Pete K.....Help!

OK, checked line pressure at 165 F Tranny temp 80 to 85 psi at idle (850 rpm) in P, D or R.

150 psi at approximately 1,500 rpm.

I really need to check the line pressure when tranny temp gets above 206 F thats when the forward clutch appears to disengage at idle in Drive when stopped, then it pops back in when the throttle is opened a little wider. Only happens when tranny is above 206F.......

Some of the many mods:

2,800 stall protorque lockup converter, LT-1 383 w/ GM Hot Cam, Ported & Polished Heads, 850 RPM idle. Have an added tranny cooler + dual core alum radiator cooler

13 vane pump that I rebuilt.

Transgo HD-2 shift kit. Raptor Torque Drive Input Drum and timken bearing reaction shaft carrier. Beast Shell. .030"Low Reverse piston hole drilled and reverse check ball removed from rear of case.

All new solenoids and wire harness.

Any ideas what could be causing this?



What a PIA this is

 

Pete where are you tonight?

 

Very seldom he spent time on CF at this time b/c he has to woke up early for work, but iam sure asap he will be here to comment, may be u can pm him.

 

Thanks, I PM'd him yesterday

 

That is definately not normal, or a typical complaint. I will stick my nose in the flow chart this morning and see what may be the cause.

 

Thanks in advance Pete.

I'm betting it's the super strong 14 anti-centifugal springs I put in the input drum so the forward clutch won't apply by itself at high RPM. This comes with the Transgo kit in a little box.

I bet they're just strong enough along with the slightly smaller forward clutch piston (modified by PATC to fit over the input shaft steel retained band) to overcome the piston apply force at idle pump line pressure.

Also, probably the pump halves being aluminum expand enough at 206F to allow for excess clearance between the steel pump rotor and blades and the casing. I'm thinking the guy whoi sold me the ebuilt pump case just polished the inside wear faces...I should have checked the pump side clearance with a feeler gage and straight edge...Oh well, lessons learned....hindsight is best sight...., etc. etc. etc.

Let's see what you come up with Pete....

So far I'm thinking I can just lower the milliampere settings at zero throttle on LT-1 Edit from 1080 to around 950...the next at 6% throttle is around 819, maybe this will give me that little bit of extra pressure at idle to keep the forward clutch applied above 206F.

 

OK, spoke to Larry at Transgo.

Seems like when I tore things apart to put the Helicoil inserts in the case, I decided to put the anti-centrifugal spring kit in the input shell assembly. Took out the 3-4, forward and overrun clutch packs, then using spring compressor the retainer clip, and spring retainer...changed these.....that's the problem, I closed it all back up changing only these springs to stronger ones. Larry says the 3-4 return springs below the forward and overrun clutch assembly work with these as a balanced set and need to be istalled. So, I'll be taking the tranny out again to install the stiffer performance 3-4 springs I didn't install earlier. While I have it apart, I'm also going to check the pump insternal side clearances and also am going to send my protorque out to have it's lock up clutch and bearings freshened up.

Any comments welcome

 

Now I'm going to comment on my own prior post...go figure

I looked at my GM service manual specifically the input drum cross section that shows all the clutches, pistons, etc.

The stiffer forward/overrun clutch return springs I put in don't in any way interact with the 3-4 return springs that I can see

There is an extended rim at the base of the forward piston that bottoms on the center hub of the input drum so it can push on the 3-4 clutch piston. The 3-4 clutch return springs are smaller and weaker so they don't push up and unseat the forward piston housing.

Sorry, I disagree with Larry of Transgo...don't think that's my problem and these guys are supposed to be the experts!

I think I'm going to tweak my LT-1 edit program to get a slightly higher line pressure at zero throttle opening before I tear this thing apart again....I will evetually tear it down, but just want to experiment a little first

 

I would tend to agree that the mismatched spring combo would not be the cause. You are correct that the forward piston returns and rests on the drum lands.
When you get back into the pump, mic the height of the pump slide and the pump rotor. They should be within a couple thou. I have seen the aftermarket stuff vary occasionally.
Something to check anyway.

 

Hey Pete, figured I would try adjusting my pressure force motor as a last resort.

Put it on my lift and drained the fluid after work, dropped the pan, looks really clean

Turned up my adjustable force motor about 1/4 turn clockwise and locked down the locknut. Reinstalled my pan with a little new red silicone sealant over reused new gasket that was still on tranny case

I'll torque up the pan bolts later tonight, fill it and check the line pressure.

Did note in my assembly notes when I dissassembled the valve body that part #373 the 1-2 accumulator valve bore plug was missing when I dissassembled it. I didn't put in a new one since I figured it had driven fine without it before.

Do you think this missing part could be causing my problem?

Nix that question, found out that the 95 version is a one piece with no valve bore plug, it's part of the valve bore insert casting.....do you agree?

