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rubber mounts or not
HAL9000v2.0 - 4/1/05 at 11:30 AM

Have anybody mounted diff and/or engine+transmission directly on chassis, without rubber mounts?

I' we done search but found no topic related?

mookaloid - 4/1/05 at 11:34 AM

Mk Indy Sierra Diff is mounted directly on to chassis.

I think that mounting engine/gearbox straight on to chassis would make life fairly unpleasant from the vibration and harshness point of view. It might even make things drop off the car!

Cheers

Mark

HAL9000v2.0 - 4/1/05 at 11:38 AM

I' we mounted diff directliy on chassis and planed to make some PTFE mounts for engine and transsmision.

I am wondering how much diff vibrations will be transsfered on chasis?

scoobyis2cool - 4/1/05 at 11:40 AM

My diff is mounted directly to the chassis, as are most peoples as far as I'm aware, and I've had no problems with vibration

Pete

Rorty - 5/1/05 at 02:02 AM

quote:
Originally posted by HAL9000v2.0
I' we mounted diff directliy on chassis and planed to make some PTFE mounts for engine and transsmision.

I am wondering how much diff vibrations will be transsfered on chasis?

A hell of a lot. PTFE mounts will be too resillient and will transmit virtually everything through to the chassis.
You'd be better off using low Shore PU bushes. They will outlast rubber and will offer a fair amount of dampening.
I have regularly used PU for car engine and gearbox mounts, but I would always mount bike engines directly to the chassis as they're a lot better balanced than your average car motor.

krlthms - 5/1/05 at 03:12 AM

When is an engine or transmission considered "stressed member"? Is it anything to do with how solidly it is attached to chassis?
Cheers
KT

Rorty - 5/1/05 at 03:24 AM

They would be considered stressed when any loads are transmitted through them externally. It's the amount of loading I'm guessing you're interested in.
If a chassis is well designed and constructed, then solidly mounting the engine/trans won't harm them as the chassis should be rigid and not flex.
A ladder type chassis that is designed to flex freely (your F Series trucks are a good example) would not be a good candid ate for a solidly mounted setup.
What's considered to be fully stressed is when the engine/trans forms part of the vehicle structure, such as in some bikes and race cars.
Many race cars also hang the rear suspension off their transaxles.
Not every engine and transmission design is suitable to be incorporated as a fully stressed member.
Idle interest, or are you planning something?

NS Dev - 5/1/05 at 02:04 PM

A solid mounted engine would be unbearable in a road car unless VERY well dynamically balanced, and even then would be unpleasant.

I have a solid mounted engine in my grasser which was not specifically designed as stressed, but is really in racing conditions, it's like an additional reinforcing member of the chassis.

The vibration from my factory std (no extra balancing) Vauxhall XE 16v engine was enough to crack the welds that hold the screen mesh in at the front of the cockpit, and also to repeatedly shear off the aluminium rivets holding various panels in place. It also makes your eyes itch at certain revs, which is ok in racing as your revs are never constant for long (other than when on the limiter) but in a road car would be nasty!!

Marcus - 5/1/05 at 08:33 PM

Mine's not rigidly mounted, but mounted on what they sell as V8 engine mounts, these are pretty solid and the engine (1700 X-flow) just sits there! The cutout for the air filter in the bonnet is only 2mm bigger than the filter itself and it never makes contact.

Marcus

NS Dev - 7/1/05 at 12:12 AM

Yep! Surprisingly, very hard rubber works fine, it still seems to remove the really high frequency vibration that breaks things on the car.

krlthms - 7/1/05 at 05:41 AM

quote:
Originally posted by Rorty
They would be considered stressed when any loads are transmitted through them externally. It's the amount of loading I'm guessing you're interested in.
If a chassis is well designed and constructed, then solidly mounting the engine/trans won't harm them as the chassis should be rigid and not flex.
A ladder type chassis that is designed to flex freely (your F Series trucks are a good example) would not be a good candid ate for a solidly mounted setup.
What's considered to be fully stressed is when the engine/trans forms part of the vehicle structure, such as in some bikes and race cars.
Many race cars also hang the rear suspension off their transaxles.
Not every engine and transmission design is suitable to be incorporated as a fully stressed member.
Idle interest, or are you planning something?


