I am checking out a truck this weekend Im considering buying. It's a 2001 with the 8.1 and Allison combo with 47k miles. I know absolutely nada about the Allison and I was wondering what I need to look or listen for, both externally and during the drive test. Can you remove the spin on filter without draining the tranny oil? I would like to check the magnet for metal particles while Im there. Any suggestions would help tremendously.

You can pull the filter and loose very little fluid. Cutting open the filter and/or inspecting the magnet is a good idea, but keep in mind he may have just changed the filter and cleaned the magnet.


Check the color and smell of the fluid also.


Check for front and rear seal leaks. There is an inspection cover in the bellhousing. Edited by: Amric

Would you all suggest one of the aftermarket shift kits? I dont race or powerbrake or otherwise play with my trucks. I plan on using this truck to tow a 22 ft. boat to the coast and back about 15 to 20 times per year and thought the 8.1 and the Allison would be ideal(in my price rangehttp://www.dieselplace.com/forum/smileys/HiHi.gif)

I believe you will be just fine with a stock Allison for an 8.1, that is, unless you plan or supercharging it or something like that. http://www.dieselplace.com/forum/smileys/HiHi.gif

No, nothing like that. Im gonna keep it stock and was just wondering if it would benefit the tranny to have a kit or would it be ok stock. One thing I do want to do is put some larger tires on it. Not anything fender rubbing, just something to help fill up the wheel well. The 245's just look too damn small http://www.dieselplace.com/forum/smileys/Wink.gif

I say put a Transgo shift kit and converter in it.


mike

I believe you will be just fine with a stock Allison for an 8.1, that is, unless you plan or supercharging it or something like that. http://www.dieselplace.com/forum/smileys/HiHi.gif





That is a very valid point. To hop up a 8.1 to beat up on the Allison is a bit more extensive as a Duramax. Not that it can't be done but definitely a bit harder and not as concealing.


I do know a 8.1 that can limp a Alley but it does have a Super Charger bolted on it.





Mac

I haven't seen many people on the forum with a stock Dmax damaging a tranny much less a 8.1 wich has less torque.

The general concensus is that a Dmax with a 90hp juice will be the max that the stock tranny will hold and that is 350 rwhp and 600 rwlbs of torque wich is alot more than the 8.1.

I haven't seen many people on the forum with a stock Dmax damaging a tranny much less a 8.1 wich has less torque.

The general concensus is that a Dmax with a 90hp juice will be the max that the stock tranny will hold and that is 350 rwhp and 600 rwlbs of torque wich is alot more than the 8.1.


2 totaly different animals and cannot be compared. Th Duramax will hurt the Ally with brute tq. The 8.1 ( if it hurts the Ally at all) will do it by rpm.


mike

Mike


Will these 2 trannys exchange, fit, 8.1 in a duramax?


Genohttp://www.dieselplace.com/forum/smileys/Hug.gif

I say put a Transgo shift kit and converter in it.

mike


Mike, are these diy projects? Im pretty decent with a wrench but as I said earlier, I dont know squat about an Allison tranny.http://www.dieselplace.com/forum/smileys/Confused.gif

geno


I am not sure if they will interchange but they sure look like they will.


Couger71


I can help you make it a DIY project. http://www.dieselplace.com/forum/smileys/Big Smile.gif I can talk you through the whole procedure.


mike

only difference in a gasser vs dmax alli is the converter and a heat shield on the gasser for the exhaust crossover

Thanks Mike. I may just do that to be on the safe side. It would be better than wishing I had done it if something were to go wrong down the road.

Mike helped me a ton durring mine and i did it myself. A shift kit in an alli is much more involved than a shift kit in a 350 or something. This aint just a drop the pan kinda deal. You have to drop the whole trans. This can be a PITA just because the alli is a fat pighttp://www.dieselplace.com/forum/smileys/Pig.gif The innards of the alli are pretty easy though, especially if you were just going to stick a transgo kit in it. Actually the innards are more simple than on a 350 or 400 or 700.....no goofy spags and roller bearings and special tools and goofy little PITA stuff that likes to shoot out all overhttp://www.dieselplace.com/forum/smileys/Ermm.gif


I would say a novice could do a transgo install in a hour or so on the bench.....its just getting it on the bench.


