XHD Leaf Springs

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PolarBear

PolarBear

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Simpsonville, Kentucky
Last fall, I replaced the factory leaf springs on my 65 Barracuda with a set of MoPar HXD springs - which made the right side of the car sit about one and one-half inches higher than the left. This was somewhat distressing, but assuming that the new springs would "sag" in a few weeks (and balance out), I drove the car. Initially, I noticed a bit of a "grinding" sound from the rear end - but it soon disappeared.

But the springs never did sag (which I assume is a good thing), and I took a look at various Web blogs to see if anybody else was experiencing the same situation. I found some information which led me to believe that the right spring is actually quite different from the left - and is perhaps suited for serious oval racing (?).....

Anyway, to level the car, last weekend I installed another new XHD right spring on the left side. Voila - the car is level, looks good with the extra "lift".... and I'd be a happy camper except for the god-awful noise coming from the rear end.

I'm not exactly sure how to describe this noise, but it's a phenomenal (and quite loud) harmonic whistling type of sound. It starts as the car begans to move, and stops when the wheels stop moving.

Any ideas?
 
It's your pinion angle. It was upset when the new springs were installed. You'll need to do a little reading and findout where it sits now and add a shim inbetween; under the rear spring and above the shock mounting plate.
MoPar Performance used to sell them and still might. Unshure of this. You'll also need a pinion angle finder. You can get one from Comp Cams, sumitt or jegs. There cheap.
The MoPar Chasiss book has the procedure for this. Excellent book to have.
 
Rumblefish360

I very much appreciate your response, and will do a little research & reading to figure out how to modify the newly induced angle.

Just to be sure, though, I'm presuming the pinion is the small vertical "plug" on the axle that aligns with the "hole" on the leaf springs? If so, I hope these "corrective" shims aren't too thick, as my U-bolts barely reach as it is. I may need to get longer ones.
 
I spent a fair amount of time this morning looking at various internet sites, and happened across several of those mentioned by OldVart. I now know what the pinion is, how to measure the angle between it and the driveshaft, and where to order shims. So I obviously need to take some angular measurements on the Cuda, and decide which shims to buy.

Curiously, though, none of the articles on "pinion angle" say anything about the ungodly harmonic noise that I'm hearing...... they do, however, mention vibration. I'm not doubting your very helpful advice, but I didn't drive it fast (or far) enough to notice if I was experienceing any vibration.
 
The only other thing I can think off is worn out rear.
 
I crawled under the car Saturday morning, and tried to determine the driveshaft/pinion angle..... and it appears to be nowhere near the -7 degrees that are "recommended" for leaf spring setups. In fact, if I'm calculating it correctly, it appears to be +2.... So I ordered some shims, and longer U-bolts.

While under the car, I noticed that one of my exhaust pipes seems to be situated very close to the driveshaft..... and I'm wondering if the spinning driveshaft is (perhaps) touching the exhaust pipe - triggering the odd harmonic noise.

Since I'm doing this investigation on the garage floor, it's difficult to really see a lot of this stuff clearly, but when the shims arrive, I'll install 'em, and hopefully all will be well.

But I did consider the gears - or at least the gear lubricant, as being a possible source of the noise. I don't really think this is the case, as the noise didn't exist with the old springs.

Again, thanks for the advice. I can't wait to get this straightened out.
 
The driveshaft touching anything will sound like metal shop. Loud, maybe bandsaw type of grind.
New gear oil is allways good. I just did mine in the Magnum. Took care of that popping back there.
 
for what its worth, the XHD Mopar perfomance springs sit lower on one side than the other. Mine does the same thing. It says it right in the MP ordering book. Now, how much is yours sagging on one side??? mine isnt off by much, but you can tell it is lower on one side. It has something to do with taking up the torque from a hard launch, due to a car torquing harder on that side.
That may be your only concern. You may not have a "problem".

maybe this info. will help.

-RPM
 
Actually, my old Cuda sits pretty even now - as I now have right hand springs on both sides....... When I had an "official" left hand spring on the left side, the car was about one and and half inches lower on that side.

I don't drag race the car, and with the (pretty-much) stock 273 V8 still on board, I really don't have to worry about a "smokey burnout" type of start - so I didn't really dig the unlevel look.

But my advice to anyone purchasing a "matched" left & right pair of the MoPar A Body HXD springs, be aware - you're car will likely sit lopsided.
 
This past weekend, I installed steel MoPar 3-degree shims between the springs and the axle, and that created "more" of the correct angle between the pinion and the driveshaft. Based on the information you fellas have shared with me, I felt pretty good about that.

Unfortunately, I still had the ungodly grinding and whistling noise, and a closer inspection confirmed that my driveshaft is, in fact, rubbing one of the mufflers and the exhaust pipe. I guess that putting on the high lift springs forced the driveshaft down a bit, and now it rubs.

Anyway, I don't have a lift, and trying to work under the car on jackstands isn't any too easy, so I'm going to have the car hauled to a exhaust shop and get them to adjust the hangers on the exhaust.

Again, thanks for the advice and help. Hopefully, the addition of the shims will decrease the possibility of driveline vibrations...... I guess if I ever get to drive it agin, I'll know.
 
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