Torque for Yoke retaining bolt?

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dixon5553
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Torque for Yoke retaining bolt?

Post by dixon5553 »

Hi;
I 'm looking for the torque spec for the service procedure found in the 1965 Service Manual, rear axle, section 4-6, note # 5 for the diff. side bearing yoke replacement, it notes a torque for the retaining bolt. I was unable able to find this spec in the shop manual. Also, any "tricks" to removing these side bearing oil seals?

Thanks.
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BobWitt
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Re: Torque for Yoke retaining bolt?

Post by BobWitt »

Rich - I can't find either in the specifications section of the 65 manual or 66 supplement. No listing for "Differential side bearing yoke retaining bolt" torque.

Have you started this job yet? As you can see from other posts here - I've been staying busy on the engine... Hopefully by mid-late January I will be doing the reseal to my trans...
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rowin4
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Re: Torque for Yoke retaining bolt?

Post by rowin4 »

Google bolt torque specs. Pick out the bolt / thread size you need and torque to spec.
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bbodie52
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Re: Torque for Yoke retaining bolt?

Post by bbodie52 »

I could not find any torque specification in the Corvair Chassis Shop Manual or the Assembly Manual.

Using the bolt size from the Chevrolet Parts Catalog and the generic torque specifications from the chart below, if there is no SAE Grade marking on the bolt, then SAE Grade 2 must be assumed. The torque specification for a 3/8" SAE Grade 2 bolt is indicated to be 20-23 Ft. Lbs. You definitely do not want to damage or break one of these bolts, since doing so would require removal and disassembly of the differential to repair such damage. Torque is not the only thing holding this bolt in place, since each bolt is secured by a 3-tab bolt lock. I would use the minimum torque specification of 20 Ft. Lbs. on each bolt, to ensure that it is not damaged. Then lock it in place using the special three-tab lock on each side.

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1965-69 Corvair Yoke.jpg
Brad Bodie
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Re: Torque for Yoke retaining bolt?

Post by 1949chevy »

I just did this job this week...

On the seals on the rear end....Just remove the bolt in the center...a little oil comes out but very little....the yoke comes right out/off...mine was full of greasy dirt on the back side and I cleaned it up...after cleaning around the seal, I used a very large wrench and pryed out the seal. The new seals I got were from Clarks...they took me a while to get in after I cleaned up the seal area. I used a very small hammer and FINALLY got the seals in...then put the yoke back on and tighten it down tight...seems 25 ft lbs....no leaks so far....I did use a little black gasket stuff on the edge but wiped most off to get the seals in. I put a little oil on the seal lips and yoke shaft.

There is a long yoke and and short one....I did one at a time....I think pass side is the long one.

I tighten the shafts that attach to the yoke tight...these torque values are all in the assembly manual...just a little tip to all...I think 20 to 35 but I don't use my torque wrench to tighten these...just tightem them tight but not over tight.

_________________________________________________________________________________________________________________________________________________

CORECTIONS: Clarks 2nd catalog in the pink sections says:

Differential Yoke bolt to Diff 40-50 ft lbs

Assembly manual shows half shaft to yoke....20 to 30 ft. lbs....again, I just tighten with 3/8 rachet or 7/16 wrench tight.

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Re: Torque for Yoke retaining bolt?

Post by 66vairguy »

The torque in the 65 book is under an incorrect name and calls for 100 FT LBS!! Simply wrong on all counts. A later spec. is 35ft lbs.

These bolts SHOULD have a locking tab you bend up to keep the bolt from coming loose after you torque them.
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Re: Torque for Yoke retaining bolt?

Post by bbodie52 »

These bolts are 3/8" bolts, so 35 Ft. Lbs. would only be correct for them if the bolts are marked as SAE Grade 5. If the bolt head is unmarked it is likely an SAE Grade 2 bolt and the 3/8" torque specification is only 20-23 Ft. Lbs. DO NOT OVERTIGHTEN! If the bolt breaks there is no way to remove the broken bolt unless you remove and dismantle the differential.

:banghead:

The properly installed special 3-tab lock washer will secure the bolt from loosening, so nothing is gained from over-tightening these bolts.

I believe that the 100 Ft. Lb. specification mentioned in the Corvair Chassis Shop Manual Rear Axle and Suspension Specifications section refers to the large spindle nut that is a part of the outer yoke that attaches to the outer end of the half-shaft — a part of the axle bearing assembly (Drive Spindle Yoke Nut).
Rear Axle Torque Spec.png
:chevy:
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Re: Torque for Yoke retaining bolt?

