Installing a Mitchell Overdrive

[Rich in Tucson]

Pray it does not leak out all the oil you put in the box at the joint between gearbox and rear torque tube as the last two I installed did. Silicone gasket maker sealant can be 100% effective if used correctly however they do not seem to know how to use it.

[waxhead]

Thanks to everyone for the great advice and suggestions. I have no doubt that it will assist in making the install easier. Just need to wait the 3 months for delivery of the OD

[53RYDER]

3 month back-up? Hang in there!

Glenn

[32forddump]

Is it necessary to remove the springs, and is it easier to install Mitchell with it removed from chassis?

[Tom Wesenberg]

Originally Posted by 32forddump

Is it necessary to remove the springs, and is it easier to install Mitchell with it removed from chassis?

You would have to remove the rear end to remove the driveshaft.

[Dave in MN]

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Originally Posted by 32forddump

Is it necessary to remove the springs, and is it easier to install Mitchell with it removed from chassis?

The Mitchell is much easier to install if you remove the rear end from the chassis. It would be very difficult working under the car if you don't.
Good Day!

[b.j.]

how many man hours to install a mitchell overdrive?

[Brentwood Bob]

Depends.
Talk to mitchell.
Bob

[Y-Blockhead]

Originally Posted by Stew

Also you need two thin wrenches to set the preload of the pinion bearing.
Snyders part # A-4634-T

Regards,

Stew

My understanding is that you don't have to mess with the pinion preload. Is that correct?

[Tom Endy]

A little tip when installing a Mitchell overdrive:

The boss where the speedo gear head inserts in the housing is below the oil level in the housing. For this reason do not oil service it until the speedo head is installed. The set screw that holds the speedo head in place will drip oil unless you coat it with some type of sealer before installing.

Tom Endy

[lvonnordheim]

I just finished installing both a Mitchell Overdrive and transmission in my 1929 model A roadster P/U. Also bought their puller kit which worked great. It was quite a bit of work......however, I love the way the Mitchell transmission shifts. No problem with gears grinding now......wonderful when down shifting.

The overdrive shifts fairly easy but stiff. Goes in to over drive easy but does not shift easily back it to direct drive. Some times I must stop in order to shift back in to direct drive. Slot in floor board has good clearance in both directions. Other than adjusting the shaft length that connects the shift lever to the overdrive......I do not see any other adjustments. Was told the overdrive has syncro's which should allow shifting in and out of overdrive while driving. I have been pushing in the clutch when shifting in/out of overdrive.

Any suggestions?

Les Von Nordheim

[Ernie Vitucci]

I would give Mitchell a call...The units usually shift very easily...How does it shift if you are standing still and the engine is not running? Also try shifting it from under the car with the linkage disconnected and see if it makes a difference...It is possible that you have a linkage problem and not an overdrive problem...Ernie in Arizona

[denniskliesen]

Originally Posted by lvonnordheim

I just finished installing both a Mitchell Overdrive and transmission in my 1929 model A roadster P/U. Also bought their puller kit which worked great. It was quite a bit of work......however, I love the way the Mitchell transmission shifts. No problem with gears grinding now......wonderful when down shifting.

The overdrive shifts fairly easy but stiff. Goes in to over drive easy but does not shift easily back it to direct drive. Some times I must stop in order to shift back in to direct drive.
Any suggestions?

Les Von Nordheim

Give it a chance to warm up. I asked Sue and Steve Mitchell at the MAFCA Convention this year about the problem shifting when cold, they told me to give it a chance to warm up.
When they delivered mine I was told to use 85w-140 GL-5. That seems too thick to me but when it's warmed up after a mile or two, it's just fine, never grinds. I would suggest changing your gear oil in it soon after it's first installed, and after that every 5,000 miles. Don't forget to pull the plugs in the torque tube one in front of the overdrive and the other behind the overdrive box and give it no more than a couple pumps when you change the oil. One of the fittings they give you is close clearance, make sure your rear axle is up on jack stands and park brake released so you can turn the driveshaft to access the grease fittings. I have good results with Ultra Black sealant between the torque tube and differential and a dab of ultra black on the set screw holding the speedometer drive. Tie up the breather tube as high as possible. I have absolutely no leaks.

[michael a]

Originally Posted by lvonnordheim

I just finished installing both a Mitchell Overdrive and transmission in my 1929 model A roadster P/U. Also bought their puller kit which worked great. It was quite a bit of work......however, I love the way the Mitchell transmission shifts. No problem with gears grinding now......wonderful when down shifting.

The overdrive shifts fairly easy but stiff. Goes in to over drive easy but does not shift easily back it to direct drive. Some times I must stop in order to shift back in to direct drive. Slot in floor board has good clearance in both directions. Other than adjusting the shaft length that connects the shift lever to the overdrive......I do not see any other adjustments. Was told the overdrive has syncro's which should allow shifting in and out of overdrive while driving. I have been pushing in the clutch when shifting in/out of overdrive.

Any suggestions?

Les Von Nordheim

My overdrive shift smooth as silk both up and down

Sent from my SM-J700T using Tapatalk

[daveymc29]

Get the best spring spreader you can and leave the spring together with the differential.
Get the best of the two pinion pullers discussed above. I have used both. The good one works, the other one bends. It takes about four hours and is a bit quicker with someone helping you. Two rolling floor jacks are what I use and have done them alone several times, much easier with two guys. Not rocket science, just heavy and I'm not as strong as I was 60 years ago. Be SAFE. I tip the torque tube up and slide the Mitchell down onto the differential. The spring and spring spreader help hold the torque tube up if working alone. This part and aligning the splines with the U-joint are easier with help. The rest is just screwing in nuts and bolts, or unscrewing them. The pinion adjustment is quite simple, I go where I think it is too tight and back it off a tad. I have been told that inch-pound torque wrenches are notoriously inaccurate so I just get the feel of some drag on the pinion and have been happy with those results. Your experience may very.

[Gil Sissons]

A tip based on my experience with the Mitchell....
After the new unit is installed you need to pin up the OD vent tube.
It's very important this tube always be in a incline from the OD unit.
If you let any part of the vent tube sag small amount of oil will
Start holding in the sag. On hard pulls the tube just may "burp"
This oil out the end of the tube. And if the end of the tube is located
Near/above the muffler.... instant smoke screen!
I know!
Locating this vent tube on the Vicky with the drop floor
And keeping it in a inclined position can be challenging... be done for sure.
Love the Mitchell.
Gil. NoCal

[lvonnordheim]

Thanks for the guidance.

I will make a shifting linkage adjustment and see if that helps. Also, I may have not had the overdrive heated up......will do more driving and see if shifting when warmed up is easier.
I'm using synthetic gear oil supplied from McMaster Carr 90/140. Also us it in the mitchell transmission. Have used this specific gear oil in my other antique cars with good results. Does not eat up bronze or brass like some other conventional gear oils.
I have the breather tube attached under the P/U bed (High) with a loop clamp.

Just joined the Model A club of america but have not joined a regional group....have several in our area. Have been a member of the HCCA and Model T ford club of america for many years. Enjoy driving and owning a Model A.

Thanks,
Les