I feel like I should lose any mechanical credibility I may have had with this problem. I've finished the reinstallation of the replaced clutch throw out bearing, rebuilt transmission / overdrive, etc., and had double checked everything along the way.
I took the car for a test drive and am very pleased with the newly smooth and quiet clutch operation and the transmission shifting (I replaced every bearing in the shift linkage). However, I noticed the speedometer was not registering and the overdrive was not engaging. I tracked the common cause to the be the speedometer drive gear slipping on the output shaft. Like many manufacturers, the gear is held in place by the rear bearing behind it and a shoulder feature on the output shaft in front of it.
I check the torque on the output yoke nut, but no improvement. I removed the yoke, checked the washer and lock washer, searched for causes and am still scratching my head.
When I disassembled the yoke originally, I noticed the washer was of the tab type, meant to engage one of the splines of the yoke. Thinking this may be causing the nut to prematurely bottom out, I removed it, retighten it and checked again but to no avail. A fellow club member believes the washer to be a plain washer, not a tabbed washer, but at this point I don't think it matters.
Has anyone ever had this happen, or have any guesses. I've run out of ideas and need help.
Thanks in advance.
Pat
Pat,
I don't know what to suggest about the gear, but if you want to see if the overdrive can engage, try not having the governor in the circuit.
If you do this and the overdrive engages, you'll have to stop the car and pull out the overdrive cable to make it go out of overdrive again.
Per
Per,
Thanks. Yes, I've been considering inserting a switch to ground the OD input circuit as a test of the rest of the system. This transmission and OD were shifting and working very smoothly before I pulled everything apart and all internal parts were in excellent condition.
Thanks for helping,
Pat
Pat,
Years ago I put overdrive transmissions on three cars that hadn't had overdrive ('41 Commodore 6, '54 Jet Liner, '36 Packard). In each car I just had a switch on the dashboard to supply the solenoid. I had to remember to turn the switch off to be able to engage reverse!
Per
Pat, a simple test/check. Pull the speedo cable out of the trans. Stick your finger in the hole and see if you are able to spin the gear. If you can, you have left a bearing out of the rear. Some early ,single lever, '48-'50 transmissions have 2 bearings on the output shaft, and if left out, everything will go together, but can cause this exact concern. You can fix it in the car if you are careful. Give us a call if we can help.
Doug,
Thanks. Indeed I can rotate the gear, which is how I pinpointed the common cause for both the speedo and OD not working. I don't think I've left a bearing out. The gear can be rotated, but not slid fore and aft on the shaft.
The most puzzling part is the question, "if the gear is not held, then what is the torque on the yoke nut tightening against?"
pm
Pat, there were 2 snap rings in the back of the rear housing. I think you left one out. The 2 are required because this makes the rear bearing fixed, and then you draw to it.
Doug, yep, both there. Still scratching my head......
Guess I'll need to man up, remove the OD and have a look.
Pat, how far can you move the speedo gear back and forth?. If it is a lot, you have surely left a bearing out of the back case. Sometime in late '49 they switched to a different rear overdrive output shaft, which only required 1 rear output bearing, prior required 2. The rear bearing still had the snap-ring retainer making it fixed. Something else to look at, when the rear yoke is slide out, does it seat all the way down to the spline, or come about 3/16th's from seating?. I still say just pull the output housing off, in the car, and have a look.
Thanks, Doug,
Yeah, I'll be pulling the OD off the transmission, while still on the car. My OD has the single rear bearing.
Regarding the rear yoke, I considered the possibility the splined shaft was pulled out such that it would stop at the plain washer. So, I machined a washer of inner diameter 1 1/8 and outer 1 1/2 such that the splined shaft could come out further. This seemed to tighten the gear a bit, but I could still turn it.
So, I'll pull the OD. Thanks again for offering your experience. I greatly appreciate it. Hope you don't get too much of the snow that is supposed to hit us tonight.
Pat
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