||1931 Chevrolet® - Troubleshooting
- Transmission vibrations
- Transmission vibration - continued
- Spark Plug gap and timing
- What main bearing gap size and how to adjust?
- What is the proper gear oil to use in the Tranny
- How to remove a stuck wheel & hub without a
- Engine Oil Leak from the rear main
We had similar problems in a couple of Chevs in the club a while back. Turned out
to be the same cause both times. The problem was caused by the drive shaft
being slightly bent. One way to see this is to jack up the car with the universal
joint disconnected. Then spin the tires so that the driveshaft turns slowly.
Watch the very tip of the splined end. If it moves up or down by any amount at all,
then the driveshaft is bent. Good or new bearings won't help at all if the shaft has
a bend in it. - Bill Barker
I have found another problem that can cause an ugly vibration and that is improper
adjustment of the ball collar. If there are not enough gaskets in between the rear
of the transmission and the ball housing collar, it will cause the torque tube to bind up
when you go over a bump. I had this happen with my '32 pickup and the fix was an
Happy New Year!
When the spark plug gap is increased from .024" to .040", the timing should
also be increased from the factory 12 degrees to about 18 degrees. There is no 18
degree timing mark on the flywheel, so the 18 degrees is approximately when the 12 degree
mark is just ready to disappear out of the timing hole on the advanced side. Setting
the timing here will also help to increase the power. If the engine
"pings" at this setting, then the distributor should be retarded slightly until
the "pinging" goes away.
Hi Bill ~ You are to be commended for all of the great effort you put into
the development of your 1931 Chevrolet home page in support of other Chevy
enthusiasts. I have a '31 special sedan and a '31 Ford Model A.
There are numerous parts suppliers and a great deal of literature for the Model
A but limited info and data in the case of the '31 Chevy. That is why I
was always looking for more information.
I turned to your home page since I cant find clearances between the crankshaft
and the main bearings. I have a persistent oil leak that comes from the
rear end of the motor. I replaced the oil pan gasket twice and am
convinced that the leak is not coming from the joining of the block and the oil
pan. It has been suggested that it is from the rear main bearing and the
tolerance between the bearing cap and the crank shaft if loose. I have not
been able to locate that clearance spec. Perhaps you might have that
information and if so would you be so kind as to email it to me. On the
other hand, is there a persistent oil leak in the '31 in that area that you are
aware. If so what is the resolution?
I have Victor Page's Chevy Six Construction and Restoration and the Chevrolet
Repair Manual - 1929 - 1932. Are there any other books or manuals that you
are aware of that have more information? Again, thanks for being so
supportive of us amateurs. -- Chuck
Don't have an exact answer for you because of the many possibilities that
occur in the older engines. I recently rebuild mine and came away with
totally different (read unique) sizes on each main bearing! ha!
Maybe the following will help..... and now that I've gone to the effort, I
should post this info on the web site too.
Thanks for the good words. --- Bill Barker, Seattle, WA
Assembling Main Bearings
Replace the bearing caps with four .002" shims on each side. Do not
the bolts too tight, just snug them down.
Adjusting Main Bearings
In order to properly adjust main bearings, remove shims from each side of
the bearing until there is a heavy drag on the crankshaft and then replace
one .002" shim. An equal number of shims should be used on each side
bearing, however, if an unequal number of shims has to be used to properly
adjust the bearings, the extra shim should be on the camshaft side of the
This adjustment operation should be done one bearing at a time with the
other two bearing caps just drawn down snug, while the bearing cap of the
bearing that you are adjusting should be tight. After all three bearings
have been adjusted, the bearing cap should be tightened and the locks
assembled. Check the fit of the crankshaft. When the bearings have
properly adjusted you should be just able to turn the crankshaft by hand.
(with engine upside down, and pushing sideways against the crankshaft rod
Q: Dear Bill, I have the 29 - 32 service manual as well as
the little green service manual which is 31 specific. The first lists gear
oils for the tranny and rear diff ranging from 90w to 160w, depending on varying
temp. conditions. Make logical sense to me. The "little green 31
specific book" lists only 600w as the only gear oil to use. I could probably find the 600w if I looked, but already have, I
believe, a gallon of 90w140 on my shelf. Which do you run/recommend.
600w seems awfully stiff, but perhaps not for a southern car. I live in
Illinois and of course only drive in the spring/summer/fall, with temps. ranging
from 45 to 95 deg. f. I know these old gals are fairly forgiving and will
run on most anything, but I want to do what's best for my faithful old friend.
Thanks for your advice.
A: Skip Geear has kindly agreed to reply to this question.
The 1929-32 service manual that Ken talks about sounds like a reproduction
manual, since the reprint of this manual was for all 1929-32 Chevrolets,
whereas, the original manuals (like the green 1931 manual that he mentions) were
for specific years only, and there were several editions of each. Anyway,
up until some time in late 1931 or early 1932, the viscosity rating of gear oil
was 600W. Then this rating was changed to 160W in late 1931 or early 1932.
That is why the 1931 service manual lists 600W gear oil and the 1932
service manual (or the reprinted 1929-32 service manual) shows 160W.
Actually, the viscosity of both the 600W and the 160W were the same, only the
rating was changed. Don't let the 600W rating fool you because the oil has
the same consistency as the 160W and it is not as thick as molasses.
The 600W (or 160W) oil is still available from the Model A suppliers since the
Ford dudes use this oil in their cars. I would stick with the 160W gear
oil (600W) if I were Ken.
I hope that this information helps you! ---- Skippy
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Bill, I plan on pulling that wheel and drum this weekend, but with no
wheel puller tool like the book mentions, I don't hold out too much hope.
Any ideas on how to pull a stuck wheel and hub off of my old Chevy?
Have a good weekend, Bill. Thanks again for the National ref. #'s. --Ken
Ken, If you don't have a wheel puller and you have a tough hub that
off, you might try the following:
Assume that the left rear is the hub that won't come off. Take the center
nut off and put the wheel back on (tight but only use 3 nuts or so... you
don't need them all, but the wheel does need to be on tight).
Jack up the RIGHT wheel so that it is just off the ground a couple of
Now standing on the left side of the car, use your hip to bump up against
the car. You might have to do this a couple of times. If your
on too darn tight, then you may be rewarded with it 'popping" off as you
bump up against the car.
How it works is that your (people) body moves the (car) body towards the lifted
(right side). Because the (car) body weighs a lot (almost 2 thousand
you can get it to move slightly with your puny body weight, the resulting
the "frozen" hub is large. In most cases this will be enough for
it to "break" the hold that
the hub has on the axle and/or brakes, etc.
This has worked for me when I didn't have a wheel puller. Good luck!
-- Bill Barker
In most cases the major problem is too large a tolerance in the rear main
bearing as identified by JYD and jimk (see other references in the VCCA forum).
Because of crank flex the back (flywheel side) of the bearing will wear greater
than the front. That will give a larger gap toward the back of the crank and
therefore greater oil flow. If the slinger and drain (w/ball valve) can not
handle the flow rate it goes out the back an onto the floor or ground. We have
found that small pieces of plastigage on front middle and rear of the bearing
will show the problem. If unevenly worn then replacement or scrapping the front
and removing shims is the solution. I suggest 0.0015` to 0.002` tolerance. This
has worked for several of us. Another problem can be too high a viscosity oil.
It will also cause problems with wrist pins and cylinder wall wear.
Chip Sweet - Dec 2000
Copyright © 1999-2001 Bill Barker. All rights reserved.
Revised: January 30, 2011 .