ok, I run a Midwest modified, roughly 350 horse, the problem is, we break our planetary in our transmission every other week. The pins that hold it together get pushed out somehow??? I am wondering if ANYONE at all has any tips or ideas on why we are breaking them, our first thought is that it was bottoming out, but that cant be the case, but it really seems like it would be, our driveshaft angle is 9 degrees, is that too much? 5 degree pinion angle, anyone have any tips at all? please help, 6 transmissions in 12 races..Thanks
take a look at this video on rebuilding the powerglide planetaries.. http://www.youtube.com/watch?v=5lYDv__qoXQi have a few thoughts... when you look at the screw retained pins...i would really think about picking up some brass shim stock selection and a washer punch from harbor freight like this 9 Piece Punch And Die SetLifetime Carbide - Item#95547with this.. and a pack of brass shim stock in various thicknesses.. you could make your own selective washers for the bolt in pins.. to prevent collapsing the case and allowing the bolt to be properly torqued.. Grainger Item # 3L521 Price $64.35 Brand PRECISION BRAND Mfr. Model # 17545i have wanted for a LONG time.. to create a super strong steel band that goes around the ring gear housing to prevent it from spreading under EXTREME loads.. it would have to be cut from some exotic piece of DOM super steel tubing. these are just thoughts.. and its not my video. but it sure is informative. how are the input shaft bushings that are way deep under the center gear???how is the clearance between the input shaft and the bushing that they showed being removed with a 1/4" pipe section and tee..
if that bushing is worn deep inside the planetary.. the input shaft is going to wobble around and gear life is going to be very short.. please let us know what you find.. or take some pictures and use photobucket to post them here..
Thanks for the reply, I watched it, everything they do, we try, we even tack welded the pins in place, but for some reason they STILL get pushed out, im wondering what could possibly cause that? could it be the driveshaft doing something? maybe the driveshaft is becoming a lift bar? or the degree of the driveshaft is too much (its at 9 degrees)? After 2 races though, the planetary is in pieces, gears and all. We just cant find out what would possibly be the cause of the pins being pushed out, people have said we are bottoming out the driveshaft, but that cant be the case.Thanks
if the transmission is OUT... and torn apart.. check for signs of wear on the sides of the tail housing bushing and the rear case bushing.. how about this...take the rear springs out with the back of the car up in the air.. work the suspension up and down thru the full range of motion the shocks will allow...check the depth the drive shaft yoke slips in... put an Oring on it... slide it forward against the rear seal.. then put the rear suspension thru its movements and see how far it pushes in by how far back the Oring is.. you can also use a rubber band.. tie it on.. this is quicker.. if you have the drive shaft out.. slip the oring on or the rubber band.. then push the YOKE all the way into the transmission to see how far in it goes.. since this has been a repeated failure.. shorten the driveshaft by an inch.. are you running a full length tail housing.. or a stubby output shaft and the rear case adaptor.. just looking around.. i came across a big Wow..these guys put big nuts on their pins.. must be an issue.,. i can see that if the yoke is bottoming out.. and pushing at an angle.. the off center thrust may attempt to push the pins out of the case..i can see how the pins that are retained by the thin disc might possibly work in a drag race transmission.. but i cannot see them lasting long in a circle track or off road racing situation..tack welding steel pins to the cast iron pinion case just won't work..
hmm... i see these on Ebay... TSI Powerglide 1.80 1.69 Transmission Planetary Gear Set Forged 9310 Pin Nut Kit
Thanks again for the awesome info, what u have there might just be what we might have to use, we took the shocks off, bounced the car thru its entire motion and then some, nothing (as far as we can tell) is bottoming out, we still have 3 inches to go before the yolk bottoms out (we run a 9 inch yolk and the shaft in the tranny is ground down) we did take 3/4" off the yolk just in case, but that shouldn't be an issue. It's just so weird because we ran this car for 7 years and didn't have ANY issues until last year. The only thing we switched was a driveshaft and yolk when we broke a universal last year.Thanks again for the replies, I appreciate it!
please check for side loading on the case and tail housing bushings..there are also roller bearing 9" long tail housings available.. don't think they are probably legal in your class.. you will have to check the rule book.. the idea of checking suspension travel.. place the rear of the frame on jack stands..use a floor jack to move the axle up and down without the springs.. the rubber band trick works well.. tight fitting orings work better.. you can also.. use graphite slippery paint... used in engine building to spray paint the yoke.. you will be able to read the wear pattern on the yoke easier with that..
Thanks again for the replies, we just got back from racing. So far so good, but it will probably break in another race or 2... We put a black mark on the yoke and the driveshaft barely moves at all, so we should be fine on the bottoming out department. When the car feels fully extended, I feel a slight vibration, but that could be anything. I just have a feeling that in another race or 2 it will be broke at we will have to rebuild it yet again. Also, do u know anything about them leaking oil? Our transmissions this year are leaking pretty bad out the rear bushing/seal where the yoke goes in. We have a brand new one on it and it STILL leaks, does that raise any flags for u?Thanks again!
Also, what do u mean by side loading and how do u check it?
with the transmission torn down...examine the stationary bushings...start at the tail housing bushing where the yoke slips thru.. is the wear even all the way around.. or is there some to ONE side.second.. when you have the output shaft out of the main case... look at the rear case bushing... is is evenly worn.. or off to one side.check the torque converter bushing... examine the fit of the input shaft into the tiny bushing in the center of the planetaries.. where the video showed them using a 1/4 NPT tap to thread it and a short piece of pipe with a tee to remove it..lastly... i am TAKING That this is a GM OEM case... it could be an aftermarket case and bell housing...if this case/bellhousing/tail housing has survived impacts with the wall.. you might want to think about how to check if for being square.. from the front of the bell housing to the tail housing mounting surface.. this could have happened before it became a race transmission.. this is usually not much of an issue with power glides or GM transmissions... but it is on some transmissions like the ford A4LD, 4R44, 4R55.. variations that were built up from the original C3 transmission. after accidents . and usually with the 4x4 versions.. the bellhousing can bend slightly.. throwing off the back of the engine to front pump alignment. transmission builders go thru heck as they have to mount the bell housing and then machine the front pump bushing on center.. this really does not cure the issue.. only moves it back.. i saw one.. that the transmission shop could not get the drive shaft yoke in.. has your engine been line bored ??? that would move the centerline of the crank away from the transmission centerline...can you toss a bare PG case onto the back of your motor with a dial indicator mounted to the back of the crank somehow.. see if there is side to side difference and up and down difference when the indicator runs around the smooth bore where the front pump would fit.. there are several articles both here at circletrack and over at stockcarracing on indicating the bell housing .. its in the tech sections either when you click the engine or the drivetrain links above left.. might be back a few pages.. sorry if i am swamping you with POSSIBLE issues.. threaded pins just like the RIVETED pins that GM installed won't come out.. i still want to put a tension band around the ring gear.. but thats only needed in the really big horsepower power glides..
you may check and see how far drive shaft inters back of trans . see how much is out of the trans while seting still . depending on the travel of shocks ect. try pulling the rear of car down to your bottom of travel . look then and see where it is . it may show you some thing your missing. most I know in dirt racing keeps there pinion angle close to a stock position. with very little changing . im not sure on your type and track you run . but from others here in the mid west figure 8 and mods kinda sticks to the reg position unless you have huge horse power to pull it out of the bite . or if you go other way you spin up the yazuuu .