I have put together some information that will help a few people at home to do a basic stage 2 style shift kit and some other improvements if they want to have a tinker themselves.
The information is primarily for the series 3 box through to series 6 as they are the majority, series 1 having a cable for kick down and series 2 being mostly for HQ, LH and the 173 LJ Torana.
The series 2 box codes are HP, HO, HT, HN and HM. Any other box codes starting with “H” will be a series 1 with cable kick down located just behind the filler tube.
To carry out these modifications you will need to remove the pan, filter, valve body, servo cover, reinforcement plate and finally the transfer plate.
There may be check balls above the transfer plate; there could be 2 balls in some models or 1 in most cases or none in a couple of models. They will have left witness marks on the plate from where they have been so there is no excuse for stuffing up their locations if they are present. Use a bit of petroleum jelly to help locate them when you re assemble the transmission.
In most of the late model Trimatic’s there was also a servo quick dump valve which is plastic; it clips into place in the transfer plate. If yours is broken then it will be very harsh on kick down or a part throttle down shift and you may find part of the valve in the servo cover when removed.
Firming Up The Shifts
To make the shifts firmer, the easiest way is to increase the oil supply to the clutch.
To affect the 1-2 shift quality all you need to do is increase the clutch feed at “A” indicated on the drawing as the 2nd Clutch. You don’t need to increase this hole by much to make it chirp into second, from factory it should be around 5/64, drilling it to 3/32 will make it a nice firm shift maybe with a chirp at full throttle depending on the transmission condition. Drilling to 7/64 will be a lot firmer again and if you just don’t care and want it hard, drill it to 5/32.
To get it any harder you will need to remove the accumulator and do other modifications that I’m not going to go into on here.
To affect the 2-3 shift quality then you need to increase the size of the feed at “B” indicated on the drawing as 3rd Clutch. I generally drill this hole to the same size as that on the gasket (5/32) which will be a very firm shift, for those with horsepower it will cause the tyres to spin easily into top gear.
Full Throttle Up Shifts.
When you kick the transmission down, detent pressure in the auto dictates when the transmission will change back up at full throttle, if your car changes up at say 4800 rpm at full throttle and that is not high enough for you. You can alter the detent pressure by changing a spring which may then alter it to change at 5500 rpm or if you can’t get the shift points high enough with the springs available then shimming can also be done but care must be taken.
Changing the detent pressure will only change full throttle upshifts and will not affect shifts at normal driving throttle openings. Valve and spring number 23 and 22 in the picture provided.
Detent Pressure Regulator Springs
Colour Spring Rate lb/in. Pressure
Pink 7.84 70 psi
No Colour 9.4 80 psi
Dark Green 9.4 85 psi
Orange 9.4 75 psi
Yellow 7.84 65 psi
Plate.jpg
To remove the pins retaining the valves in the valve body, use a suitable sized pin punch and knock them out from the top of the valve body. Re-install them from the underneath side with the swaged end in last and tap home with a small hammer.
Fine Tuning.
When you want to get more in depth or start fine tuning your Trimatic then we can look at some other aspects such as:
Modulator valve and sleeve: There are several different modulator valves and sleeve combinations that also affect line pressure, at higher road speed the governor supplies pressure onto the modulator valve to help reduce modulator pressure and lower line pressure slightly to improve fuel economy. They are a matched pair and must be replaced as a matching pair. It can also stretch out your shifts slightly by going to a less reactive valve and sleeve.
Shift Control Valves: These valves can have slightly different diameters from model to model and can be interchanged to suit the power curve of your motor and diff ratio, it’s these little changes that can make a real difference as to how the car drives. These valves are also a matched pair with their sleeve and must also be changed together, you still use your original springs, only the valve and sleeves are altered.
Shift Control Valve.jpg
Shift Control Valve/Sleeve Identification
Shift Diameter "A" Diameter "B" Colour
1-2 0.6004" 0.4246" Orange
2-3 0.5402" 0.4246" No Colour
1-2 0.6004" 0.4996" Yellow
2-3 0.5602" 0.4246" Black
1-2 0.6152" 0.5214" Dark Green
I won’t go into altering the Accumulator control valve or changing springs as there are a few different ways to do it and really is something that you would only look at when you go to a full manual valve body and eliminate the accumulator completely. Commonly a steel servo piston would be used as well.
The high and low speed timing valves are also not altered unless there is a problem specific to their function like a slip or a clunk on a 3-2 coast downshift, harsh 3-2 part throttle downshift above 60 kph. Or flaring on the shift when the oil level is correct.
Raising the line pressure by changing the boost valve and sleeve to a 5.0 litre version and changing the regulator valve spring can only be done when the transmission is in pieces as the regulator and boost valves are located inside the oil pump body and they cannot be accessed like a THM400 or 700.
If your car shifts down at part throttle too easily without kicking it down or it does not part throttle at all and will not shift down unless kicked down then altering the 3-2 control valve spring is the cure(19 & 20 in the picture). A lighter spring increases the sensitivity and a heavier spring will reduce the sensitivity.
3-2 Control Spring Identification
Colour Spring Rate Pressure
Pink 2.4 lb/in. 60 psi.
Violet 3.4 lb/in. 67.5 psi.
Blue 3.4 lb/in. 75 psi.
Dark Green 5.1 lb/in. 82 psi.
Yellow 5.1 lb/in. 90 psi.
Light Green 5.1 lb/in. 93 psi.
Orange 5.1 lb/in. 97.5 psi.
Red 5.1 lb/in. 105 psi.
Valve Body.jpg
Hope someone can get something out of this.
I just copied that from another forum. Could someone please help me. apparently my trimatic has a "shift kit" in it (was told this when I bought my car) It doest change gears hard at all. Actually its quiet poo. doest chirp gears.
To do this all I have to do is drill out the 2nd and 3rd clutch holes I’ve circles in yellow?
What is the 3rd clutch hole circled in red??
So its as simple as drilling 2 holes and I’ve got myself a “shift kit”?? also what hole size would you recommend? I know there is 3 different hole sizes noted but what is the best?
Thanks heaps
Plate.jpg
Edited by injlc304, 20 December 2011 - 12:42 PM.
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