Stock you shouldnt be able to hurt the ally. *shouldnt* but if you do then you are going to be yanking the trany to stuff new frictions and steels in it and paying for up to 5 clutch packs(depending on what ones you take out) instead of just a couple hundered dollar shiftkit. Rebuilding an ally is still a DIY job if you do cook em(doubtfull I think) You arnt going to take out any hard parts in an ally, just clutch packs worse case.

Anyone know the approximate weight of the ally transmission. Also how much will the truck need to be lifted to get that puppy outa there. This is the only part that really held me off this long. http://www.dieselplace.com/forum/smileys/Ermm.gif

I am going from memory so I might be a little off


380lbs and 20"

I dont think 20" closer to 10"(this is with 265's for tires). I did run into that SNAFU durring my R&Rhttp://www.dieselplace.com/forum/smileys/Embarrased.gif Second time in my life my Dumbass forgot to take into account the trany wont fit from under the truck. http://www.dieselplace.com/forum/smileys/Embarrased.gif A skidsteer with some forks and an excavator saved my but thoughhttp://www.dieselplace.com/forum/smileys/Stern Smile.gif


Better have a pit or a lift IMO, doing it on your back would suck IMO


Edited by: ratlover

380 pounds! http://www.dieselplace.com/forum/smileys/Cry.gif


Looks like I better get a little help. I do have the jack but it may take a two six pack stare down between me and that mutha after I rool it out. http://www.dieselplace.com/forum/smileys/Confused.gif

I dont know if she is that heavy drained and with the converter off. 2 guys can pick it up and move it around ok. Be carefull though or your will pop a hemroid. I've stuffed a 350 by myself but aint going to happen with an alli and no jack.

All you guys be carefull. The Ally is not a toy (weightwise) and you can get hurt. If it slips or falls, you will not catch it, it will hurt you.


mike

Cougar check out my sig... pull gooseneck with son's 6 show cattle all over Fl with 8.1/ally. Also have 315's (35") on it with rancho 4" lift. ABSOLUTELY NO PROBLEMS yet with trans(36000+ mi.), still has dex fluid in it but as I'm a tech I'm anal about draining pan and changing filter. No discoloration at all, temp hangs at 190 or so. only gripe is MPG, best I've gotten is 10 on interstate w/trailer, I won't even mention around town(7-9). Almost bought 04 Dmax but dealer tried the old "raise the price by a couple grand, he won't notice". Didn't like the nose job on the 04 anyway

I havent ever heard of a stock 8.1 tearing up an Allison, I dont know why you would need to do anything with it. There arent too many gas guys on here though. A couple of other forums I have been to though have some gassers on there. Although they dont have this great info on the Ally.

Im not gonna gripe about the mpg's. I have a 97 Z-71 with the Rancho 6" kit, 315 mud grips and 4:88 gears front and back. The mpg's SUCK! 7-8 unloaded! I think the 8.1 will be an improvement.

Anyways, I went and check the truck out, took a mechanic friend of mine with me. The truck appears perfect. Tranny fluid was nice and red, truck was very clean. On the test drive, tranny shifted great, no noted slippage or hesitation. Engine ran excellent, no evidence of piston slap according to my mechanic(Who works at a GM dealership BTW) He gave it his full approval so I now own a 2001 2500HD CC 8.1 with the Allison tranny. I think Im gonna enjoy this ride. BTW, I got a 97 Z-71 for sale if anyone is interested!

hey cougar,


not to interested now that you said the mpg's suck. lol

Yeah, But it looks goodhttp://www.dieselplace.com/forum/smileys/Rock On.gif

Lets see some pics of the new and old trucks!

I will try to do that tonight. It's raining cats and dogs here right now.

http://www.dieselplace.com/forum/uploads/14E_964234855.164936708.IM1.MAIN.565x421_A.562x421 .jpg

http://www.dieselplace.com/forum/uploads/7172003_024.jpg

http://www.dieselplace.com/forum/uploads/7172003_025.jpg


http://www.dieselplace.com/forum/uploads/7172003_023.jpg


http://www.dieselplace.com/forum/uploads/7172003_012.jpg Edited by: GMC-2002-Dmax

Couger71


http://www.dieselplace.com/forum/smileys/Big Smile.gif Nice truck.


mike