Author Topic: Overdrive engagement speed  (Read 1143 times)

MarkH

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Overdrive engagement speed
« on: June 06, 2020, 09:59:49 AM »
We've been putting a few miles on the new engine, at relatively slow speeds. The overdrive has not been engaging & I fault traced everything down to supposedly the governor being the issue. Swapped another one in from a parts transmission which didn't seem to make a difference till we hit 50mph for the first time. Seems to be shifting just fine at somewhere between 45/50mph but the Borg Warner manual states 28mph. At this point I'm not even sure the one we took off wouldn't have clicked at the faster speed.
Anyone got any input on this?
Fully restored '54 Aero Lark
Rusty '58 Austin Healey 100-Six
Barely running'74 Chevelle Malibu

Fid

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Re: Overdrive engagement speed
« Reply #1 on: June 06, 2020, 10:33:43 AM »
There were different pinion gears  used on different governors.  Perhaps you've got one for a different trans/rearend configuration which means it won't reach closing RPM till the car is going faster.
1953 Henry J Corsair Deluxe
Edgar Kaiser's custom 1951 Henry J
1951 Kaiser Special
1952 Allstate Deluxe

Need your classic car radio repaired? I repair vacuum tube radios

MarkH

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Re: Overdrive engagement speed
« Reply #2 on: June 06, 2020, 07:14:29 PM »
There were different pinion gears  used on different governors.  Perhaps you've got one for a different trans/rearend configuration which means it won't reach closing RPM till the car is going faster.
Well, I didn't think to count the teeth on the first or second one, just assumed they were the same since they came out of Aero transmissions. Differential is my original.
Fully restored '54 Aero Lark
Rusty '58 Austin Healey 100-Six
Barely running'74 Chevelle Malibu

Fid

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Re: Overdrive engagement speed
« Reply #3 on: June 06, 2020, 07:44:31 PM »
Quote
Well, I didn't think to count the teeth on the first or second one, just assumed they were the same since they came out of Aero transmissions. Differential is my original.

Sounds like you got that covered then.  I hope you can get it figured out.
1953 Henry J Corsair Deluxe
Edgar Kaiser's custom 1951 Henry J
1951 Kaiser Special
1952 Allstate Deluxe

Need your classic car radio repaired? I repair vacuum tube radios

kaiserfrazerlibrary

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Re: Overdrive engagement speed
« Reply #4 on: June 07, 2020, 10:39:32 AM »
My first K-F car back in 1975 had a problem with the overdrive governor not kicking in at the proper speed as yours seems to be doing.  I found that because of non-use, the mechanism was stiff and it took some time driving it on lesser traveled country roads with various hills to get the mechanism back to regular operating mode.  Also, the 28 mph figure is an approximation, coupled with the inaccuracy of your speedomer.  Here's what I did as a diagnostic:

1.  Several runs on a measured mile at 30, 45 and 60 mph to verify the degree if inaccuracy (the 1951 Frazer I had was 12 mph high at 60).  I found the o/d working around 45 MPH actual speed. 
2.  On a not so busy country road with hills do some driving where the car can engage/disengage via kick-down switch at around 30-35.  It took several tries but finally the o/d engaged at around 35 mph actual.

THIS IS WHAT WORKED FOR ME AND THIS PARTICULAR CAR.  WHAT WORKED FOR ME MAY NOT WORK FOR YOU.  ALSO, TRY THE DIAGNOSTIC FOR OVERDRIVE ISSUES IN THE KAISER-FRAZER FACTORY SHOP MANUAL FOR YOUR CAR for possible supplemental info on the problem that the Borg-Warner book does not offer as the situation may be K-F specific.

Fid

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Re: Overdrive engagement speed
« Reply #5 on: June 07, 2020, 01:24:23 PM »
Jack makes some valid points (no pun intended).  There are two different types of governor switches that I've seen. The most common one has a set of plates in it which spread out and down as the RPMs increase. When it's down far enough, the hub in it no longer makes contact with the contacts and they fall and close together completing the circuit.  If the plates are gummed up it may take more RPMs for them to "spread" out and drop the hub down. 
The other type I've seen has two brass weights which do the opposite - as they rotate they push the hub up and it presses the contacts together.  That type is less common and not as easy to test.
What I've done is put them in a vice, remove the top cover and put a drill on them and spin it with a drill and see if they spread open etc.  A bit of lube may do the trick.
1953 Henry J Corsair Deluxe
Edgar Kaiser's custom 1951 Henry J
1951 Kaiser Special
1952 Allstate Deluxe

Need your classic car radio repaired? I repair vacuum tube radios

MarkH

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Re: Overdrive engagement speed
« Reply #6 on: June 08, 2020, 09:14:22 AM »
I'll put some more miles on it and see if it limbers up any, otherwise I'll take it off & see what I can do. We opened it up to check the points before installing it, but I didn't think to spin it up or lube it.
Thanks fellas.
Fully restored '54 Aero Lark
Rusty '58 Austin Healey 100-Six
Barely running'74 Chevelle Malibu

MarkH

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Re: Overdrive engagement speed
« Reply #7 on: June 15, 2020, 12:59:24 PM »
After reading you guys experience we decided to take the governor out & check it again. It had some fairly gummy oil on the inner workings so we cleaned it with some spray carb cleaner till it was much easier to push the weights down, then reassembled for a road test.
Turns out that 50mph on my speedometer is actually 45mph on the GPS. We did a couple up & down shifts, OD kicks in now at 40mph speedometer speed, GPS battery died before confirming what that actual speed was though.

Thanks again for the input!
Fully restored '54 Aero Lark
Rusty '58 Austin Healey 100-Six
Barely running'74 Chevelle Malibu