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| | | | Joined: Mar 2012 Posts: 240 'Bolter | | 'Bolter Joined: Mar 2012 Posts: 240 | Hi All,
The '51 216 I'm prepping to put in my '47 has oversized holes in the engine front mount. Swapping out the mount is an option, but requires a near complete teardown of the engine.
Does anyone on here have experience with the use of a hardened washer between the engine front mount and the isolator/mount cover? Is so, would it be correct to thin the thick standoff washer below the isolator/mount, or add the thickness below the rear mounts to level the engine?
I'd appreciate some advice.
Thanks and best regards,
Bill
1947 3100 Advanced Design
Never, never, never, never give up. - Churchill
| | | | | Joined: Oct 2006 Posts: 9,671 'Bolter | | 'Bolter Joined: Oct 2006 Posts: 9,671 | If you mean the holes in bottom of the front plate are oversized, that's pretty common. Originally the hoes were square and the "special" carriage bolts were swaged into the plate. Over time the holes would get wallowed out and give the impression that they were installed loose. There was a thick washer used under the outer holes of the front mount: http://www.pbase.com/dennygraham/image/149005339 These are also illustrated in the FAM http://www.pbase.com/dennygraham/image/141529223I've never heard of a need to shim the rear mounts, I wouldn't shim them if it were mine, I can see no reason to do that. If your original front mouth is questionable, all the parts are available from any of the vendors. If you are at this point in your work, then you would be best off replacing all three mounts with new parts. dg
Denny G
Sandwich, IL
| | | | | Joined: Mar 2012 Posts: 240 'Bolter | | 'Bolter Joined: Mar 2012 Posts: 240 | Hi Denny,
You are correct, the holes in the front plate are oversized, but my impression is that the prior bolts were ground out or removed with a "flame wrench". The holes are now approaching the diameter of the center contacts in the new rubber mount. I'm concerned that front plate will shear past them and rest the engine on the top plate of the motor mount.
If I use a hardened washer, I can support the weight of the engine, but that raises the front end up beyond nominal by the thickness of the washer I use. So, should I compensate for this by removing thickness from the standoff washers at the outer bolts between the mount lower plate and the frame, or would it be better to add the same thickness to the rear mounts to keep the engine level. Or, is the slope change (due to a 3/16" add at the front end) over the length between the front and rear mounts not an issue?
Thank you for your thoughts on this.
Best regards,
Bill
1947 3100 Advanced Design
Never, never, never, never give up. - Churchill
| | | | | Joined: Oct 2006 Posts: 9,671 'Bolter | | 'Bolter Joined: Oct 2006 Posts: 9,671 | I doubt if the added thickness of a washer under the front plate
would make any difference. These trucks run decades with the
rubber mounts turned to jelly from being oil soaked.
If it were me, I would weld up the plate and re-drill it. But
you're not me and I don't know how far you want to take it. A
1/8" shim drilled to match the mount or two washers between the
front plate and mount would be a quick fix and simply replace
the standard thick washer with a thinner one.
dg
Denny G
Sandwich, IL
| | | | | Joined: Jan 2001 Posts: 5,337 'Bolter | | 'Bolter Joined: Jan 2001 Posts: 5,337 | I often weld nuts on the top side of the plate and run bolts up from the bottom.
See the USA in your vintage Chevrolet! My Blog | | | | | Joined: Mar 2012 Posts: 240 'Bolter | | 'Bolter Joined: Mar 2012 Posts: 240 | Denny and Dave,
Thanks for the feedback and advice.
Welding is out of scope for me, so the other options are more attractive.
Thanks again.
Bill
1947 3100 Advanced Design
Never, never, never, never give up. - Churchill
| | | | | Joined: Jan 2010 Posts: 4,263 Shop Shark | | Shop Shark Joined: Jan 2010 Posts: 4,263 | Do you have a pic of the oversize holes in the front mount?
| | | | | Joined: Dec 2000 Posts: 3,399 Gas Pumper | | Gas Pumper Joined: Dec 2000 Posts: 3,399 | I am just shooting from the hip here, but if the holes are such that the 3/8? bolts are wallered out, go to a 7/16, or whatever. Next higher size. The truth is, if I were closer to you, I could easily weld it and redrill it on the truck. That means if I can do it, any welding shop in your area can do it. Its the CORRECT way to solve this problem. Then, think about something Dave said... drill the hole round to avoid machining costs, then put the bolt in from the bottom. This is something GM overlooked and caused a lot of problems because of it. The square hole wallers out. Bringing the bolt up from the bottom eliminates that entire square hole issue. Dave is a genius!
