The Stovebolt Site Forums The Shop Area Engine Shop Will you teach me about motor mounts? '54 3100

I believe that I have a problem with my front motor mount, but I don't have the knowledge to know for sure.

The two outer bolts on my front mount are tight. There are two hex head bolts without nuts sitting loose through front plate and the holes in the center bushings. The rubber mount cushion has some cracks.

The Shop Manual and Assembly Manual aren't clear to me regarding the center two holes in the motor mount.

> How/where should the mount be bolted to the truck?

> What hardware is used to bolt the mount to the engine and frame?

> What is involved with replacing the mount, and the rear mounts while I'm at it? I'll have a local shop do the work.

This pic is looking straight up at my front mount.

This pic is looking up from the drivers side.

This is the Assembly Manual diagram.

This is the Shop Manual diagram.

This is a pic of a mount from pugetsoundvintagechevrolet.org

It's been this way since I bought the truck 12 years ago. Probably put in about 15 years ago. No problem noticed with noise, shifting engine, or fan blade touching the radiator.

When I get if fixed, I'll return to prepping my engine for paint.

I really appreciate your help, knowledge, and experience.

Looks like you are just missing the nuts on two of the bolts. Also Most of the 'truck' vendors should have the parts to freshen up this mount and probably a diagram of how it goes together.
Best of luck

http://www.oldchevytrucks.com/cart/index.asp

Weird! All this time and it looks like the lock washers are still hanging on.

I know that I am being thick about this, but I can't quite picture how the front mount goes together. Can someone explain to me what bolts to what?

Boltr#43 and Jim - Those flat spots around the inner two floating bolts are not washers, they are the bottom of the rubber motor mount cushion.

===

I have these two items on order from the Filling Station: Sorry, the site won't let me link the pics and descriptions.
Part #TR-182 "Metal retainer"
Part #CV-223 "Rubber Cushion"

Both items state "Replaces #3657520" which is the "CUSHION ASSY" part number in the '54 Assembly Manual. However, the Assembly Manual shows four items needed for the motor mount:
#3656502 "SHIELD"
#3657522 "PLATE"
#368449 "RETAINER"
#3657520 "CUSHION ASSY"
Here are pictures of the four parts in the '54 Master Parts Catelog. - top of page.

But to add to my confusion, P. 94 in the MPC states "NOTE: When using 365720 {Cushion Assy} on 1937-40 jobs it is also necessary to use 1-3657522 plate, 1-3636502 shield and 2-352282 washers." Sounds like they are not needed in 1954, but they are in shown in the '54 Assembly Manual diagram. (???)

>> What was the bolt or stud labeled "FURNISHED BY ENGINE PLANT" in the Assembly Manual diagram?
I cross referenced the bolts and washers in the Assembly Manual with the '54 Master Parts Catelog:
Bolt #3701135 is 3/8-24 X 1-7/8 Carriage Bolt
Washer #365685 "SP WASHER" is 3/8"ID X 1-1/4"OD
Washer #352282 "SP W" is 7/16"ID X 13/16"OD

FYI - These are the three pages of front motor mount parts in the '54 MPC:
P. 93
P. 94
P. 95

I'm probably over-thinking this and writing a post that looks like War and Peace. Thanks again for your help,

Not sure what you’re asking Lonnie, but here are a few pictures
of how the front mount should go together:

http://www.pbase.com/dennygraham/image/128165791/large
http://www.pbase.com/dennygraham/image/128165811/large
http://www.pbase.com/dennygraham/image/136995331/large

Denny G

Nice pics Denny. Isn't it simply two bolts to hold the mount together and to the crossmember and two bolts to hold the motor to the mount/crossmember!! From Lonnie's pics it looks to me like he is just missing the two nuts to hold the motor to the mount and crossmember.
....its been awhile since I had one apart so I may be off my rocker!

Thanks for the pics Denny - got three more questions for you.

I'm starting to see why I am confused about the mount. Your pics show that I am missing a piece ... part #3656502 "SHIELD." I hope that is the piece that I have on order.

Here is a close-up pic of the top of my motor mount. No shield. It looks just like the the diagram in the '54 Shop Manual. I guess the Shop Manual diagram does not show the entire mount. I believe that the bump on my plate is the head of a carriage bolt, not a dimple in the plate. The two center bolts are just sitting on the front plate. They are not secured to the cross member. I can poke them up with my finger.

