The Stovebolt Site Forums The Shop Area Engine Shop Front motor mount

I have a 53 chevy truck 235 engine . On the front motor mount is the retainer suppose to touch the plate after you snug the two carriage bolts that hold the assembly to the frame .. Does anyone know the torque for those bolts too? I'm not sure if the retainer needs that Clearence for the plate .. The rubber mount was almost flush in the retainer so I shave down the retainer so it would not touch the plate is that normal ?

http://www.stovebolt.com/techtips/engines/motor_mount_front/index.html

You do not want it to touch, you will get a bad vibration transfer.

The shop manual calls for clearance.

Bottom right
http://chevy.oldcarmanualproject.com/shop/1948_51truck/51ctsm0613.htm

I don't believe there is a torque value. Just snug, my original bolts had a provision for a Cotter pin.

When u install the motor do u attach the front mount to the engine then stab it in or bolt the mount to the frame then sit engine in ?

Install on motor first(if possible)

Denny has some real good pics on his web site
http://www.pbase.com/dennygraham/1950_motor_mounts&page=all

the two center bolts are imposed
http://www.pbase.com/dennygraham/image/136995331

This may save you some time finding fasteners for your motor mount.

I used these parts and fasteners for the front and rear motor mounts on my '54 3104. I believe that they are as correct as I could find to the original fasteners.
+ item name
+ original GM part numbers and size
+ new Fastenal replacement number and sizes
+ original GM motor mount part numbers
+ Filling Station or Truck Shop replacement motor mount part number

FRONT MOUNT HARDWARE:
> Shield - GM #3656502; Filling Station #TR-182
> Cushion Assembly - GM #3657520; Filling Station #CV-335A
> Plate - GM #3657522, used original plate that was on the truck
> Retainer - GM #368449, used the original retainer that was on the truck
> Middle Bolts (2) - GM furnished by engine plant; Fastenal #21879 7/16"-14 x 2-1/4" Zinc finish SAE J429 grade 5 round head carriage bolt
> Middle Washers (2) - GM #352282 7/16" ID, 13/16" OD, 0.062 thick; we used 3/8" stainless washers that are the correct OD and filed the hole to 7/16". the 7/16" washers that I bought were 15/16" OD and might touch the crossmember.
> Middle Nuts (2) - GM furnished by engine plant; Ace Hardware 7/16"-14 top lock nut.
> End Bolts (2) - GM #3701135 3/8"-24 x 1-7/8" carriage bolts; used the GM carriage bolts that were on the truck. If you need the end bolts, you could use Fastenal #0159808 3/8"-16 x 2" Zinc Finish SAE J429 Grade 5 Short Square Neck Round Head Carriage Bolt
> End Washers (2) - GM #365685 3/8" ID, 1-1/4" OD, 0.187 thick; Fastenal #11101273 3/8" x 1.250" x 0.125" Thick Zinc Finish Extra Heavy Fender Washer
> End Nuts (2) - GM #117212 3/8"-24 hex; Fastenal #37464 3/8"-24 Cadmium Finish Grade A Flexible Lock Nut
(Some references specified castle nuts and cotter pins, others specified for lock nuts.)

REAR MOUNT HARDWARE:
> Upper Mounting Assy (2) - GM #3705444; The Truck Shop #54-07609
> Lower Mounting Assy (2) - GM #3705447; The Truck Shop #54-07610
> Bolt (2) - GM #3705450 1/2"-13 x 3-1/2; The Truck Shop #54-07611
> Bolt Lock (2) - GM #3717280; The Truck Shop #54-07612

> Assembly Manual part numbers & locations
> 1954 Shop Manual "Motor Mountings" starts on p 6-13
> Master Parts Catelog part numbers and descriptions 0.002 - 0.027 + illustration p. 95

=========

Here is a Stovebolt post that recaps the installation of motor mounts in my '54. It includes the list of fasteners. NOTE: I installed the two thick washers incorrectly. So disregard the photo of the underside of the crossmember.
> Installation of my motor mounts

Here is a post by Denny Graham describing the correct location of the two thick washers. Follow his info.
> The correct way to install the two thick washers

- Lonnie

Thanks for the post Lonnie. I will head to Fastenall today, BTW the lock retainer has been discontinued by the Truck Shop but I am sure I can rig something up.


