Whining transmission

[ProJect]

Hey fam!

 

My 510 has a dogleg 5spd from an old sx, but i think the issue is just a general tranny issue, so hopefully im not in the wrong to post here.

 

When i get to the 3rd gear, i start getting a whining sound coming from my tranny. It only whines when the clutch is out and the gas is in, starting around 3500rpm. It whines on gear 4 & 5, too, but the whine starts at a lower rpm on 4 and even lower on 5. It turns into sounding like a sander or something rubbing on a belt at higher speeds. The threshold rpms lower on downhills and increase uphills. At the bottom of the rpm range at higher speeds, the sound will "bounce on" like wii-wii-wiiiiiiiii... and then increase in pitch as the rpms go up. Eventually it hits like some resonance where it's really high pitched, more like a metallic singing and barely audible. Like a whistle almost.

 

Initially i thought it was the pilot bearing, but I've watched a bunch of pilot bearing noise youtubes and mine is way different, not crunchy or grindy. More of a high speed rub.

 

Any thoughts? 

Edited July 19, 2019 by ProJect
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[wayno]

I dislike dogleg 5spds because I went thru 4 of them in 5 years in my 521, but I use my 521 as a work truck and they are not made for trucks or to be in 5th gears for long periods of time.

I wrote this article for all those out there on how to make a short shaft 5spd for their 521 like I did, I suspect it will bolt right into your 510 also, You do have an L block, correct?

 

Edited July 19, 2019 by wayno

[ProJect]

Yes, L20B.

 

So are they just worn gears then? It doesn't have any issues shifting and it seems to have great torque. The only identifiable issue is the noise.

 

I've heard the same thing about dog legs having issues, but not about the 5th gear.  I figure an SX would be made with commuters in mind. Either way, I'm not trying to replace this one because sadly it's time for me and this 510 to part soon. I have an 82 720 D that takes priority and is a more sensical vehicle for my life right now(and of course i need the money).

 

Any thoughts on how to at least get it to quiet down? Maybe swap the tranny fluid for something thicker?

[datzenmike]

2 hours ago, ProJect said:

 

 

 

Initially i thought it was the pilot bearing, but I've watched a bunch of pilot bearing noise youtubes and mine is way different, not crunchy or grindy. More of a high speed rub.

 

Any thoughts? 

 

 

You said when the clutch pedal is up and you are driving. If you think about it, if the clutch is engaged the engine and transmission are locked together and the end of the transmission input shaft is not spinning inside the pilot bushing. You could only have pilot bushing noise if the engine is running with the clutch disengaged. 

 

There's not much you can do to a transmission from outside. But one thing is to check the oil level. The plug is about half way up the left (driver's) side. Remove the fill plug and dip your pinky in the hole. If full, it will be at the bottom of the hole and easily touched. I have 2 feet of old garden hose and a dollar store kitchen funnel jammed in the end. Shove down past the brake master and into the transmission and fill from the engine compartment. When oil spills out, you're full. If you are low you have to wonder where it went. Is the front of the driveshaft wet? Rear oil seal. Is the front bottom where it mates to the engine wet? Front seal in the cover plate.

 

Not good to run a transmission out of oil, if you did. Filling it may cushion the bearings and reduce the noise. But if the damage is done... it's not going away.

[wayno]

5th gear is the worst gear in a dogleg, I was told a long time ago if your going to haul weight or tow on the freeway use 4th gear, this is especially true on the dog leg 5spd.

Maybe you can find a 4spd to sell it, they are cheap as everyone wants 5spds.