Q1 >>> Are the bolt holes in the engine front plate square to accept a carriage bolt? (The two center bolts.) Looks like a carriage bolt in your pics.

Q2 >>> What size & thread pitch are the two center bolts. The Assembly Manual defines them as "Furnished by Engine Plant." They are not listed in the MPC.

Q3 >>> Do the washers and nuts of the center bolts press against the rubber cushion?

So it looks like I need
+ a new Shield (#3656503) on order
+ two bolts and nuts for the center holes. What type?
+ two 7/16"ID X 13/16"OD washers for the center bolts
+ two 3/8-24 X 1-7/8" carriage bolts and nuts for the outer holes.
+ two 3/8"ID X 1-1/4"OD washers for the outer bolts

Clarification: I mentioned in my opening post that the rubber cusion appeared to be cracked. I was wrong. I was seeing the paint on the metal retainer (#368440) instead of the cushion.

Yes you are missing the shield. Just about everyone that I've seen is pretty well chewed
up by the time the rubber needs to be replaced, that's why the shields are sold by most of
the vendors. The shield is just that, a shield to protect the rubber, it’s probably left out of
the illustration for clarity as it‘s not actually part of the support mechanics.

The first picture I posted shows the shield that I made. The square shoulder under the
head of the carriage bolt has yet to be pressed into the holes on this one. Here is the link
again: http://www.pbase.com/dennygraham/image/128165791/large . You can scroll thru
the rest of the pictures in the album by hitting the [previous] & [next] buttons in the upper
right corner.

The bolts are special, they are not standard carriage bolts because they’re fine thread and
carriage bolts are course thread. My bolts were in good shape so I reused them but if I
had to make new ones, I would buy longer bolts, cut them to length and re-thread them
with a fine thread. The center bolts clamp the front motor plate, the upper plate and the
engine mounting bushing to tightly together. The outer bolts are tightened down just
enough to get the gap shown in the manual. This leaves a little float in the rubber cushion.
The reason for the castle nut on the outer bolts is because they are drilled for a cotter pin
much as your spindles are and after you adjusting the gap you pin them.

Denny Graham
Sandwich, IL

Thanks again, Denny.

I'll have a shop replace the engine mounts.

> Is the slotted nut on the motor mount bolts a Marsden lock nut or a castle nut for a drilled bolt and cotter pin? You're right about 3/8-24 (fine thread) carriage bolts ... they don't exist. Just spent an hour searching internet sources and phoning local suppliers. Next time you need a NOS motor mount - here's a source.

UPDATE - I found a source for the two outer 3/8-24 carriage bolts #3701135, but they do not have the two inner bolts "supplied by the engine plant." My outer bolts are OK. I need the inner bolts. Rats!

> Will the tranny floor plate for my 4-speed shifter need to be removed before the engine is jacked up to replace the motor mounts? I'm gonna replace the rear mounts too "while I'm at it." Gotta order more parts.

This all started when I decided to replace my water pump. You, 51 ashton, and '53moneypit accurately predicted my plight. You called it "Mission Creep."

Plans so far -
Replace water pump
Investigate water flow to heater
Paint engine and components
Clean and touch up paint on frame
New gaskets - valve cover, pushrod cover
Replace motor mounts
Blast and paint headlight buckets
Install new inner fender wire junction blocks for headlights/parking lights
Paint inner fenders (?)
Torque head (maybe)
Adjust valves (maybe)
Remove broken screw for flywheel cover
Paint "ball" on flywheel
Check compression
Set timing
Replace drain petcock in block
And I'm just gettin' warmed up.

Lonnie, I would be very cautious about new-old-stock or new-old-replacement stock
rubber components. They might look good and come in the original box but old rubber
doesn’t age as well as a bottle of wine. Their price for rubber $40, vendor price $10.95.
Their price for the shield $30, vendor price $9.75 but the vendors shield is just a square
box with the corners welded up and the original ones were formed by a die and look like
the one in the picture I posted.

No the transmission cover does not have to be removed to get to the rear mounts. As with
most of these trucks that have been in service for decades, the mounts in my ’50 were
shot when I brought the old gal home in ‘05. I wouldn’t doubt that they were the original
mounts since they were virtually a blob of jelly and the engine was simply supported
metal to metal.
I cut a 4/4 wood saddle in my band saw that was radiused to spanned a large portion of
the oil pan so as not to dent it. Using that on a floor jack I supported and steadied the
engine while I changed the mounts front and rear.

