I tried contacting Frank from CPT for some help here, but I think he's cut off his entire customer base.

The rotor broke in my front pump a month after I got it back from Frank (4 bell housing bolts backed out, oops) and I'm gonna swap it out for a new one. I plan to swap out the valves and springs, but just want to make sure I dont miss anything.

Is there any other modifications to the pump besides the boost valve and slide spring in order to make it live in a high torque application?

Also, I've heard that the 13 vane pump is weaker than the 10 vane, which is easy to see when ya look at it, but I've also read that more vanes were added to reduce the harmonics in the rotor which lowers the chance of it breaking. Whats the verdict on this?

 

If your pump is a 10 vane pump originally, then you stick with the 10 vane setup. You can add the TransGo Hi-rev priming spring and steel rings, if you have shift points over 5,500 rpm. The 13 vane is not necessarily weaker, bit it is designed to work with a different slide and a different back half of the pump. There are different lead in and exit slots for the oil to feed the rotor/slide setup. The 13 vane is "quieter" and smoother at low rpm's. Not much difference at hi-rpm's. If you have a later pump that calls for the 13 vane setup, then use it if you want in your case. If you need to machine the pump, make sure you have .002" - .0025" rotor clearence, and .002" - .003" slide clearance. Frank and I never agreed on much of anything, but he was a good builder, but somewhat arrogant from what I have seen. I hope this helps.

 

Thanks a lot for the input, my experience with CPT makes me appreciate folks like you and the guy from performabuilt a lot more.

 

Make sure to replace or machine the pump when doing this. I have seen many guys just try to swap in new parts into a damaged pump. Not a good idea! The main thing to look at is the pressure regulator springs and the boost valve. Also as Dana mentioned the pump slide spring is an excellent idea. Just make sure that your new pump looks good and you should be good to go.

 

Thanks for the response. I had planned to buy an entirely new pump. The rest of the transmission is still good, I definitely dont want to risk tearing up the rest of it by tryin to re-use the old housing