The following are a list of items that I found on various websites that can be done to your BTR 4 speed transmission (fitted to EA to BA Falcons) to beef it up (mainly for high torque blown motors). If anyone can add anything please do. If anyone knows the exact weaknesses of this trans i.e what bands or clutches fail first with high torque, please specify.This is all I can find out at this stage.
1. Taxi spec bands and clutches are meant to be of higher quality than stock bands and clutches
2. Someone on this site stated that they have an Adjustable V8 valve body installed (I assume that the line pressure in the valve body is increased somehow. If anyone knows how to do this adjustable part please expalin) Increasing line pressure puts a tighter clamping on bands and clutches of the trans making it take more torque
3. A large transmission oil cooler is essential to keep the trans as cool as possible. Heat is a major killer of transmissions
4. A Magnafine filter installed inline with the transmission lines catches alot finer particles in the trans fluid that the standard filter cant. Its these small particles that make the solenoids stick and shifting problems occur.
5. The S5 resistor modification to increase line pressure via the S5 solenoid does NOT increase the overall line pressure in the transmission at full load, therefore does not offer any overall benefit for transmission strength.
6. Its one of the bands that lets go first (I dont know if its front or rear?)
Transmission strengthening is largely kept a secret by trans builders and its hard to get info on it. Nevertheless we gota start somewhere.
As far as I know the BTR transmissions are pritty much the same with the newer transmissions having adoptive shift. What ford has done to make the transmissions last is program the EFI computer to momentarely retard the timing on the engine between the shifts which lowers the torque and strain on the BTR auto....
Unfortunately I was looking into this months ago and have spoken to many reputable automatic rebuilders and every one of them has told me the same thing which is to get rid of the BTR auto if i was going to modify the motor. They made sugestinos of using holden Turbo 700 4 speed or use a C4, C9 or C10 auto. In the end I've decided to buy a manual gearbox instead and do a manual conversion.
Unfortunatly BTR doesn't build any performance auto parts for their boxes and no one in australia to my knowledge does either.
The only reason there is performance parts for the holden T700 and Ford AOD is because they are US made autos.
It's the front band that fails first and can damage the C3 drum it runs on.When this happens you lose 2nd and 4th..
The filter inline is a good idea since the fins in the radiator cooler disintegrate with age and go into the trans or block the cooler return.
Also during the rebuild pay special attention to the grooves in the shafts where the teflon sealing rings run.They do wear. There are oversize seal rings available to rectify this.
Turbotrana, The S5 solenoid only regulates pressure when a shift is taking place, this is the only time that the ecu outputs a current ramp to the s5.
All other times, ie when its in a gear and cruising, or its in neutral etc, the ecu only outputs 0.2A, which results in high line pressure. The only thing regulating line pressure in this instance is the pressure releif valve. (The current ramp varies between models but on average can range from 0.5 to 1.0 amps) The more current, the less line pressure.
Thanks for that 9psi EB. Do you think that increasing the spring pressure on the line pressure relief valve is the way to go for increasing line pressure in the whole tranny. I know this sounds obvious but may cause other problems. I see that the S5 resistor mod would be beneficial for saving the clutchs by changing quicker. I'm reading a Ellery publication "Ford Transmission Repair 1960 to 2001". In the BTR 4sp section,it states "
#2 clutch piston is prone to cracking around the centre bore, this will cause pressure to be applied to C4 clutch at the same time and burn out clutches". Does anyone know whether this was the problem with the early EA 4sp that was subsequently rectified or whether this is a possible problem on all of them. The book is not clear on this.
IIRC, the 1st 4speeds had problems with a circlip jumping off, but not sure whereabouts.
The s5 solenoid controls line pressure with in the whole trans (i think) so there wouldnt be much point in playing with spring tensions.
I dont know how the valve body would hold up with pressures beyond what the releif valve bypasses.
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