Alternator adjustment bolt

[Gary S.]

Re: Alternator adjustment bolt

Guys, this has been a great thread. The book says one thing, but there are enough examples showing the AIM not being followed in all cases on the assembly line. As I asked in a prior response, was it followed 100% of the time on the line? I think the two Joe's (Ciaravino and Ray) have it right in the two previous threads. And, those two boxes of washers were probably setting side by side and did the worker always get the right box? I would not deduct for either washer showing up for a 65 to 67 year but would for the toothed washer if not the correct squared off ear type. IMHO Gary

[Mike M.]

Re: Alternator adjustment bolt

OK, while we're at it, no one has commented on the "Ears".
Th GM spec sheet shows ten, the "Original" examples shown appear to have nine???
It seems that the repops have even more "Ears" and the outside diameter is larger than the GM's???
Can't figure out why the other brand owners call Corvette guys anal.
HaND

[James M.]

Re: Alternator adjustment bolt

HELP!!!

67 BB

Just finished the review of this thread and I think I am just as confused as I was before reading it. The confusion comes from what appears to be correct in the AIM (bolt, split lock washer, wider thicker washer to the bracket); then the JG says BB and SB have WB bolt, external tooth lock washer followed by a thick flat washer into the bracket; then there is the way the car is actually judged vs what is said to be correct here as far as a 67 BB goes.

As I have learned, the AIM is not always considered to be correct and is in conflict with the JG at times. This seens to perhaps be one of those times. The second thing I was taught recently at a meet is that judging is usually about getting the points and not necessarily about correctness.

Thus my question is " what is the correct configuration for judging my BB?"
Second question is "were these items black or plated?"

Thanks for any advise and help for this issue.

James

[Peter L.]

Re: Alternator adjustment bolt

James - As far as 67s (and also 66s) are concern, I would expect the 67 sb & BB to have the following sequence on the alternator adjusting bolt per the AIM (UPC 6 Sheet A2):

1) special washer (thick flat washer against the brace)

2) lock washer ("Shake-Proof" type lock washer with "external wide ears.
NOTE: Not a split ring lock washer)

3) bolt - bolts can have various headmarks including WB, NAT, plus some
others.

Pete

[James M.]

Re: Alternator adjustment bolt

James - As far as 67s (and also 66s) are concern, I would expect the 67 sb & BB to have the following sequence on the alternator adjusting bolt per the AIM (UPC 6 Sheet A2):

1) special washer (thick flat washer against the brace)

2) lock washer ("Shake-Proof" type lock washer with "external wide ears.
NOTE: Not a split ring lock washer)

3) bolt - bolts can have various headmarks including WB, NAT, plus some
others.

Pete

Thanks Pete,

Would you expect to see this hardware in a black or what finish for judging?

[Mike M.]

Re: Alternator adjustment bolt

James,
you have answered your own question:
JG says, WB bolt, external tooth lock washer, thick flat washer to the bracket.
All three pieces of hardware are Zincad.
HaND

[James M.]

Re: Alternator adjustment bolt

Mike,
Thanks for the the confirmation.

[Ronald L.]

Re: Alternator adjustment bolt

So with one JG comment and another post we throw out the AIM for BB???

There was a reason for this or Chevrolet Engineering would not have released a lock washer for the big block.

Think durability test results - think high HP and torque and vibration.
Star lock washers have a very low, relative to lock washer resistance to break away. That is why you do not see star washer used on critical chassis parts nor inside the engine.

I'm leaving my 49,000 mile original alternator in place with its original RBW grade 2/3 bolt, p washer and LOCK WASHER.

Additionally,

"IF" you look at AIM, you will see that most ALL the attaching parts for the bracket are different too! Bolts and washers.

How do you know this car was processed? Was the engine in the chassis at this time?

On engine dress assembly lines in assembly plats to this day from one engine to another different stuff gets bolts on.

Let's get the data, get back to basics the AIM has part numbers, those part numbers have a print, and that print specifies a configuration.

The GM Engineering Standards book, that some members have and have posted the cover and perhaps a page or two on this board, show all the detail about these parts we will ever need. Finish, hardness, threads on bots, etc. etc.

[Peter L.]

