A body rearend in an E body ?

[Frank VP Challenger]

being fairly new to the site I had posted this topic in the "conversations" section rather than the correct forum. So I will now post it for anyone to respond.

I have a 72 Challenger with a 440, 727, and 8.75 rear with 3:89 ratio. The previous owner had installed an A body complete rearend (that is about 6" shorter in width drum to drum) in the car to allow room for the big tires and wide reversed wheels he was running. In my ongoing endeavor to bring the car back to a more original condition, I installed the stock 14" Magnum 500 wheels - that's when I notice the wheels and tires appeared to be more tucked in
than normal. Anyway, I was just wondering if this narrower rearend might be causing the loud vibration that occurs any speed I drive the car. Maybe because the front to rear wheel tracking is different ? In trying to eliminate this vibration (not a rattle or shimmy), I have set the pinion level, balanced the drive shaft, checked to ensure the torque converter has no weights welded on (my engine is a 1969 440 with the steel crank and is internally balanced), and checked all front and rear motor and trans mounts. So, if anyone has ever heard of this A body swap into an E body, I would appreciate any thoughts.

 

[DetMatt1]

Is there any play at the yoke on the rear end?

 

[Frank VP Challenger]

There isn't any play in the rear yoke. Both ends of the drive shaft u-joints are also nice and tight and the shaft was recently checked for balance. There is however a small drip from the rear yoke pinion seal. Nothing major right now - but I'll replace the seal at a later time. Thanks for your thoughts.

 

[DetMatt1]

Do you have any pics of how the car looks with the magnums on it? Where do you feel the vibration the most? Is it different on deceleration?

 

[Frank VP Challenger]

Posted some photos on the garage photo section of this forum - under Frank's garage.

 

[DetMatt1]

They are tucked way under there, aren't they? Great looking Challenger though. Are you going to replace the housing eventually?

 

[Frank VP Challenger]

Thanks. I'm going to install 2" wheel spacers on each rear side that I found on an eBay site. They are new Ford / Dodge billet spacers and were only $35. I'm not a big fan of spacers, but thought I would see if they would make any difference when driving. They should bring the rear tires/wheels out more and will look better. They should be here early next week.

 

[IRON MAN]

You stated "I have set the pinion level." What do you mean by that?
I have set rear ends up so the pinion shaft centerline is parallel with the transmission output shaft centerline, when the weight of the car is on the suspension. Use an ANGLE FINDER to determine the driveline angles. I set them up at a 2 degree angle. I have set up 4-link suspension and leaf spring suspension this way and they are vibration-free.
A friend of mine chased a slight rear end vibration for years. Turned out the rear end had a bent passenger side rear axle flange.

 

[Frank VP Challenger]

I have set the drive line angles using an angle to the correct specs I had looked up (I believe it was ~ 3 degrees) and installed the thin angled shims to get the adjustment right. There was still no change and the buz like vibration was not eliminated. I suppose I could pull both axles and inspect them to see if one might be bent.

 

[Cudafever]

U-joint must have at least 1/2 of a degree to 3 degrees. make sure your not reading them degrees from the ground. they are yoked to drive shaft angles.
The rear tires making a narrower track will have 0 to do with your vibration.
Is the vibration there just sitting still or at freeway speed? deceleration ? exceleration? make more vibration turning left or right? hard braking?

 

[Frank VP Challenger]

The vibration starts when the car gets going from about 25 mph and continues. There is no play in the rearend yoke, drive shaft is new, balanced and with good u- joints. Drive line angles were set to specs.

I have car on lift and checked the front yoke going into the trans tail shaft. I found some up and down movement / play (about 1/32") - indicating some wear in the rear tailshaft bushing. I'm currently in the process of ordering a seal and bushing to install. I'm hoping this will resolve the vibration.

 

[Cudafever]

One more thing to look at, and that is the drums. they have balancing weights on them. if they got knocked off some how this could be a problem.

 

[Frank VP Challenger]

OK. That's easy enough to do. Thanks for your thoughts.

 

[IRON MAN]

Did you drive your 72 Challenger when the wide reverse wheels were on it? If so, how fast did you drive? Was there vibration then?

 

[IRON MAN]

Also, study the diagram below, then look at your Challenger's drive shaft to see how the u-joints are aligned/positioned/welded. The yokes at opposite ends on the drive shaft should have their bores aligned parallel. If the yokes are more than 40 degrees out of phase there will be a noticeable wobble when torque is applied. I built a pro-touring Camaro and installed a 200R4 and 1974 Nova SS 8.5" posi. The drive shaft ended up 3/4" too long. I had read in a racing journal some builders clock the universal joints 15 degrees too preload the driveshaft. I asked Driveline Specialties to do this when shortening the driveshaft. The owner at DS scratched his head and said okay. Worked fine and no vibration. I was curious and it didn't cost anymore.

 

[Frank VP Challenger]

I did drive the car with the big tires/wheels. The vibration was the same as it is now when driving up to ~ 60 mph. I will change out the tail shaft bushing, bearing and seal when the parts arrive early next week to see if this helps.

 

[Cudafever]

I have seen a drive shaft that was twisted. could only see it with a straight edge or a angle finder on the cap but it caused a droning vibration. this was on a dodge pk with a cummins diesel in it.
If the caps are not parallel, drive shaft balance will do nothing to help(drive shaft shop should have checked all of this before they balance it.......but things slip thru the cracks some days. check it while you have the drive shaft out for tail shaft bushing repair.
here is a couple youtube videos that well explain it better

 

[Frank VP Challenger]

Thanks for the very informative info. I'll definitely check the u-joint end alignments. I'll be taking it apart early this week to install the new tailshaft bushing. I'll provide an update when it's back together - and after a test drive. Thanks again for the info.

 

[Mikael L.]

Hi Frank!
This is exactly what I am thinking to do ön mine Challenger. Do you have any pics from under the car? Curious of the leaf spring solution.
Thanx and you got an nice car.

 

[70Barracuda]

Pull the DL, have a buddy tow you down the street. That V should be easy to tell where its coming from.

Me thinks its the rear end. I would tow it before putting more dollars in it. IMO