 

So I reprogrammed my ECM tonight with LT-1 Edit. Lowered the zero throttle tranny milliamps above 56 C (132 F...I wanted a little insurance ahead of my 206F problem temperature) from 1074 to 918 see chart below (the first row is the column header which is % throttle opening, all the other numbers are the programmed force motor milliamp settings):

% Throttle 0___ 6__ 12__ 18__ 24 30 36 42 48 54 60 66 72 78 84 90 96
-40 Deg C 1074 879 879 879 840 801 781 742 684 645 605 547 488 410 332 215 215
-28 Deg C 1074 918 898 879 840 801 781 723 684 645 605 547 488 410 332 215 215
-16 Deg C 1074 918 898 879 840 801 781 742 703 645 605 547 488 430 352 254 254
-4 Deg C 1074 918 898 879 840 801 781 742 684 645 605 547 488 410 332 234 234
8 Deg C 1074 918 898 879 840 801 762 723 684 645 586 527 469 410 332 215 215
20 Deg C 1074 820 781 742 703 645 605 566 508 430 371 313 234 137 59 59 59
32 Deg C 1074 820 781 742 703 645 605 566 508 430 371 313 234 137 59 59 59
44 Deg C 1074 820 781 742 703 645 605 566 508 430 371 313 234 137 59 59 59
56 Deg C 918 820 781 742 703 645 605 566 508 430 371 313 234 137 59 59 59
68 Deg C 918 820 781 742 703 645 605 566 508 430 371 313 234 137 59 59 59
80 Deg C 918 820 781 742 703 645 605 566 508 430 371 313 234 137 59 59 59
92 Deg C 918 820 781 742 703 645 605 566 508 430 371 313 234 137 59 59 59
104 Deg C 918 820 781 742 703 645 605 566 508 430 371 313 234 137 59 59 59
116 Deg C 918 820 781 742 703 645 605 566 508 430 371 313 234 137 59 59 59
128 Deg C 918 820 781 742 703 645 605 566 508 430 371 313 234 137 59 59 59
140 Deg C 918 820 781 742 703 645 605 566 508 430 371 313 234 137 59 59 59
152 Deg C 918 820 781 742 703 645 605 566 508 430 371 313 234 137 59 59 59

Note that I only lowered the ma numbers to 918 (in bold) in the 0% thottle settings 56 degrees centigrade and higher tranny temperature.

Only time will tell.

 

Do you think this missing part could be causing my problem?

Nix that question, found out that the 95 version is a one piece with no valve bore plug, it's part of the valve bore insert casting.....do you agree?[/QUOTE]

I just discovered this same info in an old gm book I had.

 

What do you think of my reprogram fix Pete?

 

I honestly do not know. I have never played with the programming. I am very curious though

 

It's quite straight forward actually.

The force motor that varies the transmission line pressure in a 4l60E is controlled electronically by the car's computer.

There are different modules that you can edit, ie, engine fuel, timing, cylinder size, transmission items such as shift speeds, firmness of shifts, TCC apply and disengage speeds, etc. There are tables of data that you can edit in each module. The table I edited above only changes the base line pressure for a specif throttle opening % and transmission temperature. If you can fix an automatic Pete this would be cake for you to understand

I don't have the GM service manual in front of me, but each of the ma readings correspond to a given pressure.


It's quite interesting to Look at.

I can email you a copy of LT1-Edit and my cars data file so you can see what I'm talking about.

LT-1 Edit is a shared program, it's the program that loads it into memory in the car PCMPROG that's licensed.

Since I know everything is solid pressure wise at 6% throttle opening, I'm basically just telling the force motor at tranny temperatures above 56C to set the line pressure to what it was normally set at for 6C and below.

I'm only changing things just a little, then I'll drive it and get it hot to see if this corrects it.

 

 

Good news I assume?

 

No, sorry, snowing like a bear here in Northern Westchester NY today.

I'll be testing the trans hopefully next week.

I took off from work.....relaxing.

Am going to change my stearing rack with a GM rebuilt new one, new pressure hose and rebuilt pump this afternoon. I also have a new set of armoroated Pacesetter shortie headers to install to replace my 6 year old cracked ones...they leak and make me go lean

 

Yes, the TransGo hirev springs that go in the input drum are a balanced set, but that should not be the problem here, unless there was a mistake in installation. Did you add the TransGo No YoYo steel rings and priming spring to the front pump on the build? What rotor and slide clearance did you wind up with? Did you add the white spring from the TransGoHD2 Shift kit to the Actuator valve?

 

BTW, this was my first rebuild

No YOYO ? What's That?

Stronger slide spring and high speed vane rings, Yes

Did you add the white spring from the TransGoHD2 Shift kit to the Actuator valve? Yes

I had CTperformance transmission of California prep a used replacement pump front and rear half...they diamond resurface/cut the mating faces of the pump.

No, this dummy didn't check the pump side clearance to the slide or vanes, but I'll sure check it the next time I rebuild one.

I'm waiting for a Tech 1 I just purrchased on Ebay, then I'll check the pump pressure at stepped pressure motor settings.

BTW, car hasn't been used now for about a month...just changed out my headers and am also waiting on new air injection pipes.....was going rich due to air leaks affecting my O2's.