47-48RE line pressure loss?

[Kodiak24V]

 2001 Ram 2500 24v 4x4 excab shortbed. 

Auto, S363, 7x.010, 4.10 gear. 36” tires.

 

had a local shop build my transmission 3-4 years ago with billet torque converter, billet input. transgo kit. 

 

trying to learn more about the transmission so I can do it myself next go around. 
 

ran some diag checks and had a few questions about the results. 
 

1 pressure gauge on the accumulator port and 1 pressure gauge on the front servo port/rear servo port. 
 

FRONT SERVO:

3rd-4th gear locked WOT-

accumulator pressure 145-150psi

Front servo pressure 135-138psi

 

the spec in (47re trans line pressure port testing guide) is 3psi difference at stock pressure  

 

is 10-12 psi lower pressure difference in the front servo @ 150psi a problem?

 

REAR SERVO:

Low 1st gear-

accumulator 135psi

Rear servo 130psi

 

I assume 5psi difference is ok on this one as the spec is also 3psi at stock pressure. 

reverse gear-

Idle 240psi / full throttle brake boost to 1600rpm 315psi

 

im assuming that’s good? 
 

I originally had an issue where turning the pressure adjuster on the transgo VB didn’t return more pressure.
 

I didn’t do these tests before hand but I did change out the Valve Body with one built by one of the popular diesel drag racing companies. Owner said they test each one on the machine for 140-150psi before sending out.

 

I have turned the line pressure adjuster 4 turns out and also changed out the old plastic accumulator piston and stock 2nd gear servo  with TCI billet units and am seeing the pressures above. max high 140s to 150. 
 

just not sure because I was told it shipped out at 140-150 and it’s taken 4 turns to get to those numbers.

 

Going by 10psi per turn it seems I should be at 170-180psi.

 

before I go in and keep cranking the pressure adjuster I wanted to make sure these numbers looked ok (no internal leaks)?

 

 

 

 

 

 

 

[IBMobile]

These are the line pressure numbers after @Dynamicrebuilt the transmission in 9/2019. 

 

Air temp 91°F Transmission fluid temp 165°-190°F

Line pressure, transmission in drive:  no throttle stopped   85 PSI       

                                                          light throttle  2ed gear 105 PSI

                                                          light throttle  3ed gear  110 PSI

                                                          light throttle  4th gear   120 PSI @ 2200 RPM

                                                          W/O throttle  1-2 shift   180 PSI @ 2800 RPM

                                                          W/O throttle  2-3 shift   175 PSI @ 3100 RPM 

                                                          W/O throttle  3-4 shift   150 PSI  

                                                          W/O throttle  4-3 shift  150 PSI  

                                                          100% throttle 4th gear TCC locked @ 70 MPH 160 PSI

                                                          0% throttle 3ed or 4th gear TCC locked down hill slowing 100PSI

                                                          reverse gear stall test 330 PSI

[Dynamic]

You're going to have a hard time getting to 180 psi with a Transgo 47RE kit PR spring(s) and a stock 47RE PR valve train. There are a few other mods necessary to get there. I would not turn that PR spring preload much further than what you already have.

[Kodiak24V]

9 hours ago, Dynamic said:

You're going to have a hard time getting to 180 psi with a Transgo 47RE kit PR spring(s) and a stock 47RE PR valve train. There are a few other mods necessary to get there. I would not turn that PR spring preload much further than what you already have.

Currently it has a high performance valve body from one of the few cummins drag racing companies.

 

does that change the advise?

 

thanks!

9 hours ago, IBMobile said:

These are the line pressure numbers after @Dynamicrebuilt the transmission in 9/2019. 

 

Air temp 91°F Transmission fluid temp 165°-190°F

Line pressure, transmission in drive:  no throttle stopped   85 PSI       

                                                          light throttle  2ed gear 105 PSI

                                                          light throttle  3ed gear  110 PSI

                                                          light throttle  4th gear   120 PSI @ 2200 RPM

                                                          W/O throttle  1-2 shift   180 PSI @ 2800 RPM

                                                          W/O throttle  2-3 shift   175 PSI @ 3100 RPM 

                                                          W/O throttle  3-4 shift   150 PSI  

                                                          W/O throttle  4-3 shift  150 PSI  

                                                          100% throttle 4th gear TCC locked @ 70 MPH 160 PSI

                                                          0% throttle 3ed or 4th gear TCC locked down hill slowing 100PSI

                                                          reverse gear stall test 330 PSI

This makes me feel better.
I was noticing that unlocked the pressure in 2nd and 3rd would spike to 165 but the max locked in 3rd-4th is 150psi.

