Transmission prospective

Tinman · **Joined:** Mon Apr 10, 2006 10:45 am **Posts:** 308

I am coming to this forum as a long-time diesel pick driver. Me (or my family) has owned 2 GM 6.2s, a '00 Powerhope :lol:

Ford, and 2 Dodge/Cummins. My wife got a CRD this spring so naturally I found this forum. I see there are transmission issues with the CRD. Can't say I'm suprised. It occurred to my that no American auto maker has ever made a good auto tranny for any diesel auto/truck. The problem is no manufactor will spend the time or money to make a diesel specific tranny. They all just try to beef up a gasser trans and make it work. This gives us torque convertors with way-too-high of a stall speed for the torque of a diesel, too low line pressure, and not enough clutches. The loose TCs keeps the engine from delivering too much torque thru the trans and clutches to keep them from self destructing. It also makes for a very ineffecient driveline for engines with the low end torque of a diesel. The GM Allison is the best effort yet and it still isn't very good. It has to defuel the engine in some gears to keep it from slipping and is it very expensive to fix or upgrade.

I got bit by the hp bug a few years ago and up rated my 01 Cummins. Of course, the trans won't handle it, so I put in a "fully built" tranny. This is a pricey undertaking but let me tell you, it is worth it. Single best mod I have made to the truck. Now I know what a real tranny is supposed to be and it makes the truck a whole nother beast. The tranny is as good as the engine now. The vendor I went with, DTT, uses a tight TC and high line pressure (with single disc clutch). Now the engine doesn't turn riduculous rpms to go nowhere. Very nice match to the torque curve of a diesel. I knew when I bought the 06 Cummins this spring the tranny would be rebuilt as soon as the funds allow (hopefully within a few months). For me, it's just a given you will have to fix a diesel auto trans and figure an addition 5K or so to the price of the truck when it is bought. Those that have never driven a properly build diesel trans don't know what the are missing.

That said, the CRD tranny in stock for doesn't drive all that bad. The smaller, higher revving 2.8 seems better matched to the TC stall speed. Much better than the stock 06 Cummins or the Powerstoke. However, the issues that people are having is still the same old song. Gasser tranny not doing well behind a good diesel. I can't say I'm suprised about the problems. Our CRD has thus far (11K miles) been flawless. Had the filter TSB and the F31 and all is good. I may not do the F37 as it seems that it may increase stall speed of the TC which is the wrong (read cheap) way to go. This is just my thoughts on the issue. CRDs are not alone in their tranny problems. It was an issue in the 80's with the 6.2s (at stock power) and is still an issue with diesels of the big three. Sad, but true.
:cry:

Jeger · **Posted:** Thu Dec 14, 2006 8:27 pm

So what would it take to make the 545 a "built" tranny? Proper pump, and TC, is that it?

crdmike · **Joined:** Tue May 16, 2006 7:25 pm **Posts:** 138

Hey Tinman, what's your connection like with DDT; can we get a tranny?

DarbyWalters · **Posted:** Thu Dec 14, 2006 10:37 pm

The stall speed is the key. We need a "built TC" and better line pressure to keep the fluid in the TC when needed. We just need to find a Tranny Shop that is familiar with Diesels. Tell them to build a 1500 stall TC and upgrade the pump.

This place has the TransGo shift kit (which can help with the pump problem) and builds a TCs for our tranny with 1500 stall speed:

http://www.transmissionsone.com/45rfe_p ... om_pat.htm

urchindog · **Joined:** Sun Apr 23, 2006 4:41 pm **Posts:** 30

Take a look at my thread, i've contacted many of these builders and none have moved on the TC for our 545rfe application, i've spoken to two that would be willing to take a look but want to look at a good or bad chrysler unit as a base line to start.

anyone know where to get one?

lets team up and get this done

tks, bryan :roll:

DarbyWalters · **Posted:** Thu Dec 14, 2006 11:01 pm

I emailed Don at the link in the above post. They already make a TC for the 45 and 545RFE trannys. Maybe he will get back to me in the morning. I also told him to jump on the forum and read a bit if possible.

urchindog · **Joined:** Sun Apr 23, 2006 4:41 pm **Posts:** 30

yes they make them for the gas / hemi but not the crd...much different animal. I as well had a full DTT in my 99 dodge cummins, great unit but little responce from them on this unfortunatly, same with Suncoast etc, etc

rgds, bryan

Weegie5 · **Posted:** Thu Dec 14, 2006 11:25 pm

For those who don't understand the concept of a stall speed (like me until 15 minutes ago), this article does a decent job of explaining it: http://bankspower.com/Tech_understandstallspeed.cfm.

Endurance · **Posted:** Thu Dec 14, 2006 11:30 pm

but a performance TC alone wouldnt solve the problem correct? We would need shift kit, pump and TC.

KenJennings · **Posted:** Fri Dec 15, 2006 5:03 am

Weegie5 wrote:

For those who don't understand the concept of a stall speed (like me until 15 minutes ago), this article does a decent job of explaining it: http://bankspower.com/Tech_understandstallspeed.cfm.

Having read that and the companion article , Understanding Torque Converters I gather that the TC is only used with an automatic transmission.(?) If DC had offered the Liberty with a stick in the US, (like I wanted), there wouldn't be as many people with problems.

Joe Romas · **Posted:** Fri Dec 15, 2006 7:23 am

Weegie5 wrote:

For those who don't understand the concept of a stall speed (like me until 15 minutes ago), this article does a decent job of explaining it: http://bankspower.com/Tech_understandstallspeed.cfm.

