Balancing GTV6 driveshaft with hose clamps - Page 2 - Alfa Romeo Bulletin Board & Forums
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post #16 of 25 (permalink) Old 02-24-2019, 08:26 PM Thread Starter
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Originally Posted by Alfistaa View Post
Backer Motorsports, Lawndale CA.
(310) 836-3160
So he has a proper fixture for balancing the driveshafts of Alfa transaxle cars? That would be great. Most of the places I called are capable of balancing anything as long as they have a reliable means of mounting it . . . .

Chris A: '81 GTV6 rescued from junkyard, "GT" car/'86 Porsche 944 Turbo track/street car/'73 BMW 2002tii fun street car/'74 Jensen Healey Lemons Rally car!
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post #17 of 25 (permalink) Old 02-24-2019, 10:05 PM
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He pulled the driveshaft, rebuilt it, had it balanced, and put it back in the car. It's nice and smooth. I'm happy.😎
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post #18 of 25 (permalink) Old 02-28-2019, 04:47 PM
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Driveshafts - a bit more...

Oh driveshafts.

Long term Lancia Aurelia and Flaminia owner here - the issue of driveshafts to the rear transaxle really starts with the Aurelia in 1950. They refine their driveshafts through the 1950s, and end up in the late 1950s with guibos and two driveshaft tubes, and its this same design in the Flaminia through the 1960s and then in the 1970s-80s with the GTV6 and Milano. Its practically the same shaft. So this issue has history.

The best guy on driveshafts I ever found was Roger Vrilikas, at Drivelines of Oregon. He worked on a few Lancia shafts for me with good success with both theoretical and practical knowledge of driveshafts Ė and he was quite familiar with Alfa GTV6ís. His shop also did big marine shafts. He wrote up an impressive article in the Alfa newsletter about 10-15 years ago about how to get rid of vibration. He believed the problem was more in alignment than balance: that is, things in the driveline get out of alignment in small ways, and send the shaft into vibration. He looks very carefully to make sure each component has its center of mass on the centerline of the shaft axis - typically the problem. There are small variations, due to wear, or to manufacturing intolerances. He fixes that, and finds the balance problems to be much less as a result.

First, they inspected the shafts, and carefully examined each part, making sure it was straight and true. In my shafts, the fitting splines were kicked slightly out off true, as the connection of the spline into the tubes (welded) had given way a bit and been tweaked to be a bit out of true over the years. This is not uncommon, as that connection takes some abuse from fast starts. To fix this, they heated the ends of the tubes, and gently pushed the splined bits into alignment, back on axis. So too, by fiddling and switching all the connecting pieces, they were able to get the entire driveshaft to spin much more straight. They also made end couplings for mounting the shaft to spin the whole thing it as a single entity on the balancing machine, and got the runout from .020Ē down to .006Ē, measured along the whole shaft, not just at one place. Once straight, the balancing of the shaft was very simple. In short, its alignment first, then balancing.

I think Roger has retired, I don't know if Drivelines still exists, and if they still do shafts. But he did a few of them for me, and they were wonderful.

The hose clamp and vibration analysis is a good home measuring unit for vibration and reduction by counter-balancing. Some Lancia folks jury rigged a similar acoustical setup in the 1970s, with a speaker and some sensors, for the same effect. It takes some time, and if the out-of-alignment isn't too bad, it can work.
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post #19 of 25 (permalink) Old 02-28-2019, 05:01 PM
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I have a 3 axis accelerometer chip mounted to a steel bracket that I can attach to any part of the car. The output can be monitored with an oscilloscope or an AC voltmeter. I was going to use it to troubleshoot my engine vibration problem but I have solved that now. My question is where is the best place to mount the transducer to analyze driveshaft vibration? The chip has five wires so it has to be stationary.

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79 Spider
85 GTV6 3L
76 Suzuki GT500
2011 Jaguar XKR

A little government and a little luck are necessary in life, but only a fool trusts either of them. - P.J. O'Rourke
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post #20 of 25 (permalink) Old 03-01-2019, 11:31 AM
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To add to what Geoff has said about (Aurelia/Flaminia) driveshaft alignment, to verify that the transaxle and motor are pointed at each other (or are at least reasonably close, as shimming either is not a standard procedure) I've made fixtures to mount a laser on the transmission input shaft and the crank/flywheel flange. Rather obvious if something's askew.

