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Early Posi Right Side Axle Yoke Questions
Posted by: REM654DPG ()
Date: October 03, 2019 07:21PM

Hello out there in the Corvair world. I’m looking for a picture, dimensions or just some known info of an early right side (short) posi axle/U-joint yoke.

Here’s what I think I know – the early right side posi yoke has a shallower dust shield and that’s the only difference.

Here’s what I don’t know – if the above statement is true, how much shallower is the shield from a standard one and is this the only unique characteristic.

Here’s what I have found going through the few cores I have - all of the left (long) side yokes have the same length splines on the shaft. Most of the right (short) side yokes have the same length on the splines as the left yokes except for a few. These few have a longer spline length by .150 and yet they have identical dust shields as all the other yokes.

So, would these longer splined short shafts be specific to a posi differential or is the only unique characteristic of a short early posi yoke just the shallow shield. And is this shield obviously shallower to where you would know just at a glance.

The picture shows the length difference between the two shafts in question – both are short right sides.

Thanks in advance for any help!

Regan Metcalf
Portland, OR

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Re: Early Posi Right Side Axle Yoke Questions
Posted by: JimBrandberg ()
Date: October 04, 2019 05:29AM

I don't know the answer but I suppose it would change the way I view my pile of old yokes. There sure is a lot to keep straight for a guy only working on one kind of a car. Does the P&A 30C list different parts?

Jim Brandberg
Isanti, MN
CorvairRepair.com



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Re: Early Posi Right Side Axle Yoke Questions
Posted by: The Californian ()
Date: October 04, 2019 07:10AM

Looks like the longer splines are an improvement.

More spline is stronger.

They could fool you though.

Long spline is early and they changed it to produce easier or something.

THE CALIFORNIAN

THE GOLDEN CHILD

PRIVATEER ENGINE BUILDER/CHASSIS BUILDER

MANUFACTURER DUAL POINT DUAL COIL RACE DISTRIBUTOR AND RACE CDI UNITS

The only difference between success and failure in any job is your attitude toward it.

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Re: Early Posi Right Side Axle Yoke Questions
Posted by: REM654DPG ()
Date: October 05, 2019 09:34PM

Bump - Still looking for help on this if any of you gurus out know the answers and maybe have a picture or two.

What I didn't really make clear on the original post was that the longer splined short shafts are actually .150 longer total length than the others and the added length is splined.

Thanks

Regan Metcalf
Portland, OR

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Re: Early Posi Right Side Axle Yoke Questions
Posted by: dryenko ()
Date: October 06, 2019 05:05AM

Not going way out on a limb here, but I would "speculate "that because of the extra parts in the posi side of the carrier, that the shorter yoke " may " go with the posi unit??

Bob C aka Dryenko
Dobson, NC 27017

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Re: Early Posi Right Side Axle Yoke Questions
Posted by: caroseiii ()
Date: October 06, 2019 06:33PM

There is only one GM part number for the stub axle 3784936 and a part number for the deflector shield 3814098. "NOTE: WHEN USING ON RIGHT SIDE ON 1962-64 MODELS WITH LIMITED SLIP DIFFERENTIAL IT WILL BE NECESSARY TO USE 3814098 DEFLECTOR."

Crawford Rose

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Re: Early Posi Right Side Axle Yoke Questions
Posted by: JimBrandberg ()
Date: October 07, 2019 05:09AM

So is there more than one deflector listed?

To further complicate things, sometimes there is a spacer mounted outboard between the wheel bearing housing and the backing plate.
My buddy Fran Schmit made a study of this but it was hard to find a pattern or draw any conclusions. Not every car had any and they were often on just one side. There may be different thicknesses as well.

Since there is only one stub axle listed and you are finding two it's still a bit of a sticky wicket.

Jim Brandberg
Isanti, MN
CorvairRepair.com



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Re: Early Posi Right Side Axle Yoke Questions
Posted by: caroseiii ()
Date: October 07, 2019 09:53AM

The other stub axle is the longer one for the left side. Not applicable to the posi!

Crawford

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Re: Early Posi Right Side Axle Yoke Questions
Posted by: REM654DPG ()
Date: October 07, 2019 09:18PM

Thanks for all the inputs everyone - were definitely making progress trying to figure out this mystery.

