Eccentric Shaft Play...
01-08-2005, 03:41 AM
#1
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Thread Starter
Join Date: Aug 2004
Posts: 21
Hi,
Just got done putting my block together (12a TD), and when the rear gear was bolted right up there was absolutely no movment in the e-shaft. Has anyone got any ideas about why there would be no play in the shaft? I understand that about 0.04mm is what you should have. Could it be because the plates have been decked too many times in the past?
We loosened the front gear and moved the shaft around and it feels like the wider portion of the shaft is pushing on the plate that bolts on after the thrust bearing, spacer etc..
Sorry if my description is a bit vague, but hopefully someone knows what I'm on about.
Cheers.
Just got done putting my block together (12a TD), and when the rear gear was bolted right up there was absolutely no movment in the e-shaft. Has anyone got any ideas about why there would be no play in the shaft? I understand that about 0.04mm is what you should have. Could it be because the plates have been decked too many times in the past?
We loosened the front gear and moved the shaft around and it feels like the wider portion of the shaft is pushing on the plate that bolts on after the thrust bearing, spacer etc..
Sorry if my description is a bit vague, but hopefully someone knows what I'm on about.
Cheers.
01-08-2005, 05:23 AM
#2
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Join Date: Jan 2004
Location: Central Ohio (Hebron) Zephyrhills Fla.
Posts: 1,322
Originally Posted by revolve' date='Jan 8 2005, 01:41 AM
Hi,
Just got done putting my block together (12a TD), and when the rear gear was bolted right up there was absolutely no movment in the e-shaft. Has anyone got any ideas about why there would be no play in the shaft? I understand that about 0.04mm is what you should have. Could it be because the plates have been decked too many times in the past?
We loosened the front gear and moved the shaft around and it feels like the wider portion of the shaft is pushing on the plate that bolts on after the thrust bearing, spacer etc..
Sorry if my description is a bit vague, but hopefully someone knows what I'm on about.
Cheers.
Just got done putting my block together (12a TD), and when the rear gear was bolted right up there was absolutely no movment in the e-shaft. Has anyone got any ideas about why there would be no play in the shaft? I understand that about 0.04mm is what you should have. Could it be because the plates have been decked too many times in the past?
We loosened the front gear and moved the shaft around and it feels like the wider portion of the shaft is pushing on the plate that bolts on after the thrust bearing, spacer etc..
Sorry if my description is a bit vague, but hopefully someone knows what I'm on about.
Cheers.
The end play is purely a function of the spacer length that separates the two hard washers on either side of the thrust plate. So if you loosen the rear stationary gear, and then the end play is OK, but it goes away when you snug it up, the engine is too short. The irons have had too much removed from them.
If this engine turned over OK when you got it, and you did not machine the irons, then logic tells me that this is not the correct explanation.
Be sure the front stack is together without trapping one of the bearings. All of the pieces are present and the bolt is snug.
If you had the irons machined, this is likely the correct explanation. Remove the rear gear and see if the front end of the bearing has run up onto the cheek radius on the rear throw. This is where things go wrong when the stack gets too short. If there has been contact, scrape a 45 degree chamfer on the front end of the bearing. Then Ink up the end of the bearing and the whole end of the stationary gear with a magic marker or similar. Install the gear with three screws to keep it lined up and tap the gear into place. Rock the engine back and forth while snugging the screws. If the engine is free all the way to tight add the three missing screws and torque them. If the engine is still free turn the engine over a few times while pushing the crank to the rear. Remove the gear and look at the inked up area. More bearing may have to be scraped away, and in some cases you may have to machine away the face of the stationary gear. This does not hurt a thing but you must clean things up completely when finished.
You can also make up a paper gasket (spacer) from 12 pack card board (Coors Lite works very well) and fit it under the thrust plate. That moves the crank forward about .015" when things are torqued up again. You can do the same under the rear gear, but that spacing defeats the little "O" ring seal, and you must add a bead of silicone on assembly.
Even if this alone frees up the engine, scrape the bearing anyway. The engine will get a bit longer as it heats up, so more clearance will be added. On hard acceleration the heavy crank uses up the freeplay and hangs on the front thrust bearing. That will touch the radius to the end of the bearing and burn it if there is not enough clearance.
The engine will still run fine with a short stack........just like IHOP.