James. Thanks for the link

DarbyWalters · **Posted:** Fri Dec 15, 2006 9:01 am

urchindog wrote:

yes they make them for the gas / hemi but not the crd...much different animal. I as well had a full DTT in my 99 dodge cummins, great unit but little responce from them on this unfortunatly, same with Suncoast etc, etc

rgds, bryan

A TC can't tell if an engine is gas or diesel. A TC with the corrrect stall speed and a beefier clutch pack will work.

litton · **Posted:** Fri Dec 15, 2006 10:17 am

Excellant info, now what is the stall speed of the old and new TC's?

DarbyWalters · **Posted:** Fri Dec 15, 2006 10:44 am

Response from Don:

If you are sure the shutter problem is coming from the converter and there's nothing wrong with the transmission then it will most likely fix the shutter. The stall speed should always be lower than the max torque RPM. I don't think the pump is the problem.

The shift kit turns the pressure up giving it more apply pressure and the converter has a better clutch material.

Did it do this from new? Do you have power adders?

Don

diesel161 · **Joined:** Tue Oct 10, 2006 11:04 am **Posts:** 4

There is much more to this issue then changing parts. There are many people out there with great ideas but the whole picture must be kept into view. When I drive my 06 CRD I did see some issues with the way it shifts into lock-up. But over all my CRD does shift very well and the programing seems to be done well. When I talk about programing it is quite easy to tell this engine and transmission uses torque management during shifts as do most modern automatics. For those that do not know torque management slightly derates the engines output just before-during and after the upshift. SHift energy management is good for shift quality, clutch life and durability. At times the rating of Allison world transmissions is quite a bit higher with shift energy management then not. Raiseing line pressure is usually not the best idea. There needs to be more informed decision made before just saying rasie line pressure. When you make a change one way there is an effect another. Usually when rasieing line pressure you reduce lube flow. Lube pressure comes from the main pressure regulator in most transmissions. So if you raise pressure by changeing a spring or by changing software you may have the same outcome, reduced lube flow. There are ways to counter this problem like a diffrent main pressure regulator valve. Also high line pressure takes more HP to turn the pump and that reduces fuel mileage. Does anyone know the main failure point?? I know there is alot of talk about changing the pump. But why is is being changed??? Please be sure what ever you do change in the transmission in your CRD you are sure of the outcome or you could be spending lots of $$$$$$$$ and be unhappy... I hope this info sheds some light on transmissions for all.

GregScuba · **Posted:** Fri Dec 15, 2006 2:27 pm

This is an awesome thread, I'm excited to see where this develops.

My previous vehicle was a Plymouth Neon. I went through one rebuild, one entire swap, and one valve body swap with it's tranny over the course of 6 years.

I hope I have better luck with my CRD than I did with that neon tranny. P.S during the valve body swap, I cranked up the line pressure. Didn't have anymore tranny problems after that.

Tinman · **Joined:** Mon Apr 10, 2006 10:45 am **Posts:** 308

I don't have an inside line with DTT. Just a satified customer. There are quite a few trans vendors out there now for truck trannys. Each upgrades the trans differently and all of them (and their customers) will tell you theirs is the "right" way. For instance, DTT uses single disc and high line pressure with the necessary upgrades to make this work correctly. ATS uses a triple disc (I think they have a quad disc now) TC and a looser stall and lower line pressure. They also lock the TC very earlier. There are many differnt variation. The point being there is no one fix or one thing to do to make the CRD trans right. Good aftermarket trans are well thought out by people who understand transmissions and diesels. I don't think D/C understands either. The 545 is a good tranny as far as I can tell. Just not well executed for the CRD and we are seeing the results.

The truck trannys from the factory are better now than in the past because they can last at stock power if maintained proper. But they still don't work with the engine very well and don't make use of the virtues of the diesel very well. By that I mean you have to load a turbo diesel to make is run well and loose TC don't load anything. (Don't forget the EPAs roll, the high stall speed TC we have are partly for emissions - the engine needs to spool quickly to keep the smoke down.) Also remember the after market truck trans business is driven in large part for the high hp crowd. The CRD market is quite different. I bet the 545 could be made to work very well with the CRD at stock to moderate hp without much modification. But I don't know who is willing to go the the trouble. Of course the best fix would be a 6 manual.

AZScout · **Posted:** Sat Dec 16, 2006 7:08 am

Tinman...with your experience with diesels and transmissions, what would you do to improve the CRD between the 2.8 engine and 545rfe transmission?

RAF 3829 · **Posted:** Sat Dec 16, 2006 8:01 am

Just curious if anyone's contacted Dave http://www.gbtransmissions.com/

He's been getting good reviews on his trannys in the Dodge CTD.

KY Liberty · **Joined:** Sat Jul 09, 2005 1:46 pm **Posts:** 1195

You might want to talk to Wayne at APS Precision.
http://apsprecision.com/

They built a custom tc with a 2500 rpm stall and a 2.53:1 multiplier instead of 1.93:1 for my 3.7 with a 45RFE. It also puts around 6-8% more power to the ground. I also got the Transgo performance shift kit from them that made it shift much better, faster, and increased the line pressure. They can probably build something for your CRDs. You need to check into getting the torque management values adjusted too. I had B&G reprogram my PCM with the torque management deleted. I'm not sure who you would need to contact for a CRD.

Transmission prospective

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