Hello everyone, I was trying to assemble my pump with the rebuild kit and it just occurred to me I wonder what the rotor to vane clearance spec should be. This pump rebuild kit is really worrying me!!! in comparison to my old and new pump parts I measured a quite a difference in terms of clearance. I attached some pics of measuring of the above mentioned clearance and I could not believe the difference. I know it doesn’t sound like a lot, my gut feeling tells me that the aftermarket rotor seems inferior dimensionally to the 200k rotor that I am replacing. I hear that the pump is very critical to the line pressure and don’t want my transmission to go blow up into crap. Also the big nasty double spring is impossible to get into the pump body

 

Ok I think I have an understanding as to why I am seeing a .003 to .0015 difference. Im guessing room for thermal cycling and expansion. I guess tight tolerances are not always better???

 

The tight ones are normally factory ones. I try to get them on the tight side, however I cannot always do this. You need to re-install the little teflon and rubber seal that you have in the slide here that sits against the pump. You have it in backwards.

 

Ok thanks for pointing this out about the seal something didn’t feel right. Should I be ok with this pump kit ???

 

From experience have you had problems with line pressure. Maybe I’m worrying over nothing???

 

Maybe a boost valve might help??

 

You want the clearance to be .002" - .003" for the rotor and slide clearance. Install the rotor in the pump pocket and check for clearance using a depth micrometer or a stiff straight edge and use a feeler gauge to check the clearance. Do the same with the slide. Too much clearance, sand the pump body. Too little clearance, sand the rotor and slide. Finish with everything being sanded smooth. For rotor and slide, finish with 600 - 1,000 grit sandpaper. Pump body, finish with 320 - 400 grit sandpaper.

 

Attached are some hand written measurements, I’m gonna be honest I know your well known on this site of building transmissions. The pump surfaces seem very nice besides the pocket I have asked a local guy in this area that remanufactures torque convertors and rebuilds transmissions and thinks it is not necessary to sand the parts. Again no offense I’m just kind of ocd. Can anyone else share a similar honest experience

 

Have you installed the parts into the pump and measured the clearance? Where are you with respect to the 0.002 - 0.003 clearance?

 

I went back and installed both the old and new pump parts in the pump body. For a straight edge I used the ruler portion of my Mitutoyo digimatic caliper which has a consistent width all along the length at several points within 0.0003, so I guess it’s pretty straight. I measured this with my Fowler 1/10 micrometer which was calibrated with a standard that I also verified with a very expensive Mitutoyo digital micrometer that has been officially calibrated by a company that does this at my work. I used a feeler gauge at multiple points around the rotor and slide and I could not get a 0.0001 feeler gauge on both my old and new pump parts. Also precisely machined parts must follow a Ra surface chart (roughness average chart) look it up on google. By using sandpaper you actually alter the surfaces that were achieved by machining

 

Sorry I meant 0.001 feeler gauge .

 

1. Both the old and new parts when installed in the pump body, have less than 0.002" - 0.003" clearance.

2. Your old rotor and slide are "thicker" than the new rotor and slide by 0.0007" and 0.0002", respectively.

3. Even though the clearance of the new parts doesn't meet the 0.002" - 0.003" desired clearance, their installed clearance is greater than the old parts.

4. Even with the tighter than desired clearance (0.002" - 0.003"), the old parts and the pump were working OK (assumption).

5. It seems you're hung up on the sanding/polishing/honing of the parts to obtain the 0.002" - 0.003" clearance.

I would install the new rotor and slide "as-is", clamp and secure the two pump halves together and call it a week.

 

I have found that running .001" clearance seems to work okay with the .421" boost valve or smaller. When going to the .500" boost valve (now having more pressure) I found that the slide with the .001" clearance would wear badly and the rotor would sometimes gall the pump. That is why I said .002" - .003" clearance. I shoot for .002" on the rotor and .003" on the slide. I have been doing this since the late 1990's. Some people have told me they have run closer clearances successfully, and that's good. I have found what I have said to work for me very well.