Geez I would love to get that oil lk fixed!!! So Here is the story. ATF lk at speed gear housing (st300). Replaced the 2 seals twice. OEM speedo was too short and over the years the speedo gear housing tube has worn to an oval shape at the output end (because the cable did not enter the housing at 90 degree and caused oblong wear/ metal fatigue)...anyway was going to order a new housing from GM. they have two housings available, one 37 to 39 tooth (50.00) and a 41 to 46 (80.00)...For the life of me I cannot figure out what would be different between the two! Car use to have 2.73 gear. Diff was upgraded to posi trac with 3.23 gears, receipt shows that 41 tooth speedo gear was installed to replace the original 36 tooth gear??? Summary: CAN A 41 TOOTH SPEEDO GEAR BE USED IN A 37-39 SPEEDO GEAR HOUSING? IF NO WHY NOT? (BECAUSE IT WILL LK IS NOT THE ANSWER I WANT TO HEAR!! :laugh: )
Well something is not right cause there is a gear in there...unless the trani place never really put a gear in there after all!! They charged the guy 120.00 for a speedo gear housing about 10 yrs ago (its worth $80 today and even the parts guy at GM complained that this was a 25.00 part not so long ago!!)
It is not a function of the shaft diameter, it is a function of the gear diameter. I gear with more teeth is larger. So the housing for a gear with more teeth has the centerline/axis of rotation for the gear farther away from the transmission output shaft. Although it may look like it is, the hole the gear goes into is NOT in the center of the housing, it may be offset. The hold down tabs keep the housing in the right orientation so that if it is supposed to be offset down, it is.
It is a simple matter to figure out which gear you need. Just need 3 figures. Your rear tire size, rear axle ratio, and the number of teeth on the speedo DRIVE gear. That gear is on the trans output shaft. Pull the sleeve out, rotate the driveshaft slowly with the trans in neutral, and count the teeth.
OK fellow gear heads! :grin: I have been in my shop this AM isolating a vibration problem...and pulled out my speedo gear housing and speedo gear while I was at it...the housing says 37 to 39. I counted the teeth on the speedo gear: 41. Could this be the root cause of my oil leak?
Yes, the gear will possibly wobble and bind, causing the leak. How come you didn't count the teeth on the drive gear while you were in there? That and the rear axle ratio, and rear tire size, and we could tell you what's supposed to be in there.
Well Larry, I know I have 27 inches of tire diameter, 3.23 gears...pressed for time :grin: , will do tomorrow...I assume to count the DRIVE gear teeth I need to peer in the opening that is left after the speedo gear housing is removed? Mark it with a sharpie...thanks for your help.
Ok...27 inches of Tire diameter, 3.23 ratio at axle and 17 teeth on the speedo drive gear located on the output shaft.
OK, a 41 tooth gear is the correct driven gear. All you need to do is get the correct sleeve, and your speedo will be right on. :TU: The GM part number for the correct sleeve (takes gears 40-45) is 1362293. It is also available from TCI under part number 880043.
Thanks Larry, I just want the darn oil to stop dripping on my garage floor. I have been absorbing your write up on advanced curve kit and vaccumm canister mods. Took a while but I get it. Thanks for your help.
found the right housing at an older trani repair shop, used for $25, guy through in some seals, center seal is type with a little spring around it instead of a c clip, said it was more effective. Good news no more drip, drip on my floor.Thanks! Have a silly question, will trani fluid have a different smell to it after a good run and everything has warmed up? I should recheck when cold...it did not have that odor when I check it cold last time (1 month ago)
Glad to hear about the leak being gone. To me tranny fluid has a stronger smell when hot, maybe due to the volatility. BUT...when cold again the odor should be as it was before. Normally as the color goes from red to brown the smell will get more & more "burnt" or "acrid", if you can even describe a smell with words, that is. The degradation in color is the telltale sign of fluid that has been or is being overheated. Devon
