Hudson overdrive - why is the governor set at 22 MPH?

m_mman

After all the usual hurdles and setbacks I now have the overdrive transmission installed in my 42 Commodore 8.  

Now I just have to get used to operating it.  

All the other B-W OD units I have experienced over the years, have the governor calibrated to cut in at 28 MPH.  (Ford, GM, AMC) Hudson has theirs's calibrated to 22 MPH(!)  this as noted in the owners' and shop manuals.

I have never seen an OD unit set to engage so quickly. Having it set so low essentially makes 2nd gear direct not usable.

First direct, then shift to second and as soon as you are in second you are going to be above 22MPH. Back off the gas at all (like traffic slowing) and it drops into OD. (too high a ratio for 22-27MPH) Shift to third and it is of course in third OD.  Yes you can kick it down into direct but then you have opened the throttle to do so, and this is not economical driving. 

When the OD is set to 28 MPH when you shift from first to second you can either drive in the 20-25MPH range (a good second gear speed) or accelerate to (a too little fast for second gear) 28 MPH and then let it engage and drive comfortably in second OD (a good faster traffic speed)  If you are in second direct at 20-27 MPH and you shift to third you are in third direct and can either hold it in third direct (traffic speed) or back off the gas and drop into third OD for the highway. 

Does anybody know why Hudson might have set the OD governor cut in speed so low? I am considering trying to recalibrate it for a higher cut in speed.

54coupe

We drove our Hudsons with overdrive around in So. Cal traffic for a lot of years without any issues. I will say, we didn't have any other makes with overdrive to compare to, so maybe we didn't know there was a problem. Ignorance is bliss, I guess.

m_mman

Perhaps it has to do with Hudson's torque curves(?) It certainly was a choice made by Hudson's engineers.
I guess I just have to spend more time with it and perhaps I can better understand their choices. 

50SuperFalcon

I just go a 50 super and I like where it cuts in, at 22 she’s wrapping up in second let off and she’s in a good cruising gear. 

At least in stepdown years the transmissions with od where given a low second so it could be driven with od engaged in second 

Is you comm original? 100%?

cheyenne7271

Hey Falcon remember that your car has a 4.57 gear, optional on all OD cars is 4.10. The other makes might have had a taller rear gear as well. 

m_mman

Today I rigged up a test light, set to light up when the points closed and sent power to the solenoid. I then activated my phone app that is a speedometer based on GPS (so it  very accurate)  The governor is activating the relay at 10 to 12 MPH! 
It EASILY hits first gear OD, that is NOT right. 

That is way too low. If you activate the OD too soon (or use it in a high torque situation like pulling a trailer up a hill) you are overstressing the planetary set and will wear it prematurely. The OD is not intended for pulling, which it would be doing if you were trying to gain momentum from a stop or slow start. 

My Commodore has it's original 4.11 gears.  If you are running even lower 4.57 then an advantage is gained at low speeds but it would still stress the OD gears. 

Guess I will be opening up the governor to see if I can tighten the spring or otherwise increase the cut in speed. 

Geoff

My Jet cuts in at 30 m.p.h.  Has 4.1 rear end.  Perfect. 

m_mman

I dug out a governor from a Ford transmission. Turns out that they are physically interchangeable.  The Hudson governor has 5 contacts and the Ford only one (the extra contacts seem to be for Drivemaster) all I need is one. 

The driven gear on the bottom of the governor is different between Hudson and Ford but they are easily changed. The both have 18 teeth.  
Installed and now it engages at 15-16 MPH. Still too low for my tastes, but getting better. 

There is a rivet holding the shaft together. They were never intended to be opened or adjusted.  Thinking that I might dig out another Ford design, cut the rivet and see what's inside and whether any modifications are possible. 

50SuperFalcon

cheyenne7271 said:

Hey Falcon remember that your car has a 4.57 gear, optional on all OD cars is 4.10. The other makes might have had a taller rear gear as well. 

As I’ve been reading is seems to be better that the 4.57 is in od cars due to the stress wear. I’m not a fan of the top speed but that’s why I have my 65 Ford haha

m_mman

Problem solved.  I didnt want to damage my only Hudson governor so I dug into my box of non-Hudson OD parts and found a governor I could open up. When new they were considered sealed and were not intended to be opened or adjusted. 

Well, to open one up all it takes is to drive out one pin and file away and remove one rivet. 

There one coiled compression type spring inside along with a collection of weights hanging from the shaft. It all comes apart easily. 

So I now had an original spring (remember non-Hudson cars are supposed to operate at 28 mph) and to make it operate at a higher speed would require a heavier spring. I dug through a box of salvage springs that came who knows where, and found one that was very nearly the exact diameter but felt heavier. (I was comparing them by doing nothing more than squeezing them between my fingers) 

I tried rigging up a postal scale to try to get some number for the amount of force that it took to compress the several springs. but the springs were too stiff for the ounces of the postal scale and too weak for the pounds of the bathroom scale.  In the end I just "guessed".

Reassembly was tricky as there are a lot of loose parts that have to held together and I was compressing a more powerful spring but after many tries I finally got it together. 

Reinstallation and test drive and it now activates at a measured 23-24 mph.  While not the exact 28 mph, it will suit me as it now makes second direct gear a usable driving gear and second OD readily available if I want it. 

Hudsy Wudsy

Congrats on your perseverance and ingenuity, Jim. Maybe 23 is ideal, but it's far better than what you started with. 

m_mman

Yes, it now makes 2nd direct a driving gear.  If activation happens at 10 mph, then as you back off to shift from 1st to 2nd it drops into OD during the shift, landing in 2nd OD every time. 

At 23 mph, you shift 1 to 2 landing in 2nd direct. Then drive in 2 direct or speed up just a little bit and engage 2nd OD.  

This is how it’s supposed to work.  The main point of installing OD is to make life easier for my splasher 8.