[goatless]

Was just out banging around town in my '79 TA- thinking about taking it out to Norwalk next week. Everything seems fine as I blast through the gears... until I tun back onto my street. I down shift into second to go up a gentle hill and holy crap is it making a loud whine! Down shift to first and its fine, up to third and it's fine. I went back out to confirm and the symptoms are pretty consistent. It shifts fine and no grinding, but just a loud whine and only in second.
Any ideas?

[Rocky Rotella]

Generally speaking, a whine occurs when the angular mesh (helix) of two gears under load (whether acceleration, deceleration, or both) isn’t ideal for the gear type. If the transmission didn’t whine before your drive, and it whines now, that’s a strong indication that something has occurred inside that changed the gear mesh.

It’s possible you may have broken a thrust bearing or snap ring but I’d suspect that wouldn't be limited to second gear only. Based on a similar experience I had with my ST-10, I had a whine and vibration when the second speed gear on the main shaft and/or cluster had fractured one or more teeth. I pressed on and ended up breaking several teeth on the speed gear and cluster driving it hard one day. The fracture would have been easy to deal with but when the gear let go, it caused collateral damage to neighboring speed gears, which meant having to replace them too (read: more money!)

Before expecting the worst, is the whine present all the time? Or is it limited to accel or decel only? You might try replacing the gear lube just to be sure it hasn’t broken down and isn’t lubricating the gears properly.

[goatless]

The whine is present when the gear is under load, either accelerating or decelerating- it doesn't make noise when the speed is just right that I can coast with no load either way.

[goatless]

Is it possible that a poorly adjusted shifter linkage could be casing issue? I've been meaning to fine tune the linkage a bit. This current trans was a used unit thrown in quickly last fall to get me through an event at Lime Rock.

[Rocky Rotella]

Assuming that the whine is noticeably irregular, I’d still suspect that if the transmission is whining while in second gear now, but wasn’t before, then something disrupted the mesh between the second speed gear and/or its opposing gear on the cluster.

Since all forward speed gears are in constant mesh with the opposing gear on the cluster, the gears don’t actually slide during gear changes. When the shifter is moved during a gear change, the synchronizer sleeve slides on the synchro hub that’s keyed to the main shaft. That then presses the synchro ring against the synchro cone on the speed gear, which slows the assembly enough that the slider locks onto to the gear and transmits power flow from the cluster gear through the selected speed gear. The rest are along for the ride until called upon.

The shifter is responsible for moving the sliders during gear changes, so improper shift rod adjustment, especially if it occurred after banging the gears, could prevent the synchro slider from being positively seated on the hub, whether too far or not far enough. I’m not totally sure that’s enough to make the transmission whine in a given gear, but if the synchro actually changes the way the gear is being loaded, then it’s certainly possible.

I’d try all the simple stuff first. Shifter adjustment and heavier weight gear oil is relatively easy to do and won’t cost too much. I’d recommend an 85W-140 lube as opposed to a 75W-90 lube that the factory called for. The heavier weight lube will cling to the gears better and may provide more “cushion” as the teeth mesh, potentially quieting it down. I’d recommend a conventional lube as opposed to a synthetic, and look for one that doesn’t have friction modifier already added.

[STEELCITYFIREBIRD]

I'd check your shifter linkage for slop, corrosion or lack of lube, (missing bushings, worn/bent external shift rods, loose adjusters) definitely check shifter alignment and opreation, looking carefully that 2nd gear is engaging completely.

Second would be gear damage, weather it be a chipped of rusted gear from sitting.

I'm leaning on a shifter problem, incomplete engagement.

Be sure this is a trans problem and not an rpm related issue, driveshaft or differential.

HTH

[HWYSTR455]

Second gear gets the most beating, and generally does seem to wear quicker than the others.

I agree, simple stuff first, heavier lube, check shift adjustment/slop. But as Rocky pointed out, it's kind of in gear or not.

Also would agree that it would more likely be the gear itself, or the 'cluster', or countershaft cluster to not shorten the name. The cluster and mainshaft bearings also can create an other than desirable mesh.

If you've never gone through it, then it may be that time. Disassemble, inspect, and replace all that is in question. If it doesn't already have it, upgrade to an iron mid plate and fork cover, it adds to eliminate deflection.

Does it leak at all? That could mean the main case is worn where the counter shaft meets the case. You can bandaid it, but the best thing to do is replace the case. That is also an opportunity to upgrade. Don't forget to check the mainshaft for straightness too.

Those transmissions were borderline even with the 220hp engines IMO, and are beaten hard over the years. Once you go through it, you will be surprised how nice they can work/shift. With all the upgrades, mid plate, side plate, front retainer, and fresh parts, the are easily good for a while with up to around 400hp.

.

[HWYSTR455]

SK Speed is in Lindenhurst, NY, they are 4 speed subject matter experts, call them for advice, and order parts from them, best prices you will find anywhere anyway.

https://www.skspeed.com/

If you call them, talk to Brian, and he can tell you what symptoms require what parts. They can even do rebuilds for you if you don't want to dive into it.

Rocky, you've dealt with Brian before yes?

.

[Rocky Rotella]

Originally Posted by HWYSTR455

Rocky, you've dealt with Brian before yes?

Yep, he's a great guy and extremely knowledgeable! I go to him when I'm stumped.

[goatless]

If I have to much more than simple stuff, or maybe even a low budget swap for another used unit, I'll probably go for an upgrade to a 5 speed. Been thinking about the McLeod Musclecar 5 speed for a while.

[track73]

I had a terrible whine in all gears except 4th . I was told the input and cluster where worn and to I purchase new ones. I did and and more whine. I suspect your second speed gear is worn. and maybe the cluster too.

[cdrookie]

I'd take it out and inspect it. Many years ago I made a left turn from a traffic light and the car made a weird sound. Luckily I was only going less than a quarter mile to a buddies house. Turns out that "weird sound" was the case cracking in several places. Upon tear down, it must have had a chipped tooth that floated around and was precisely in the right place to lay between gears that were in the process if messing together. I don't remember if it made noise before that happened or not, but if you have a chipped tooth the results could be catostrauphic.

[TAQuest]

The sound starting tells you the gears moved. Either bad bearings or a cracked case.

[goatless]

Update.

Finally got around to checking out the basics yesterday. Had it up on the lift to check out the linkage adjustments. 1st thing I found- reverse arm was loose! Fixed that and learned the proper way to get the shifter linkage adjusted properly.
Topped off the fluid, which was on the low side. Took her out for a test drive and everything is good.

[Sirrotica]

Jeremy FWIW, The roller bearings (cluster gear, and main shaft) in the ST10s are very prone to premature wear. Back in the 70s when they came in Firebirds and camaros I replaced a bunch of them in transmissions that whined. The chevy dealer in town stocked new needle bearing kits because it was a frequently needed part. In all the ones I had done they usually whined in every gear, not just second.

If yours are good after refilling the trans with lube and tightening up the linkage that's great. Just wanted to note that they do become worn in under 50,000 miles and it was a common complaint back in the day when they were everyday drivers.

[goatless]

Yeah, what was confusing me was that it was only 2nd gear that suddenly got noisy. Everything I've read talked about whine in 1st, 2nd and 3rd and then goes away in 4th. I've got to assume that the reverse lever being out of place was a contributing factor to the noise.