Denny Graham
Sandwich, IL

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

Quote from above tech tip

The Rubber Mount

I replaced my soggy original with a rubber repo from one of the major suppliers. It's a drop-in, but wait a minute .... you'd better make sure that you get it oriented properly (slots up) and the required clearances between the bottom housing and the top plate. If you assume that a new rubber insert will bring the clearances back up to snuff, you may be in for some nasty vibrations that won't be evident until you get everything installed and the engine cranked up!!! I found the clamping the assembly in the vise ... to simulate the weight of the 620+ pound engine ... left me with little or no required clearance. The lower "box" had to be dressed down. Evidently, the repo rubber insert was not quite as thick as the original.


I used an new original rubber mount with metal inserts purchased from the swap meet section. Repos are all rubber

Thanks again Denny -

>> Are the two center bolts on the front mount 3/8" or 7/16"? The washer for the inner bolts is listed as 7/16" in the MPC. No listing for the center bolts.

Thanks for the info on the tranny floor shifter. I'll check with the shop to see if they can use a wood support like yours when I take it in to have the motor mounts replaced.

I thought the same about the condition of old NOS rubber mounts. I was referring more to the round edge metal shield like the one you made. I bought front rubber and square shield from the Filling Station; and rear mounts, rear bolts and bolt locks from the Truck Shop.

I'll use either #8 grade course thread carriage bolts or #8 fine thread hex bolts for the two center bolts on the front mounts. The outer two fine thread carriage bolts look OK.

Thanks Gus -

Good idea to check the Stovebolt Tech Tips - don't know why I had not done so.

The '54 Shop Manual says that the upper plate and lower retainer may need dressing to provide 3/64" to 5/64" clearance between the two. The Shop Manual also notes that if the clearance is more than 5/64", a new lower retainer must be installed. Yeah, right -- I'll just run down to my local Chevy dealer parts department and buy one! ha

EDIT - That is a great write up about the front motor mount. My thanks to Don "down2sea" McLendon for writing it and to you for linking to it.

Lonnie,

I'd be wary about having a shop replace the mount.
It seems like the authenticity matters a lot to you.

IMHO, the shop -
- won't understand how the mount works as well as you do now.
- will value functionality over authenticity.
- won't have or care to make jigs such as Denny mentioned to avoid collateral damage.
- will have to charge a high labor rate in order to protect themselves from rework due to the above.

YMMV, and after all, I've never been accused of lack of cynicism.

good luck to you.

regards,
Leon

Leon -

This is why Stovebolt is such a great forum. My understanding of motor mounts grew from zero with a lot of confusion to being pretty confident with their installation. And then you followed up by pointing out the pitfalls of having the wrong shop do the work. Thanks for your concern and to all Stovebolters who "educated" me!

I pondered the question about having a shop do the work. But I don't have the tools or experience to lift a 600 lb engine and install the new mounts by myself.

I have been pleased with the people at the shop that will replace my motor mounts and with their previous work on my truck. They've watched the progress of my truck over the years and often give me free advice. The shop has been in business for 40 years and does a lot of work on 50's and 60's collector cars - Chevys, Studebakers, Avantis, Chrysler 300s, T-Birds, etc., plus the three guys are longtime old car lovers and hot rodders themselves. And they are only a few blocks from my house. They are fair and I trust them more than any other shop in town. Even so, I hope to stay in their shop while they replace the mounts.

I'll have all the parts including bolts, nuts, and washers ready. The radiator will be flushed ready to remove. And I'll give and discuss a copy of the Shop Manual, Assembly Manual, Stovebolt Tech Tip, and the replies to my post. We will discuss Denny's 4"X4" jig to avoid damaging the oil pan. I'll make one if needed. We'll also discuss removing the harmonic balancer as described in the Tech Tip.

The only thing that may cause a delay in the installation is the clearance between the top plate and the lower retainer of the front motor mount assembly. (3/64" to 5/64") Hope we don't have to file the lower retainer. An even bigger hope is that the clearance is not too large, as Gus quoted.

In more realistic terms those dimensions are guite small,
.047"-.078"(3/64-5/64"). What they are really trying to say is
you want "some" clearance between the top plate and retainer.
Don't worry about there being to much cleareance, you won't
have that and even if you did have as much as .125"(1/8") you
would still be fine. The technical writer had to put something
down so he picked that for a range.

As far as the support, that was simply my way of doing it with
out hanging it from the top while I removed the rear mount, you
just want to be sure that you don't dent the pan.

