5th gear slippage - Chevy and GMC Duramax Diesel Forum
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Old 06-18-2011, 03:06 PM   eBay Motors  #1 (permalink)
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5th gear slippage

I was searching the classifieds on another site and came across a guy selling an ATS Co-Pilot. I'm curious as if to what he says in his ad is right?:

The ATS Co-Pilot Upgrade Kit for the Allison 1000 Transmission solves the major problems with the stock Allison LCT-1000. When you increase the power of the Duramax, the stock Allison 1000 transmission begins to slip in 5th gear. The factory single-disc torque converter lockup clutch begins to slip. This slippage causes the Allison 1000 to go into "fail safe" mode preventing you from getting your Duramax power to the ground.

The stock Allison transmission only receives approximately 86 PSI oil pressure to the clutch packs when in 5th gear. After the addition of the Co-Pilot transmission system, the clutch packs receive approximately 230 PSI, allowing the transmissions clutch packs to receive full line pressure (clamping force needed to apply the clutches) during high power situations. With the simple addition of our Co-Pilot transmission kit pushing the available line pressure to the clutch packs, we have designed a system that increases the torque capacity of the Allison transmission by over 200 foot pounds. This kit makes it possible to transfer 100% of the power developed by a modified engine to the rear wheels without causing the transmission to slip and the "fail safe" condition to occur.


If this is true is there a less expensive route to get more pressure to clutch packs while in 5th gear? My truck often limps out in 5th especially when towing.
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Old 06-18-2011, 03:16 PM   eBay Motors  #2 (permalink)
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Gotta build it.... not sure how the co-pilot works.... pressure is produced mechanically and applied by valves which that only have an on off setting.... there are no stepper motors in the tranny to control the pressure via computer.... only on off pressure which would be max pressure produced by pump unless it has a regulator before it. Hopefully mike l reads this.... but no building the trans is the only way to stop the 5th gear slip
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Old 06-18-2011, 03:23 PM   eBay Motors  #3 (permalink)
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With the 5 speeds you gotta build it. The 6 speeds can take advantage of shift kits, but the labor involved in installing one in a 5 speed is not worth the cost. Better start saving some $ if you've limped it!
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Old 06-18-2011, 08:41 PM   eBay Motors  #4 (permalink)
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Ahhh, Ohio and Bucks County...thanks for weighing in. Wilmington, DE roots here. Thanks for your takes on the situation, my Allison acts so weird I have to think it's something besides a full on build but who knows. Sometimes it will run 10 hrs at 95 mph (no tow) and not code, other times it will limp more frequently but only when I don't keep my foot into it (drive aggressively). If I tow anything over 5T it limps in 5th constantly but at strange times..like not when I'm on on the throttle or going uphill etc more when I'm backing off the throttle it will code. Seems like it will limp on a whim but more frequently under tow. Also on hitting sharp bump at low speed (-10mph) trans will go a neutral for a second then engage after a momentary pause of acceleration or increase in rpm (results in slight slam engagement).
Wish I had the $$ to throw a complete ML TC and kit at it right now but I'll have to wait........
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Old 06-19-2011, 01:50 PM   eBay Motors  #5 (permalink)
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Hmm, yeah that's wierd. How much power over stock are you running? It might just be so toasted that it's having a hard time holding even under normal conditions. 5 tons should be no big deal...I would start putting some money into savings because if it's limping that much, one day it's just going to leave you stranded somewhere.
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Old 06-19-2011, 05:37 PM   eBay Motors  #6 (permalink)
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If 5th gear is slipping it will throw a P0735 code in a blink of an eye. If it hasn't thrown this code, you have other problems.
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