I am looking at a new truck with the Allison tranny. Anything I need to know? I have heard some good & bad. Any personal experience?

Thanks

Dave

www.thebeasst.com

 

I have a brother-in-law who is the tranny man at a local gmc dealership. He says they have had a lot of issues with the case cracking on these. At this point the mechanics are not allowed to open them up, just replace them and send the bad one back to GM for analysis. Sounds like they are still trying to figure it out....

 

I haven't had the case crack on mine nor have I seen any come back for that at Elmhurst Chevy. And before you say "well you don't use yours!" I towed 5 cars alone last week.

This transmission is the greatest thing since sliced bread when it comes to towing. It matches the engine's powercurve perfectly (in my case, the 8.1). When in tow/haul mode, I've noticed under moderate to full throttle acceleration that it holds second gear only momentarily and goes right into third. One thing I am still getting used to is around 40mph when cruising, it won't upshift to the next gear. So you end up running down the road with the engine screaming along at 3,000rpm when in reality all you need is 1,800-2,000rpm like the way it happens when you are out of tow/haul mode. At about 42-43mph it'll finally shift to the next gear. I guess I wish it'd realize this a tad sooner is all I'm saying and shift sooner.

When in tow/haul mode, the grade braking feature is unreal. If coming up to a stop well in advance (I.E. not a panic stop), I simply let off the gas, and lightly touch and cover the brake pedal. From there the grade braking does all the work. It's so nice I only need to cover the brake pedal to actually bring the truck from a roll to a stop.

FOR PERFORMANCE NEEDS THOUGH...LOOK ELSEWHERE!!!!

This Transmission simply isn't a hi-po minded unit and in effect strangles the engines' power. In many stoplight grand prix's I've been in, I've found it to be sluggish (partly due to the torque management feature) and shifts too short at the top of every gear. Another 500-750 rpm would be nice in both 2nd and 3rd gears, but the algorythims simply don't pick up this fact. Why? Cause it's programming is not meant to be set for performance.

What I REALLY like about it is it's serviceability. While it may need more routine maintanance then a 4L80E (if you want optimum performance from it), it makes it sooo easy compared to a GM Hydramatic (4L60E, 4L80E/4L85E) transmission. In order to change the fluid all you do is pull the drain plug just like changing the oil. To change the filter, it too is just like changing the oil by twisting off the screw on filter. With this transmission there is no need to drop the pan, get trans fluid all over the place, mess with removing a trans fluid filled old filter and then replacing with a new one then having to re-line a gasket and putting the pan back on.

The only drawback to this (and you DON'T have to do it, but I do) is go over to your local Allison distributorship and pick up the trans fluid they recommend. DexronIII will work fine, however they prefer a synthetic that Castrol makes for them called "Transynd". A complete trans fluid change will take approx. two gallons of fluid and the two gallons of Transynd was around $50. Filters aren't all that much more expensive than a regular oil filter, but I don't think many GM dealers actually stock the Allison filter. So this too for now will also have to be bought at the local Allison shop.

GM/Allison recommend that under heavier usage, at the first 5,000 miles, change the filter and fluid. Then at every 5k intervals afterwards (10k, 15k, 20k, etc, etc) simply replace the filter and top off the needed fluid. Then at the 40-50k mark change the fluid.

All in all, I'm extremely happy with mine. I just wish it had a performance mode too in it's programming.

 

Looks like you have the first hand experiance with these. I was just forwarding some info I had .
Maybe you'all don't haul big trailers full of cattle in IL like Everyone does down here in Texas <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />

 

Wow, thanks for the information. I think it will suit my needs well. Now if I can get the dealer to get right with the price <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" /> They are kinda proud of those things aren't they <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" />

Dave

www.thebeasst.com

 

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by L82gofast:
<strong>Looks like you have the first hand experiance with these. I was just forwarding some info I had .
Maybe you'all don't haul big trailers full of cattle in IL like Everyone does down here in Texas <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" /> </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">LOL...no I must not; <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" />

Here it is with 5,000lbs of gravel in the bed (well, technically 4,970lbs)
<img src="http://www.chevy4x4trucks.com/CMNTMXR81/4,970lbs%20of%20gravel%208.jpg" alt=" - " />

Here it is with my old Tahoe on the trailer. The Tahoe weighed 5,500lbs and the trailer weighs 1,500lbs, so that's a total of 7,000lbs out on the hitch;
<img src="http://www.chevy4x4trucks.com/CMNTMXR81/2500HD%20pulling%20Tahoe%201.jpg" alt=" - " />

 

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by CMNTMXR57:
<strong>so that's a total of 7,000lbs out on the hitch</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">yawn... <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" /> J/K! <img border="0" title="" alt="[Razz]" src="gr_tounge.gif" />

FWIW, one of my buds has an early '01 2500HD with 8.1/Allison. I believe he is on his 3rd replacement. The only thing he hauls is a trailer load of goats every now & then.
On the other hand, another guy I know has a Dmax/Allison and hasn't had any trouble at all. It's all luck of the draw, nothing is fail safe. Even my 4L80E crapped out @ 11K. I would definetly get an extended warranty though, just for the tranny alone. I hear it's about ~$5000 for an OEM replacement after warranty is up. <img border="0" title="" alt="[Eek!]" src="gr_eek2.gif" />

 

Oh yeah, over on The Diesel Page you will see a post every now and then about the tranny going into limp-home-mode or something else that is goofy.

All in all, it is a pretty good unit. Ford apparantly thinks so too, because they are working on one very similar to Allison's design for their upcoming 6.0 Powerstroke trucks.

 

Man you sure are making that truck earn its money! What kind of exhaust do you have on that truck? I am looking for something without the head pounding drone inside the cab.

 

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by Neil 6.0:
<strong> </font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by CMNTMXR57:
<strong>so that's a total of 7,000lbs out on the hitch</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">yawn... <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" /> J/K! <img border="0" title="" alt="[Razz]" src="gr_tounge.gif" />

FWIW, one of my buds has an early '01 2500HD with 8.1/Allison. I believe he is on his 3rd replacement. The only thing he hauls is a trailer load of goats every now & then.
On the other hand, another guy I know has a Dmax/Allison and hasn't had any trouble at all. It's all luck of the draw, nothing is fail safe. Even my 4L80E crapped out @ 11K. I would definetly get an extended warranty though, just for the tranny alone. I hear it's about ~$5000 for an OEM replacement after warranty is up. <img border="0" title="" alt="[Eek!]" src="gr_eek2.gif" /> </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">I'm looking for bigger stuff to pull, I just don't have it in my driveway. <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" />

The exhaust actually was modified between the 1st and 2nd pictures.

Basically I chopped off the stock muffler of death and replaced it with two Magnaflow's standing upright (if you go this route, you need two mufflers as the outlets are offset on the stock unit). Originally (in the first picture) I just then piped them into the stock "Y tailpipe."

I later took it to FLP and had Don there take that stock "Y tailpipe" off and plumb two individual tailpipes going out behind each wheel from each muffler for a true dual system.