Flywheel Shims Q.....
- Thread starter hardtimes
- Start date
Joe K
Well-known member
Read the article below for a first introduction. In the article he references an article in the "How To Restore Your Model A" series of books Volume 4. THIS article has the pix.
www.ocmafc.org/techarticles/Clutch%20Housing%20Alignment.pdf
The basic principle is that you use the crankshaft flange (or exterior flywheel rim) as the base for a dial indicator which you then rotate the crankshaft and Dial indicator to determine how out of alignment the flywheel housing flange is parallel to the axis of rotation.
As you swing the indicator around, the "dips" and "humps" of the flange connection should be within 0.006 (it says) It's possible to get it closer if you're willing to use a mill-******* file on the lands that the shims are used at - but you have to understand what you're trying to accomplish. And you're taking a risk by making a non-reversible change. As you may observe when you're doing it, the shimming can sort of work in "reverse" to what you might expect - the housing is quite flexible.
By playing around with different shims - including those made of paper or thin cardboard, you can get a sense of where you should be and how do make it happen using the preferred metal shims.
Some flywheel housings ARE beyond adjustment. It's a thin casting and cast iron can take on a "set" depending on it's life and environment.
Anyway, read the article(s.)
Heh. I'm not sure at all why the word flywheel is getting underlined?
Joe K
earbleeder
Senior Member
Patrick L.
Well-known member
I just use a heavy chunk of angle iron bolted to the crankshaft with an adjustable bolt at the flange so I can measure with a feeler strip. Crankshaft end play has to be considered, don't let the crank walk.
I've had them as far as .032" off. Sometimes shimming just doesn't do it. I've had to file them. Just go easy cuz its hard to put back what you just scraped away. This takes time.
I feel this along with pressure plate finger adjustment are the two keys to smooth clutch operation.
I've had them as far as .032" off. Sometimes shimming just doesn't do it. I've had to file them. Just go easy cuz its hard to put back what you just scraped away. This takes time.
I feel this along with pressure plate finger adjustment are the two keys to smooth clutch operation.
Kohnke Rebabbitting
Well-known member
The shim, if any depends on how thick of gasket is used between the flywheel housing and the block. The thicker the gasket, the more shims you will need.
The first thing to note, when you get it as close you can get the first time, you have to let it set for 24 hours, as if there was much pressure on the flywheel housing ears, the housing will warp to the pressure, and then you adjust again, and as many times as it takes.
The 4 bolts that hold the housing on, should have Indian head gasket cement on them, or oil will seep out of the bolts sometimes.
So, all the setting, and leveling will be done with the two top bolts. Ford had all the same new parts to work with, so those .010 thousandths shims don't mean much now.
I get the two sides to read Zero first, and then get the top and bottom to read the same, even if they don't come out the same number as the sides.
The whole reason for this shimming is so the out put shaft runs an a 90 dergee angle to the rear main bearing.
I hope you got the rear flange ground, as many are sprung.
I use old Model A main bearing shims, and cut one side off, and I also have a little handle to slide the shim between the housing, and the block, that way.
You have to pry the housing up from the block to get the right amount of shims in.
Herm.
The first thing to note, when you get it as close you can get the first time, you have to let it set for 24 hours, as if there was much pressure on the flywheel housing ears, the housing will warp to the pressure, and then you adjust again, and as many times as it takes.
The 4 bolts that hold the housing on, should have Indian head gasket cement on them, or oil will seep out of the bolts sometimes.
So, all the setting, and leveling will be done with the two top bolts. Ford had all the same new parts to work with, so those .010 thousandths shims don't mean much now.
I get the two sides to read Zero first, and then get the top and bottom to read the same, even if they don't come out the same number as the sides.
The whole reason for this shimming is so the out put shaft runs an a 90 dergee angle to the rear main bearing.
I hope you got the rear flange ground, as many are sprung.
I use old Model A main bearing shims, and cut one side off, and I also have a little handle to slide the shim between the housing, and the block, that way.
You have to pry the housing up from the block to get the right amount of shims in.
Herm.
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harleytoprock
Senior Member
Since the gasket is compressable and really not that stable, why not eliminate it and use silicone seal.
RockHillWill
Well-known member
Just for general reference the archive drawing for that lower gasket shows it to be .012" thick. Apparently, when torqued it will be .010" thick, and I have not had to re-do anything to make adjustments since I figured this out. If you are able to set the housing on a 'granite table' and discern no unevenness you will be fine. If you have any question about it, have it Blanchard ground using shims to support the lower edge prior to the first pass. It has been my experience that both the granite table inspection and the Blanchard grinding totals less time that the setting up and rechecking procedure. If you do use the shim testing procedure, the above mentioned recheck after 24 hours is a very good idea.
My recent experience has been to find the repro gaskets are as thick as .030". Careful investigation will show that you can find .012" material in the older type grocery store paper bags, and I have had good success using them.
I also feel that this is a good procedure to do if you are encountering transmission 'issues'.
As always, this is just my opinion.
My recent experience has been to find the repro gaskets are as thick as .030". Careful investigation will show that you can find .012" material in the older type grocery store paper bags, and I have had good success using them.
I also feel that this is a good procedure to do if you are encountering transmission 'issues'.
As always, this is just my opinion.
harleytoprock
Senior Member
RockHillWill, Are you Blanchard grinding both surfaces? If so, which surface are you grinding first?