Don't give up on your project and make do with your current skillset. You can either learn welding, if I can do it anyone can, or have someone else do it easier than you think. | | | | | Joined: Jan 2001 Posts: 5,337 'Bolter | | 'Bolter Joined: Jan 2001 Posts: 5,337 | Deve, the problem with using larger bolts is, we will call them pipes embedded in the rubber, will only accept the 7/16" original size.
See the USA in your vintage Chevrolet! My Blog | | | | | Joined: Mar 2012 Posts: 240 'Bolter | | 'Bolter Joined: Mar 2012 Posts: 240 | Dave, Deve, & Gus, Thanks for your comments. A picture of the front plate holes is here . Maybe it's not as bad as I thought it was. The underside is smooth (I couldn't get a good picture of it). Thanks in advance for your thoughts/comments. Best regards, Bill
1947 3100 Advanced Design
Never, never, never, never give up. - Churchill
| | | | | Joined: Jan 2010 Posts: 4,263 Shop Shark | | Shop Shark Joined: Jan 2010 Posts: 4,263 | Probably not kosher to most But I ran those bolts from the bottom ...pic... If your worried about them backing out then use a nylon self locking nut. Or peen the bolt with a center punch. The thick standoff washers mentioned earlier are not used under those bolts They are used under the retainer. | | | | | Joined: Jan 2010 Posts: 4,263 Shop Shark | | Shop Shark Joined: Jan 2010 Posts: 4,263 | Here is some good info from Lonniec May or may not help you 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 & locationsMaster Parts Catelog part numbers and descriptions 0.002 - 0.027 + illustration p. 95 | | | | | Joined: Mar 2012 Posts: 240 'Bolter | | 'Bolter Joined: Mar 2012 Posts: 240 | Okay, I'm convinced. I'm working on removing the front plate from the original engine - square holes are not "wallowed out", much better condition. Thank you all for encouraging me to not take a short cut.
So the next question is: the new front mount cover's holes are offset front to rear; what is the correct orientation?
Thanks again,
Bill
1947 3100 Advanced Design
Never, never, never, never give up. - Churchill
| | | | | Joined: Oct 2006 Posts: 9,671 'Bolter | | 'Bolter Joined: Oct 2006 Posts: 9,671 | I suppose you're talking about the top 3657522 plate that's under the outer shield? I believe the general interpretation is that the lip is to the front. http://www.pbase.com/dennygraham/image/141529223/originaldg
Denny G
Sandwich, IL
| | | | | Joined: Mar 2012 Posts: 240 'Bolter | | 'Bolter Joined: Mar 2012 Posts: 240 | Hi Denny,
Your pictures have been very helpful.
The part that I am asking about is the 3656502 Shield. Mine is an aftermarket part and the holes are offset. Is this typical or not, and if it is, which way should I mount it?
Thank you all for your patience.
Bill
1947 3100 Advanced Design
Never, never, never, never give up. - Churchill
| | | | | Joined: Oct 2006 Posts: 9,671 'Bolter | | 'Bolter Joined: Oct 2006 Posts: 9,671 | No sweat with the patience at this end, I've had "a work in process" for the last decade, the only way I've learnt her little idiosyncrasies has been thru asking questions. This is an accurate reproduction of an original shield and as you can see, they were symmetrical: http://www.pbase.com/dennygraham/image/128165819/largeThe vendors shield that your talking about I believe is in this picture. the holes are offset slightly, I don't think it makes any difference as long as it clears everything. Probably just the way they made the form that they used. The squared off edges of the repro are evidence of how much care they used to reproduce the shield. The dimples and holes are actually in a straight line, just look at your rubber motor mount to verify that. http://www.pbase.com/dennygraham/image/128165820 Denny Graham Sandwich, IL
Last edited by Denny Graham; 08/31/2015 3:00 PM.
Denny G
Sandwich, IL
| | | | | Joined: Mar 2012 Posts: 240 'Bolter | | 'Bolter Joined: Mar 2012 Posts: 240 | The improved mount is on the engine. I think it's a much better option than what I was considering. Thanks again for the encouragement. Best regards, Bill
1947 3100 Advanced Design
Never, never, never, never give up. - Churchill
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