2004.5 CTD with 48re vs. GM allison transmission

[CUMMINZ]

I love my CTD and auto transmission but I spent some time in a new GM with allison transmission this weekend. What can we do to our 48re to get the performance results to match the allison? I love the way they control your downhill braking and automatic downshifting.

 

[mberry]

Buy an '05. It has a similar feature thanks to some extra programming.

 

[cerberusiam]

... . or take $5000 out of the kids college fund and got to your favorite performance trans shop.

 

[bchesley]

DTT will do the trick. I towed last friday for the first time with mine and it was awesome.



Brad

 

[CUMMINZ]

aftermarket transmission

Brad,

One of the things I notice about my 48re, I think it is doing a good job but I do baby it. With my TST turned up and towing my 5er, I don't push it greatly. I have noticed if I am traveling down the interstate in high gear and TC locked and come up to a grade with cruise control on, when it unlocks or downshifts I see a small increase in rpms before the transmission catches up. Is that slippage and does the aftermarket trannys stop that?

 

[ThomasLawrence]

when it unlocks or downshifts I see a small increase in rpms before the transmission catches up. Is that slippage and does the aftermarket trannys stop that?

You're always going to get an RPM increase when the TC unlocks. Yes, that's the TC "slipping", but it's designed to do that (as opposed to a clutch pack slipping inside the transmission, which is a bad thing). What will happen is you'll be in OD with the TC locked. The TC will unlock, the transmission will downshift to 3rd, then the TC will lock again.



My ATS remains in TC lockup all the time, so it will downshift from OD, to 3rd, to 2nd without unlocking the TC. More importantly, it will upshift with everything locked up, which makes for a firmer shift, but better acceleration.



-Tom

 

[kcnizdodge]

Dtt?

DTT will do the trick. I towed last friday for the first time with mine and it was awesome.



Brad

I hate to sound stupid (probably will though), but can you explain the DTT thing to me?

 

[BillGotthelf]

I think this will explain www.dieseltrans.com

 

[ThomasLawrence]

but can you explain the DTT thing to me?

They're one of several aftermarket transmission builders - they re-build the stock Dodge AT to handle more HP, torque, and just generally perform better. Other companies include ATS, BD Power, Goerend Brothers, and (to a lesser extent) Banks Engineering.



-Tom

 

[bchesley]

I am not going to go crazy with the bombs so I was looking for better performance. DTT was the builder I chose because they have a great semi-local installer to me. The converter stall speed is now where it should be and the shifts are firm and when they should be. It really made my truck a joy to drive and tow with. Look up their website or other builders and read up and learn. From this truck forward the transmission is the first bomb for sure!!!



Brad

 

[RMalone]

These dudes are right! I just got my DTT 89%tc,vb, and billet guts a couple of weeks ago. The shifts are way firmer and the rpm of the engine doesn't go way up right after a shift. The tc is so tight that my truck, on flat ground, will now go from a dead stop to 8-10 mph at idle. When slowing down on flat ground the truck will maintain about 15-20 mph at 750 rpm in second gear with no throttle. Now that is a nice, efficient tc. The smart controller is great also, you get to pick the speed of 3 to 4 and 4 to 3 shifts, also lets you lock up second at will. Makes the truck seem like a manual/auto hybrid. All in all a better driving experience, spendy though!

 

[CUMMINZ]

48re

All of you hit on some good points but I don't think my question was fully answered.



My 48re never downshifts automatically going downhill to help in braking. The stock allison I rode in did do that. It was a sure help in slowing the truck down.



Do any of the aftermarket rebuilds do that for the 48re?



CUMMINZ

 

[mberry]

I don't believe so CUMMINZ. Not like the Allison anyway.

 

[ThomasLawrence]

Do any of the aftermarket rebuilds do that for the 48re?

Generally, no - because the 48RE (the entire 4xRE line, actually) is still hydraulically shifted, so it can't be automatically downshifted. ATS does offer a special valve body, with additional shift solenoids, that are controlled via an electronic box. That is the only possibility (that I know of) of an automatic downshift. Contact them (http://www.atsdiesel.com) for more info.



-Tom

 

[jnelson]

I drove my DTT upgraded transmission 433,000 miles towing oilfield hot shot. Truck was upgraded with a injectors and a edge comp. In 433,000 I replaced the TC twice and a 2nd gear band once. After the upgrade the transmission performed completely different.



"These trany can handle the h. p. but not the torque. " As per phone conv. with Piers.

 

[CUMMINZ]

Dodge wake up

It sounds like Dodge Cummins needs to wake up. Oo.

 

[BHolm]

As already noted, they did wake up. The '05 version of the 48re has the ability to downshift on grades to control speed. I just hauled 15k behind mine over I-70 without an exhaust brake and it worked well. I have owned two Allison trucks and while they work better in grade braking, they are way too busy trying to find the d-maxes weak torque curve in most other situations. The Allison also can't handle the torque the Cummins has, my '03 Alli was burning up behind a babied stock d-max I do NEED the convertor and valve body though. With that 15k load behind the revs soar before the truck moves, that part is pretty sad. I suspect we have to wait for whatever the next DC auto brings to get the features GM and Ford already offer.

 

[CUMMINZ]

With that 15k load behind the revs soar before the truck moves, that part is pretty s

BHolm



I am glad you mentioned this. That is what I am noticing. Other than not being able to brake with it I have had good luck with my 48re. I made a sharp turn in a campground on the BlueRidge Parkway several months ago on about a 20% grade and had to stop because of my 5er laid down on the tip of my tool box and I had to stop and backup and make a wider turn. I should have put it in low/4wd but I didn't. I bet I reved 3k before it would move. The two allisons I camped with last week just sounded different when they were backing into their spot. :-{}

 

[GWBourne]

yes and no... . from what i hear, as i have a 6 speed and will NEVER BUY A DODGE AUTO!!!. . anyway... from waht i hear you can do some thigns to get the torque convertor to lock up and use an exhaust brake. i have an exhaust brake on my 04. 5 with 6 shooter and i tell ya what... loaded or unloaded i stop a LOT better. it is great loaded or unloaded for downhill decents. i use it 90% of the time when i drive. only when im at the beach looking at ladies or on slick road conditions do i turn it off.

grant

 

[BHolm]

Cumminz, You might also note that the Allison has a much lower reverse gear than our trucks. I have a '99 F350 plow truck and it sails in reverse, as do the auto Dodges. The Chevy is much slower going backwards because of gearing, that is part of what you saw.



Yes you can do a convertor and controller to fix pretty much all that is wrong. It just stinks that we spend $40k and have to start adding aftermarket stuff. Of course I had to do this with both my Chevy's too. They need decent sized tires, decent shocks and decent trailer tow mirrors. I added all three to each before I could consider them good tow vehicles. None of the big three are perfect, Dodge is just the closest IMO.