I am in a hurry to assemble my race car by next week. I am installing a lockup a904 transmission from an 83 truck. I think it's actually considered an a999, for those who like to be correct about it.

I've been told to stay away from the lockup converter for racing. The advice I was given was to swap the front shaft, front pump, and converter from a non-lockup trans. I do not have the time or experience to do this procedure yet.

I would like to find a way to disable the hydrolic lockup feature. I would expect there is a spring or a port which can be changed in the valve body to disable the lockup. Anybody know?

I don't want the converter to lock up while I'm still in first gear! I don't really care if the lockup ever works, just as long as I don't destroy the transmission at the track. If there is a quick fix now, I can rebuild the nonlockup transmission over the winter. Otherwise, should I put the tired old nonlockup one back in for this race?

_________________
1980 Aspen 225 super six

I wouldn't worry about it. The converter will not lock up in any gear, except high, and it will not lock up at wide open throttle.

_________________
Charrlie_S
65 Valiant 100 2dr post 170 turbo
66 Valiant Signet 170 nitrous
64 Valiant Signet
64 Valiant 4dr 170
64 Valiant 4dr 225

You can disable the hydraulic lockup the same way you disable the accumulator for firmer shifts: Drop the pan, remove the lockup spring, and replace it with a spacer that holds the lockup piston in place and doesn't let it move.

_________________
一期一会
Too many people who were born on third base actually believe they've hit a triple.

True, or just find a rod that fits inside the spring so you can leave the spring in there. Then in the future when someone needs it to lock up all they need to do is remove the rod and not have to search for a long lost spring.

Great, the transmission is already drained, because I installed a new filter. I'm going to do it now while it's easy to reach. I have a transmission manual which should provide pictures and diagrams, so I just need to read through and find which spring controls the lockup. Thanks for the suggestions!

_________________
1980 Aspen 225 super six

Reading my techtrans manual reveals no listing that the A999 was every used behind any slant six in any application car, truck or otherwise. Now, the manual could be wrong or I could be reading it wrong, but this is the info I'm getting out of it. The A999 was only used behind a 318 (or larger?)

So, sorry for the B.S., I believe I've got a good ol 904, and I've now disabled the lockup with a spacer in place of the spring. I made the space by cutting a short section of 3/8 fuel line to replace the spring. The valve won't move, and therefore the converter won't lock, but I could re-install the spring if I ever wanted. Only took a half hour because the transmission was already drained and out of the car.

_________________
1980 Aspen 225 super six