Post by 66vairguy »

Brad - Correct the outer axle assembly flange nut spec. is "Drive Spindle Yoke Nut 100 ft. lbs. "--- AND never reuse this nut for final assembly. It is a standard spindle nut and I find the threads will start to distort after the fourth or fifth (selecting shims) torque down. On the final assembly I always install a new nut and NEVER torque over 100ft. lbs. If the cotter key slots don't line up - try another nut. The slot to thread alignment varies so trying another nut is better than under or over torquing the nut!!

The "Drive Spindle Flange 100- 150 ft. lbs." is incorrect and per Bob Helt the flange bolt spec. is 35ft. lbs. Clarks data sheet shows 40-50ft. lbs. and I suspect they used a Grade 8 bolt spec. My notes show the factory bolts were Grade 8, BUT the grade of the retainer the bolt goes into is NOT specified. So I go with Bob Helt's specification.

As you said - if the bolt breaks or the differential retainer plate threads are damaged - you WILL be dismantling a differential to fix it.
1949chevy
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Re: Torque for Yoke retaining bolt?

Post by 1949chevy »

66vairguy wrote:The torque in the 65 book is under an incorrect name and calls for 100 FT LBS!! Simply wrong on all counts. A later spec. is 35ft lbs.

These bolts SHOULD have a locking tab you bend up to keep the bolt from coming loose after you torque them.

Thank you 66vairguy for that info....went back and re-torqued mine to 38 or so.
rnd5553
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Torque for Yoke retaining bolt?

Post by rnd5553 »

Thanks for the replies on this, just go easy on the torque. Is someone suggesting (66Vairguy) that you should also replace the two 3/8 inch bolts that hold the yokes on as well?
billb1561
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Re: Torque for Yoke retaining bolt?

Post by billb1561 »

Same area but a different question regarding he yoke retaining bolt.
65 Monza Vert 4 spd
I have some end play on the right rear yoke. Not sure exactly how much but a casual measurement was in excess of .020". I thought at first I had a wheel bearing issue but I was wrong.
Someone told me I have a worn retaining nut. I have been looking at the drawings and I can't see how wear on the yoke retaining nut would cause end play. It looks like it just clamps the yoke to the differential carrier. Does the nut itself control end play?
The bolt is tight, maybe the wrong bolt? Too long?
Anybody familiar with this setup that can give me some guidance?

Bill B
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66vairguy
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Re: Torque for Yoke retaining bolt?

Post by 66vairguy »

billb1561 wrote: Sat Dec 09, 2017 1:38 pm Same area but a different question regarding he yoke retaining bolt.
65 Monza Vert 4 spd
I have some end play on the right rear yoke. Not sure exactly how much but a casual measurement was in excess of .020". I thought at first I had a wheel bearing issue but I was wrong.
Someone told me I have a worn retaining nut. I have been looking at the drawings and I can't see how wear on the yoke retaining nut would cause end play. It looks like it just clamps the yoke to the differential carrier. Does the nut itself control end play?
The bolt is tight, maybe the wrong bolt? Too long?
Anybody familiar with this setup that can give me some guidance?

Bill B
If the upper link (drive shaft from dif. to wheel) is moving in and out of the differential, then THAT IS NORMAL within reason. If the yoke moves in and out 0.020" then that is fine. The exception is POSI differentials, one side will move in and out the other side WILL NOT, or no play. It's just the way the design works. It's a little disconcerting, but hundreds of thousands of LM Corvairs ran just fine like this.

If the wheel rocks in the wheel bearing (side to side), THAT'S BAD. The factory spec. for the wheel bearing play is way too generous. I followed Steve Goodmans advice and shim my rear wheel bearings to 0.002-0.003" WITHOUT GREASE. When greased the play will be imperceptible, so don't shim with grease in the bearing, just a film of light oil. Usually wheel bearings will run 50 to 80K miles (sometimes longer) before they need service. You must disassemble to grease, which is so labor intensive it's not much more to install new bearings. Once rebuilt (properly - use a qualified Corvair shop like Rear Engine Specialists - Colorado, Steve Goodman) they will go another 80K, or you'll never touch them again. Attemps to drill and grease the bearings (same design as Corvette) have not worked that well and usually you end up with greasy brake shoes!!

"Worn or loose yoke wheel bearing nut" - next to impossible as a cotter pin holds it and at 100 ft lbs it's not coming loose.

Yoke retaining bolt at diff. has a tab to hold it. Spec. is 35 ft. lbs. at Grade 5 rating (later GM spec. as 65 manual is incorrect). Clark's did sell a grade "8" bolt(s), but that bolt screws into a retaining plate INSIDE the differential and if you strip the threads your looking at a complete disassembly to fix - so don't exceed 35 ft lbs even with a grade "8" bolt. The retaining tab will keep it from coming loose. I suppose someone has had one come loose, but I've never heard of it happening. Yes the bolt looks small, but it works fine.
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