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Duramax Diesel Performance Shop What's it take to make big power? From a little to a lot, find out what it takes. Post a question or offer your advice.

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  #11  
Old 08-08-2012, 06:51 AM
Kennedy Kennedy is offline
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What fluid are you running in the trans?

My only experience with the company that you mention is getting fallout from issues when people realize that they should have done it right the first time.
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2002 Chev K2500HD D/A CC Long LT 11.77@ 124mph at 7700# fuel only-e.t. needs help
2005 Chev K3500SRW D/A CC Long LT(SOLD)
2007 Chev K2500 Classic EC Short LT (Sold)
2012 GMC K3500SRW D/A CC Long LTZ Happy Birthday to me! Built 1 working day after my birthday and delivered 7 days later.
2016 GMC K3500SRW D/A CC short LTZ

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  #12  
Old 08-08-2012, 09:49 AM
Aepozzi Aepozzi is offline
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Whatever is at the GM dealership; I'm not sure what they use.

Andy
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  #13  
Old 08-13-2012, 09:07 AM
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More Power More Power is offline
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Quote:
Originally Posted by Aepozzi View Post
Hello Everyone,

I am new to this site. I just joined today. I have a 2003 GMC 1 ton.
I'm curious about the history of this 9 year old truck. Have you owned it since new? How has it been used since new? Does it have a history of performance mods? History of trans replacement? How fast do you tow?

Jim
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  #14  
Old 08-13-2012, 10:03 AM
SoTxPollock SoTxPollock is offline
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Aepozzi, you might get better results if you list what truck you have and what is on it, especially any add on's. These guys have given you some good advice, but I'm thinking it's base on a lot of assumptions of things we don't know about your truck. I tow a 36' 5er that weighs in a little lighter than yours with Kennedy's boost valve and edge set on 2, I think that's something like 60 addidtional hp and 140 additional ft. lbs of torque. The only anomoly I experieced so far is if it's on cruse control and pulling a really steep grade if it ever downshifts it will overslip the clutches in the trans. trying to lock them up after the shift. I've learned to just tap the brake real quick and nail the accelerator at the same time to keep the power on and then just back off until I can feel it lock up then put the power on and it will hold it after that.
I really should not have been in cruse in the first place, just got lazy and relaxed and forgot about how hard the truck was working once. After that happened I checked my gauge memory and it had hit 27 lbs of boost and exh. temp of 1457 F.
You really need to monitor those things closely if your truck is a diesel.
I think JK is on the right track about trans slippage. I'd watch that real close, it probably wouldn't take too long to glaze over the clutches and then it won't want to lock up and the problem will just escelate to more of a problem. What kind of trans temp's are you seeing?
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  #15  
Old 08-13-2012, 10:12 PM
Aepozzi Aepozzi is offline
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The truck is a 2003 GMC dually. It is bone stock right down to the wheels. Tires are 245/75R 16.

I purchased the truck used with 60k miles on it. It ran well and pulled the trailer well.

I had the injectors replaced about 3 years ago. That cost a pretty penny, after I found it should have been covered under warrenty.

When I got the truck back from the dealer, who is now long gone, the truck never had the power it had prior to the injector replacement. The tech/mechanic went for several rides with me with the GM scanner. According to him the truckwas fine.

I was told the truck was "flashed" after the injectors. I do not know for sure. The dealer went out of business before I could ask.

Last year I went on vacation and was pulling about a 4-5% grade. I was down to 40 mph. That was enough.

While on vacation I spoke with anyone who would talk to me about diesels.

Most that pulled large trailers had some sort of chip in their truck. Some had switchable on the dash others just flashed the existing computer.

I went with the re=flash the computer route. I went with Power up Diesel. I installed the 80 hp and everything worked fine. Until my last trip.

I just spoke with a GM diesel gearhead. He told me the 2003 GM Allision transmissions were light in the torque converter, and if the converter had any slippage it would trip off the 0735 code, and go into "limp" mode.

That makes sense.

