crd transmission

crawdad-480 · **Joined:** Fri Jan 19, 2007 12:03 pm **Posts:** 47

This may be a stupid question, but here it is anyhow. In an experiment I recently put my 05 CRD TCM (no F37) into
my 06 CRD (F37) mainly to see if the TCM was VIN protected and how the 06 would drive with having the ECM (F37)
and the TCM (non F37). The 06 started right up and drove with no problems. Since it worked it got me to thinking.

What are the differences between the programming of say an 06 liberty gas model TCM versus and 06 CRD TCM?
If there is no difference between the two, is there anything that would stop us from putting a gas model TCM into
our CRD's.

Any thoughts?

DarbyWalters · **Posted:** Mon Dec 17, 2007 2:55 am

Different tranny...42RLE vs our 545RFE...if you got one from a 2002 that had the 45RFE you would at the least lose your extra OD

Probably not a good idea

gmctd · **Posted:** Mon Dec 17, 2007 3:50 am

Good question, but no prize, here............

Gassers (patooie!) have a JTech PCM with self-contained engine\transmission management all in one box - it's basically Mitsubishi-derived.

The Diesel gets a stand-alone TCM because the ECM is a German Bosch unit required for managing the Italian CRD engine, as owned by Detroit Diesel.

Jeger · **Posted:** Mon Dec 17, 2007 8:43 am

What tells our torque converter to lock and unlock? Is it a solenoid or something else simple? probly not.....

We used to have an S10 that someone somehow had rigged up a switch on the dash that would kick it into overdrive, whether it was TC lockup or another gear I do not know. But I think it would be nice if we simply had a switch to tell the TC when to lockup, when to unlock, when to act normal and when to sit, stay, lie down, and roll over. Athough something like this used incorrectly might be a shortcut to teaching your TC how to play dead....Is it possible?

longview · **Joined:** Tue Sep 25, 2007 3:28 pm **Posts:** 88

Actually, what I have thought would be interesting would be to clone the software from a pre- to a post-F37 TCM.

A buddy of mine figured out to control the software in the Harley ECU. He buys them cheap from eBay since they are no good to anyone since they are VIN locked. However, he can unlock them and change the software however he wants.
So, instead of buying an aftermarket performance chip or inline override computer, he does a core swap with Harley owners and sends them a 'stock' ECU that has his custom software. (I have seen some funny emails from folks begging him to tell them how to unlock theirs - of course he is making money from this so it is a no-go) The Harley ECU basically only controls the fuel map and some ignition timing, so it is no where near as complex as the software in the TCM of the Libby, but still is seem doable.

Of course, the problem is getting a pre- and post-F37 TCM to play with as there would be a few months of downtime as well as the real possiblity of turning them both into bricks.

longview · **Joined:** Tue Sep 25, 2007 3:28 pm **Posts:** 88

Also - Crawdad - What where your impressions with the non-F37'd TCM?
Could you tell a difference?

danoid · **Posted:** Mon Dec 17, 2007 11:47 am

Mixing model years between 05 and 06 will disable the transmission pump variable line pressure for one thing, there may be other small issues.

Disabling variable line pressure will mean a small fuel economy drop, probably not noticable in the scatter from tank to tank, but a drop nontheless.

gmctd · **Posted:** Mon Dec 17, 2007 12:59 pm

Would you explain that a little more - is one year less-managed than the other?

All 545's get the dual-output pump, intended to reduce engine overhead as powertrain load is reduced - this would seem to indicate variable line pressure management in both year models.

TCM\ECM controls TCC with pwm solenoid(s) - additional slip is guaranteed by EMCC software, so a simple switch could work, but TCM and possibly ECM would go all pms'y on you, prolly wind up in total limp mode.

danoid · **Posted:** Wed Dec 19, 2007 10:17 am

They are both managed. However the ambient temperature signal changed between the two years. If the car thinks it's -40° F outside (because it's looking in the wrong place for the signal because it's the wrong model year TCM for the vehicle) the software will just keep transmission line pressure at maximum.

gmctd · **Posted:** Wed Dec 19, 2007 12:42 pm

I've been studying that temperature management thing, and the TMR\TRS, and the CVI stuff, and the EMCC stuff - I just can't get any hands-on with #2 son's long enuff to try some cause\effect\response type things - does seem to me as tho the Hemi PCM should use the same routines for the 545 as the CRD TCM - seems like anyone modding the Hemi stuff should be able to work with the TCM - maybe something will break loose now that the 6.7 is running the 68RE - don't take things long to start shaking when the Cummins boys get upset.

retmil46 · **Posted:** Wed Dec 19, 2007 1:20 pm

gmctd wrote:

maybe something wil break loose now that the 6.7 is running the 68RE - don't take things long to start shaking when the Cummins boys get upset.