Joe

I was able to get a front mount from the parts wanted section of the forum. I've seen them on ebay also. I don't think any vendor carried the retainer.

Joe -

I made bolt locks for the rear mounts before I bought the (now discontinued) locks from Truck Shop.

I'm pulling this from my foggy memory. You'll figure it out when you see the mount and frame ...

I used a fender washer. Make four cuts about half way into the fender washer with a hacksaw. Space the cuts as needed. Place the sawed washer under the bolt head when you install the mount. Bend two of the "flaps" up to wedge it. Bend two of the "flaps" down to lock against the flats of the bolt head. Use a hammer to bend the flaps tight.

- Lonnie

A MUCH EASIER way to lock the nuts would be to buy a $2 center punch and either stake the nut or the threads of bolt.

My preference is 3 stakes on the nut.. that way the threads are not mangled.

Of course your standard $0.10 lock washer will work wonders, also.

A lock washer needs to be crushed flat to work properly PF,
however, upsetting the threads might also work but not as
positive as commercial locking nut. The nuts on the outer bolts
are not meant to be torqued down, if they were they would crush
the support closing up the required 1/16" clearance between the
upper plate and lower retainer.
In the absence of the correct castle nuts which are locked with
a cotter pin after snugging them up, a nylock or better yet, a
commercial distorted thread high temp nut can be used to make
the adjustment.
There has always been some cornfusion as to what the engineers
had in mind. It's really quite simple though. You want the
support held snug between the plate and retainer but you want
the clearance so when the engine torques over it will absorb
the movement by compressing the rubber slightly. When that
occurs the tension is off the outer bolt and that's the reason
for the locked nut.

Denny Graham
Sandwich, IL

The max spacing allowed is 5/64ths.. that's a pretty big gap to try and 'squish' out. My mount does have the castle nuts and the bolts are drilled for a cotter pin.

One cool think I noticed was the thick washers had a bow tie emblem stamped into them.... at least I know they are a chevvy part.

Just in case anyone wants to make the bolt locks for the rear motor mount, I scanned a couple of unused bolt locks and photographed side views. The .pdf scan can be printed actual size as a pattern.

Send me a PM with your email address.

- Lonnie

One thing which has always annoyed me is when a lock nut is combined with a carriage bolt. Especially if the square hole is not a tight fit with the bolt head, and the bolt is really long. From discussions which I have read on this forum, the carriage bolts were originally tack-welded to the engine bracket but don't hold up over time. If you were to weld the carriage bolts more securely, you could use any kind of lock nut that you want and not have issues when it is time to take them off. I suppose if you used a nylon lock nut, you could heat it with a torch to melt the nylon to make it easy to remove the nut. Now I need to log off and get out and practice what I preach and loosen mine up and hope I have a gap to eliminate the vibration in my truck.

Staking the a regular hex nut in 3 places would hold. As long as you got a good upset on the dimple. Staking nuts is a lost art.. not a lot of fasteners use it anymore.

The bolts that are attached to the engine mount bracket are not the bolts that set the gap(outer bolts).

The outer bolts are locked in by the top plate of the mount. These are the bolts that you do not want to over torque as mentioned above.


On a side note. when I got my 50 back after many many moons. I found the front mount with no retainer. just a mushy piece of rubber sitting on the crossmember. Only two bolts holding the works. AMAZING

I'm interested to know why you keep mentioning that the gap is set by the outer bolts. Is that just how you were told it was done or is there a manual that says to do it that way.

Not saying its right or wrong.. it's your truck... just interested in hearing how you learned of it.

Read the service manual. It's rather vague but that was why I
posted what I did earlier. The gap 1/16" +/- 1/64" is actually
gauged with just the weight of the engine on the support. The
adjustment, if necessary, is made by removing metal from the
top of the lower retainer. Then the outer bolts are simply
snugged down to take up the slack, no tightening involved.
The center bolts are not welded to the front plate, they are
originally swaged into the plate.

