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SM465 eternal rattle (spark knock) on highway

JoeliusZ28

JoeliusZ28

1/2 ton status
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Location
Utica MI (Metro Detroit)
Hey All,

I'm new to the board, I've wanted a squarebody since I was a kid (grandpa had a bright red 85 Scottsdale K20 I always drooled over). I bought my first squarebody back in April, an all original 84 Scottsdale K10, and ever since then its been a constant work in progress. Overall it was in really good shape, just needed some past due TLC on a number of maintenance items. Gave it a full tune up, buffed the paint out, added new dual exhaust, and actually pulled the trans because it was knocking and I thought I had a bad throwout bearing... turned out the trans just needed some real gear oil and the previous owner had been using motor oil. Whoops. Thankfully its an enjoyable truck to work on and I at least got to learn more about the truck in the process.

Since that time ive been driving and enjoying it. I'm just having one problem that I can't figure out I hope this forum can help with. About 2000 miles after i put the trans back in the truck started making a noise at highway speeds. (also lower speeds under heavy throttle). Its load dependent and sounds rotational, but after 2 months of poking around i cant figure out what it is. Its been doing this since august and seems to be slowly getting worse. It typically needs a good 15 miles on the highway before you really start to hear it, otherwise its quiet. Ive eliminated the inspection cover, u-joints are good, I can't find anything thats vibrating. Clutch and gearshifter both work perfect. A loose throwout bearing / fork is suspect but the noise doesnt really change if i put pressure on the clutch pedal while cruising. If I stay on the highway at 65+ for an extended period of time the noise gets rather loud, to the point you cannot ignore it. I want to take the truck on some road trips next year and the way it is acting i can't trust it to do that. I'm suspecting an input bearing but I want to be sure before I pull the trans all the way out again... I just finished this project so I'm well practiced but that was a lot of work!

Anyway, here's a picture of my truck and a video of the noise. Thanks for any help!

-Joel

79F31DC7-A049-4DCF-ADBB-02C99FB866EB_zps9c0fzybc.jpg

 
See both those springs on the clutch fork...both top and bottom? See if both of those are attached. That is the easiest thing to look at first. I am guessing your 84 has a mechanical linkage. Who's Ferrari is that?

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Thanks, I'll check those springs. It is a mechanical linkage and I know it does have two springs but I recall only being 90% sure i had them installed correctly. I can confirm the feel of the clutch pedal is good.

Lamborghini is my buddy's ... ironically enough, he had trans issues with the hydraulic e-gear system right after buying it too. He's a doctor but he's an experienced wrench too. diagnosed and repaired the e-gear system himself for a tenth of what the dealer wanted to fix it (like 30k lol).
 
If not the clutch fork, check the rear u joint
 
bent72 said:
If not the clutch fork, check the rear u joint
Click to expand...
I had that thought too. I have replaced just the front joint on the driveshaft, but not the rear one (nearest the diff) because it looks like someone dropped it and pinched the yoke slightly so i'm not sure if i'll be able to successfully do an R&R on that u-joint. Still seems to function fine however. The noise seems to come from just ahead of the shifter. I know its not impossible for noise to travel through the vehicle. I'd like to find another driveshaft and eliminate that possibility once and for all, but on the other hand I'd be surprised if this is the problem.
 
Could be an idler shaft bearing ready to be replaced?? But that's inside the trans.
 
My gut feeling has been that the noise is coming from the trans, even though I just had it inspected by a shop this spring/summer. Maybe the drastic change in gear oil aggravated something. I'm trying to avoid pulling a transmission over something simple again. But if i can't pinpoint it in the next few months, thats what im going to do. I was thinking this trans is simple enough to try rebuilding on my own.
 
JoeliusZ28 said:
My gut feeling has been that the noise is coming from the trans, even though I just had it inspected by a shop this spring/summer. Maybe the drastic change in gear oil aggravated something. I'm trying to avoid pulling a transmission over something simple again. But if i can't pinpoint it in the next few months, thats what im going to do. I was thinking this trans is simple enough to try rebuilding on my own.
Click to expand...

