engine mount experience

[Zedn]

Hi all,

I am up to fabricating engine mounts for my car and i cant decide what to use.

Can some of you give me feed back on what you used for engine mounts and how they have performed. eg vibration, longevity etc.

Currently deciding between buying some nolathane bushes and fabricating some brackets out of tube and 5mm sheet with a bolt in double shear. kind of like these.
http://cgi.ebay.com.au/TUFF-MOUNTS-G...item3cb463d758


Or going with the square rubber typed engine mounts and fabricating some brackets to work with them. Using these.
http://cgi.ebay.com.au/Holden-V8-eng...item519850f468

Any pics of what people have made up would be appreciated. Im running an LS3.

Cheers.

[Rob. Smith]

G'Day Zedn,
I've got the double shear type with nolathane bushes and have no vibration problems or noise transfer. Alignment for the 'pins' is a challenge but I simply loosen the plate from the engine and the holes can be aligned easily

[HISSIN]

i fabrica ted steel mounts on the chassis then used the original factory mounts no vibration at all have some photos

[Rebel1]

Whiteline have an after market LS mount"

http://www.clubcobra.com/photopost/d...nts_Small_.JPG

[Zedn]

Originally Posted by Rebel1

Whiteline have an after market LS mount"

http://www.clubcobra.com/photopost/d...nts_Small_.JPG

I havnt seen those before. Quick search says they are around $300. Thats pretty similar to what i am going to make.

Bushes from supercheap auto are about $30, i already have heaps of 5mm steel and i just need a couple of bolts and a small bit of pipe. Should be under $50 in materials.

I was just a bit concerned because of the way nolothane bushes tear and crumble. Worried about how long they will last.

[Rebel1]

Originally Posted by Zedn

I Bushes from supercheap auto are about $30, i already have heaps of 5mm steel and i just need a couple of bolts and a small bit of pipe. Should be under $50 in materials.

I was just a bit concerned because of the way nolothane bushes tear and crumble. Worried about how long they will last.

Frankly, I would suggest you make them myself. Indeed, this is exactly what I did because I wanted a mount with a different vertical height above the side rails. ie. get a better tail shaft alignment to the diff pinion.

The whiteline units are made to replace the Holden round donut type unit which has shown some shearing problems. ie. The standard holden mounts are great for NVH issues but have little resistance to lateral movements.

If you search on LS1.com.au I think you'll find these (Whiteline) are very reliable. Providing you protect them with the GM heat shields.

[Rebel1]

Should also mention the whiteline units look fairly "small" in that pic but they are quite substantial mounts.

The bolts you see are all 10mm. The inside of the urethane bush has a steel sleeve which increases the diameter of the metal support surface area inside the urethane bush. Did I explain that correctly?

Gawd...just noticed the pic clearly shows that bush. )

[400TT]

Urethane would be the best choice for your application.

I expect you have already thought about this stuff, but as some positive reinforcement:

* Use quality brand Urethane bushes.
* Use a common enough size/application Urethane that it can be replaced years down the track if required.
* Substantial enough for the application.
* Make sure the design has failsafe in case of Urethane breaking/tearing.
* Make a solid version or sold insert to replace the Urethane for when you are aligning the mounts on your chassis, you want the Urethane mounts to be unstressed.
* Be consistant in your mounting, make sure the gearbox mount is of a similiar material/movement/design.
* Make the mounting system strong enough to future power upgrades, Cobra's only get more power, a huffer etc.

For our mid-engine applications we use pair front Urethane mounts, pair Urethane mounts off the bellhousing/adaptor plate and Urethane gearbox mount. So all up 5 - 6 mounts. Enough to limit drivetrain movement to an acceptable level as it seems everyone is in the 500-800HP bracket these days or planning to be.

[Zedn]

Thanks for those points Craig.

The solid mount for mock up is a good idea that i hadnt thought of.

The bushes i am looking at are for lower control arms so should be substantial enough.

Cheers.

[Rebel1]

Excellent post Craig ... Point 5 (solid insert) for initial fab of the mount is very important. We spun up an alloy insert.

Another point I would make is ensure the side cheeks of 1/2 mount without the urethane bush is at least the same diameter as the OD of the bush.

In other words the whole urethane bush is covered at the ends.
Zedn, rather than purchase lower control arm bushes you might try whiteline for the replacement bushes for their mounts.

[boxhead]

I used factory Holden mounts, I figured GM had invested a fair chunk of change, so they should be ok

[Rebel1]

Originally Posted by boxhead

I used factory Holden mounts, I figured GM had invested a fair chunk of change, so they should be ok

Totally agree but the RMC chassis rails are very close together so the GM alum engine mount brackets and the rubber engine mount are not suitable without major surgery.

Look in Baz's gallery and one can see the surgery that Neil Streeting did to that RMC chassis to use the standard GM bits. Chassis mods which could well cause an engineer to insist on another beam test.

Not all Cobras are manufactured to accept GM engines.

[renovationinnov]

i agree boxhead , i just got new one from repco but used a old set for the set out

[boxhead]

The CR requires the American mounting ears, I had a left and right Aussie one.
Cost me $100 to get the R/H mount modified to suit.
This is the factory L/H mount, you see it did not line up, after investigating, I found this mount was correct, but R/H was wrong.


And modified R/H mount.

Which is the same now as the American R/H mount. They are closer to the block, If needed, when I get home I am happy to measure my engine mount spacing from one side to the other.

[Rebel1]

Yep... been there, done that. Got the GM alum thingys and the GM mounts.

To give you some idea, The bolt protruding from the top and the bottom of the GM rubber engine mount hits the very center of the chassis side rail, That chassis rail is a 4" section. Whereas in the pic posted by Boxhead that bolt is inside the chassis rail.

Further the center of the diff pinion is in a line 1" above the bottom plane of that chassis rail and is horizontal ... that is 0 degrees.

[Rebel1]

So as in the pics in Baz's gallery the base of the rubber mount shown in Boxheads pictures as being level with the top of the chassis rail has to be level with the bottom surface of the RMC chassis rail.

Real bugga really

[Rebel1]

Here is the pic from Baz's gallery. As you can see Neil cut the inner rail and boxed to the side rail and a flat plate at the base on which the rubber mount sits.



That is major surgery to me. Much better to leave the inner chassis rail. Toss the alum GM mounts and make new compact steel ones and use a urethane mount not unlike those shown earlier.

[Rebel1]

And here is a cut and shortened GM mount in my chassis in an attempt to get the mount bolts inside the inner side rail. Achieved the narrowing but was still too high in the chassis.


Problem was ... tailshaft to diff pinion alignment ....was still 40mm too high above the side rail.

That lil pink vehicle in background belongs to #1 grand daughter. )

[Tenrocca]

Originally Posted by Rebel1

And here is a cut and shortened GM mount in my chassis.


Problem was ... tailshaft to diff pinion alignment ....was still 40mm too high above the side rail.

That lil pink vehicle in background belongs to #1 grand daughter. )

OMFG - it is REAL!!!!!!!

First Rebel1 pic ever.....I was starting to think you were some deluded old fart who thought he had a cobra in the shed somewhere, but it was really just a 120Y pedal car.

[Rebel1]

Originally Posted by Tenrocca

I was starting to think you were some deluded old fart who thought he had a cobra in the shed somewhere

Correct, leastwise the bit up to fart.

Originally Posted by Tenrocca

but it was really just a 120Y pedal car.

See that lil pink and yellow thing in the background. I'll bet my grand daughter driving that will beat your cobra to ermmmm 5 mtrs distance and not even raise a sweat.

Cheeky bugga