Engine/Transmission (1994 - 1998) #6 too much for transmission

[tgrfan2]

I just put a #6 plate in my 98 automatic 3. 54 gear. I debated on the #10, but had good results with the #6 in my 95 with stock transmission and did not need more rpm. The 98 was strong before the plate, but real strong now. I put #6 plate in same position as OE plate. Problem came towing my fiver(13K#) for the first time today. The TC starts slipping at about 24# boost at any speed, but I tried to keep it above 2000 or 70mph and that did not help. It never slipped stock in over 4k miles pulling the same route. transmission is stock with 118K but has been serviced regularly. Temperatures never exceeded 120 on a 65 degree day in 100 miles of towing. My probe is in the pan. I just backed off on big hills today, but I was wondering if going back to the old boost fitting or sliding the plate back would help until I can get a transmission rebuild.

 

[SEmerson]

Unless you can aford a trans I would slide it back way back. A auto won't slip much before it is gone.

 

[tgrfan2]

Yes, I am going to start sliding it back this weekend. I hope to get the pressures checked next week. Sure will be glad when I can see what the engine really has with the plate where it is. If the pressure is OK I am going to check the fluid. I started thinking that I may have overdosed it with lubegard. Bill K told me several years ago that was possible when my 95 seemed to be slipping, but running cool. When I serviced it in December I used the +3 ATF made by Exxon.

 

[98rammer]

the stock governor winds up a little more in the 180pump over that 160pump so it'll allow better top end fueling. up the line pressures 3 turns and if need be, add an unlock switch.



Tom

 

[Jim Fulmer]

A #10 is much more friendly with a stock auto than a #4,5, or 6! It has nothing to do with that chart, it's about how much fuel and when it comes in, the 10 if setup correctly will come in later when you have some pump speed for the transmission, and yes it needs Gov springs to get the most out of it as do all of them... ... . like timing they all need it!



Jim

 

[tgrfan2]

I did the transmission adjustments on last service in December. They helped considerably as far as the feel of the shifts. I had started to put an unlock switch on as I have one on my 95 because the computer is brain dead. I just have the feeling I am not getting enough pressure to the TQ though. I am going to check with my transmission shop today to see about checking the pressures next week. I will tow the fiver about 80 miles this weekend and try to get a better feel of when it slips.

 

[Jim Fulmer]

Get a pressure gauge 0-160 and 10-12 ft of high pressure hose and do the test your self, the ports to test are on DTT's site, front port is for servo middle one is for line pressure. The #10 is fine as long as you don't get greedy, this is also Piers's favorite plate..... that's were I got the idea!



Jim

 

[98rammer]

the way my truck is set up right now, i can still slip the transmission, but not too bad over the stock pump. however, i'm putting out about 32 pounds of boost worth of fuel so maybe 230-250ish hp. (marine pump acts funny). the transmission's holding it fine and i can tow a small trailer without it slipping too much. however, when i had the stock pump with gsk, #0 plate, stock timing, etc. i had to go up the hills in third gear at 2800rpms or it'd just slip. hence, yeah, keep those rpms up there and she should hold... . for a bit.

 

[tgrfan2]

Thanks Jim for the suggestion. I got the gauge kit today. Will have to wait until this weekend to test. I did a little more testing with the fiver last weekend. I did not get any slip in third with TQ locked. I could feather the throttle and not get slip in OD lock up at 2000 rpm+ and 26# boost, but if using the cruise when I hit a hill it would slip quickly. No slip in OD when I kick the empty truck.

 

[tgrfan2]

I had a chance to use my NAPA pressure test kit today. Everyone is right in saying you need 10-12 feet of hose. The six feet is just enough hose to aggravate you! I tested the 2 ports on Bill's DTT page that are described as Main Line Pressure & 2nd Gear Release before I lost my religion. These pressures were taken after at least 30 miles of driving. Gauge temp was reading 110 with ambient air at 65-70 degrees. The pressure read at the line pressure port was 58# at idle and 105# at WOT locked in 3 or 4. When the transmission unlocks the pressure will spike another 15-20#. At 70mph and 2000 rpm the pressure reads 75# in 4 locked. Basically the same pressures were seen in the second gear release port in 3 or 4. I will get some more hose and swivels before another check, but do you think it is safe to go a few more rounds on the adjustment screw?

 

[Jim Fulmer]

Sound like stock pressures, the main thing your looking for is a difference between line and front port, this is were internal leaks show there face, if the difference is more than a few percent then the servo is bypassing fluid, a few things to remember are the same pressure circuit that apply's 3rd also releases second, if the timing isn't right then you either have 2nd gear band and the direct clutch on at the same time..... not good, or you will get a flash of RPM going from 2nd to 3rd... . to much time, also whenever the converter locks or 4th gear is picked up you will get the rise in pressure but not both, if your in 4th and the converter locks it will not boost pressure, it already happened on the 3-4 shift, you can learn allot watching guages, you will see a flicker of pressure then the gear change will happen, the flicker is the shift valve moving.



You could up the base line pressure some as long as you don't put it in limp mode... ... direct clutch killer!



Jim

 

[tgrfan2]

Front port?

Thanks Jim, I hope a little extra hose will help me understand your description. I could see some of the fluctuation you are talking about, but need to get the gauge a little closer to my old eyes! I am glad you mentioned the 4th gear and lockup pressure. I was wondering about that. When you say front port, which port is that on Bill's picture? Thanks again.

 

[jimk]

95 pressure

I have a 95 with the #6 fuel plate slid all the way forward along with 17. 5 deg. of timing. My pressure for at idle is a lot higher than 58. The way I got the higher pressure was to make a bracket and hold the throttle lever from going all the way back to where it usually goes. The result was higher pressure and extended shifts. I have the lever set to have a minimum of 1800 rpm shifts. This did not help the high rpm oil pressure however.

I have not had any problem yet. I would never use full throttle when towing heavy loads. I use the rpm and the manual shifting of the transmission. I don't like to do that but the transmission still works as good as it did when I bought it. Or a good as a stock transmission. I don't let the hammer down when I am towing as I dont think it could take it. jimk

 

[tgrfan2]

I have been running a #6 in my 95 for 85K and pulled a 9K TT for a number of years. I could always set the cruise and it would hold in lockup at 70-75 without slipping. I know i am towing heavier, but I am a little surprised at how easy the transmission slips. I have always done like you and shifted manually. I guess I will do the same with this transmission till it starts heating up or slips under "normal" driving.

 

[Jim Fulmer]

When you say front port, which port is that on Bill's picture? Thanks again.



The second gear release port, same circuit as the 3rd gear(direct clutch) apply circuit. In a truck like mine you can really see why the direct clutch catches so much abuse, on the street 2nd doesn't last long as it's usually chunking the tires, 3rd is were it really loads the truck and suspension up and starts fighting for life.



Jim