Re: Alternator adjustment hardware

Ron - Thanks for the additional comments. I rechecked the 1967 AIM and adjusting hardware, specifically the lockwasher called out, on the 327 engine as shown on UPC 6, SHEET 2, and found it does differs from the lockwasher called out on the adjusting hardware on the 427 engine as shown on UPC L36, SHEET A3.

For the 327 engine the AIM part number call outs are 122017 BOLT; 138485 L. WASHER; & 3792420 SPL. WASHER.

For the 427 engine the AIM part number call outs are 122017 BOLT; 187119 L. WASHER; & 3792420 WASHER.

The Chevrolet Parts & Accessories Catalog shows p/n 138485 [Grp.# 8.932 TOOTH LOCKWASHERS (Cadmium)], EXTERNAL TOOTH, 5/16"; and p/n 187119 [(Grp. # 8.931 LOCKWASHERS (Cadmium Plated)], 5/16" (Med.). The drawing of the Grp. # 8.931 LOCKWASHERS shows a split ring lock washer.

The dimensions of a NOS 3792420 SPL. WASHER or WASHER from a '64 A/C KIT are 5/16" I.D. x 7/8" O.D. x 3/32" Thickness. The description from the AC KIT is WASHER - SPECIAL PLAIN CAD OR ZINC.

Sorry for the err on the LOCKWASHER. Hopefully this information will help clarify the differences in the lockwashers used in the adjusting hardware on sb and BB alternators.

Pete

Pete

[Ronald L.]

Re: Alternator adjustment bolt

Peter - such good detail, thanks for those part numbers and specifications.


I'll eat only a very very small bit of my last comment and only after looking at the picture of my original bolt to alternator configuration - here is why:

If you look at the AIM - the 327 the bolt/ star washer/P washer was going into a 693 alternator - the base 37 amp alternator, so the L36 base 427 got the 693 alternator and on the Engine dress line - would have been been built this way.

BUT>>>

the L72 got the 696 alternator and so there is our answer right in the AIM, it got the lock washer.

The difference in the washer has to do with what alternator the car got, not the specifically the motor.

Something new for Bloomington and the next edition of the JG!

And yes, my L36 has the star washer...ouch I cracked a crown on that lock washer.

[Joe L.]

Re: Alternator adjustment bolt

Peter - such good detail, thanks for those part numbers and specifications.


I'll eat only a very very small bit of my last comment and only after looking at the picture of my original bolt to alternator configuration - here is why:

If you look at the AIM - the 327 the bolt/ star washer/P washer was going into a 693 alternator - the base 37 amp alternator, so the L36 base 427 got the 693 alternator and on the Engine dress line - would have been been built this way.

BUT>>>

the L72 got the 696 alternator and so there is our answer right in the AIM, it got the lock washer.

The difference in the washer has to do with what alternator the car got, not the specifically the motor.

Something new for Bloomington and the next edition of the JG!

And yes, my L36 has the star washer...ouch I cracked a crown on that lock washer.

Ronald-----


As far as external configuration is concerned, all 1966 alternators were absolutely identical. So, the difference in alternator part numbers could not represent a functional reason that the bolt and washers needed to be different.

[John H.]

Re: Alternator adjustment bolt

Mike Garver (fastener engineer) would know better than I, but there had to be a reason why the SB application used the star washer and the BB used a split lock washer; might be related to the stiffness of the mounting brackets and a difference in harmonics between the BB and SB.

[Joe C.]

Re: Alternator adjustment bolt

Mike Garver (fastener engineer) would know better than I, but there had to be a reason why the SB application used the star washer and the BB used a split lock washer; might be related to the stiffness of the mounting brackets and a difference in harmonics between the BB and SB.

That was my initial thought as well, but, no...............then why wouldn't mild cammed vs.SHP SB have had the same principle apply?

I'll speculate that somewhere in March, 1965, Chevrolet took advantage of a fire sale on split lock washers.

[Ronald L.]

Re: Alternator adjustment bolt

AIM shows 693 alternator with star washer.

693 alternator goes on the base L36.

This original alternator and attaching hardware look just like it is specified.


What data do we have that says anything other than L72 got a lock washer for 1966?

[John H.]

Re: Alternator adjustment bolt

What data do we have that says anything other than L72 got a lock washer for 1966?

Ron -

If you look at the L36 contents sheet (A1), it shows that both the alternator bracket and brace are installed the same as on L-72 (same part numbers), and the L36 sheets don't call out any different part numbers for the alternator attachments.