Gx390 torque converter mounting

[Branderino]

Just got a torque converter for my gx390 but the backing plate bolts are a different thread pitch than the motor. Can somebody tell me what bolts I need to get to mount the backing plate to the motor?

 

[Denny]

Ones that fit the motor.
Actually the proper way to do it is use a 40 series with a jack shaft.

 

[Earthy]

I believe the mounting bolts are 5/16"-24 x 3/4" bolts (according to BMI). I've also run into metric size bolts on some of the clone castings.

 

[madprofessor]

My experience with Predator motors has been that the supplied bolts never screw in real easy, maybe even feel wrong. I've just oiled the threads and put them in the way I use a tap, CW a little, CCW to clear threads, repeat, repeat, .......................

 

[panchothedog]

Earthy is correct on the bolt size, at least on the 212 cc predator. I have built two of them in the past year. Kinda strange how a Chinese motor with everything being metric uses SAE bolts there. BTW the end of the crankshaft is also the same.

 

[karl]

My experience with Predator motors has been that the supplied bolts never screw in real easy, maybe even feel wrong. I've just oiled the threads and put them in the way I use a tap, CW a little, CCW to clear threads, repeat, repeat, .......................

You mean supplied with the torque converter? Ive never seen bolts included in the box of a predator.
Ouch yeah sounds like ya jammed a M8x 1.25 fastener into a 5/16 fine thread hole. Would not recommend doing that.
If they do not thread in by hand something's wrong.

The crankshaft is 3/4in, and the mounting flange is a universal standard. So standard keyway, mount threads and crank bolt/threads.
A little counter intuitive , right?

 

[RustyShackelford]

I'm also having an issue with with torque converters on the GX390. Every 40 series drive clutch i can find has a built in key that is only about 1/16" deep. The keyway on the motor is 1/8". So, there's slop in the keyway that will eventually cause damage. Can anyone recommend a clutch that has a 1/8" key that will fill the entire keyway? Ideally the clutch would have a 1/8" keyway as well, so i can just use a .25 X .25 key and be done with it.