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Author Topic: 1969 Z/28 motor mounts  (Read 8617 times)
69Z28-RS
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« Reply #30 on: February 17, 2013, 02:45:09 PM »

I didn't even mention items 5 through 10 (UPC Z28, sheet A4), which were added to the AIM on 6-2-69 (?). I believe these were a stop gap measure before the locking mounts were available. In fact, item #5 is called a "STOP"! It's a LEFT HAND item only, so it kind of adds to the above chart. Note the P/N 3886466 shows A.R. (As Required), and the P/N 3939728 shows only 1 being used.

For service requirements, I believe the 3886466 (non-locking mount) was attached to the right side of the engine and the 3939728 (locking mount) was attached to the left side of the engine!

For production, I have a feeling (no proof) that locking mounts were never used on the 302, but a stop gap measure was applied at some point during the production run. My copy of the AIM shows the date, but the month is kind of light and I can't be sure it's a 6 (June). Does anyone have a better copy that shows the month?
Ed

Ed,
you wrote:  "For service requirements, I believe the 3886466 (non-locking mount) was attached to the right side of the engine and the 3939728 (locking mount) was attached to the left side of the engine!"   
Did you mean in the subsequent year service manuals?  or ??   Why do you believe that?
.. also, from the latest photos posted of a supposed-original 3939728 mount, it doesn't appear to be 'locking'.   Was that a typo in your post?  or am I missing seeing something in those photos?
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Gary W.  /  69Z28-RS, 72 B 720 cowl console rosewood all tint
69 Corvette convertible, silver/black 350 hp,
60 Corvette white/red, 72 Corvette coupe (2), 
90 ZR1 red/red #246, 90 ZR1 white/gray #2466
72 El Camino, '55 Nomad, '57 Nomad, '57 B/A Sedan
rszmjt
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« Reply #31 on: February 17, 2013, 03:02:59 PM »

In the last photos posted, the 'nut' appears to be 'welded' rather than molded in.   Wouldn't a molded in nut be on the opposite side where all the rubber is located?    What is the purpose of all the rubber on the side of the mount?  the holes (for the large bolts) in that mount appear to be round, rather than oblong.   Correct?

The nut is not welded but notched into the mount, the shape of the hex part of the nut but smaller, this is the drivers side mount, the bolt goes in from the back, and Yes the holes are round in both mounts, the frame brackets have 1 bracket that is oblonged. I also have the same passenger side mount that James Posted, and the bolt goes rear to front also.
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rszmjt
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« Reply #32 on: February 17, 2013, 03:06:23 PM »

.. also, from the latest photos posted of a supposed-original 3939728 mount, it doesn't appear to be 'locking'.   Was that a typo in your post?  or am I missing seeing something in those photos?

It is not "supposed-original", it IS a real "ORIGINAL" Production line installed Z28 Drivers side Mount.
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69Z28-RS
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« Reply #33 on: February 17, 2013, 03:20:39 PM »

Sorry if I offended you; I wasn't doubting what you said, but simply noting that I haven't seen any GM documentation confirming the part numbers.   Is the mount 'locking'?  it didn't appear to be....  but it did seem to have 3 layers of metal, with each pair of metal layers laminated to the next using rubber, which seems to make it very thick?   What is the purpose of the middle metal layer?
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Gary W.  /  69Z28-RS, 72 B 720 cowl console rosewood all tint
69 Corvette convertible, silver/black 350 hp,
60 Corvette white/red, 72 Corvette coupe (2), 
90 ZR1 red/red #246, 90 ZR1 white/gray #2466
72 El Camino, '55 Nomad, '57 Nomad, '57 B/A Sedan
Ed Bertrand
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« Reply #34 on: February 17, 2013, 05:05:40 PM »

I believe the 3939728 was a early version of the locking mount. Not what we're used to seeing, but kind of a preliminary design.