I should note that later Flaminia Berlinas and PF Coupes had a single piece driveshaft, mounted between a short bell housing and extension shaft off the back of the motor, and a rather long extended clutch nose.

Early Aurelias (1 -> 4 Series), with vane and rubber sector joints, use shims for the center bearing height adjustment. Fixed spacing with later Giubo jointed shafts.

One of our friends who vintage raced a B20 used a modified GTV6 driveshaft; another friend then had one made for his Spider. While they worked fine, I never quite understood the need, as neither produced much more than stock power. I find a well sorted original quite up to the task, and now that parts are available, there's no excuse for such mods.


For electronic balancing/vibration analysis see:

Transaxle Balancing: we solve your car's transaxle vibrations

Photos | Transaxle Balancing


That's the kit I'd like!
-Steve

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post #21 of 25 (permalink) Old 03-04-2019, 02:58 AM
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Steve -

Good addition. I've heard of these guys. For a moment, they had a Florida presence. Its pretty neat - I suspect they get good results. Notice they have a bolt on balancing place in the front and rear of the driveshaft. Likely to allow for rapid adding of weights, precisely.

Didn't know about the later single piece driveshafts for Flaminia. Along those lines, in the Aurelia parts books there is oddly a three part shaft on a later model (at least in the parts book)!

Your point about aligning transaxle and engine with a laser is well taken - years ago a friend used to work on 275 GTBs and used that technique to align engine to trans, finding they were not always aligned. Remember the old Jay Heumann B20 (with a vibration no one could find....)? He made a teflon puck, and mounted a laser light in the main bearings (engine apart), and found it shined about 5" off the transaxle input shaft in the back. The cause was that one motor mount had been tweaked about some 20+ years earlier in an accident - and no one had spotted it as it was hidden under the generator. The tweak stressed the driveshaft, but also made it so the engine mounting bols had a direct metal-to-metal connection, transmitting engine vibration through the car. A simple readjustment to the mount, and a freshly balanced shaft and no more vibration!

On using a slightly modified GTV6 driveshaft for a B20 s.4, there is still one in the garage - if anyone is looking for one...

Geoff

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post #22 of 25 (permalink) Old 03-05-2019, 07:41 AM Thread Starter
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Thanks to Steve and Jeff for the additional insight----I was hoping for posts like this!

In a perfect world I would have found an expert like your guy in Oregon to properly repair the shafts; I don't like the idea of using a large amount of weight to counter-balance anything (whether it is a wheel or a driveshaft), but the hose clamps happened to work in my case!

I did rig up a laser pointer tool a while back (using a cheap gun sighting tool from Amazon) and found that the alignment between the engine and transaxle was good.

In my case, I knew that it was a balance issue (or bent driveshaft) because the nature and severity of the vibration did not change even after making drastic alignment changes by moving the engine/transaxle every which way . . . . .

Chris A: '81 GTV6 rescued from junkyard, "GT" car/'86 Porsche 944 Turbo track/street car/'73 BMW 2002tii fun street car/'74 Jensen Healey Lemons Rally car!
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post #23 of 25 (permalink) Old 03-06-2019, 07:19 AM Thread Starter
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Here's a link to Drivelines of Oregon, which Geoff referred to above:

Driveshafts.com

Anyone looking for driveshaft balancing should give them a call to see if they can still service an Alfa GTV6 shaft.

Chris A: '81 GTV6 rescued from junkyard, "GT" car/'86 Porsche 944 Turbo track/street car/'73 BMW 2002tii fun street car/'74 Jensen Healey Lemons Rally car!
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post #24 of 25 (permalink) Old 03-23-2019, 02:16 PM
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Los Angeles area driveshaft shop

After a dozen tries I found General Driveshafts in Monrovia, 133 W Maple Ave. They balanced it as a whole with new flex discs. Was smooth afterwards.
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post #25 of 25 (permalink) Old 03-23-2019, 06:14 PM
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I've just edited my last post to correct the spelling of Giubo, the flex donut. I knew better, but did it anyway....

-Steve

https://en.wikipedia.org/wiki/Giubo
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