Broke another motor mount.

[69427]

Halfway through the autocross Saturday I heard a wierd noise, but couldn't quite decipher what it was. I lifted the hood after the run, and noticed chunks of plastic sitting on the intake manifold. I then noticed a few gouges out of the fan shroud. I surmised from that (and the smudge marks where the air cleaner was rubbing on the hood) that I broke the left motor mount. I'm not sold yet on solid mounts for an aluminum engine, but I definitely need to do something so that the engine is captured a bit better than it is now. I'm pretty sure the mount I presently have on it is the capture type, but the motor sure seemed to move a bunch to chew stuff up like it did. I hate to have to weld up a custom mount, but I need something I can trust.

Thoughts or suggestions?

thanks,
Mike

 

[big2bird]

Poly mounts?

 

[mrvette]

Decades ago, with out 389+++ Poncho engines, the 4 speed Hydro trannies, and the 411 rears, the torque was pretty good, and so engine mounts were a casualty....

we put on 'torque' chains....tied from a intake bolt or some such point to the top of the frame, a favorite was the left over threads of a shock absorber....

so a limit was that chain....we used a stud/bolt for it on the engine, and another nut with some hose wrapped on the chain over the valve cover....

:surrender::thumbs:

some cars had it tied to front of the engine....

sorry can't be more specific, but i'ts only been 40 years.....
:hissyfit:

 

[Twin_Turbo]

Another option would be to add another mount off the front of the bock, surely you can fab a mouting system for the front motor mounts using a bushing of some sort, kind of like a partial motor plate

 

[mrvette]

Another option would be to add another mount off the front of the bock, surely you can fab a mouting system for the front motor mounts using a bushing of some sort, kind of like a partial motor plate

:rofl: Saw a old Mustang with a 460 Lincoln motor done like that, 1/2" aluminum tied in like it was a aircraft or something....

 

[damoroso]

Mike,

I had this happen years ago. Broke a mount, went to the local parts store and got a replacement. It was about half the price of the same part at the dealer. It broke a month later. Went to the dealer and bought the more expensive part once.... Point is, maybe it's the just the mount. I'm not really sure how you'd make sure you have a quality part, but Rock Auto allows you to choose where your parts come from alot of the time, that might be an option.

 

[69427]

Another option would be to add another mount off the front of the bock, surely you can fab a mouting system for the front motor mounts using a bushing of some sort, kind of like a partial motor plate

We're on the same wavelength. I was kicking around ideas of using some sort of dogbone piece off a front wheel drive engine, or some rubber bushing heim joints I've got sitting on the shelf.

Regarding Bird's post, I realize poly mounts will be a bit stiffer in compression and tension, but what is the forum's opinion regarding the relative strength? I'll probably put a backup restraint on the engine regardless of which mount type I install, but if the poly mounts are actually stronger in peak tension I might give one a try.

Outside of the inconvenience of changing this mount, my main complaint is I paid for a day of fun at the autocross, and a twenty dollar part put an end to the activities halfway through the day.

 

[SmokinBBC]

I put the energy suspension poly mounts on about 3 years ago. I don't tear it up like autocross, so it's hard to compare. The BB has 534lbs of torque and I've jerked it quite often from a rolling start. The mounts are still in tact.

 

[shipy59]

my 79 sbc has a chain now from head(alt bracket bolt) to upper a arm mount bolt, just a small amount of slack and i dont feel it at all. In fact i forget all about the broken mount till a thread like this comes up.

 

[clutchdust]

Pick up point on the frame -> chain -> pick up point on the block or head (preferrably the head)

 

[69427]

Pick up point on the frame -> chain -> pick up point on the block or head (preferrably the head)

Nah, unless I'm pulling the engine I just can't stomach the look of a chain hanging in the engine compartment.

 

[clutchdust]

Why not? Just gold plate it and call it "bling".

 

[JPhil]

Regarding Bird's post, I realize poly mounts will be a bit stiffer in compression and tension, but what is the forum's opinion regarding the relative strength? I'll probably put a backup restraint on the engine regardless of which mount type I install, but if the poly mounts are actually stronger in peak tension I might give one a try.

I too have been considering them--my engine is not nearly as strong or used like yours, but when I do get after it hard, the torque twist jams my exhaust pipe up into the shifter of my TH400 and locks it up. (NAPA rubber mounts) I've dimpled it, but that hasn't really helped completely. I know I need to change that section of pipe, but I have ground clearance "issues" as well. So I've been thinking of stiffer motor mounts to reduce the torque twist of the engine....

 

[Fuelie74]

How about a fancy aluminum motor plate? That shouldn't hurt the block like solid mounts would.

 

[68/70Vette]

Probably not applicable for you're situation,..

I've read that if you use poly motor mounts, you have to use a poly transmission mount. If you use use poly motor mounts, you can't use a rubber transmission mount. If you use a poly transmission mount, you can use rubber motor mounts.

This is what I've read. Don't know if it's true.

 

[big2bird]

Probably not applicable for you're situation,..

I've read that if you use poly motor mounts, you have to use a poly transmission mount. If you use use poly motor mounts, you can't use a rubber transmission mount. If you use a poly transmission mount, you can use rubber motor mounts.

This is what I've read. Don't know if it's true.

I would never use a poly tranny mount. It will break the tail piece.

 

[TimAT]

I would never use a poly tranny mount. It will break the tail piece.

All the data I've seen says that using poly mounts for all three is not a good plan for that very reason. Either the trans OR the engine.

I have poly mounts on Ol' Red. They are stiffer than the rubber ones. If they are more prone to breaking, I haven't seen any signs of problems yet.

 

[69427]

Why not? Just gold plate it and call it "bling".

Well, I suppose that's one way to work around my initial preference to not use a chain. :amused:

 

[SmokinBBC]

I would never use a poly tranny mount. It will break the tail piece.

All the data I've seen says that using poly mounts for all three is not a good plan for that very reason. Either the trans OR the engine.

I have poly mounts on Ol' Red. They are stiffer than the rubber ones. If they are more prone to breaking, I haven't seen any signs of problems yet.

Well now I need to rethink what I have on mine....poly for both the trans and engine.

 

[Twin_Turbo]

solids and poly trans mount, never cracked a case, have that on multiple cars. A solid tranny mount, wouldn't run that but IMO the poly breaks trannies is an old wives tale. I would have broken one by now.