Bob, as far as I can see with measuring the side gears and other components inside the diff - all of the splines whether and open or posi are the same length and in the same proximity to the centerline of the spider gear shaft. So it seemed logical but nothing is different which still does not explain the two different shaft and spline lengths for the right side yoke. Which as Jim says still leaves us in a sticky wicket.

And Crawfords info regarding only one part number for a short shaft must imply another one of those GM mid production anomalies that was never updated.

I'm going to guess that the longer of the two shafts must be a later production upgrade as either will work but it's still a mystery. The short shield is what I'm really wanting to see just so I know how much shallower it actually is.

Thanks again guys and here's better picture of the two shafts showing the .150 difference in length.

Regan Metcalf
Portland, OR

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Re: Early Posi Right Side Axle Yoke Questions
Posted by: The Californian ()
Date: October 07, 2019 10:58PM

Crawford

Here is a picture of yokes for sale on Ebay.

Quite a big difference in length.

He is calling these 'short and long' for '61-64 Corvairs.

THE CALIFORNIAN

THE GOLDEN CHILD

PRIVATEER ENGINE BUILDER/CHASSIS BUILDER

MANUFACTURER DUAL POINT DUAL COIL RACE DISTRIBUTOR AND RACE CDI UNITS

The only difference between success and failure in any job is your attitude toward it.

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Re: Early Posi Right Side Axle Yoke Questions
Posted by: JimBrandberg ()
Date: October 08, 2019 04:31AM

That is the difference between left side and right side. What we are talking about here is only in regard to right side.

Jim Brandberg
Isanti, MN
CorvairRepair.com



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Re: Early Posi Right Side Axle Yoke Questions
Posted by: REM654DPG ()
Date: November 09, 2019 10:42PM

I finally got hold of an authentic early posi right side yoke with the shallower shield thanks to Rex and the Fanbelt toss and figured I would share what little I learned.

The early rt side posi dust shield is .125 shorter or shallower and .100 smaller in diameter than the standard one. Shown in picture 1. Enough to compensate for the added amount that the side adjuster sets outboard due to the difference in the posi cover that fits the clutch pack.

I’m not really sure that this shallower dust shield is actually necessary on an early posi but figured since GM went through all the trouble it must have been needed.

My intent on this search was to figure out how much additional amount this shield needs to be offset when you fit a late 9 bolt posi unit into an early case. The late posi cover is .090 thicker and will set the side adjuster that much further outboard. So, about .250 offset from the stock dust shield will give plenty of clearance.

My simple solution was to make a flat plate that is the same diameter as the posi shield and attach it to the yoke. The flat plate does sit further outboard than it needs – about 3/8 inch (picture 3) – but it’s an easy fix and all it really does is keep the big rocks out of the seal.

And that’s all I know for now – thanks for looking.

Regan Metcalf
Portland, OR

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Re: Early Posi Right Side Axle Yoke Questions
Posted by: v8vair ()
Date: November 10, 2019 05:29AM

The difference in length is do to which cross shaft you have. One Cross shaft has the center machined flat on both sides and can take the longer yoke.The completely round shaft uses the short yoke. I Really don't think it matters but I took the shields off the early racer to get at much spline engagement as possible when I had my axles made. You can also use the flat shaft when making a 4 spyder coversion to lock the pins from spinning and drilling another hole for a roll pin opposite from the other. Mike

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Re: Early Posi Right Side Axle Yoke Questions
Posted by: JimBrandberg ()
Date: November 10, 2019 06:06AM

This is all very interesting, thanks for posting follow-ups.

Jim Brandberg
Isanti, MN
CorvairRepair.com



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Re: Early Posi Right Side Axle Yoke Questions
Posted by: cnicol ()
Date: November 10, 2019 04:31PM

I always thought the flatter deflector was due to the posi side-adjuster which doesn't have the deep V-groove found on non-posi adjusters. I've never seen the spline-length difference you've discovered.

Craig N. Coeur d'Alene ID.
66 Black Monza 4dr, 4.2L V8 49k
61 Seamist Jade Rampside 140 PG
60 Monza coupe (sold, sniff sniff)
66 Sprint Corsa convt - First car! Re-purchased 43 years later
2+2 gnatsuM 5691

+17 Tons of parts

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Re: Early Posi Right Side Axle Yoke Questions
Posted by: caroseiii ()
Date: November 10, 2019 05:55PM

The flat metal approach you used is good. Particularly if you buy the Clark's replacement posi adjuster nut which does not work with either factory shield.

Crawford Rose

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