ALFAGTV6.COM

[Mats]

What? I said thebest way is to balance while in working condition, since that is difficult it's better to balance it at rest then do nothing.

[Maurizio]

My sketch was only to show that the guibo's have the same angle when they correct an error.
No direct sketch of the real world. This can be placed in any plane....
And still that would be a bit to simple, your drive shaft isn't just one piece.

I ones suggested an alignment with a laser pen for the guy who did the one piece carbon shaft here on the forum. That would work for a static alignment.

I agree that the most deflection in present under load. So who is going to abuse his car while a camera monitors the shaft displacement Who is going to the dyno in a short while, the mirror idea of Mats is great! You something like a ruler in the picture though.

[Zamani]

What? I said thebest way is to balance while in working condition, since that is difficult it's better to balance it at rest then do nothing.

Balance or align? I was saying that for practical purposes, aligning the gearbox and engine at rest is probably the most practical thing one can do oneself. I wasn't talking about the best thing to do.

[Mats]

Ah, communications breakdown...

"To balance the angles" was what I meant, normally what you do is balance the nominal angles depending on what you think is most important, forward cruise, forward abuse or reverse. In this case we're looking at 'nominal' or static which is usually only of academic interest (but not unimportant mind you).

[killaz]

Aren't donuts designed to be weakest spot after all? How long do you take to brake them if they are not perfectly centered?

Personally I think that the best mod would be carbon fiber prop shaft.

[kevin]

Killaz, you can break a brandnew front coupling same day if you thrashing a 24v 3,0l motor on track. Note the word thrashing. Off the track it does not break.

Mats why is it the front coupling Always breaks first.(All couplings new to start off with). Hence the reason I have only one coupling cage and thats on the front(no breakages in +- 20 races). Is it because the greatest stresses are on it from engine at angle(horizontal angle) in the v6 while the rear coupling the angle is smaller as the centre coupling 'absorbs' some of the angle.(alternative anlge does not apply - I think).

[MD]

Personally I think that the best mod would be carbon fiber prop shaft.

For an exposed propshaft, nobody is going to argue with that. Reducing the spinning mass means you could reduce it to a one piece. You still need to deal with the angularities generated by the engine and transaxle. How do you porpose to do that exactly?

[killaz]

Well, first I would determine centers of rotation of engine and gearbox and bring them in center with laser tool (with prop shaft taken off). Then, we should measure angularity of engine and transaxle. Transaxle's angle would be a guide for further centering since its level is only changeable in front segment... Problem occurs with middle prop shaft section - don't know exactly is it adjustable..?

Now that I think a bit more, seems pretty hard to get all measures required and tools too.

[Mats]

Kevin: The change in angle is the greatest in the front one due to the small bushing span of the engine and it also takes most of the load in engine fire pulsation

[MR2 Zig]

I don't know if this is going to help the discussion or not, but here goes....

I had read somewhere (on the internet, i dont remember source) that part of the reason for the heavy front flywheel was to absorb some of the odd power pulses of the 60deg v-6. The commentary ran along the line that the V-6, in any configuration, had vibration/tortional load problems due to the V-6 layout of the engine. buick tried a 90deg V-6 and ended up using an odd firing order(the "odd fire" engine) to deal with the vibration.

I have ZERO experience with lightened flywheels on these cars, but maybe that is a factor? (i doubt it would be the whole reason)

How about running a length of box tube from the bell housing to the transaxle to hold things put. I know it would be adding weight, but it would be adding weight low and in the center of the car. This wouldn't be as rigid as a torque tube, but it might be enough to keep the flex discs from failing and leave the engine and transaxle in their rubber mounts for vibration control.

I'll run and hide now

zig

[MD]

Hey ziggy. No need to duck for cover mate.We are all experts here..and that includes you

I think the principle of what you say is correct. However, the execution would produce pretty much a torque tube or a crude form of one in which case, you may as well purpose make a torque tube or install one by adaptation from an existing something.

Perhaps a torque tube from a boat..

[MD]

For an update on my suggested procedure, please refer to page 2.

[Jim K]

I'm only butting in for a comment regarding the V6. The inline 6 and 60* V6 engines are in the group of the best balanced engines, there are no odd firing intervals. What you are surely referring to are the abominable V6's created by chopping 2 cylinders from existing V8's, like many automakers have done with their 90* V8's.
Happy New Year everyone!
Jim K.

[MR2 Zig]

Jim,

I was going over some stuff I had read on the internet (the most brutally honest place to find facts )

Their ranking of vibrationless to vibration prone had inline 6 at smoothest and 90deg v6 at roughest, hence the "odd fire" buick engine using a gimmik to get around the vibration caused by penny pinching/ poor design.

They said Lancia came up with the first production v6, but didn't say anything about how it ran....basically they said the thing was the first one and that was all.

The comments on the Alfa V6 related to the fact that it was a sucessful engine at the best bank angle for a v6...therfore had the least vibration problems of the v6 engines out there.

they went on to talk about 90deg v8's and inline fours.

The point they made about v6 engines that i found interesting and related to the topic was that the power pulse was rather abrupt on all the v6's. then went on to discuss how the various manufacturers went about minimizing that trait in the v6 layout (alfa by going to 60deg bank angle, buick 90deg bank angle and odd staggered firing order)

If ...If that article is correct then I can see the stock use of the heavy flywheel and rubber couplings. It would also explain MD's racket that showed up with his modified prop shaft and Kevin's noting that it is always the front coupling that fails...the power on and off cycle, being abrupt, works the front coupling the hardest so it fails first...the abruptness of the load unload cycle manifests itself as a harsh rattle when you put a CV joint at the front coupling location. From what I've seen of industrial power transmission couplings I am beginning to think our coupling troubles may have alot more to do with torsional loading and unloading than previously thought.

I don't mean to discount getting the alignment right, I'm saying there is more to this picture than we've been discussing.

Scott

[kevin]

Well that clears that up. Thanks Jim. At this stage I am chainging nothing on the race car because it works. The coupling cage limints the coupling from expanding and also its rotation. The marks indicate it rotates or twists up to 13mm each side. Thats huge. So if there was no cage its its obvious thsi coupling will fail with continous abuse on the TRACK. I dont think the E of the rubber is correct on the Alfa coupling. BMW have got it right with there compounds .
On similiar lines in this topic to reduce inertia(save couplings), what negative effect is there for having a lightweight clutch??