Denny Graham
Sandwich, IL

One final question (I hope.)

Is there any secret to installing the 7/16" carriage bolts into the two center holes of the front motor mount? Does the timing cover or harmonic balancer need to be removed? The two center bolts were originally installed by the engine plant, so the Assembly Manual and Shop Manual do not show how they are installed.

The Stovebolt Tech Tip about front motor mounts says that "the assembly needs to be installed before you install your harmonic balancer."

I'm taking it to the shop this Friday to have the front and rear motor mounts replaced. I have all of the parts, plus some 7/16 hex bolts in case they can't insert the two center carriage bolts. If needed, the hex bolts will be inserted from the bottom and nutted on top. Trying to avoid doing this.

Pics by Don "down2sea" McLendon, author of the Tech Tip;
> Front view without mount
> Front view with mount installed
> Side view with mount installed

Thanks again for your help. I think I'm starting to learn motor mounts!

I also would avoid installing the front motor mount bolts from the bottom. When I got my 1951 they were installed that way, after some miles on it I ended up with no bolts holding the motor down in the front.

I tack welded my in place on my front plate before engine assembly.
It kept them in place and no movement when I installed my engine.Once you install the timing chain cover,you will not be able to install the 7/16"x2" carriage bolts in the front plate.

Tim

This doesn't sound good. If all of the screws are removed, can the timing chain cover be moved a little to allow the 7/16 carriage bolts to be inserted through the front plate?

Any suggestions on how to make this work?

What are my best alternatives? I'm not gonna pull the engine.

<BUMP>
I'm getting a little nervous. Can you tell me the best way to insert the two center bolts of the front motor mount through the front plate?

How did you replace the two center bolts when the engine was in the truck?

If 7/16" carriage bolts won't fit without removing the harmonic balancer - what should I use? Diameter? Special heads/nuts/washers?

I think that I've figured out that removing the timing cover is not an option.

I'm taking it to the shop Friday morning. Thought that I had all the parts including bolts and nuts. Now it looks like I need different center bolts.

Guess I haven't learned as much about motor mounts as I thought!

Thanks for your help.

What's the condition of the existing bolts?

The current center bolts are 3/8-24 hex head with no lock washer under the head. The non-threaded shoulder of one extends below the area needed for the nut to thread onto. Both center bolts are sitting loose in the holes - not nutted.
< PIC >

I figure that a previous owner discovered that he couldn't insert 7/16" carriage bolts through the front plate after he had assembled the engine. Don't know why he chose the long-shouldered bolt. Also don't know why he didn't secure the nuts better. It's never had nuts on the center bolts since I have owned the truck (12yrs). I believe that one of the bolts on the side motor mounts was missing when I bought the truck. The weight of the motor was all that kept it in place!

You can insert the center bolts but you have to take a little (tiny) bit off the top on one
side and bottom of the other side of the square hole with a rat tailed file. Then you can
angle the bolt just enough to get it in with everything in place and the square still locks
the bolt from turning. Originally the bolts were lightly crimped in place on the front plate
but they usually work loose. If you could find a NOS front plate it would have the two
bolts locked in place with the square crimped in a little.

Denny Graham
Sandwich, IL

I can get the bolts out by raising the engine up a little and they will come out but you have to tilt them to get them out. the only thing I do not have the radiator in the truck. You might have to use a punch to tap them out from the bottom of the frame

I have a 49 p/u the front fenders are off and the radiaror is out of the truck. I got the only carriage bolt out by jacking the front of the engine up a little and then using a punch to push the bolt out it will have to be tilted a little to get it out.
Bennie

Thanks DG and Bennie -

I'm starting to feel a little better. I'll bring your info and some files to the shop tomorrow when they replace my motor mounts. I'll also bring some hardened 3/8-24 hex head bolts - just in case the 7/16 carriage bolts decide to throw a hissy and not go in.

I'll post my results when the job is done.

Hi Denny,

I would like to come and see you sometime to look at your truck. I talked to you last year and you were down at Harbor Freight an I did not have time because of a dr app. I live in South Elgin. Give me your e-mail address so I can talk to you my cell phone number is 847-899-2585. blackward@sbcglobal.net e-mail. I have read all the topics about front motor mounts. I looked at mine and am missing the 7/16" carriage bolts and nuts. Do you have a place to get these bolts. I do have questions about some of the wiring Thanks

Bennie Blackward

SUCCESS! The new front and rear motor mounts on my '54 3100 235 are in. Thanks to all of you that helped me with your ideas, personal experiences, and encouragement.