 

Wasn’t sure because everything I’ve read said the locked pressure should be more than unlocked but I was seeing those spikes unlocked.
 

the 165psi unlocked in 2nd is a spike though and quickly goes back down to the 150 at the 2-3shift.

 

I think my previous issue (not gaining pressure when turning up the pressure adjuster) was fixed by the new billet TCI accumulator and 2nd gear servo. The plastic stock accumulator was very sloppy in the bore.

[Dynamic]

I didn't see in your post where you swapped valve bodies until I reread it. My bad...

 

If they setup the VB for 150 psi, then you're pretty much there. If you want more pressure than that then the overall PR setup should be revisited. Simply increasing the spring preload (on a spring of unknown rate) will only get you so far.

[Kodiak24V]

3 hours ago, Dynamic said:

I didn't see in your post where you swapped valve bodies until I reread it. My bad...

 

If they setup the VB for 150 psi, then you're pretty much there. If you want more pressure than that then the overall PR setup should be revisited. Simply increasing the spring preload (on a spring of unknown rate) will only get you so far.

Ok thanks for the clarification. I just wasn’t sure if the 12psi difference between accumulator and front servo was a loss somewhere.
Also confused me that 4 turns later it’s at 150psi max. I figured it would be at 180ish 

 

I have a S363 and 7x.010 injectors. It was slipping on my Quad tune 6 before I got into all this. I haven’t tried on tune 6 after the VB and billet servos and 150psi but I do know it doesn’t slip on tune 4. 
 

my worry is down the road. I have a 2005 5.9 Commonrail to eventually swap in and shoot for 700+ HP.

won’t I need more pressure for those HP levels?

 

Edited June 14, 2022 by Kodiak24V

[Dynamic]

The front servo pressure tap is reading 3rd gear oil. It's the pressure that pushed the band off (and is holding the band off) from 2nd to 3rd gear. It would be on the downstream side of the 2-3 shift orifices, so any leakage (ie. flow...) at the servo would show up as a loss of pressure. The one thing that I would verify when using two different gauges to measure two different pressures at the same time would be that the gauges are accurate. Gauges can vary, sometimes significantly. I have several pressure gauges kicking around the shop, and some of them definitely are not accurate. I, obviously, would not any of use those when needing down-to-the-exact-psi accuracy on something.

 

The amount of pressure gained per turn of the PR preload adjustment depends upon the rate of the PR spring. It's anyone's guess what the spring rate of your PR spring setup is. The one thing that is worth saying is to make sure it's the PR preload adjustment that you are turning. It never ceases to amaze me how many people wind the TV lever stop to the moon, thinking that they are turning the PR preload. You should be turning the PR preload adjustment counterclockwise to increase line pressure. But again, it is an adjustment, yes, but meant for fine tuning only. The meat and potatoes of setting up the line pressure curve occurs elsewhere in the system.

 

If you're going to make a legit 700 hp, you'll need a whole lot more than you have right now, line pressure and otherwise. 150 psi max won't get you too far. But, you're only seeing 150 psi at WOT. Ironically enough, with high hp setups, it's not really WOT pressure that kills transmissions (although things would not last long at your current 150 psi). It's everywhere else in the curve that needs pressure, particularly the middle "third" of pedal travel (and thus, TV cable travel...when everything is setup correctly). An aggressive pressure curve is as important (if not more) than peak WOT pressure.

[Kodiak24V]

Appreciate the tech. the gauges don’t bounce around and hold pretty steady. (Not that means they’re an accurate piece)

 

the pressure spring is orange and I’m definitely turning the correct bolt counter clockwise.
I never touched the blue locktite TV adjustment. 

 

not sure I understand about the “leakage (ie flow…)at the servo would show as a pressure loss.”

 

assuming the gauges are correct is a 12psi loss excessive? 

 

Just trying to figure out if the reason I have a lower pressure than bench tested (had to crank 4 turns to hit 150) is I’m loosing pressure somewhere and the trans needs to come apart. or?

 

also while I’ve got you talking transmissions!

what would adding a 2nd spring in the front servo do? right now I have a white spring in there but I’ve seen some with a larger/wider spring also. what is the benefit of 2 springs?

[Dynamic]

Any time there is flow across a fixed orifice, there will be a pressure drop. If you're leaking oil at the servo, you will see a reduced pressure because the oil that is flowing to the leaky servo has to go through the 2-3 shift orifices. The greater the low, the greater the pressure drop. There will always be some leakage, but 12 psi would not make me too happy (again, assuming your gauges are accurate). What, if any, mods did they do to the front servo?

