far-fetched vocabulary thread

[Cedric]

Matra et Alpine suggested I create this thread, since my questions about rather mysterious car parts might be of interest to other UCP-members.

Here we go.

What is a "bell-crank" like the bell-cranks that operate the exhuast valves in the BMW 328-derived Bristol racing engine? Is it a right-angled rocker?

[RacingManiac]

bellcrank on a race car with inboard suspension(pull or push rod) is basically the rocker that actuates the spring/damper when the pushrod or pull rod moves...

[Cedric]

I agree, but I am talking engine here. I would like to know if the rocker (bell-crank) has a 90° angle to it.

[Matra et Alpine]

a bell crank is used in many places and in ALL of them it conveys that the two arms of the lever are at 90 degrees to each other - a right angle.
So your first thought was right.

[Cedric]

OK.

This one: proprietary engine, is it the same as stock engine, or rather standard engine that is also used by independent chassis builders to squeeze into their cars?

[Matra et Alpine]

never heard that in any circles. But taking just the English meaning then proprietary would imply the engine is exclusive to that manufacturer.

As we'd gone through a few you'd PMed me on before, if you can put the context you've seen it used in will make any answer much more accurate.

[Cedric]

I had never heard this either, but this is the sentence:

"Coventry-Climax had been a pre-war maker of proprietary engines for road cars, Morgan among them."

From what I have read, I can say that they are alluding to Climax building standard racing engines (off-the-peg engines) and supplying them to whoever wants to buy one. I assume a synonym must be donor engine then.

[Matra et Alpine]

yes and yes

[Cedric]

What are chassis jigs exactly and what do they look like?

[Matra et Alpine]

They are frames to either BUILD a new chassis on or to re-align a bent one

It's a metal frame on whcih the parts fo the chassis are laid before welding.
In the case of repair, it's a metal frame with fixed points to measure alignment against and in some cases strong enough to fit hydraulics to to push/pull the frame back into alignment.

[RacingManiac]

http://www.fsae.utoronto.ca/2002/large/work029.jpg

don't mind the pic itself.....the metal frame in the foreground is a chassis jig...

[Cedric]

this one:

Tramp, referring to wheel tramp and/or axle tramp. What does the wheel movement look like and how is it brought about?

[Matra et Alpine]

Happens with leaf springs.
When you aply power, the rear wheels grip the tarmac and their is then a rotational force applied to the solid rear axle which imparts a rotation. The leaf spring then bends down in the section before the axle and up behind it like an S shape on it's side.
As the car moves forward and their is less torque reaction through the axle then the leaf spring returns to 'normal' shape.

In poor setups this can be quite sever and actually oscillate. When it does it also affects the tyre contact and traction.

Easily solved with links from the body to the top and bottom of the live axle to prevent the rotation.

[Cedric]

I once saw this in real life when an overpowered Mustang accelerated heavily. Its wheel hopped up and down like mad.

But I have read it happens to de Dion-suspensions as well, how does that come about then?

Moreover, is tramp the same as bounce?

[Matra et Alpine]

De Dion contain SIDEWAYS movement of a live axle.
It isn't very good at tramp as it doesn't have much leverage.

Bounce would come from poor damping with soft springing. So the wheel is allowed to move UP as the wheel gains traction and with poor damping continues and then repeats. Another nasty trait easily removed with decent suspension.