The process wasn't as difficult as I had anticipated ... 'course Darryl at the shop did the job instead of me.

Not saying that this is the "best" or the "right" way to do the job. But this is a recap of our installation and a list of the hardware used.

Follow the instructions in the Shop Manual 6-13, 6-14. Place the rubber cushion for the front motor mount into the retainer with the slots facing up. The radiator does not need to be removed for access, but you probably want to remove the hoses.

Insert the end carriage bolts into the front mount through the rubber cushion, the retainer, and the cross member before adding the shield. I don't believe that my 3/8"-24 carriage bolts were drilled for a cotter pin. I used flexible lock nuts to secure the end bolts.

The middle carriage bolt on the drivers side of the front motor mount drops into place through the square hole in the front plate with a little wiggling and the motor raised about an inch.

The middle carriage bolt on the passenger side binds against the timing chain cover which prevents it from dropping through the front plate. Darryl ground off one side of the carriage bolt head to allow it to clear the cover. I'm not overly concerned about grinding the bolt head because the bolt on the drivers side is intact, and because a bolt with a ground-off side is still better than what I have had for the past 12 years ... 3/8" hex bolts with NO NUTS!

The washers on the middle bolts that are in the front mount must cover the metal sleeve inside the rubber cushion, but not touch the cross member. GM specs are for 13/16" OD. The washers that I bought were 15/16" OD. So he used stainless 3/8" washers and enlarged the hole to accept the 7/16" bolts.
< CLICK > Completed bolts, washers, & nuts on front mount.

"All bolts should be kept tight except the two self-locking nuts on front motor mount. Self-locking nuts should be tightened securely but not too tight to cause damage to the front support assembly."

The rear mounts were installed as described in the Shop Manual. One of the upper mounts from the Truck Shop (made in India) was identical to the pic in the Shop Manual and to the one that was on the truck. The other upper mount was different. A corner had to be ground down to fit. I shoulda checked them when they arrived. Torque the rear mount bolts to 65 ft-lb.

I noticed a little engine vibration through the steering wheel after the new mounts were installed. We had checked the clearance between the plate and the retainer on the front mount before installation per instructions in the Shop Manual. The clearance seemed OK. I won't be able to fully test drive it for a couple of weeks to see if I have a problem.

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

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

Master Parts Catelog part numbers and descriptions 0.002 - 0.027 + illustration p. 95

Thanks for your post - it helps me out some. Regarding the outer bolts - did you use cotter pins or self locking nuts?

I also have some confusion over the bolt sizes. The used retainer and plate that I received from Old Car Parts in Oregon included 2 bolts @ 1/2 inch and 2 bolts @ 7/16 inch, and they fit nicely into the rubber cushion.

Bob

This information is gleaned from the five engines that I have here and the 1929-1957 Parts Book.

The comm., util (1st Ser) front outer mounting bolts from 1937 to 1955 were 3/8”-24 x 1 7/8" drilled
carriage head pn.3701135 used with a ‘slotted’ nut.
The inner front truck cushion mounting bolts as I mentioned were part of the front plate but were
7/16”-20 x 2” un-drilled and were the same from 1937 to at least 1953. I have nothing newer here to
compare the front plates to and the parts book gives no description of the attached hardware.

Denny Graham
Sandwich, IL

> Bob -
The original 3/8-24 carriage bolts in the ends of my 1954 front mount were not drilled. I used a lock nut on them. See my reply to Denny Graham below.

re: 1/2" bolts - I don't know if the front mount for a '46 is the same as for a '54. A 'Bolter with a '46 like yours can give a better answer.
1/2" bolts are used in the rear mounts. I don't know about 1/2" bolts for the front mounts. I couldn't find any listing in the MPC.

> Denny - The detective work continues!
I searched for confirmation of the 3/8 bolts drilled for cotter pins when I was buying nuts and bolts. The MPC describes bolt #3701135 as "3/8-24 x 1-7/8 carr. hd." Hardened carriage bolt, but no reference to drilled. <EDIT - "carr. hd." means "carriage head", not "hardened."> Nut #838283 for '37-'53 was described as "3/8-24 sltd" which implies that a cotter pin was used with the slotted nut.

The '54 Assembly Manual shows the 3/8 nuts with a different part #117212 or #451010. I couldn't find the part in the MPC.

The '54 Shop Manual describes the torque on the front motor mount nuts "All bolts should be kept tight except the two self-locking end nuts on front motor support."

