How do you engage the Overdrive in 1937 8

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Hello, Dumb question from a new Pierce-Arrow owner. How do you engage the OD? I assume in 3rd gear you release the accelerator as with other makes of the period but that does not seem to work.

Thank you

C Rence

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You must push in the free wheeling lever. Above 45 mph, remove foot from accelerator, car will shift into overdrive.

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The transmission must have freewheeling active for the OD to operate. You can push in the freewheeling handle at any speed.

HOWEVER you MUST follow this procedure when you pull on the Freewheeling handle to lock out the freewheeling and get engine braking again.

YOU MUST match the engine speed and the road speed. So:give the engine a bit of throttle, just enough to have the engine pushing the car, and NOT COASTING. Then pull out the freewheeling handle. If you do not match the engine and road speeds, you will grind up the gears in the freewheeling box.

Repeat: gentle acceleration with throttle, pull the handle. If you are in hilly terrain, and will want engine braking on a downhill run, it is best to remember on the climb to pull out the freewheeling handle. Otherwise, you will have to gently accelerate while descending the hill in order to lock out the freewheeling, it is not intuitive.

Greg Long

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Many of the OD units have been damaged and have parts missing, it is possible your unit is welded up. They usually are issue free unless parts are missing. It may be time to drop the drive shaft and pull the rear OD unit cover. Ed

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Greg: I have just put in the clutch when disengaging the overdrive unit, then pulling out the lever. I never heard any bad noises or grinds?

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Hi Tony, IF your clutch releases completely, has no drag on the flywheel or pressure plate that will work as well, but if there is any drag or miss-match on gear/road speeds then you will get gears grinding.

What happens a lot is someone is in OD, crests a hill, lets off the throttle, the engine idles, the gears in the trans are at idle rpm. But the output shaft is at road speed. The driver realizes that they are in freewheeling and just pulls out on the freewheeling handle, forgetting about the clutch. The freewheeling cannot mesh and it grinds up the freewheeling.

If the throttle is applied, the engine and road speed are then matched, then the freewheeling handle pulled, then there will be no chance of miss-matched speeds, no risk of grinding up the freewheeling.

I just checked my 836 owners/operator manual, and it says to ‘depress the accelerator to match driving and driven gear speeds, THEN push in the clutch and at the same time pull the freewheeling handle out.”

Hmm,.. I’ve never used the clutch and it locks right in. I guess both operations should be done.

Learn something every day !!

Greg Long

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Christopher,

Friendly words of advice passed along at the time we acquired our ’36, “don’t ever let the car lug up a hill in overdrive.”

If speed cannot be maintained going up & over the top of a hill in O/D, I’ll back off the gas until the O/D disengages around 40 MPH.

The reason is to avoid the added torque & stress put through the O/D back into the crank and babbitt mains.

Regards, Stu Blair

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Stu is correct…….unless you have a twelve…..then lug away!

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Another issue to consider is lubrication. If the lube is old & thick engagement can be very slow or not at all. I had this issue with one of the P-A Museum cars. Drain thoroughly when warm from running and put in GL-1 lube from NAPA…very important to use a non-EP lube.

Once the O/D engages, watch out for the cops!

Dave

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I do not believe that a 9 main bearing inline 8 cylinder is in ANY danger from ‘lugging’ up a hill on the freeway. our 8cylinder engines have no problems running 1200 rpm, and smoothly slow down to 8=900rpm under load.

The 12 is no different. and it has fewer main bearings. it too will run fine at lower rpm’s without damage.

The 8 is in every way equal to the 12 in performance and longevity. I remember at the Bartlett NH meet, On one of the tours I was behind a ’33 1236, my car then was my ’33 836. I was following the 1236 on one hilly road that had the double lane on the uphill side to allow for passing on the fairly steep grade.. I remember thinking that I’d never keep up with the V12 version of my car.. but on the hills the v12 never out pulled my 8, and on one long run I pulled out to pass, and we grinned at each other and ‘raced’ up the hill, and there was no difference, we were still neck and neck at the top of the long grade.

And I seem to remember a ’31 roadster at the Fariport Ny meet, when on the race track at Glens Falls, was out running a V12 quite easily.

Even Pierce Arrow had problems with getting the expected performance from the v12, it took an increase in displacement to see a noticeable increase in performance.

Anyway, lug ’em down as much as you want.. once you ‘lug it down’ to 40mph, just let off for a momet, it will downshift to 3rd/direct and you then can accelerate back up to speed .

Greg L

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