Denny Graham
Sandwich, IL

On the plate part no. 3657522 does the lip go towards the front or the rear of the engine?

Thanks,

Joe

The factory assembly manual has a very bad drawing that looks like it going to the front

Lonnie's link

The term I'm using is incorrect. I guess my point was to not overtorque the two outer bolts. Maintain the clearance
Original mounts have a two metal bushings inserted in the rubber.
These Metal Bushings are in the two center holes.
No adjustment possible there with the bolts.

Aftermarket rubber have no metal bushing inserts.

Key is no contact with top plate and retainer.

Set your engine on the mount, check your gap.
If all is well, lift it up install the oil shield, tighten/secure and your good to go.

I have read a few post where guys would put the assembly in a vise to check gap. But I don't know how they mimic engine weight that way?

About two years ago, I bought the front motor mount rubber/assembly with the metal tubes/bushings in the rubber, around the middle two holes. These codes are on the rubber: 112 over 2007 (maybe the year it was molded?).

I do not recall if I bought them from Jim Carter, Classic Parts, or Chevs of the 40s (I have two mounts with the tubes/bushings).

I had to call and ask the venders, to be sure the metal tubes/bushings were in the rubber mount.

Joe -

RE: LIP ON PLATE PART NO 3657522 -

As DADS50 said - the diagram in the reproduction FAM is pretty degraded and not possible for me to tell which way the lip faces.

I asked the same question in Feb 2012. Here's what Denny Graham guessed, which matches DADS50's responce.



- Lonnie

that's good

the one I purchased in 2010 from classic parts was all rubber.
MADE IN THAILAND EM-2007 stamped on it

Whoa Gus, all the three replacement supports that I've gotten
from Classic Parts of America have had the steel bushings
potted or vulcanized into the rubber. I don't see how the mount
would work properly if it weren't bolted up solid to the front
plate on the engine.

And on that curved lip of the top plate, we did a lot of
searching on that one as Lonnie mentioned. This is the way the
mount came apart on my '50, 216 and I did talk to the people
that bought the truck new and maintained it over the years.
They had never changed the mounts, and I believe them cuz the
front and rear of the engine were simply sitting metal to metal
in a mass of JELLY that was once rubber.
http://www.pbase.com/dennygraham/image/128165791

Denny Graham
Sandwich, IL

I have installed a lot of these and have never seen any without the metal inserts. All have had rubber covering the insert but they were there.

Dave and Denny are correct.
Just took a razor to the repo rubber and buried was the insert.
This was on the repo setting in the garage that I didn't use.

My apologies to THAILAND
(and everyone else)

Thailand forgives you

I've been working on the mounts on the '48 2 ton.
bought a new rubber for the front mount - says EM-2007 "Westar" no "made in".
After completely cleaning the original housing I bolted it to the engine solidly, set the top plate with rolled edge to the back, lowered it on the cross member on the 2 big washers, bolts in, no nuts.
The head is off the engine and the clearance was 5/64 on the front and both ends.

Lifted the engine, unbolted the mount and rotated the top plate and did it again and had 5/64 on the back and ends.

Spun up the castle nuts finger tight and then tightened them until the the top plate just moved and put in the cotter pins.

got 1/16+.

Now I just need to get or make a new mount cover.

I don't know which way the rolled edge of the top plate came off. but I would think it would be to the rear so that on a hard stop or bump, it would hit the back of the mousing and stop the engine from moving forward.

I can say for sure that the 1943 GMC parts manual for the 2.5 ton CCKW shows the lip forward.

The mount I just bought has the steel sleeves, also.

Thank you, lip forward. I wonder what the reason is?

The plate is pretty thick (like 1/16th inch) so I don't think its for stiffness. My guess would be a drip edge... with the lip there any oil/water would drip down rather than seep back due to capillary action.

Since the timing cover bolts do not have a crush washer or fiber washer they are not going to be liquid proof... so oil could get in through the bolts that way.