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Discussion Starter · #81 ·
So yesterday I took the variators apart with help of a friend that got a engineering shop and got all the special tools.
I am going to post few photos. I first needed to clean all the parts before I took photos so I can inspected every thing...remember the cvt belt snapped.
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Discussion Starter · #82 ·
So I inspect the balls that mostly can be brittled and can cause alot of damage..what can I say..I am happy the belt snapped before the ball bearings exploded
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Discussion Starter · #84 ·
The pistons that are in the variators to that work very hard are actually in perfect condition..normally if the balls exploded,pieces of metal can damage pistons and then you need to replace it
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In the first photo of both variators, I would like a better picture of the piston seal ring lap joint, and what the thickness is of the ring. The kit I have did not have that good type of lap joint, and is why I am using the old rings, the ones from the kit leaked too bad and didn't seal good wet either, old ones are much better lap joint. You might start with a small dark red scotch bright sanding disk on a 90 degree air motor to rough that belt deposit off, you will have to start with a bit rougher grit on that, the radial marks on the one pulley must be chatter from the belt. I wonder if someone purposely beat up that transmission doing burn outs or what ever.
 

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Discussion Starter · #87 ·
I will take some photos after work and message it to you.
I also think someone drove the car a bit hard...too much torque went throught that transmission.
I wanted to replace seal on the piston I will feel much better...but yeah I wonder now...what rebuilt kit will send you the correct seals?
 

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I have no idea where to get the good seals if anyone even has any. The thin seals in the kit have very good lap joints, but they don't fit the piston. They give a selection in the kit of different thickness of piston rings.
 

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Have you started trying to clean the variator pulley faces yet? Looks like that should keep you busy for awhile, they are pretty bad. Too bad your friend doesn't have a lathe and tool post grinder.
 

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Discussion Starter · #90 ·
Oh yes that will keep me busy!! I have not begin yet to cleanup the pulleys,I am still shopping around for rebuilt kits..
I have a friend that got a lathe machine so I wil go there and use it.
 

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The grooves took little wear but are okay, nothing serious.
I am deciding to use the pin kit as it is an upgrade. J
If you use pins in place of balls, wouldn't pins be sliding (instead of rolling) back and forth, and cause more friction and wear to the groove?
I have no experience with CVT repair and I am reading the interesting discussion here for my own education.
 

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If you use pins in place of balls, wouldn't pins be sliding (instead of rolling) back and forth, and cause more friction and wear to the groove?
I have no experience with CVT repair and I am reading the interesting discussion here for my own education.
My understanding (and chidog can correct me if I'm wrong) is that those ball bearings mainly serve two purposes: To facilitate smooth in/out motion of the pulleys to allow variation through the gear ratios, but also to lock each of the pulley sides in place to prevent either side from rotating as the twisting force is applied to the pulley assembly (...if this happened the belt would slip). The problem with the ball bearing design, I believe, is with the latter and it would appear this is evident by the OP's picture of the condition of one of them. The twisting force the bearings have to resist seems to cause them to chip/crack over time. I've also seen tear-down videos that clearly show the balls destroying the grooves they ride in. A pin design would offer a much larger surface area to help prevent these problems and the pulleys would simply slide in/out over the pins. If the pin design didn't work, transmission rebuilders wouldn't be using them. It should be noted that the later generations of Jatco CVTs switched from ball bearings to larger roller bearings with keepers.
 
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I need coffee, is correct. It is my opinion that the balls will in time wear the divots into the grooves and those divots will catch the ball and hold it when under torque and when the pulley tries to move on the shaft that movement helps over stress the ball and starts to break them like in the photo that Redline posted, it is once those balls start to break up that the real damage starts to happen and they tear up the grooves in the shaft, and sometimes get wedged and then crack the sliding pulley's hub, like in some pictures online. And Wolfgang yes that is probably why the engineers used the balls in the first place, thinking of the sliding that you mention. It can work in some applications, old cars and trucks far back had recirculating ball steering gears and yes into the now times as well, modern machine tools have recirculating ball lead screws, you can look this stuff up on you tube to see what that is. The key word is recirculating, the same balls don't hammered all the time they get changed out sort of and most important are larger size as well.
The contact surface on a ball works out to only being a very tiny spot on its surface more like a small line around part of the ball on the load side in a radius'd groove, that is pretty high stress. Like, I need coffee, said the pin helps spread that load across the surface (so much more than a ball), and like he says Jatco started using them later on, and I think other CVT makers were using them years before. It would be interesting to know if the Jatco rebuilds now use pins or not? I think Redlines transmission belt broke because of the apparent abuse and the rough balls and slight divots in the grooves helping temporarily restricting pulley sliding movement and the high torque load that caused the radial lines across the face of that pulley, sort of a belt chatter effect, and that real badly worn flow control valve, causing low pressure all adds up, just look at the metal deposits on his pulley from slippage.
 

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This guy really is a good trouble shooter especially the electrical, he is not a transmission expert but does a great job here.
You can skip to the 35:34 minutes or so, the point of him starting to look into the pulley, and show what the steel balls end up doing to the shaft.
At 43:10 he actually starts pulling the pulley off the shaft to better see the damage.

That whole pulley assembly is pretty much scrap, all because of the steel ball design. And like he says the shaft may need to be heat treated a bit higher in that area.

This shows how lucky Redline was with his steel balls and grooves. His grooves are bad enough that pins are the only option, balls may not last long because of the roughness near the retainer ring.


 
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