Hello Rorty,

Yes and no, as you would say.
I am currently doing my year's worth of rersearch as per instructions in Kmini's site (he says something like not to go near any hardware until you've spent a year reading and researching!). In the long term, I would like to build a locost but with a streamlined art deco / 1930's shape. I am inspired by the shapes of Morgan aero 8 (minus the cross eyes), Bugatti Atlantic, and 1938 Alfa Romeo 8C 2900B.
There is a guy in New zealand named Lyle who built a couple of cars that are very beautiful; do you know of him? I have some pictures of his cars but I have not yet figured out how to upload images to the forum. I would like to build something similar to what he built.
The reason for my question is that I am generally interested in the concept of one component doing two (or more) jobs, and wondered why the engine in the locust is not used as a structural element, since the engine compartment "box" is topless. Surely, this is not good for torsional strength. In fact, I have wondered why there are no (e.g, cross) braces on top of the engine. I assum it is because of lack of space.
Along the same lines, I have a while ago asked about torque tubes in place of prop shafts, because I imagine a torque tube enclosure acts as a stressed chassis member as well as part of the drive train.
You can tell that I am still in the early stages of my "reading year".
Cheers
Karl Thomas

Rorty - 7/1/05 at 06:15 AM

You're showing admirable self control. I haven't heard of Lyle, do you have a URL for him?
I think like most things automotive, the Locost compromises function for form. Yes, its engine bay could do with being braced on top, but the bonnet/hood is already in very close proximity to the engine, as many will attest to.
I like the idea of bracing above the engine, which is exactly what I do on my mid engine Beetle chassis. It adds tremendous rigidity to the upper rear shock mounts and the chassis as a whole.

krlthms - 7/1/05 at 06:27 AM

quote:
Originally posted by Rorty
You're showing admirable self control. I haven't heard of Lyle, do you have a URL for him?
I think like most things automotive, the Locost compromises function for form. Yes, its engine bay could do with being braced on top, but the bonnet/hood is already in very close proximity to the engine, as many will attest to.
I like the idea of bracing above the engine, which is exactly what I do on my mid engine Beetle chassis. It adds tremendous rigidity to the upper rear shock mounts and the chassis as a whole.


Here is the URL for the pictures and a write up; it is a club site. At the bottom of the write up there is a pointer to the second car he built. He is talking about making a straight 8 engine out of two 4age's welded end on.
As I said, I don't yet know how to upload images to the forum.
Cheers
http://www.constructorscarclub.org.nz/profiles/profile-samlyles.html

Rorty - 7/1/05 at 06:40 AM

quote:
Originally posted by krlthms
As I said, I don't yet know how to upload images to the forum.

When you post a reply here, there's a line directly above the "Post Reply" button at the bottom of the page.
The heading of the line is "Attachment" and to the right is a window and to the right of that is a button marked "Browse".
Click the browse button and navigate to a file or picture in your hard drive. I think from memory this forum setup baulks at bitmaps, but any .gif or .jpeg will work fine.
If you want to start your own photo archive on the forum, go to the top left of your screen and click on "Photo Archive". There you'll be able to upload images from your hard drive in a similar fashion.

Rorty - 7/1/05 at 06:43 AM

Lyle's cars are sheer beauty. I'll post that link over on Anything Else if you don't mind.

krlthms - 7/1/05 at 06:55 AM

quote:
Originally posted by Rorty
Lyle's cars are sheer beauty. I'll post that link over on Anything Else if you don't mind.


Please do; don't you love those pontoons?
Cheers
Karl