This morning I drove my new 84 5th Ave to the store and heard a god-awful banging noise from the rear axle whenever I turned (more accurately when I was coming out of a turn). It wasn't so bad when I went slow, but if I took a turn at speed or was accelerating through the turn I got a horrible BANG-BANG-BANG-BANG.

I do hear a slight humm from the rear axle when driving in a straight line, and there is a mild clunk, like a u-joint needing replacement when I first accelerate or if I let it coast then accelerate, but this banging is way way louder. My only though is that it is a Sure-Grip rear axle that needs lubricant? The axle is a 7 1/4, 2.2 gear ratio unit original to the car, so it has 88,000+ miles on it.

Any ideas? How about advice for a cure?

Thanks.

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Casually looking for a Clifford hyperpak intake for cheap.

Sounds like my car when the pinion bearing got Loose......

Could be the spiders....


Get it in the air.

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Yeah....Im the one who destroyed this rare, vintage automobile.....

What gear oil is in there? Is there any friction modifier in the oil?

The bang bang bang around the corner is most likely due to lack of oil, or the oil not having the recommended friction modifier in it if in fact it is a SG, but can also be due to incorrect backspacing on the pinion, incorrect side spacing on the differential case or bad/loose bearings/cups.

The clunk on take off could be the pinion bearings like sandy said, but you will also get a whining noise at speed, and/or on deceleration.

Jack the car up, crawl under there, and grab the flange on the driveline that mates to the pinion. Try to get axial and radial movement out of it. You can also check the U joint this way.

Let us know what you find out.

~THOR~

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1984 D100 Shorty Custom
Certified Auto Appraiser - RevItUp Classic Appraisals
President - Cherry City Bombers CC
Part of Tyrde-Browne Racing

By '84, I don't believe that anything with a 7-1/4 got a SG; I think you'd have to have an 8-1/4 for that to be available. but yeah, it sounds like missing teeth somewhere; side gears and spiders come to mind; on my old 90 Dakota after I sold it to my brother in law (it was originally a 3.55/7-1/4 truck) it did something similar; when I pulled the cover I found a split carrier because the busted tooth wedged itself between the 4 small gears before it "fell out" and wound up with a carrier busted in 2.
so I went to the yard and found a 3.55 8-1/4 to put back in there.

come to think of it Moms '84 5th, also with a 2.2x 7-1/4 did the same thing eons ago. I put a 2.45 SG 8-1/4 in that car as a result.

Being such a "tall" gear there's alot of torque going into that puny rear w/o near as much being able to be "released" compared to, say a 2.76, 2.94 or numerically higher gear, as in having to give the car more gas to get rolling. (less mech. advantage) so I'd think a num. higher gear would tend to hold up way better even being only a 7-1/4,(as long as you aren't "one wheel peeling" or neutral dropping it). Lot less torque load being put onto the gears,= hold up longer.

Thanks guys. Since I bought the car I haven't even had time to clean it. As soon as I can, I will get under the rear and and check for slop and see what kinf (if any) and how much lubricant is in the rear axle. I know SG was an option on the 84 7 1/4 rear axle, and the guy who ordered this one got just about every other option. I think he just went down the option checklist and checked everything off. It is possible it has a SG.

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Casually looking for a Clifford hyperpak intake for cheap.

It's really easy to tell.

If you haven't seen one, yank the cover, look inside and if there are a bunch of springs and plates where there is usually a big empty space on the inside of the case, it's a SG.

In case you have seen one, disregard that part

~THOR~

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1984 D100 Shorty Custom
Certified Auto Appraiser - RevItUp Classic Appraisals
President - Cherry City Bombers CC
Part of Tyrde-Browne Racing

Barrister Rumpole,

Suregrip or unSuregrip, that is the question. Your old pal Jack can help with this. You don't even have to soil you hands in the process, and we know what dirty hands in the court room will do for yeah...

Have Jack lift one rear wheel while zee auto is in Neutral, if you can't turn the elevated wheel this is a sure bet she's a Suregrip. Surely you knew this method, and I like wasting electrons filling little gray boxes with blather.

Regards from the Right Coast,
WA

rumpole

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67' Dart GT Convertible; the old Chrysler Corp.
82' LeBaron Convertible; the new Chrysler Corp
07' 300 C AWD; Now by Fiat, the old new Chrysler LLC

I have a feeling that it will not matter a bit whether it has SG or not, I think that he will find the same problem once he pulls that cover, either way.

Yup. I knew about the jack and tire spinning trick, but there is definitely something wrong in the rear axle. The BANG is very loud and shakes the whole car. I need to get out there and pull the cover and se what falls out- gear lube, shavings, or chunks.

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Casually looking for a Clifford hyperpak intake for cheap.

Oily gearburger! I'll bet you've lost at least one tooth off a spider gear.

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Joshua

Any word Reed? May want to check the whole under carrage...noises can transfer around the car. When I felt it, it sounded like it came from around the front....could be a broken (worn out) transmission mount since it happend around corners/sharp bumps.

I have had similar noises out of trannys when a clutch pack is about SHOT and theres alot of "free-pack" clearance to take up as it hits the next gear on acct of most of the friction being other than on the clutch discs; could the goin around the corner be a coincidence, where you've got "just enuf" gov/throttle pressures to make it try to shift at that load/throttle opening???

I didn't get a chance to check the rear axle, but I was reading my shop manual and sure-grip WASN't offered on the 7 1/4 that year. I was wrong. I am 90% certain it is coming from the rear axle, but I will drive it tomorrow and pay very close attention. At first I though it was coming from the front too, and i will be checking the front suspension out carefully, but this latest noise sounds like the rear axle.

Argh.

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Casually looking for a Clifford hyperpak intake for cheap.

So its a different sound than the one I commented on last weekend?

Possibly. It is much louder, harsher, and more frequent than that sound. Hopefully today I will get a chance to pull the diff. cover and have a look-see. With my luck, I will need a new rear axle AND a front end rebuild, all at the same time! However, I was looking over the paperwork in the glove box and I saw that the car was ordered with the heavy duty suspension. I wonder why the guy just didn't order an 8 1/4 too?

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Casually looking for a Clifford hyperpak intake for cheap.