 

The second spring in the front servo helps to push the band off quicker so you don't have tie-up on the 2-3 shift. It becomes necessary when the line pressure gets up there. The Transgo 47RE kits have you discard the OE spring and replace it with their spring. In reality, it works better with both springs in there if you have higher line pressure. 150 psi is kind of low to be needing a second spring, especially if 150 is the highest pressure, and only at WOT. Down where your transmission spends most of its time is much lower than that, especially with stock PR hydraulics.

[Kodiak24V]

The issue was the trans felt like it blew through the converter. Like it had the loosest converter ever. it would also blow through 2nd/not shift to 3rd/tach out the engine only WOT. Only unlocked though. Locked it pulled hard 3rd and 4th. It would not do a brake stand either. 
 

The original trans shop left the stock front servo and the plastic accumulator in there. 

 

I replaced those with the black TCI billet units. 
 

i put the springs back in that were in there previously. The front servo was a narrow white one(I reused). I’ve seen a wider one before just wasn’t sure if needed. The accumulator piston had 1 spring.

 

what would be an acceptable amount of pressure loss at 150psi?

 

and if that’s low what is it usually caused by? 

 

I 1st started out cranking the original VB (transgo)adjustment and did see a gain but had it cranked down pretty good. The gauge in accumulator port jumped around a lot. 
 

It also was having a hard time down shifting into 1st(before starting messing with the trans/VB).
 

I was never really happy with the “built transmission” I got back from the shop so to eliminate doubt last December I ordered a performance valve body. 

 

Before installing I turned the PR 2 turns (I don’t remember the max pressure/didn’t take a picture driving. It had 90psi at idle up from 65psi stock with the last valve body) it still would not shift to 3rd WOT It would blow through 2nd and tach out the engine. 
 

the builder recommended I check .090 hole in boost plate orifice. It was in fact .090. I figured if I had to take the VB out again I would install the TCI stuff. I also turned the PR bolt another 2 turns(total now 4). 

 

it now is at 150psi locked/ doesn’t feel like it’s blowing through the converter. And it holds WOT 2-3 shift. Also will start spinning the tires in a brake stand around 1800rpm. 

 

I do think the TCI accumulator/servo made a difference.
 

it’s noticeably better but my goal is to get it cranked up more. 

jist wasn’t sure if the 12psi difference is a take the trans out and rebuild or maybe give it a couple more turns and see where it’s at.

 

 

[Mopar1973Man]

@Dynamic is a good guy to ask those questions with him.

[Dynamic]

Yeah, it sounds like you may have a bit of a confused package there. It's really tough to say what all was done and not done, what parts were used, clutch counts, clearances, stall speed of the converter, etc. Lots and lots of variables in play...

 

One other huge thing you can do performance-wise, once you get a good transmission setup, would be to regear the truck for those 36" tires. You'll feel like you got let out of jail!

[Kodiak24V]

7 hours ago, Dynamic said:

Yeah, it sounds like you may have a bit of a confused package there. It's really tough to say what all was done and not done, what parts were used, clutch counts, clearances, stall speed of the converter, etc. Lots and lots of variables in play...

 

One other huge thing you can do performance-wise, once you get a good transmission setup, would be to regear the truck for those 36" tires. You'll feel like you got let out of jail!

It has Yukon 4.10 gears. it’s @2k rpm at 70mph in OD.

I can’t figure out how to edit my sig from before the many mods since…

 

I guess it all comes down to if you think the trans needs to come apart for the 12psi pressure loss? 3% at stock pressure but what is normal loss at 150psi? 
 

im not going to hold you to anything just want your opinion. I’ve been in a dealership collision center for 20years but I’ve lost my mechanic contacts from the service side. 

 

This content is way over most peoples head and I have no one else to ask!

 

 

[Dynamic]

Yeah, 4.10's are a good choice. So many people run around with gearing that is way off.

 

As far as your transmission goes, I'm not really in a position to offer much by way of suggestions. There are simply too many variables in play. It's currently so far from the way I would set things up that without putting my hands on it, there are just too many unanswered questions.

[Kodiak24V]

8 hours ago, Dynamic said:

Yeah, 4.10's are a good choice. So many people run around with gearing that is way off.

 

As far as your transmission goes, I'm not really in a position to offer much by way of suggestions. There are simply too many variables in play. It's currently so far from the way I would set things up that without putting my hands on it, there are just too many unanswered questions.

Ok that’s fair. I appreciate all the help!

 

Ill probably pull it apart when I get to the commonrail swap. For now I’m going to see what happens with a couple more turns.

it’s not my daily so it can sit if something happens.