I finally got around to putting another(longer) drive shaft in the Coronet.It's an inch longer and puts the yoke approx 1/2 inch from the tailshaft. Anyway it's worst than the other driveshaft ...you can see this one wobbling around. Anyway...It will be a while before I'm able to get this shaft aligned and balanced. I've been laid off and need to find a job before I spend any more on the Coronet......Ill be back guys ...thanks again for the advice.


Dave/Trysix

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65 Coronet 4dr
Always being Modified

Chrome the yoke? It probably cost more than the $5 I spent buying a new bushing at a local trans shop and took longer to get back from the chrome platers than the 1-1/2 hour at most it takes to change the rear tail bushing and seal the right way....

Donram,
This problem had been a problem for a long time....started when I swaped in a a833 OD for the stock 3 speed.I had already replaced the tailsaft bushing twice and tried many other things along the way. Anyway most reciently I had the driveshaft straightened again....also refabricated the rear trans mount it was bumping the crossmember on accel. I'm reasonably happy now....I don't have any vibration until about 90 MPH now. The thing won't run but about 84 MPH in the 1/4 so I,m happy for now.

Trysix

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65 Coronet 4dr
Always being Modified

I've been chasing down a significant driveline shake and I think I can trace it's origins back to when I lowered the car. I've crawled under the car, measured angles as per this website and actually bought the same magnetic protractor.
http://www.flash.net/~ivc1/cobra/irsvibes.html

I created an XL spreadsheet to help with the calculations (those trigonometry formulas were covered with cob webs) and came up with the following angles, sketches and proposed fix. IMHO, what appears to have happened is that the lowering violated the basic two rules of driveline alignment.
1. I had the front U-joint running with 0 angle.
This is undesireable since it appears to be the tension created by pushing power thru an angle with negates all the 'play' in the system. No angle appears to allow harmonics to build.
2. The front and rear U-joint were running at different angles.



In order to comply with both of the rules, I'll need to shim up the tranny tail end and re-angle the rear end.

Mopar performance sells the shims packages (pn: 4529536) for about $65 US. Each kit includes 6 wedges ( 2 each of 1,2 & 3 degrees).

So this is the theory . . . let's see what happens in reality!
I'll keep you posted . . .

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Cheers!
Al T

Hey, it's great to hear you're still working it out, AND keeping us up to speed, no pun intended. It seems too often we hear about problems, offer some possible solutions, and never get any feedback on what worked (or didn't!). Keep us in the loop, and we'll all benefit. Thanks, again.

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

After the first few hours of playing around underneath the car . . .
1. I had lots of oil leaking out of the pinion shaft seal on the 742 - 8 3/4 pumpkin. This 3:55 diff had been installed last summer to compliment the EFI/blower project.
First surprise - someone had very discretly tack welded the yoke flange /seal protector cup to the carrier body. After this came off I chiseled out the old seal ( once in they don't come out nicely! ) and pulled out the tapered roller bearings to have a look. They appeared to be in good shape so I reassembled the bearing, drove in the new seal, torqued on the yoke (180 ft-lbs) and promptly discovered that the pinion had play in it. At this rate, the seal would be damaged in no time. I also now understand why the seller had so carefully tack welded the yoke flange. This effectively took the slop out of the diff and hide the fact that the pinion was loose. This also may have contributed to the vibration. Buyer beware!
I now had to disassemble, pull out the new seal ($13 down the drain) and pull out the bearing. I removed a shim from between the yoke and spacer behind and reassembled/retorqued without the seal. The slop was now gone but I could still turn the pinion by hand. I'll take a chance that the pinion pre-load is close enough to being right.
I also noticed that the old 'double lipped' seal had worn grooves into the yoke shaft sealing surface. In order to get the seal to ride on a different shaft area, I make an 1/8" gasket/spacer to go between the carrier and the seal and drove it into position. I then had to grind 1/8" off the cupped yoke flange to compensate/maintain clearance. I re-torqued the yoke. Its now ready for road testing.
2. I also found out that I will not be able to shim up the back of the tranny by 5/8". . . there's not enough space at two locations: the rear of tranny parking brake structure & drum and front U-joint and floor hump. I'll have to re-assess my plan.

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Cheers!
Al T

You want to be careful about shimming-up the back of the tranny. I believe the lube for the bushing and seal is probably gravity fed. So, maybe, shimming up the back of the trans (too much)may adversely the lubrication.

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

I've been battling a vibration for quit awhile. As some of you know, I installed a stub shaft [ fabricated from a newer tranny output shaft ] at the end of my 1960 tranny where the old ball & trunion used to be. I then used a shortened regular style drive shaft. Despite driveshaft balancing, runout testing, drive alignment checking . . . I could not get rid of the shake. I finally found a good ball & trunion to fit on my original driveshaft and give the old setup a try again tonight and . . . miracles. The dreaded shake is gone!
One step closer to Vegas!

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Cheers!
Al T

Great "trouble-shooting" work, you get my award for sticking with the problem until you fix it!
DD