Result of over tight End flote?
12-06-2006, 01:13 PM
#11
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Originally Posted by Lynn E. Hanover' post='848100' date='Dec 5 2006, 04:48 PM
There are some interesting points to think about here.
Plain bearings require a bit of running clearance for a full oil film to develope. So a rod bearing clearance might be .002" and a main bearing might be .003". Roller bearings can run with no clearance at all, and in most cases, with a preload. Tapered rollers require a preload to maintain locus. (like front wheel bearings)So oil requirements are minimal.
The amount of load that a roller can support is a function of its diameter. Note that the Mazda thrust bearing has very small rollers. Note also that in a radial application, a nontapered roller is always sliding one end or the other, because the outer end of the roller is traversing a larger diameter circle than the inner end. So, the outer end may be sliding a bit underspeed, or the inner end may be turning a bit faster than required.
So, it is not the ideal application for this bearing style, but if not preloaded, and is well oiled, it performs nicely.
If there were too little clearance, (so long as no preload exists) not much goes wrong, until the engine is screamed and the crank flexes a bit, and the bearings are run out of square on the thrust plate at very high pressure. Goodby bearings.
If there is too much clearance, not much goes wrong until you use the engine hard enough to cycle the rev limiter. You do run a rev limiter do you not? Anyway you can shake the engine hard and damage a bearing. More likely if you are running a crank trigger and two MSDs, one for the front housing and one for the rear. One trigger always cuts a few RPM before the other. Also, extra clearance allows a slightly higher load when the clutch is punched during a shift. Also very high spring pressures used in some clutch covers causes early failure of the rear thrust bearing. When you push in the clutch pedal, the throwout bearing pushes on the center of the clutch spring, and every ounce of that force appears in the rear thrust bearing.
The rotary has very poor low end torque. It also has poor high end torque. So why do you need a clutch cover with all of that spring pressure? For longer life from trans and rear end parts, a clutch that slips just a bit on upshifts is a good deal. It needs only enough pressure to hold on for your launch. That's all.
When racing with a dog ring box, road racing or drag racing with split dogs, you will be breaking things right and left, until you lighten up on the cover spring pressure. And then your rear thrust bearing will last a good long time.
Lynn E. Hanover
we scattered an engine with revlimiter(s). literally, peices came out. turns out with the stock gearing at thunderhill, theres about 50ish yards between top of 3rd and turn 1, and then its a lift, and get back on it, and then another 100+ yards to turn 3.
10-20 seconds @the 8500rpm limiter is bad
12-06-2006, 02:13 PM
#12
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Well i pulled the Motor today, i have to say its not what i expected.
The washer that sits between the Two bearings has split into two pieces and the Thrust bearings have sort of jamed up on the damaged washer.
It was not what i was expecting? I have seen a Pic of it before when people have hit the Flywheel with a hammer to loosen it but i never did that?
I also checked all the parts closly when it was striped and cleaned and there was No cracks there then? this has happened within 15 minutes of Running an no more than 2000rpm.
The washer that sits between the Two bearings has split into two pieces and the Thrust bearings have sort of jamed up on the damaged washer.
It was not what i was expecting? I have seen a Pic of it before when people have hit the Flywheel with a hammer to loosen it but i never did that?
I also checked all the parts closly when it was striped and cleaned and there was No cracks there then? this has happened within 15 minutes of Running an no more than 2000rpm.
12-07-2006, 07:23 AM
#13
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It does sound as if the end-float was too tight to begin with and it roached the bearings. How tight was the front pulley torqued?
I've never had a problem with smacking a flywheel to remove it, but it never takes me more than one or two hits.
I've never had a problem with smacking a flywheel to remove it, but it never takes me more than one or two hits.
12-12-2006, 08:02 AM
#15
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Originally Posted by diabolical1' post='848814' date='Dec 12 2006, 02:19 AM
2 questions: how do you tell if the thrust bearings need replacing? what's the difference between regular and competition?
I didn't know there was a competition set.
Anyway, you can use the later (larger diameter) bearings by buying the latest stationary gear, or machining an older gear well just a bit wider.
The larger diameter moves the thrust load out a bit and closer to the bolt circle where the thrust plate is stiffer. The plate cones a bit when stiff clutch cover springs are used. The bigger bearings may be of a better design also, and or have more rollers. I cannot comment on that. I have never seen a set of them.
If the engine comes to you as new in a crate. The thrust bearings are probably fine. If it came from a junk yard. They need replaced. If you did not build this engine the last time it was out, they need replaced. In short, if you do not personally know the history of the engine, replace the whole shooting match.
The bearings and thrust plate are as hard as Chinese arithemtic. When the thrust plate cones a bit such as sitting on the flywheel in the junk yard, or from a miss adjusted clutch touching the driven plate, or sombody hitting the flywheel or automatic counterweight to get it off, or hitting the front pulley bolt to free it up, the plate cones a bit and the shock load appears only on the very ends of the rollers. They will not do that even once without some damage. The fragments that spall from the roller tips are microscopic, (means you cannot see them) and go right through the bug screen on the oil pickup tube and lodge in the oil pump elements. Some but not all, will end up in the oil filter. But there is no filter protecting the pump.
I keep the spacers, and a thrust plate now and then. The spacers seem to hold up to anything pretty well, and the thrust plates can be brazed to the bottom of oil cans to keep them upright.
Don't put an unknown thrust part on a nail or in a drawer. It will find its way into an engine some day and come back to bite you.
Lynn E. Hanover
12-21-2006, 12:11 PM
#16
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as always, thanks for the response and advice, Lynn.
i got my new thrust bearings today and will assemble the front cover tonight. anyway, i just wanted to report to any interested parties that the bearing needles are notably longer in the competition bearings (by the way, they come from Mazda). i will try to remember to count the needles later and see if there is a difference in number, too.
i got my new thrust bearings today and will assemble the front cover tonight. anyway, i just wanted to report to any interested parties that the bearing needles are notably longer in the competition bearings (by the way, they come from Mazda). i will try to remember to count the needles later and see if there is a difference in number, too.
12-21-2006, 02:08 PM
#17
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Originally Posted by diabolical1' post='849808' date='Dec 21 2006, 01:11 PM
as always, thanks for the response and advice, Lynn.
i got my new thrust bearings today and will assemble the front cover tonight. anyway, i just wanted to report to any interested parties that the bearing needles are notably longer in the competition bearings (by the way, they come from Mazda). i will try to remember to count the needles later and see if there is a difference in number, too.
i got my new thrust bearings today and will assemble the front cover tonight. anyway, i just wanted to report to any interested parties that the bearing needles are notably longer in the competition bearings (by the way, they come from Mazda). i will try to remember to count the needles later and see if there is a difference in number, too.
Its an Ingersoll-Rand part, but those #s arent legible.
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