Lynn E. Hanover
01-08-2005, 05:16 PM
#3
Junior Member
Join Date: Jan 2005
Posts: 21
Originally Posted by Lynn E. Hanover' date='Jan 8 2005, 06:22 AM
The end play is purely a function of the spacer length that separates the two hard washers on either side of the thrust plate. So if you loosen the rear stationary gear, and then the end play is OK, but it goes away when you snug it up, the engine is too short. The irons have had too much removed from them.
If this engine turned over OK when you got it, and you did not machine the irons, then logic tells me that this is not the correct explanation.
Be sure the front stack is together without trapping one of the bearings. All of the pieces are present and the bolt is snug.
If you had the irons machined, this is likely the correct explanation. Remove the rear gear and see if the front end of the bearing has run up onto the cheek radius on the rear throw. This is where things go wrong when the stack gets too short. If there has been contact, scrape a 45 degree chamfer on the front end of the bearing. Then Ink up the end of the bearing and the whole end of the stationary gear with a magic marker or similar. Install the gear with three screws to keep it lined up and tap the gear into place. Rock the engine back and forth while snugging the screws. If the engine is free all the way to tight add the three missing screws and torque them. If the engine is still free turn the engine over a few times while pushing the crank to the rear. Remove the gear and look at the inked up area. More bearing may have to be scraped away, and in some cases you may have to machine away the face of the stationary gear. This does not hurt a thing but you must clean things up completely when finished.
You can also make up a paper gasket (spacer) from 12 pack card board (Coors Lite works very well) and fit it under the thrust plate. That moves the crank forward about .015" when things are torqued up again. You can do the same under the rear gear, but that spacing defeats the little "O" ring seal, and you must add a bead of silicone on assembly.
Even if this alone frees up the engine, scrape the bearing anyway. The engine will get a bit longer as it heats up, so more clearance will be added. On hard acceleration the heavy crank uses up the freeplay and hangs on the front thrust bearing. That will touch the radius to the end of the bearing and burn it if there is not enough clearance.
The engine will still run fine with a short stack........just like IHOP.
Lynn E. Hanover
If this engine turned over OK when you got it, and you did not machine the irons, then logic tells me that this is not the correct explanation.
Be sure the front stack is together without trapping one of the bearings. All of the pieces are present and the bolt is snug.
If you had the irons machined, this is likely the correct explanation. Remove the rear gear and see if the front end of the bearing has run up onto the cheek radius on the rear throw. This is where things go wrong when the stack gets too short. If there has been contact, scrape a 45 degree chamfer on the front end of the bearing. Then Ink up the end of the bearing and the whole end of the stationary gear with a magic marker or similar. Install the gear with three screws to keep it lined up and tap the gear into place. Rock the engine back and forth while snugging the screws. If the engine is free all the way to tight add the three missing screws and torque them. If the engine is still free turn the engine over a few times while pushing the crank to the rear. Remove the gear and look at the inked up area. More bearing may have to be scraped away, and in some cases you may have to machine away the face of the stationary gear. This does not hurt a thing but you must clean things up completely when finished.
You can also make up a paper gasket (spacer) from 12 pack card board (Coors Lite works very well) and fit it under the thrust plate. That moves the crank forward about .015" when things are torqued up again. You can do the same under the rear gear, but that spacing defeats the little "O" ring seal, and you must add a bead of silicone on assembly.
Even if this alone frees up the engine, scrape the bearing anyway. The engine will get a bit longer as it heats up, so more clearance will be added. On hard acceleration the heavy crank uses up the freeplay and hangs on the front thrust bearing. That will touch the radius to the end of the bearing and burn it if there is not enough clearance.
The engine will still run fine with a short stack........just like IHOP.
Lynn E. Hanover
That was an awesome explanation,
And i have never thought to use the coors spacer idea.
Over time wouldn't the oil deteriorate the cardboard causing fibers to be in the engine oil?
01-08-2005, 05:30 PM
#4
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Thread Starter
Join Date: Aug 2004
Posts: 21
Originally Posted by Lynn E. Hanover' date='Jan 8 2005, 11:22 PM
The end play is purely a function of the spacer length that separates the two hard washers on either side of the thrust plate. So if you loosen the rear stationary gear, and then the end play is OK, but it goes away when you snug it up, the engine is too short. The irons have had too much removed from them.
If this engine turned over OK when you got it, and you did not machine the irons, then logic tells me that this is not the correct explanation.
Be sure the front stack is together without trapping one of the bearings. All of the pieces are present and the bolt is snug.
