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interesting sound on deceleration


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I know its tough to  fix things over the inter web, but help me get to the right direction perhaps?

 

71 521 with a four speed. shifter has a ton of slop when in a gear, but its been that way for a while and i've heard thats "normal", (not the linkage, its tight)

 

recently i noticed a fairly loud sound coming from center of the vehicle near the dash, really sounds like speaker feedback, but i have no speakers.

 

it only happens on deceleration (or at least thats when i can hear it over my loud exhaust), and the sound changes if i move my shifter from left to right while in a gear and slowing. Not sure this is related but its a change.

 

No slipping of clutch, solid engagement and the sound never happens with my foot on the clutch. but won't seem to come back if i slow and put the clutch in then back out. also won't do it with just rev's in neutral...

 

I know i have a tight ujoint, could this be my sound? carrier bearing also has some play. otherwise i'm thinking pilot and/or throwout bearing? 

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Most commonly caused by loud exhaust. At certain rpms it will resonate, and cause part of the body to vibrate too.

 

Although the "move the shifter" makes me wonder if its an exhaust pipe touching the body. My Datsun had that problem, it only touched while decelerating.

 

Do you move the shifter lightly, or hard enough to move the transmission slightly?

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there is a spot thats really close, just downwind of the collector flange, I expect this is my issue. i'll try to bend it outta the way a bit, and i'm looking into getting my exhaust done, just not for $400 like midas wants, 

 

thinking 2in exhaust. if it can be outta the way at this pinch point. 

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A stock 521 will make more HP with 1.75 exhaust than with 2" exhaust. But the 2" definitely looks bigger.

i could care less about looks. want a deepish tone and any extra ponies i can find. and to get rid of this NOISE!!!

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the more i drive this truck, the more i'm sure its a driveshaft issue. sound changes pitch and "feel" as it wants, cold or warm, high or low rpm's, clutch pedal out only. noticed the carrier bearing has a lot of play. getting a one piece driveshaft today. and exhaust will be done next week if funds allow. Hopefully this fix all of my issues.. well all the issues related to mentioned on this thread anyways.. 

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Rare for the carrier bearing to give problems. What does wear out is the rubber isolator around the bearing. It rots and the driveshaft becomes unstable. You can wrap a strip of rubber around the driveshaft and tighten the holding strap down to hold it. This works well. Try the search function for info and pictures.

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Rare for the carrier bearing to give problems. What does wear out is the rubber isolator around the bearing. It rots and the driveshaft becomes unstable. You can wrap a strip of rubber around the driveshaft and tighten the holding strap down to hold it. This works well. Try the search function for info and pictures.

I read about that yesterday but I know I have a tight u joint. Figured I'd kill two birds with one stone. Always loved the ingenuity of ratsun folks!

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MY bolts were loose on ther drive line where the 2pcs mate up.

Nothing wrong with a stock 521 drive line. Wouldnt waist my money buying a 5 pc one. Carrier bearing is a plus what Im thinking.

 

 

1.75 inch is fine for a L motor. I got a Superturbo. Now that Im older I would get the quiet walker type now. I like nice and quiet.

 

 

if exhaust was hitting most times you catch the exhaust titting when you start as the motor lfexes to one side or the other.

 

 

also ck the engine to trans bolts soemtimes they looen up.

 

 

the shifter loose i the ears being spead out over time where the pin goes thru.but still alot compared to a new car.

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