How true. I know Ron at Suncoast is pretty tickled about the 68RE, sees the possibility for all kinds of goodies with that tranny.

Give the aftermarket guys time to dig into it and learn what's going on, we might end up with stuff such as being able to transplant that manual gear selection feature into our 545's.

danoid · **Posted:** Wed Dec 19, 2007 9:55 pm

I'd just like to transplant the 68RFE into my CRD. But it would require (at least)...

New adapter plate from back of block to bellhousing (and it would be a honker)
New front & rear driveshafts (68RFE is significantly longer due to length of torque converter)
New driveplate (6 bolts on front of 68RFE torque converter vs. 4)
New transmission mount
and the real kicker - New software.

But the good news is the elecrical and hydraulics are straight out of the 545RFE (it's really a six speed anyway, the 68 just has better spaced ratios). So the existing TCM (with reprogramming) and wiring should do the job (if the wiring reaches because the transmission is now farther back in car).

All technically feasible stuff (except for the software), just a lot of $$$. But it would be pretty bulletproof in the end.

gmctd · **Posted:** Thu Dec 20, 2007 12:51 am

C'mon, Dodge!!!

Uffe · **Posted:** Thu Dec 20, 2007 3:15 am

danoid wrote:

I'd just like to transplant the 68RFE into my CRD. But it would require (at least)...

New adapter plate from back of block to bellhousing (and it would be a honker)
New front & rear driveshafts (68RFE is significantly longer due to length of torque converter)
New driveplate (6 bolts on front of 68RFE torque converter vs. 4)
New transmission mount
and the real kicker - New software.

But the good news is the elecrical and hydraulics are straight out of the 545RFE (it's really a six speed anyway, the 68 just has better spaced ratios). So the existing TCM (with reprogramming) and wiring should do the job (if the wiring reaches because the transmission is now farther back in car).

All technically feasible stuff (except for the software), just a lot of $$$. But it would be pretty bulletproof in the end.

Hold on here a minute. The 545RFE is a 6 speed tranny? How come you say that? From the name alone you cannot misunderstand this is a 5 speed one. Is there something I don't know? (amongst the universe there are few things I know)

What really sounds EXCELLENT to me is the option of mounting some way to select gears in our trannies, if we could take that from the 68RFE. I'd love to cruise in top gear at 80kph (it shifts to 4th when going below 90kph it seems).

danoid · **Posted:** Thu Dec 20, 2007 12:59 pm

1st gear 3.00 : 1
2nd gear 1.67 : 1
other second gear 1.50 : 1
3rd gear 1:1
4th gear 0.75 : 1
other fourth gear 0.67 : 1

Six forward gears, drives like a four speed.

DarbyWalters · **Posted:** Thu Dec 20, 2007 1:11 pm

Actually drives like a 5 speed...at a constant rate of acceleration you will go thru 5 shifts. No matter what they call it tho...it is a 3 speed (1:1 or greater) with 2 ODs (less that 1:1) IMHO.

dirtmover · **Posted:** Thu Dec 20, 2007 1:22 pm

danoid wrote:

1st gear 3.00 : 1
2nd gear 1.67 : 1
other second gear 1.50 : 1
3rd gear 1:1
4th gear 0.75 : 1
other fourth gear 0.67 : 1

Six forward gears, drives like a four speed.

He's correct, there are two 2nd ratios but it actually drives like five speed. From lowest to highest gear there are 5 discrete ratios used and the same from highest to lowest. The difference is it will select a different 2nd ratio depending on whether it shifts up into it from 1st or down into it from 3rd. It will never directly shift between the two 2nd ratios.

