it really does depend on how much power you are puting through it though, Remember Heat is the biggest killer of Auto's, More regular servicing, A good Tranny cooler (biggest you can go) will help it live longer.

A c4/c6/c10 are stronger, smoothness isnt comparable, but the strength they have (and can be built up to) is 2nd to none. Unless its a 727 torqueflite.

Are torqueflites that much stronger than a C series box? But having said that I think the gm powerglide is the mother of all auto boxes.

The torqueflite 727 , especially the ones behind the Wedge 440's, 392 and 426 hemi's were near on bulletproof from factory, if you did a gearbox, it was due to incorrect assembly more often than not.

Compared to a powerglide off the shelf, I'd say their stronger, though beefing up a powerglide would be much stronger than a beefed up 727, maybe just though.

Both great boxes, stil rather the third gear though.

With forced induction . The vacuum modulated auto's would have to be manualised..
Only the electronic auto's can be full auto...
A G.M T350 is a good option ??
C4 with 2.9 / 3.08 gears 2800 converter would still spool a turbo nice and use it's high mid rpm torque....

Lol mine only lasted 2 weeks with only 140,000 on it. end quote


Yeah i was trying to look after my box no sideways action or anything.

Bloody s**t auto stuffed up on me when i was driving away from a set of lights, first idea somthing was wrong was when i was hand timing a run and shifting at 5500rpm and it sort of went funny like it would hold a gear than flare up then grab it again.

I always looked after her but i guess it couldnt handle the extra grunt

I feel sorry for you guys blowing up perfectly good boxes so I will let you into a secret mod.

The BTR 4 speed is actually a very good box and can take alot of power if you do a very cheap mod to it. Otherwise it flairs when turbo power is put thru it and it stuffs it up very quick.

Now when you do a shift kit it tightens up the shift which is good, but because it still uses the S5, S3 and S4 solenoids in the shift, you can only speed the shift up so much.

The next step in speeding the shifts up in the BTR is not to use the S5,S4 or S3 solenoids at all. These solenoids are there primarily to make a nice shifting box for the pussys out there.

With the mod the box shifts hard but not that hard that you cant drive with it. IMO it shifts very good and even better than using the shift kit on the hardest setting.

Now you cant just disconnect the S3 and S4 solenoids as it will put the ECU into limp mode.

What you do is that you cut the wires to the S3 and S4 solenoid at the harness leading into the computer (you need to look up a wiring diagram to work out which wires they are. They are different for EA-ED and EF onwards) and put a dummy load to earth. I use 2*54ohm 5 watt resistors in parellel which would give 27 ohms to ground, so you could use a single 27ohm 5 watt resistor to ground to do the job, one for each wire on the computer side.

I ran my turbo ED falcon with 400RWHP and the box shifted fine at full load.

There is really no reason to change the BTR 4sp with this mod and along with other mods that can be done with this box 500ATW in something like a light EA-ED with some durability is possible IMO.

Now this box can take a high load in 1st, 2nd and 3rd BUT NOT 4th.
So if you want it to live dont load it up in 4th with a turbo.

Try it out and see how you go

turbotrana do you have any info for the s5 , im trying to control it with PWM and have the best of both worlds , my box controler is controlling my box and changes and is drivable but whould like toget it to shift smoother at light cruise , cant get the PWM outputs just right eg. 0%-100% , freq??? and when it actually actervates , my controller is working all 7 soleniods and the factory ecu is gone.

any tech on the btr 91le 93le would be great

thanks paul

turbotrana... that sounded so much like a "intake mod chip! increase your BHP!!!" thing lol sorry

I dont know how you would control the S5 with the aftermarket controller. Which controller are you using and how easy was it to program? Did you program the S3 and S4 soleniods to work. How sophisticated are the shifts.

For guys using both original ECU to control the trans and an aftermarket one for the engine, what you can do is have a relay connect the S4 and S3 to ground via the resister on one side and the original connection on the other side. This way you can program for normal shifts under normal driving and hard shifts at what ever point you want to program it i.e RPM,PSI

Last edited by turbotrana on Fri May 30, 2008 12:55 pm, edited 1 time in total.

No, its not an intake mod chip type mod. When/if you learn a bit more about cars you will understand the importance of this mod to the turbo guys.

Screw the S5 in 3/4 of a turn.

you are talking about the BTR?
err how do you do that? they have no threads, all the solinoids in the valvebody push in and a clamp holds them in place!
hope you are just having a lend

No he's not having a lend. I had to to do this to my car as the auto is on its way out (has an internal oil leak).
on the end of the s5 solinoid there is a allen key slot, turn it for more line pressure, all btr's from AU onwards have this...

thats better, NOT the solonoid!!

I had some initial issues with mine in the ute but a full service, all internals adjusted/shimmed to correct clearances, Penrite Synthetic oil then the shop fitted something along the lines of what turborana has mentioned in this thread. It now has variable shift quality adjustment however firm I want, and it is seriously awesome now Nuthin bad about the BTR once this little bit of attention has been lavished on it and I would agree with others here who suggest it works really well when subjected to big power gains.

Also the mod that badcooky suggested is the other option if you have the pan off.