then its smooth for the rest of the way. Can't even get it to go on the shaft without a LOT of force.

Also, the shaft is fully grooved much like the old gear.

What's going on here?
Old 05-11-2014, 06:41 PM
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Looks like it may have a cts-v or similar mainshaft. So Should I just find a different 5/6 driven gear?
Old 05-12-2014, 02:28 AM
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The gear should take a press to get on. There should be a flat surface on both the shaft and gear. (LS1 T-56)

From the factory the original shaft was too narrow by a couple thousandths. This caused the 5/6 driven t become loose and destroy the main shaft in the process. This was in the LS1 f-bodies.

Are the splines on the shaft and old gear in good shape? As a loose 5/6 driven gear will usually eat into the splines. Mine had almost 80% of the spline missing. Again an LS1 -T56.
Old 05-12-2014, 08:30 AM
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That's the thing, the shaft is completely splined in that area. I will post pictures tonight.
Old 05-12-2014, 11:51 AM
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Someone did a mainshaft swap; GM didn't use a full-spline mainshaft there in the T56, nor separate 5th / 6th driven gears.
Old 05-13-2014, 05:12 PM
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Originally Posted by jmd
Someone did a mainshaft swap; GM didn't use a full-spline mainshaft there in the T56, nor separate 5th / 6th driven gears.
What do I do? What gears do I use?
Old 05-16-2014, 12:33 PM
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Need some help guys
Old 05-16-2014, 02:34 PM
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Where's the pics? Thats the best way to start here. Aston Martin T56s has full spline under the OD driven gears....you could have one of those.
Old 05-20-2014, 10:02 PM
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Some pictures finally!


Link if image doesn't work: http://imgur.com/a/kqnKW
Old 05-21-2014, 11:42 AM
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Don't know what you have. A spool OD gear with a full spline did not come in any TREMEC T56. I would suspect off-shore parts. That shaft is in the same boat....maybe they came on the same boat..JK
Old 05-21-2014, 01:32 PM
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Aren't there separated 5/6th gears though?
Old 05-21-2014, 01:50 PM
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I was thinking that it was probably a cobra shaft though, since they have 2 separate, fully splined gears.
Old 05-22-2014, 08:33 AM
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From what I have seen, the cobras used a combined 5/6 driven gear just like the GM T-56's. Just a different less OD ratio.
Old 05-22-2014, 03:29 PM
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Call Tremec. They'll be able to tell you it's on back order / they just doubled the price and then tell you which Magnum you should buy.



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