Solid Engine / Transmission mounts

[Xavier]

Anyone using solid mounts for their Small Black Ford? Lets say I am not concerned about the vibration; what other down sides are there? Pros and cons please.

[tcrist]

If you are drag racing then they are fine but if it is a street or autocross type of driver then vibration is the main concern. If you have a motor that has a good cam in it then you will shake every nut and bolt loose,...Oh yea, and your teeth too.

Terry

[Xavier]

Other than vibration the cons are:

[csx wnab]

i don't care what kind of racing or driving you do. a solid trans mount is stupid. solid motor mounts-ok. not trans. i don't like subjecting my aluminum case to that kind of stress. go with a urathane mount for trans.

[tcrist]

Originally Posted by csx wnab

i don't care what kind of racing or driving you do. a solid trans mount is stupid. solid motor mounts-ok. not trans. i don't like subjecting my aluminum case to that kind of stress. go with a urathane mount for trans.

WOW, tell us how you really feel.

Terry

[csx wnab]

just tell'in it like i see it

[jmarsey]

My JBL is a solid mounted configuration using a front motor plate and special bellhousing. Tail shaft is soft mounted, of course. In my case, the engine block is a chassis stress member: adds to the torsional rigidity (stiffness) of the chassis. It’s as smooth as silk with very little vibration and not one loose bolt in 6500 miles. However, the rotating assembly was neutral-balanced, and not externally balanced as most Fords are. Other than for strictly drag racing, this is a key component and requirement for solid mounting in my opinion. The motor is much happier for it too.

If you have to ask the question, then it’s not necessary. For any kind of longevity, there’s much more required than you realize and the polyurethane mounts (great invention) are a good compromise for a street application. Hope this is helpful.

[jams]

How can you use a combination of hard and soft mount? That sounds like trouble to me. One end is allowed to move and the other is not?????

[jmarsey]

It’s very basic. When bolted together, the engine, bellhousing, and tranny become a beam. You want to fix the beam at two points only, meaning: front & mid mount or front & tail housing. If you were to fix the beam at three locations (front – mid – tail) somewhere along those 3 points will get stressed and most likely fail. You are not mixing solid and soft mounts in this case. The soft mount at the tail housing allows it to float and absorb any movement given the beam is already fixed at two points (front & mid) and the tranny is cantilevered. This is a typical configuration and works very well.

Mid Mount:


Front Mount:

[csx wnab]

damn john, if that ain't the sh%t. that is a very cool set up. and you are 100% correct.

[jmarsey]

Hey Jeff,

I hope to see you and Mike in Sonoma on Sunday! I'll have the blue car there and you can take a closer look at the crazy thing if you want :-))

See you soon, John

[Dominik]

I mounted engine solid and never had problems. Initially the tight fit headers were the reason, because otherwise they wold have touched booster and steering.

Best way to do it: as described by jmarsey. However, can you still change the clutch w/o taking the engine out?

I cannot recommend mounting front of engine and at transmission. The gap between the two mounts is too long.

Did anyone compare torsional stiffness before and after drivetrain has been mounted solid?

Dom

[jams]

John,

Thanks for a great explanation and for the super pictures. Nice setup!!!!

[zrayr]

these are nice. Not solid, but I've experienced minimal movement with them.

http://www.ronmorrisperformance.com/...Code=Eng_Parts

Z. Ray

[scottj]

I don't run anything but solid motor mounts and a urethane trans mount. The urethane trans mount is needed in a 3-point mounting arrangement so you don't stress the trans case when the chassis twist- and the typical Cobra chassis twists a lot. Vibration has never been an issue.

Scott

[Xavier]

Thanks for all of the great feedback.

I have solid motor mounts now, I have been using them for only a few weeks with no issues. Honestly, the virbation is no worse than it has been, I do not mind it at all. Its a Cobra for Lord sakes, not a Lexus. I did this to prevent my filter from hitting the scoop every now and then when I really punch it, I do not want to give up my air filter and have to go to a smaller one, and I am reading everywhere about the eventual side pipe problems that will occur from the engine rotation (flange cracking, mounting cracking, welds snapping etc.). It just seemed like good preventitive maintenance, but like everything else, all the peolpe who don't have one, and who never used them, said it was a huge mistake. All with zero experience (like me) using solid mounts.

I chose solid motor mounts because it was cheap ($39.99) and there was really no nice way (nothing I would be happy with) in mounting a torque link. A lot of time and headache and money from something I would be pleased with. And I know I would never disconnect it for "cruising". Who am I kidding? It would be connected all of the time.

But I have been reading else where stating that solid motor mounts must have a solid trans mount, the twisting of the trans mount, however slight, will eventually cause the trans case to fatigue and crack, which did make sense to me. If the engine stays still, and the trans moves, eventually something is going to give. That did make sense, although I never heard of anyone using them.

In short, I have been second guessing myself and needed a little reassurance that this indeed is not for everyone, but is hardly a bad thing. Getting more launch to the rear wheels is just a bonus.

[jmarsey]

You will probably have an issue at some point, a few weeks of driving is hardly enough time, and just wishful thinking at this point. Sounds like you might be swapping one set of problems for another.

The difference in cost between tearing something up and the poly mounts is a no-brainer. I would recommend installing the poly mounts and just be done with it (do what is needed so you have the clearance required. The motor is not going to move that much under full-hammer).

However, if you keep the solid mounts, give us a report after 2,000 miles. Ultimately, I hope it works out for you. '-))

[scottj]

Originally Posted by Xavier

But I have been reading else where stating that solid motor mounts must have a solid trans mount, the twisting of the trans mount, however slight, will eventually cause the trans case to fatigue and crack, which did make sense to me. If the engine stays still, and the trans moves, eventually something is going to give. That did make sense, although I never heard of anyone using them.

In short, I have been second guessing myself and needed a little reassurance that this indeed is not for everyone, but is hardly a bad thing. Getting more launch to the rear wheels is just a bonus.

The motor and trans are one unit- solidly connected to each other. Solid motor mounts AND a solid trans mount will cause the engine/trans unit to become a stressed member of the chassis- the trans case is not up to the task. By using a urethane trans mount the trans is no longer a stressed member, now the mount will absorb chassis twist- an amount which is significant.

Scott

[Xavier]

ScottJ, thanks for the explanation. That makes sense.

My motor sits on these Dodge motor mounts, and the only guy who sells these polyurethane mounts (no, the bigger brands do not have them) wants $148 a pair. Again, this is a small amount to pay IF THEY WORK and the engine does not rotate. Its not like I am not willing to dump money where I need to, but I want to be smart about it, and I want to KNOW the polyurethane is going to do it without and manufacturing involved.

So it looks like everyone is saying solid mounts are great, use them, but not as a cruiser or driver. Polyurethane should do the trick. I will have problems (and I never can get from anyone what those problems are?) with solid motor mounts.

The responses to the posts are becoming cryptic, solid motor mounts are okay, but don't use them because ???. I am not trying to be a smart a$$, but it seems like people here use them, but don't recommend them for my problems. Maybe because plyurethane will do the trick?

At either rate; it looks like the concensus is go to polyurethane.

[scottj]

I've got 3500 miles on mine, about 2000 on road courses, and all on race tires. My HP and grip level has far exceeded the chassis. The chassis design is lacking in torsional rigidity to the extent that the inner and out door skins split from binding in the door openning, but I've never had a problem with the driveline using the solid-engine/urethane-trans mounts. My reason for using solid motor mounts is different than most though. By using a dirt Late Model style motor mount I can easily lower the motor a couple of inches for the track and raise it with spacers for the street. Otherwise urethane motor mounts are a good solution.

Scott