ATXKJ · **Posted:** Thu Dec 20, 2007 2:10 pm

Well folks can correct me on this but
part of the confusion on automatic gear ratios is that a given gear cluster, can actually have 3 different ratios
i.e. a gear cluster is a main gear on a shaft – a set of planetaries (commonly 3) and an outer carrier gear.
if your power comes in the main gear and the planetaries are held fixed, the power will exit the outer carrier as 1 gear ratio.
If the power comes in the main and the carrier is held fixed, the power can exit the planetaries as a 2nd gear ratio.
If the power comes in and out the main (or planetaries and cluster fixed to the main) you have the 3rd (1:1) ratio.
(you can also reverse it and have power coming in the outer carrier and exit planetaries or mainshaft )

So basically 1 cluster – 3 gear ratios, and the 545 actually has 3 gear clusters so

1st gear and reverse are 3:1 ratios
2nd gear upshift is a 1.67:1 ratio
2nd gear downshift is a 1.50:1 ratio
3rd gear is 1:1
4th gear takes the 1.50 gear cluster but takes the power off of a different point and gives a 0.75:1 OD
5th gear takes the 1.67 gear cluster – takes power off of different point and gives a 0.67:1 OD

From a gear standpoint you might be able to make more combinations – however from a reality standpoint getting the power into/out of a gear set takes a lot of work so there may not be a physical way to connect – so this may be the limit
(I think the 45 has the same gear clusters – and doesn’t get to 5 ratios)

However as Uffe said what we really need is a manual valve body – but I don’t like the gear choices the transmission makes – I want to choose my own.

danoid · **Posted:** Thu Dec 20, 2007 3:43 pm

ATXKJ wrote:

From a gear standpoint you might be able to make more combinations – however from a reality standpoint getting the power into/out of a gear set takes a lot of work so there may not be a physical way to connect – so this may be the limit
(I think the 45 has the same gear clusters – and doesn’t get to 5 ratios)

No correction needed really. You are pretty much there from a theoretical point of view. There are actually 7 ratios used in the 68RFE (can't forget Reverse), 6 ratios used in the 545RFE (5 go forward). There is also an unused reverse ratio (I think). The rest are lost in the connections.

I call the 545RFE a six speed that drives like a four speed because two of the ratios are so close to others (1.50 and 0.67) that they don't appreciably help vehicle performance. A true five speed automotive transmission will have gearing more like 3.50, 2.25, 1.50, 1.00, 0.80.

flash7210 · **Posted:** Thu Dec 20, 2007 10:13 pm

I think there is more to this tranny than you think. Example...

With OD on, you get five forward speeds- 1,2,3,4,5. TCC only applies in
4 and 5
With OD off you are only supposed to get the first three. But, the TCC will
lock-up in third.
So, here is what I've noticed...
When driving with OD on at about 40-45 mph, I'm in 3rd gear w/no TCC,
RPM's around 1650. If turn OD off at this speed, RPM should stay the
same right? Same third gear right? In fact I would even expect RPM to go
down a little because the TCC should be applied.
But no! RPM's go up to around 1850. It's not dropping to 2nd because if I
go faster it doesn't shift again. Also, the TCC is applied.
So, whats the deal? Are there two possible 3rd gear ratios too?

So here is what I know about auto tranny's. Our's has three simple
planetary gear sets. That is, one sun gear, 3-4 planets, all inside 1 ring
gear. One simple planetary gear set is capable of two forward speeds and
one reverse. Well, actually you can get three forward speeds, but it is
usually at the sacrifice of some strength because of the additional holding
devices required. Anyway, so you can get six forward speeds and three
reverse out of this arrangement. You could possibly get even more speeds
by combining different ratios. But, this is all dependant on the arrangement
of the holding devices. Holding devices are either bands, clutch packs,
or one-way clutches. Clutch packs are the strongest, applied by a hydrualic
valve, and usually are very quick. They are also accompanied by an accumulator
that slows application a little to reduce shift shock. Bands can be as stong but
usually are'nt and apply kinda slowly through a hydraulic servo. One-way clutches
are weak but are passive and require no hydraulic pressure.
I have not idea what holding devices are used for each gear in our tranny.
But I do know that they all effect how it operates and why we have the
gears we do.

I just don't understand why one Ravenoux gear set was not used instead
of the three simples.

crd transmission

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