If you had the irons machined, this is likely the correct explanation. Remove the rear gear and see if the front end of the bearing has run up onto the cheek radius on the rear throw. This is where things go wrong when the stack gets too short. If there has been contact, scrape a 45 degree chamfer on the front end of the bearing. Then Ink up the end of the bearing and the whole end of the stationary gear with a magic marker or similar. Install the gear with three screws to keep it lined up and tap the gear into place. Rock the engine back and forth while snugging the screws. If the engine is free all the way to tight add the three missing screws and torque them. If the engine is still free turn the engine over a few times while pushing the crank to the rear. Remove the gear and look at the inked up area. More bearing may have to be scraped away, and in some cases you may have to machine away the face of the stationary gear. This does not hurt a thing but you must clean things up completely when finished.
You can also make up a paper gasket (spacer) from 12 pack card board (Coors Lite works very well) and fit it under the thrust plate. That moves the crank forward about .015" when things are torqued up again. You can do the same under the rear gear, but that spacing defeats the little "O" ring seal, and you must add a bead of silicone on assembly.
Even if this alone frees up the engine, scrape the bearing anyway. The engine will get a bit longer as it heats up, so more clearance will be added. On hard acceleration the heavy crank uses up the freeplay and hangs on the front thrust bearing. That will touch the radius to the end of the bearing and burn it if there is not enough clearance.
The engine will still run fine with a short stack........just like IHOP.
Lynn E. Hanover
If this engine turned over OK when you got it, and you did not machine the irons, then logic tells me that this is not the correct explanation.
Be sure the front stack is together without trapping one of the bearings. All of the pieces are present and the bolt is snug.
If you had the irons machined, this is likely the correct explanation. Remove the rear gear and see if the front end of the bearing has run up onto the cheek radius on the rear throw. This is where things go wrong when the stack gets too short. If there has been contact, scrape a 45 degree chamfer on the front end of the bearing. Then Ink up the end of the bearing and the whole end of the stationary gear with a magic marker or similar. Install the gear with three screws to keep it lined up and tap the gear into place. Rock the engine back and forth while snugging the screws. If the engine is free all the way to tight add the three missing screws and torque them. If the engine is still free turn the engine over a few times while pushing the crank to the rear. Remove the gear and look at the inked up area. More bearing may have to be scraped away, and in some cases you may have to machine away the face of the stationary gear. This does not hurt a thing but you must clean things up completely when finished.
You can also make up a paper gasket (spacer) from 12 pack card board (Coors Lite works very well) and fit it under the thrust plate. That moves the crank forward about .015" when things are torqued up again. You can do the same under the rear gear, but that spacing defeats the little "O" ring seal, and you must add a bead of silicone on assembly.
Even if this alone frees up the engine, scrape the bearing anyway. The engine will get a bit longer as it heats up, so more clearance will be added. On hard acceleration the heavy crank uses up the freeplay and hangs on the front thrust bearing. That will touch the radius to the end of the bearing and burn it if there is not enough clearance.
The engine will still run fine with a short stack........just like IHOP.
Lynn E. Hanover
Awesome, thanks for the reply.
I bought the motor in bits and pieces and slowly collected a few more to put it together. It is probably worth mentioning that this is the first time I've been near a rebuild.
I didn't have the irons machined, but it is highly likely that they've been done a few times in the past. I will mark up the rear gear as suggested and have a look at it. It turns out that apparently there was an alloy spacer for the rear gear that I never got.
So spacers or machining are the options. Silicone and cardboard sounds like me! But do you think that is a reasonable long term option? Oh, and whats IHOP?
Nick
01-08-2005, 06:06 PM
#6
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Join Date: Nov 2002
Posts: 3,108
Originally Posted by revolve' date='Jan 8 2005, 06:32 PM
We thought about using gasket paper, but I wasn't sure if I had the right idea. Over to Lynn....
I'm pretty sure that won't work. You could try to re-nitride the plates to build it back up to spec, but that probably won't do it... another choice would be use some sort of cermanic coating.
01-08-2005, 07:24 PM
#7
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Location: Central Ohio (Hebron) Zephyrhills Fla.
Posts: 1,322
Originally Posted by SS124A' date='Jan 8 2005, 03:15 PM
That was an awesome explanation,
And i have never thought to use the coors spacer idea.
Over time wouldn't the oil deteriorate the cardboard causing fibers to be in the engine oil?
And i have never thought to use the coors spacer idea.
Over time wouldn't the oil deteriorate the cardboard causing fibers to be in the engine oil?