Ed
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rszmjt
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« Reply #35 on: February 17, 2013, 05:59:10 PM »

No Offence Taken., I was just clarifying. No the mount is not locking, but I do have the anti/lift/locking plate and through bolt/spacer etc. The Locking Plate is repro from Heartbeat, but the bolt and spacer are original, as are the 3 longer captive washer hold down bolts.
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69Z28-RS
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« Reply #36 on: February 17, 2013, 10:08:50 PM »

thanks for the additional photos!   They show a very interesting motor mount design, and also a very complicated one.   I'm pretty sure I've never seen one quite like that, although I did participate in pulling some original engines from Z28's back around '71-'72..  but motor mounts did not get a lot of my attention back then either.. Smiley
PS.  Does the additional height of that mount cause you any other issues, such as the one I had using the '3962748 mount' which caused my header collector to come too close to the bottom of my floor?  Or do you think my problem likely stemmed from either the header fabrication/design, or the trans mount?
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Gary W.  /  69Z28-RS, 72 B 720 cowl console rosewood all tint
69 Corvette convertible, silver/black 350 hp,
60 Corvette white/red, 72 Corvette coupe (2), 
90 ZR1 red/red #246, 90 ZR1 white/gray #2466
72 El Camino, '55 Nomad, '57 Nomad, '57 B/A Sedan
firstgenaddict
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« Reply #37 on: February 17, 2013, 11:59:00 PM »

In the last photos posted, the 'nut' appears to be 'welded' rather than molded in.   Wouldn't a molded in nut be on the opposite side where all the rubber is located?    What is the purpose of all the rubber on the side of the mount?  the holes (for the large bolts) in that mount appear to be round, rather than oblong.   Correct?
The purpose of all the rubber is additional surface area for bonding so as to keep the mount together, remember these do not interlock.

The metal plate with the rectangular hole is the mid-production change used for the early locking system, used with the existing non-locking mount.
Few of these ever made it back onto a car if the engine came out-
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James
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Check out the Black 69 RS/Z28 45k mile Survivor and the Lemans Blue 69 Z 10D frame off...
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paceme
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« Reply #38 on: February 18, 2013, 11:08:51 PM »

Here is a pic of one found on my 9A of 69 Z.
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Steve Shauger
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z28z11
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« Reply #39 on: February 18, 2013, 11:33:16 PM »

And mine, 01C X77. Sorry they are not as legible as Steve's, but the numbers corelate the same. All bolts are original as well. Man, I had forgotten that I put these away -

Regards,
Steve
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1968 Z28 BRG/W
1969 Z28 X77 LeMans/W
1969 X66 L78 Cortez/BVT
1969 Z11 L48
69Z28-RS
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« Reply #40 on: February 18, 2013, 11:35:09 PM »

Steve,  Were they still functional?  or were they broken apart?  if functional, why did you change them?
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Gary W.  /  69Z28-RS, 72 B 720 cowl console rosewood all tint
69 Corvette convertible, silver/black 350 hp,
60 Corvette white/red, 72 Corvette coupe (2), 
90 ZR1 red/red #246, 90 ZR1 white/gray #2466
72 El Camino, '55 Nomad, '57 Nomad, '57 B/A Sedan
z28z11
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« Reply #41 on: February 18, 2013, 11:38:50 PM »

Additional pic of the 466 mount -
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1968 Z28 BRG/W
1969 Z28 X77 LeMans/W
1969 X66 L78 Cortez/BVT
1969 Z11 L48
z28z11
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« Reply #42 on: February 18, 2013, 11:43:58 PM »

Gary,

Still functional - engine has been on a stand in the garage since 1980, as has the rest of the "garage car" - my new term for the hobby-on-hold for 33 years. Patiently waiting either for death or restoration - my death, or the car's restoration.

Regards,
Steve
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1968 Z28 BRG/W
1969 Z28 X77 LeMans/W
1969 X66 L78 Cortez/BVT
1969 Z11 L48
69Z28-RS
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« Reply #43 on: February 19, 2013, 09:10:52 AM »

Let's shoot for 'restoration', Steve!!  Smiley
PS.  Are you in Murfreesboro?  I'm just north of Huntsville;  we should try to get together sometime... compare notes!

Gary
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Gary W.  /  69Z28-RS, 72 B 720 cowl console rosewood all tint
69 Corvette convertible, silver/black 350 hp,
60 Corvette white/red, 72 Corvette coupe (2), 
90 ZR1 red/red #246, 90 ZR1 white/gray #2466
72 El Camino, '55 Nomad, '57 Nomad, '57 B/A Sedan
paceme
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« Reply #44 on: February 19, 2013, 12:21:50 PM »

The left side mount was interlocking part# 3962748 DK Green.
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Steve Shauger
Vintage Certification™ Program, Providing Recognition And Status To Unrestored Vehicles. Website www.vintagecertification.com
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