Ever Shim the Motor Mounts? Please come in!!!
03-19-2013, 06:42 AM
#1
Ever Shim the Motor Mounts? Please come in!!! Guys,
I need to raise the motor slightly - 1/8 to 1/4 inch to get the pan off my rack. I have the Canton RR pan and it's pretty much sitting on my rack and I'm afraid it's going to damage it over time, plus it's translating a lot of vibration into the body from the motor. I know this is a common thing with the Canton pan and they recc to shim the motor mounts or lower the rack. Has anyone ever used shims on the motor mounts to raise the motor slightly? I want to know the best way to do this as it doesn't seem to me if this will work as it will throw the angle off and cause the mounts to not line up. Any help is greatly appreciated.
BTW - My motor mounts are Poly and only have about 500 miles on them, so I know that's not my issue.
I need to raise the motor slightly - 1/8 to 1/4 inch to get the pan off my rack. I have the Canton RR pan and it's pretty much sitting on my rack and I'm afraid it's going to damage it over time, plus it's translating a lot of vibration into the body from the motor. I know this is a common thing with the Canton pan and they recc to shim the motor mounts or lower the rack. Has anyone ever used shims on the motor mounts to raise the motor slightly? I want to know the best way to do this as it doesn't seem to me if this will work as it will throw the angle off and cause the mounts to not line up. Any help is greatly appreciated.
BTW - My motor mounts are Poly and only have about 500 miles on them, so I know that's not my issue.
03-19-2013, 07:58 AM
#2
What "angle will be thrown off"?
If you consider the tranny mount the pivot point and raise the engine 1/8" at the mounts how many degrees do you think that is?
Just some quick math says if the motor mounts are 3 feet ahead of the tranny mount, just a ballpark off the top of my head in no way meant to be accurate number then 1 degree of rotation is .314" at the motor mount. So what angle are you worried about that is sensitive to a third of a degree?
I would be surprised if the cam and crank are any more accurate than that.
Someone feel free to check my math, haven't had coffee yet.
If you consider the tranny mount the pivot point and raise the engine 1/8" at the mounts how many degrees do you think that is?
Just some quick math says if the motor mounts are 3 feet ahead of the tranny mount, just a ballpark off the top of my head in no way meant to be accurate number then 1 degree of rotation is .314" at the motor mount. So what angle are you worried about that is sensitive to a third of a degree?
I would be surprised if the cam and crank are any more accurate than that.
Someone feel free to check my math, haven't had coffee yet.
03-19-2013, 08:32 AM
#3
What "angle will be thrown off"?
If you consider the tranny mount the pivot point and raise the engine 1/8" at the mounts how many degrees do you think that is?
Just some quick math says if the motor mounts are 3 feet ahead of the tranny mount, just a ballpark off the top of my head in no way meant to be accurate number then 1 degree of rotation is .314" at the motor mount. So what angle are you worried about that is sensitive to a third of a degree?
I would be surprised if the cam and crank are any more accurate than that.
Someone feel free to check my math, haven't had coffee yet.
If you consider the tranny mount the pivot point and raise the engine 1/8" at the mounts how many degrees do you think that is?
Just some quick math says if the motor mounts are 3 feet ahead of the tranny mount, just a ballpark off the top of my head in no way meant to be accurate number then 1 degree of rotation is .314" at the motor mount. So what angle are you worried about that is sensitive to a third of a degree?
I would be surprised if the cam and crank are any more accurate than that.
Someone feel free to check my math, haven't had coffee yet.
03-19-2013, 10:31 AM
#6
I'm actually running the 244m pan as my builder back in the day converted my block to a two piece rear main and installed a two piece seal crank. I run the older style with the two piece rear. The design is very similar, just a little deep up front. Not much, just need a little room to clear it better. As to my mounts I replaced them a couple years ago with the Polys and they only have about 500 miles on them, so I doubt they've settled. What do you think?
03-19-2013, 10:36 AM
#8
Village Troll 
iTrader: (2)
I'm actually running the 244m pan as my builder back in the day converted my block to a two piece rear main and installed a two piece seal crank. I run the older style with the two piece rear. The design is very similar, just a little deep up front. Not much, just need a little room to clear it better. As to my mounts I replaced them a couple years ago with the Polys and they only have about 500 miles on them, so I doubt they've settled. What do you think?
03-19-2013, 12:30 PM
#11
? - I installed them myself in the clamshells 2 years ago. Don't know how they could have settled that much. Also, Canton clearly specifies that with this pan I may have to shim the motor mounts are lower the rack a bit for clearance. That being said, will either of those work?
03-20-2013, 08:14 AM
#14
Not really without pulling the pan and I really don't wanna do that since I have to pull the tranny as well. Done this several times over the past year and just tired of it. The front of the pan is sitting on the top of the rack so a quarter inch would work wonders. Using the pivot method, would lowering the Trans mount with shims do the same by raising the motor? I'm worried that might put too much stress on the motor mount bolts?
03-22-2013, 01:18 AM
#16
I know it's not the correct way, or the way everyone is suggesting here. But I'll take a stab at answering your original question. GM did use a spacer in between the clam shell mount and block in a few applications. You wouldn't be able to catch all the holes in the Lt1 block with it, but you could cut out your own from some plate stock. It's about 3/16" thick and usually only installed on one side of the engine. What vehicles actually came with them, I don't know for sure. I recently pulled apart a 350 from an 89 G20 van, had it on the drivers side. I've also seen them in 3rd gens, who knows if they were factory though. Just a thought.
Kind of a crappy pic, but you get the idea.
Kind of a crappy pic, but you get the idea.
04-02-2013, 01:13 PM
#17
Thanks everyone for your help and inputs, and I thought I'd follow this up as it seems most threads I search these days have no conclusion so it's hard to get an idea of how things worked out.
We installed the new prothane black mount inserts this past weekend along with the Moroso mount shims. I ordered this kit:
Moroso (62535) as it has various thickness plates and are made for the SBC 3 bolt pattern on our blocks.
Ended up having to open the holes a bit with my drill press to get them to line up better and drill an additional hole for the bolt on the clamshell on the driver side holding in the Prothane mounts. After some considerable tweaking and lining up we finally got her all bolted back together using the 1/16in thick shims as the rest were just too thick and the mounts would not line up at all with the pin/bolts.
All said and done, the drive angle did not change and the vibration is gone as I now have about an 1/8 inch air gap between the pan and the rack. I did have to go to Ace and source some new motor mount (mount to block) bolts - grade 8 of course - to account for the thickness of the shim as I didn't want to use the stock bolts since they weren't biting too much into the block. Car runs beautifully and feels much better and no vibration from the driveline as well.
Thanks again!!!!
We installed the new prothane black mount inserts this past weekend along with the Moroso mount shims. I ordered this kit:
Moroso (62535) as it has various thickness plates and are made for the SBC 3 bolt pattern on our blocks.
Ended up having to open the holes a bit with my drill press to get them to line up better and drill an additional hole for the bolt on the clamshell on the driver side holding in the Prothane mounts. After some considerable tweaking and lining up we finally got her all bolted back together using the 1/16in thick shims as the rest were just too thick and the mounts would not line up at all with the pin/bolts.
All said and done, the drive angle did not change and the vibration is gone as I now have about an 1/8 inch air gap between the pan and the rack. I did have to go to Ace and source some new motor mount (mount to block) bolts - grade 8 of course - to account for the thickness of the shim as I didn't want to use the stock bolts since they weren't biting too much into the block. Car runs beautifully and feels much better and no vibration from the driveline as well.
Thanks again!!!!