The deterioration would be no faster than any of the other fiber reinforced gaskets in engine. Even the stock filtration is below 20 Microns (20 millionths of a meter) so to won't make it through the filter if it does get loose. The pump won't even notice it going through.
Lynn E. Hanover
01-08-2005, 07:58 PM
#8
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Location: Central Ohio (Hebron) Zephyrhills Fla.
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Originally Posted by revolve' date='Jan 8 2005, 03:29 PM
Awesome, thanks for the reply.
So spacers or machining are the options. Silicone and cardboard sounds like me! But do you think that is a reasonable long term option? Oh, and whats IHOP?
Nick
So spacers or machining are the options. Silicone and cardboard sounds like me! But do you think that is a reasonable long term option? Oh, and whats IHOP?
Nick
Objection your honor. Mr. Hanover has been asked to determine an outcome based on a subjective opinion.
No problem. If what you say is accurate, and my suggestion actually applies to the situation inside your engine as I described it, and you have not hosed up some other part of the assembly and are now keeping that A) a secret from us, or, B) are unaware of said "hose up" then, baring some unforseen occurance, such as (in part and only for an example) running it out of oil, or missing a shift and reving it to the moon or similar) then I can assure you that this engine will outlive the car its installed in. This was humorus, yes?
You have my word on it.
IHOP is the International House Of Pancakes. A Short Stack is their most popular
menu item.
Lynn E. Hanover
01-08-2005, 10:04 PM
#9
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Location: Central Ohio (Hebron) Zephyrhills Fla.
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Originally Posted by Cheers!' date='Jan 8 2005, 04:06 PM
I'm pretty sure that won't work. You could try to re-nitride the plates to build it back up to spec, but that probably won't do it... another choice would be use some sort of cermanic coating.
Gas Nitriding is a hardning operation that can make cast iron as hard as Chinese arithemtic. It would add no noticable thicknes. Assuming that the irons were worn past the wear limit (twice) you could be missing as much as .045".
The irons are not costly enough to put much money into saving them. So if a piece of card board can save the engine, start drinking.
The SAE racing deal is very big around here (Ohio State University). The engineering department students built the Buckeye Bullit, an electric streamliner. They own the US and international records with a 316 MPH pass.
One of my drivers drove the car for them. Roger Schroer, He is the test driver instructor for the Transportation Reaserch Center.
I was at an SAE model airplane meet at the Air Force Museum. Some very inventive student designed airplanes.
But I run on as is usual.
Lynn E. Hanover
01-09-2005, 03:06 AM
#10
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Join Date: Aug 2004
Posts: 21
Originally Posted by Lynn E. Hanover' date='Jan 9 2005, 01:58 PM
Objection your honor. Mr. Hanover has been asked to determine an outcome based on a subjective opinion.
No problem. If what you say is accurate, and my suggestion actually applies to the situation inside your engine as I described it, and you have not hosed up some other part of the assembly and are now keeping that A) a secret from us, or, B) are unaware of said "hose up" then, baring some unforseen occurance, such as (in part and only for an example) running it out of oil, or missing a shift and reving it to the moon or similar) then I can assure you that this engine will outlive the car its installed in. This was humorus, yes?
You have my word on it.
IHOP is the International House Of Pancakes. A Short Stack is their most popular
menu item.
Lynn E. Hanover
No problem. If what you say is accurate, and my suggestion actually applies to the situation inside your engine as I described it, and you have not hosed up some other part of the assembly and are now keeping that A) a secret from us, or, B) are unaware of said "hose up" then, baring some unforseen occurance, such as (in part and only for an example) running it out of oil, or missing a shift and reving it to the moon or similar) then I can assure you that this engine will outlive the car its installed in. This was humorus, yes?
You have my word on it.
IHOP is the International House Of Pancakes. A Short Stack is their most popular
menu item.
Lynn E. Hanover
It is quite possible that "B" has occured, but I can assure you that there are no "A's" around here. I took your earlier advice and radiused my ports etc, so hopefully they are all up to scratch. I accept full responsibilty for any "hoseing" that's gone on....
No Coors Lite or IHOP, what am I doing in this country??
Are we talking about the slightly thicker corrugated 12 pack cardboard or the thin stuff? (I can't believe I'm getting all technical about cardboard, I just googled looking for some pictures...)
Any other tips for the budding corrugated fibre board technician???
But yeah, a short stack it is then. I'll space the rear gear, hopefully tomorrow night.
Nick