Since the nut number changed from 1953, and the '54 Shop Manual called the nut a "self-locking" nut, perhaps the drilled bolt and slotted nut changed to a solid bolt and lock nut in 1954.

There’s only so much room for the description in the pars book Lonnie. I mean they could further tell
you how much thread there is and whether they are plated and the head size but they don‘t. Those bolts
are not meant to be tightened up tight, instead they are used for the adjustment of the mount. There for
they have to have a way of locking them after the adjustment.
I don't ask this often without having documentation but, trust me, the original “special” part number
bolts were drilled for a cotter pin and were threaded only far enough to put a little tension on the rubber
pad. I have the original factory outer bolts in my mount but like you I choose not to use a cotter pin and
like you, I choose a Nylock nut. Any other self locking safety nut could be used, but originally the slotted
nuts were pinned.
There were no ½” bolts used in the front center motor mount for the 6cylinder Chevy trucks,
unless someone got the drill out and opened up the holes.

Don’t know where you got the “Hardened carriage bolt” from Lonnie, that is not a hardened bolt just a
specially made carriage bolt. My guess for the two numbers on the nuts would be that the were supplied
with different style castle (same thing as slotted) nuts at different assembly plants. West coast plants
where fastener suppliers catered to the aircraft industry may have even supplied self locking nuts.

Denny Graham
Sandwich, IL

Denny -

Thanks for the catch. I'm trying to write my recap as accurately as possible for anyone who finds it when searching for info on mounts.

I was wrong about the "hardened" 3/8-inch end bolts in the front mount. I interpreted the MPC 3/8 "carr hd" to mean carrage hardened. It means carriage head. I should have read the meanings of abbreviations in the MPC before I posted my recap. I edited it to correct the error.

Regarding the drilled 3/8" bolts. I'm still not convinced that my '54 were drilled. It's no big thing either way. Darryl and I both looked at them to see if they were drilled. We didn't see a hole. I believe that they are original to the truck, but who knows. The '54 Shop Manual describes the nuts for the 3/8" bolts as "self-locking."

EDIT: Well, I just checked the '48-'51 Shop Manual. It also says that the 3/8 nuts are "self-locking". The MPC describes the nut for those years as "sltd" (slotted). I assume for a cotter pin. Bottom line - I dunno! All I know is that the 3/8" bolts in my mount were not drilled.

I'm glad that you forced me to dig a little deeper.

Archaeology Lonnie, we're involved in a mini dig here. You never know what you may
turn up when you start to dig into one of these old Stovebolts.

Castle/slotted, same-o/same-o
http://en.wikipedia.org/wiki/Castellated_nut

As I was saying, there are lots of contradictions between the Service manual, the Parts
manuals, the Factory Assembly manual and what was done on the production line. Yes
the technical writer wrote in the service manual "self-locking nuts" but if you look closely
at those outer bolts in Fig.20 on page 6-13 of the 1948-51 service manual you can clearly
see holes drilled in them for cotter pins. And the parts manual also calls out slotted, ie.
castle nuts for that application. My 53.000 mile 1950 had the original front motor mount
and it had pinned castle nuts.

And you my friend are forcing me to dig a little deeper. I just went out to check my
48,000 mile 1954 which is up on blocks in the barn, (0° out there today) and it has self
locking nuts, no castle or cotter pins. So somewhere down the line they did make a shift to
the self-locking nut for adjustment and so you are correct on your ’54.
But, the fact remains that we will probably never know for sure just like many other
things about how these trucks were assembled and when some of these changes took
place.

Denny G
Sandwich, IL

None of my 54 motor mounts had castle nuts and cotter pins. But, I would not bet on what was originally there.

Thanks to all for the feedback. I think that this will help to get my engine anchored to the frame. I will keep monitoring this thread - sounds like it may not be completely resolved.
Bob

Did your rubber mount have the metal inserts?

Yes, Gus. The rubber cushion has metal sleeves in the end holes for the 3/8" bolts. Not sure about the 7/16" middle holes, but I assume that they do too. I'll go on a hunt for the source of the vibration in a couple of weeks.

Funny - I read your post on another thread about bolts missing in your front mount for years. The nuts on my two middle bolts were missing for 12 years. Never saw any evidence of the engine shifting postion.

Got that backwards Lonnie, the metal bushings are molded into
the rubber for the center 7/16" bolts. They anchor the rubber
solid to the front plate.

DG