He suggested installing a new H.D. converter, and future problems would be gone.

He also suggested that I downshift sooner and not let the trans downshift on its own.

I always tow in the "tow" mode. On level ground I do tow in O.D. with the RPM's at around 2,000 at 60 mph.

When I hit a hill and the truck starts to load I will take it out of OD by pushing the button.

I appreciate the help and advise.

Andy
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  #16  
Old 08-16-2012, 03:07 PM
Kennedy Kennedy is offline
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P0735 is a slip in the 5th gear clutches and not the converter. I don't buy the 2003's being light in the converter. We had a customer that beat the hell out of one truck pulling with the stock trans for quite some time.

A properly written tune wil not limp the trans, BUT I have had cases where synthetic (super fluids) tend to decrease holding capacity. Must be friction modifiers.
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Kennedy Diesel-owner
More than just a salesman-I use and test the products that I sell on a daily basis!
Superflow Lie Detector in house
2002 Chev K2500HD D/A CC Long LT 11.77@ 124mph at 7700# fuel only-e.t. needs help
2005 Chev K3500SRW D/A CC Long LT(SOLD)
2007 Chev K2500 Classic EC Short LT (Sold)
2012 GMC K3500SRW D/A CC Long LTZ Happy Birthday to me! Built 1 working day after my birthday and delivered 7 days later.
2016 GMC K3500SRW D/A CC short LTZ

Custom tuning in house using EFI Live tuning software!
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  #17  
Old 08-16-2012, 10:08 PM
Aepozzi Aepozzi is offline
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Not sure I understand. Are you saying the trans fluid needs modifiers, and if so what type?

I know very little about automatic transmissions. For that matter I know little about diesels.


Thanks,
Andy
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  #18  
Old 08-17-2012, 06:40 AM
Kennedy Kennedy is offline
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Allison Transynd (not knockoffs either) is my recommended fluid. That or good old Dex III. Back when we were stretching the limits of the stock trans and before the good mods were out I had experience with customers who changed their fluid to wiz-bang synthetics. Immediate transmission limp at the same power levels. Switch back to Dex III or Transynd and worked fine again.
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Kennedy Diesel-owner
More than just a salesman-I use and test the products that I sell on a daily basis!
Superflow Lie Detector in house
2002 Chev K2500HD D/A CC Long LT 11.77@ 124mph at 7700# fuel only-e.t. needs help
2005 Chev K3500SRW D/A CC Long LT(SOLD)
2007 Chev K2500 Classic EC Short LT (Sold)
2012 GMC K3500SRW D/A CC Long LTZ Happy Birthday to me! Built 1 working day after my birthday and delivered 7 days later.
2016 GMC K3500SRW D/A CC short LTZ

Custom tuning in house using EFI Live tuning software!
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  #19  
Old 08-19-2012, 07:45 AM
Aepozzi Aepozzi is offline
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I will go back to the dealer and ask what they are using.

The dealer (Chevy) onlyflushed the system. Acording to my bill they did not replace any of the filters, which I thought was strange. I doubt the 2 filters would cost that much.

I asked for the trans fluid to be flushed and that's what I got.

Some say do not flush the fluid, just replace it without flushing. I don't know what is right. Mayby someone can shed some light on this.

Thank you,
Andy
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  #20  
Old 08-19-2012, 08:17 AM
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DmaxMaverick DmaxMaverick is offline
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They should have replaced the external spin-on filter with any type of service. The internal filter is recommended for replacement only at overhaul, not during a routine service, absent a specific reason.

The Allison tranny is somewhat unique, when it comes to the "flush". Allison states a power flush machine will damage the tranny. However, a passive "machine" can be used, or the home/driveway method (repeated on this forum numerous times) can be used. Ask the dealer which method was used. If you get the deer-in-the-headlights-look from them, they either didn't do a flush, or did it wrong. I recommend a flush (home/driveway method) if you are changing fluid types (dino to synthetic, for example), or the old fluid is burned or worn out. Only a drain/fill/filter is necessary for a routine service.
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