BRENT in 10-uh-C
Well-known member
I don't grind both surfaces, ...just the cylinder case side. Use the Clutch Housing side as the reference. Most Flywheel Housing that come thru here are warped due to this is the "crossmember" that the driveline pushes off of. As Will says, when you mic your gasket, allow for gasket compression and install appropriate shims. The runout-out will generally be less than .001" the first check. Your comment about silicone is a nice thought however silicone is rubber, ...and rubber will compress at variable rates also. Paper can be compressed (especially if it is the correct thickness) to be stable.
Patrick L.
Well-known member
So what I'm taking away from this is that when an engine is rebuilt the deck, side of block ,and, rear of block should be ground. As should the cover.
Joe K
Well-known member
Not necessarily. For purposes of alignment between the block and the transmission, the shims at the flywheel housing give "adjustment." It does not matter the perpendicularity of the rear face of the block to the crankshaft axis as you're "setting" and more important "proving" the truth of the rear flange of the flywheel housing by doing the test and making the adjustment using the shims.
My two engines were never touched on the rear face, although he did "flatten" the top deck - and make it parallel to the bottom flange in the process.
I confess I have given one or more of the flywheel housing "shim locations" a stroke or two with a mill-******* file. But I had some confidence to what the effect would be on the flywheel housing flange, having played with a variety of shims over a period of several hours and having gotten a feel for "how it reacts" to various tensions and shimming.
I've not heard of anyone "decking" the bottom flange of a motor. I suppose it's possible. But it does upset the rest of the standard dimensions of the block. Bottom flange is normally kept as "reference datum" for rework - hence the warning on another thread about "used blocks" and to inspect how corroded the bottom flange was after these found sitting on the ground.
Joe K
oldbike99
Senior Member
So if I am understanding this process correctly, one should bolt the flywheel housing to the block with the four lower bolts, including the gasket and sealant, and then check the housing. Then use the shims to move the top of the housing in or out. If so, does one, at any time, disturb the lower four bolts?
Thank you in advance,
Paul
Thank you in advance,
Paul
Joe K
Well-known member
Probably not as one might "lift" the housing from the block rear pad thereby creating an oil leak.
You can "stack" a gasket or two providing they fully cover and are compressed between the two mating surfaces.
You might even try cutting a gasket and using permatex no. 2 to fill the "wedge" open shape created between gasket and mating faces. But now we're reaching for solution - and permatex, while good stuff, is not a guarantee against oil leak.
Joe K
RockHillWill
Well-known member
Harley, Brent.
I did grind both sides. From my random 'granite block' encounters, If I found a 'good/uncracked/unrepaired' housing, I more often than not found small undulated uneven ness but small in nature. (.001 - .002"). Because the block side is the largest in 'diameter', I sat it on the Blanchard table and looked for even the minutest gap with a feeler gauge and using misc. assorted feeler gauges I would put them in the gaps. I found that the grinder that was accessible to me had a strong enough magnet that it would pull down hard enough to erase the gaps if I did not reinforce them. By inserting the feeler gauges my feeling was that the top side would not be under any stress when grinding the top side. In doing it this way, I felt that when turned over, that side was flat with no stresses and subsequent grinding could be counted on to be both flat and parallel and stress free.
I have only done this nine times because I am not a 'motor' man, but after the first six times doing it this way, I have quite checking altogether (when using the .012" grocery bags paper). For the reason that Brett states, I do NOT use sealant of any kind as well.
Again, just as a side note: If you are not doing this for 'Fine Point' or specific about originality, just buy two similar lower gaskets and cut the upper 'shims' from the same gasket material. ALL the bolts are the same size equating to the same torque. Once you feel that you have addressed the housing flatness, this should be a no-brainer for the shim issue.
Again, just thoughts from an old man!
I did grind both sides. From my random 'granite block' encounters, If I found a 'good/uncracked/unrepaired' housing, I more often than not found small undulated uneven ness but small in nature. (.001 - .002"). Because the block side is the largest in 'diameter', I sat it on the Blanchard table and looked for even the minutest gap with a feeler gauge and using misc. assorted feeler gauges I would put them in the gaps. I found that the grinder that was accessible to me had a strong enough magnet that it would pull down hard enough to erase the gaps if I did not reinforce them. By inserting the feeler gauges my feeling was that the top side would not be under any stress when grinding the top side. In doing it this way, I felt that when turned over, that side was flat with no stresses and subsequent grinding could be counted on to be both flat and parallel and stress free.
I have only done this nine times because I am not a 'motor' man, but after the first six times doing it this way, I have quite checking altogether (when using the .012" grocery bags paper). For the reason that Brett states, I do NOT use sealant of any kind as well.
Again, just as a side note: If you are not doing this for 'Fine Point' or specific about originality, just buy two similar lower gaskets and cut the upper 'shims' from the same gasket material. ALL the bolts are the same size equating to the same torque. Once you feel that you have addressed the housing flatness, this should be a no-brainer for the shim issue.
Again, just thoughts from an old man!
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Jon
Senior Member
You may have to loosen a little to help with changing shims, but shouldn't need to change anything there. Gotta remember these parts are "old" no telling what someone foolishly did 50 yrs. ago. That's why I said you can't assume putting .010" in there will align it. Certainly that will happen to a lot of them but not all and it's better to spend a day at this and not have trans. problems later and then have to come back and do this right. I've done a lot of indicator reading in setting machinery and this one is tricky because of the shape of the bell housing and the location of the bolts. It can surprise you how .001" change at the top effects the readings. It's also best to take good notes. Take a reading draw a picture and note the readings. Add a shim, note that above your next set of readings and see what changes, may have to do this 3-4 times to see how shims effect it. If you're patient you can see what's happening and correct it. I enjoy doing this because it makes you think!