snap ring question that's never been asked

[Russ]

It's been said that checking the transmission case for potential snap ring failure is not possible - case replacement is the only sure remedy.

If that's true, then according to this article, how were the original machinists able to catch the machining error in order to know that it was time to realign the two piece cutting tool?

In other words, if the machinists who made the transmission could measure the snap ring chamfer, why can't a technician who is fixing the transmission measure it?



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Russ
'91 black/black

 

[NyC NsX]

food 4 thought....and anyone thought about just making a snap ring that fits the case that are having this snap ring failure problem ?... please dont flame me if this idea is wee tar did.

 

[DutchBlackNsx]

Thought about that as well.

Making a snapring which is thicker won't work, cos it won't fit in the bearing, which is the right size for the standard snapring.
The cut-out in the trannycase is not a standard measurement also.

I also suspect that the tranny housing is damaged by the snapring in variuos ways (i had to hammer some bits out, keep in mind that is the tranny which was cut to wide).

I do think though that making an imprint from the groove should be possible, and thus afterwards measureable.

I also can see now how people have replaced the snapring without taking the tranny apart, see other thread way back. A bit of a butcher job, and not very proffesional, leaving the original problem existing.


Mich

 

[Lud]

Originally posted by Russ:
In other words, if the machinists who made the transmission could measure the snap ring chamfer, why can't a technician who is fixing the transmission measure it?

I suspect the machinists were seeing the failure of the multi-part die, or maybe even just replacing it on a set schedule after X number of cuts as opposed to actually measuring the chamfer, but that is just speculation since I don't think any of us have first-hand knowledge.

Of course if they wanted to spot check the actual cases, and had a special measuring device, and more importantly knew the specification, they could measure it if they had the case sitting in front of them.

I think the main issue with saying owners can't measure it is that we have neither a tool designed to measure it nor any kind of specification on what is acceptable. Possibly these could be developed, but they do not exist right now. Additionally, since the labor involved to remove the case for measuring is extensive (the same as the labor to replace the case), I don't think anyone felt it was worth developing either the tool or the specification.

Possibly a more practical measurement is to measure the play in the countershaft which can be done quickly and easily. Larry Bastanza rigged a jig (hey that rhymes) with a dial indicator to measure this. But again the problem is we do not necessarily know what we are measuring because there is no published tolerance spec. If we had enough data and kept track of which transmissions experienced snap ring failure perhaps we could figure it out, but the data just isn't there right now.

[This message has been edited by Lud (edited 16 July 2002).]

 

[Larry Bastanza]

Hey Guys,

Well, as Lud pointed out I did make a tool the check the "end play" of the countershaft. However..... after long discussions with Mark Basch after many samples, I checked about 7 transmissions in range and out, we have concluded that, unfortunately the test results are meaningless.

This is due to the fact that the groove has a chamfer that's cut too wide (deep) in the case of a bad case (did I say that right!?). Which means that the "end play" is not effected by the groove having a chamfer too deep. So the groove will be the same width on either a good or a bad trans case. Based on that measuring the end play tells us nothing

Hey, I tried. My original goal was to see if we could detect failures before they occured.

I guess you could visually inspect the case and the chamfer if you have a good and a bad one side by side, but this is not an easy thing to do. I actually thought about using something like "silly putty" to make an imprint of the groove and chamfer to see the difference, but never got to it, especially since I do not have access to 6-7 trans cases, good and bad.

If I recall from my in depth discussions with Mark, the tool was checked to see when it was going out of alignment in production, not the cases.

The original tool was a three piece affair, one middle piece to cut the deep groove and two side pieces to cut the chamfer on either side. The tool was redesigned into a one piece tool to eliminate the problem.

So, I am really not sure if they actually jigged and tested the cases. Remember we do have a snap ring "range". If they tested them they would have never been used!!!!!!


I believe this was left as part of the "customer test" scenario

Food for thought.

LarryB