You need to have a hydraulic press, V-blocks, Ram Forcing blocks, and the like to rebuild a manual transmission.
 
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I rebuilt one of those transmissions with a hammer, block of wood and some snap ring pliers. They're pretty simple.

Here is a copy of the rebuild manual:

zieglerdigital.ca/public/downloads/sm465rbman.pdf
 
Russell said:
I rebuilt one of those transmissions with a hammer, block of wood and some snap ring pliers. They're pretty simple.

Here is a copy of the rebuild manual:

zieglerdigital.ca/public/downloads/sm465rbman.pdf
Click to expand...

I have never attempted to rebuild a transmission with a hammer and a block of wood, but as the saying goes "Where there's a will there's a way". :D
 
@chulisohombre - thanks, thats helpful. Mine also gets louder as it warms up (or the longer you drive it). but there are some occasions it does it right away, or even not at all. It seems to be getting gradually worse. 80% of the time the noise is there, and I am hearing it in the 45-60mph range now whereas before it used to be only 65+

And i think mine also gets worse "between coast and gas" like you said, although mine is quiet when you coast. I took a new video this weekend to show how the gas pedal affects it.


Russell, thanks for that link. I also saw a couple detailed videos on youtube on doing a bench build on a 465, planning to sit down and thoroughly read/watch both and determine if its something i can handle.

I am undecided on whether or not its the input or TO bearing, but my money is for sure on it being one of the two. If its the TO bearing making the noise, its not the bearing itself that is bad but rather that its loose in the fork or rattling against the pressure plate somehow. Clutch engagement is perfect and everything is quiet when i press the clutch pedal.
 
Sounds more like throwout bearing to
Me. Mine actually makes a slight grinding between coat and power almost like bad rearend gears. But I already rebuilt everything back to front except the trans.
 
the only thing that has me second guessing the TO bearing as a possible culprit is that when i put pressure on the clutch pedal while cruising at 65, the noise doesn't stop until the clutch slips/lets go. It does however, change the frequency/volume very slightly.
 
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This is what the trans shop said based on the video:

"It may be a couple fingers sticking up on the pressure plate touching the throw out bearing.... it sounded somewhat tinny.... more like the crank hitting the inspection cover to me.
Also check crankshaft end play."

I'm not sure how i can check crankshaft endplay, and ive already eliminated the inspection cover as a possibility (removed it).
 
That should be eliminated by the pilot bushing. Unless it is also worn out. Then you can get a metal to Metal sounds engaging and disengaging. If you have the inspection plate off you Can look into the front area and try moving the pressure plate fingers maybe or t.o. Bearing and see if it seems loose. It spins on the main shaft and also on the clutch fork as it's running. So if one side is worn more than the other it will make noise as it's spinning. Same with the front main bearing. But I get more of a grind as I let off gas and not as I'm gaining speed. May not be the same as you.
 
It also depends on what type of clutch you have in yours. I don't know what I had in mine when I bought it but I replaced it with a diaphragm one I believe it's called from luk and it is quieter. And also is easier to disengage.
 
The clutch I have is the one Oreilys sells as the replacement clutch kit for my truck, the previous owner of the truck installed it about a year ago. I believe it is a diaphram clutch, not sure what the alternative is. When i had it apart the last time, it all looked brand new and I torqued everything to recommended spec when i put it back together.

I'm going to take a look at things through the inspection cover and also try a drain and refill of the trans to make sure that fluid is still OK.
 
If it was mixed with oil it might be diluted. It holds a gallon or so if you drained it good that shouldn't be the problem. It may have worn out parts inside the trans depending on how long it was ran like that though. I'd change all the fluids if you Havnt already to Make sure you are running the correct fluid and nothing else is getting damaged. But it sounds like something in front of the trans. Not Inside. But sounds like to bounce around inside the cab.
 
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