Model A Rear Main Cap Removal

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Bmoody

Junior Member
1929 Model A
With the engine in the car, will a box end wrench loosen the rear main cap nuts for a bearing adjustment? Or do I have to build a special wrench? I built this engine a while back and have put a lot of miles on it & it's starting to get a little noisy.
 
I think you will have a hard time with a box wrench. Either the bolt won't be quite lined up right to get the wrench on, and or you won't be able to get enough leverage on the box wrench. They are torqued to 80+ pounds. I have broken them with the proper socket and a breaker bar. There is just enough room to work. Just be sure not to break off the bearing oil pipe. That is right there in the way when the nut breaks loose.
 
I have taken the rear cap off with the engine in the car several times but I have to use an old socket handle. It is decades old and Australian made which means top quality steel was used (before the same company went to China chasing cheaper prices and higher profits). Later tools are made with poorer quality metal so they have to use more of it for the strength which makes the tool thicker and with one of those, you will have trouble. Once you drop the sump and remove the cover from the front of the flywheel cover, you will see how confined it is. I suggest you search for an old handle made the way they used to be.
 
Bmoody said:
1929 Model A
With the engine in the car, will a box end wrench loosen the rear main cap nuts for a bearing adjustment? Or do I have to build a special wrench? I built this engine a while back and have put a lot of miles on it & it's starting to get a little noisy.
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21/32 socket 12point.
 
Yesterday I pulled the pan to remove the rear cap on a club members car. I asked him for a 3/8 drive breaker bar which he did not have. Instead he gave me an old 3/8 drive ratchet and a one foot piece of pipe to slip over the handle. I said this won’t work, the ratchet can’t handle it. Well I was wrong. Like synchro909 said, the old tools are stronger.
 
This is a mechanics tool from the era, square on one end, hex on the other, and the length is such that you can get the bolts tight enough, but not too tight----in the era of no torque wrenches
 

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Kurt in NJ said:
This is a mechanics tool from the era, square on one end, hex on the other, and the length is such that you can get the bolts tight enough, but not too tight----in the era of no torque wrenches
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That is what I used. Did a test to see what torque the main cap nut had when done using a modern beam torque wrench. Found that using the tool as intended, the nut was in the 80 foot pound target range.

Pulling the rear cap under the car is not a fun job and one I hope not to repeat any time soon! Rods are a cake walk in comparison.
 
Synchro909 said:
I have never seen a 21/32" socket. 17mm is easy to get (I've got several)
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Well now you have!Hard to find,but proper size for caps and piston rods.per Henry Ford.
 

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Synchro909 said:
I doubt any tool shop will carry such a rarity. There are not many imperial tools about these days. It's been 50 years since we converted.
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Have you heard of UES International company from Australia? My son is UES USA Inc CEO here in the U.S.Been in Australia since 1904.Close by,? Next time he's in Aust. he can drop off a socket to you.
 
Synchro909 said:
I have never seen a 21/32" socket. 17mm is easy to get (I've got several)
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The first tool I ever bought for myself, as opposed to using Daddy's tools, was a 21/32 inch socket. I bought this to tighten the mains on my first running Model A. Did it with the engine out of the car. My older cousin did the work and showed me how to do it, using plastigauge. About 1970?

W. Michael
 
Gary WA said:
Have you heard of UES International company from Australia? My son is UES USA Inc CEO here in the U.S.Been in Australia since 1904.Close by,? Next time he's in Aust. he can drop off a socket to you.
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Thanks for the offer, Gary. No, I haven't heard of them so I did a search. The nearest one is nearly an hour away.
It's the big end nuts that cause most angst so I file them to take the nearest metric. Better still, I replace the originals with new 12 point nuts, even Nylocks. 16mm is 5/8" which is what I use on the mains and 21/32" is 17 mm.. With a decent set of metric sockets, I have one for every mm. That is 0.040". 1/32" is 0.031" It is not until we get to the smaller sizes that a step of that size might cause an issue. I also have some old Whitworth spanners and every now and then, one of those fits.
 
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An old Snapon 3/8 flat style torque wrench will allow you to re-torque those rear main bolts in the car.
 
Yes, the top of the bolt is "D" shaped and is wedged in there. It will not come out or turn, when you are accessing it from below.
 
31Tudor said:
Yes, the top of the bolt is "D" shaped and is wedged in there. It will not come out or turn, when you are accessing it from below.
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Ditto, but it will push up, so one has to be careful when re-installing the cap.
 
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