Well a couple of months ago I hamered on You guys about driveline vibration.I ended up balancing my driveshaft with a couple of radiator clamps and got rid of 90 percent of my vibration. Anyway, the other ten pecent has been above 80 MPH, especially on deceleration.
The other day I blew the seals out of an air shock and the car is basicaly sitting on the springs now. Today I took it out and ran it up to about 90 before the vibration got bad(without shocks and sitting about 1 1/2 " lower in the back then in front. This only brought the yoke about a 1/4 " inch closer to the tailshaft. So could this be an indication that I need a longer driveshaft ?....or.... a difference at only 10MPH faster may not be any indication at all.
I haven't had the time or funds to try chroming the slip yoke (thightening the yoke to bushing clearence ) yet.
As David Letterman says "is this anything ?"



David/ Trysix

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65 Coronet 4dr
Always being Modified

How exactly were you able to balance it yourself?

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'74 Duster w/ HEI ignition, beat to snot suspension, A904, 8.25" 3.55 SG rear, still being tuned up and gets 17 MPG

Know how they always build a better idiot? That's me

Search for post Titled "Tailshaft Bushing".
Trysix

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65 Coronet 4dr
Always being Modified

Huh? I'm totally lost

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'74 Duster w/ HEI ignition, beat to snot suspension, A904, 8.25" 3.55 SG rear, still being tuned up and gets 17 MPG

Know how they always build a better idiot? That's me

Trysix,

You are also changing the driveshaft joint angles when the rear end drops, so it could be driveshaft length (less likely), or driveshaft/joint angles that are changing your vibration. You can buy 2 degree wedge plates from Summit that allow you to change the rear DS angle.

My 2 cents...

Lou

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Home of Slant6-powered fun machines since 1988

Lou,

Is there a starting point on adjusting these angles or is it just trial and error?

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65 Coronet 4dr
Always being Modified

http://www.slantsix.org/forum/viewtopic ... ft+bushing

It always helps to get that slipyoke as far into the bushing as possible, I set them up so they slide all the way into the tailhousing, except for about 1/2 inch less, needed to get into the U-joint saddles on the rear end knuckle.

The change of height also points to a pinion angle problem, you can buy some wedges to adjust the pinion angle. If you have a protractor (angle checking tool) you can take some measurments to see how much to shim and in what direction.
DD

I guess it's time to start all over again since it's never been right from the start. I need to find another junk yard shaft to send to the Driveshaft shop.....or I can just stop driving above 80 MPH.....

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65 Coronet 4dr
Always being Modified

.....stop driving over 80 mph....in Texas That's a good one!
You know what they say.... "I spent a week driving through Texas,....one day"!
I will send you a private message, get me some specs, I have a bunch of used driveshafts.
DD

The idea to keep in mind when adjusting the pinion angle is to keep the c/l of the tailshaft and the c/l of the pinion parallel, horizontally and vertically. Not necessarily, pointing straight at one another.

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'66 Cuda 225/4spd
'66 Dart GT convertible 225/auto
'64 Dart GT 340/4spd

Try,

Get ahold of a factory service manual from the '60s and it will have instructions on how to adjust angles. When I just did mine, I bought a magnetic-base 12" level with a graded bubble reader (Sears) to measure small angles. This is cheap and worked great for measuring angles up to about 4-5 degrees.

Lou

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Home of Slant6-powered fun machines since 1988

Once you've got the centerlines parallel, then you can adjust the pinion to the 'nose down' attitude that works best for your application.

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'66 Cuda 225/4spd
'66 Dart GT convertible 225/auto
'64 Dart GT 340/4spd

Thanks again guys. I hope to tinker with this thing again this weekend. I'll let ya know what I find. Last time I at least made it drivable up to 80MPH ...so I'm trying to tell myself that I'm makeing progress.

Trysix

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65 Coronet 4dr
Always being Modified

I saw on another forum, somebody was saying the service manual suggested checking the torque on the spring plate u-bolts. They should be to spec and consistent. It doesn't cost anything and it's easy to check.

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'66 Cuda 225/4spd
'66 Dart GT convertible 225/auto
'64 Dart GT 340/4spd

Well It's too cold and nasty this weekend to do much to the Coronet....also I'm still gathering stuff up.My new shocks are on the way and a friend gave me a driveshaft( that I think) will put the yoke about 1/2 " from the tailshaft. I do have concrete with a carport over it, but when it's cold and rainy it takes the fun out of it, if ya know what I mean. Anyway thanks again for the help and I'll give ya'll a full update later.

Trysix

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65 Coronet 4dr
Always being Modified