Sudden popping out of 3rd

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Bruce2
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Joined: Sat Oct 13, 2001 3:01 am

Sudden popping out of 3rd

Post by Bruce2 » Sat Sep 09, 2017 9:43 pm

A customer with a trans built by someone else suddenly had it start popping out of 3rd. When I drove the car it would immediately kick the shifter out of 3rd gear and grind loudly as soon as you started to let the clutch pedal up. If you forced it into 3rd with about 30 lbs of force, it would stay in like normal.
When I took the nose cone off, this is what I saw.

Image
Image

I think that maybe the mainshaft was able to slide back and forth in the bearing's inner race.
I've only seen this clip come out twice, and both times it was the same builder!

Instead of just putting the clip back in the groove, I took the trans apart for an inspection. Good thing, because the CHINA main shaft bearing was JUNK. The inner race was badly pitted over about a 6mm diameter area. The trans had just over 20k miles on it.

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Pablo2
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Re: Sudden popping out of 3rd

Post by Pablo2 » Sun Sep 10, 2017 8:08 am

Ugh .. From the tips, it looks like a reused circlip. I never cared for that arrangement, which is why we specified threaded ends on our very first batch of 002 & 091 mainshafts. Still, done correctly, the circlips just shouldn't come off ..

There was the day when U.S. Customs "protected" us from "Bearing Dumping" .. the flooding of the U.S. market with cheap Chinese bearings. Every shipment containing bearings was held up requiring extra paperwork. No such protections today, apparently ..
aka Pablo, gears, Geary
9.36 @ 146 in '86

Casting Timmy
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Re: Sudden popping out of 3rd

Post by Casting Timmy » Sun Sep 10, 2017 3:26 pm

I had a trans come in where 3rd wasn't an option, the mainshaft had moved very badly and eventually exploded the bearing. I think based on the clip being nicked around the edges on both sides that it had the mainshaft clip re-used. The extra power of a V6 on an early mainsahft didn't help anything either.

I can't remember where I saw it, but someone that built a lot of gear boxes for drag racing commented on someone's pinion shaft clip coming off and destroying the box a little in the process. When asked for his opinion, he said he never saw a new clip do that.........why do some people reuse clips so much?

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Pablo2
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Re: Sudden popping out of 3rd

Post by Pablo2 » Mon Sep 11, 2017 12:21 am

Looking at Bruce's 2 photos, it appears the bottom photo has the circlip installed backwards .. concave outward.

With the pinion being anchored at the opposite end, a reused pinion circlip isn't as likely to be disastrous as on a mainshaft (which is actually anchored by the circlip).

I would actually place my shafts in a lathe, and with a carbide tip, slightly deepen the circlip grooves.
aka Pablo, gears, Geary
9.36 @ 146 in '86

Bruce2
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Joined: Sat Oct 13, 2001 3:01 am

Re: Sudden popping out of 3rd

Post by Bruce2 » Tue Oct 03, 2017 1:14 am

Pablo2 wrote:
Mon Sep 11, 2017 12:21 am
I would actually place my shafts in a lathe, and with a carbide tip, slightly deepen the circlip grooves.
Have you measured how much you cut?

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Pablo2
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Re: Sudden popping out of 3rd

Post by Pablo2 » Tue Oct 03, 2017 9:53 am

It's been over 25 years, but I only remember deepening the groove slightly on pinion shafts .. I don't remember doing this specifically on mainshafts (which is obviously more critical). But if the mainshaft groove is like the pinion shaft groove, it's slightly tapered and can stand a bit of squaring off (so the circlip has more purchase). Squaring off doesn't deepen the groove at its deepest point, but it does give the circlip more bite.

If I were you, I'd measure the ID of a new circlip and compare it to the groove to determine how much taper to square off. I suppose you could compress a new circlip a tad before installation, too .. they do lose a bit of their dimension, even with a single expansion for installation.

That's the bitch about installing a circlip over a Belleville .. the awkwardness of installation sometimes has you expanding that circlip more than necessary. When installing circlips on output flanges of late model Vanagons, I use a specific size socket, which allows a quick, one-time whack with the hammer.
aka Pablo, gears, Geary
9.36 @ 146 in '86

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