GTA 3 speed auto, slight whine- normal?

[purtypitcher]

Wondering about a faint whine in my transmission, or maybe it's the differential. Would appreciate input.

'87 full camper, Subaru 2.5, auto 3 speed, Peloquin diff. All have less than 30,000 miles since rebuilt. All were installed by Small Car in Tacoma. Small Car rebuilt the engine, and the trans/diff were rebuilt by German Transaxle. All this was done by the previous owner. I've put a little over 5000 miles on since purchasing this summer.

I posted about a month ago that the auto trans dumped all its fluid due to a hose coming loose from the external cooler. I was on a trip in the Smoky Mountains. The shop I had it towed to tightened everything up and refilled the trans fluid, but I don't know what kind of fluid they used.

I called GTA last week because the PO had given me some maintenance specs and I wanted to confirm about the trans fluid. They confirmed it should be BG full synthetic part #312. But as we chatted I mentioned there is a faint whine coming from the transmission. Small Car had previously told me it was typical for this drivetrain they had installed. The PO said it had always had the whine since day 1 after the rebuild and it had never changed or gotten worse. But the phone receptionist at GTA was concerned. She said if very specific break-in procedures were not followed it could lead to premature failure. I don't know if the procedures were followed.

You hear the whine under very light throttle. No whine while coasting, and only the faintest of whine under "average" throttle. But a very light tap on the gas after coasting is when you most hear it. Sounds like someone is way off in the distance playing a trumpet note. It changes pitch with speed of the van. It's most prevalent in 3rd gear after about 30 mph. Once you hit a little over 50-55 you hardly hear it due to road/wind noise. I plan to swap out the trans fluid for the GTA required BG 312. I also want to swap the diff oil for the GTA required BG Ultraguard GL-5, because I am not sure what is in there now, and GTA says all the fluids need changed at 30,000 mile intervals anyway.

I have checked the trans fluid dipstick while warm and in Park and the level looks good. GTA did put in taller final drive gears- 3.72 vs stock 4.09, their website says this is something fairly new for them. (They did it for this van during their rebuild four years ago.)

Should I be concerned?
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First VW! '87 Westfalia camper, Subaru 2.5, 3 speed auto, Peloquin

[MarkWard]

Automatics by their nature are pretty quiet. Based on your description, it sounds more like a ring and pinion mesh issue. It’s something you can check with the transaxle installed.

You’d be dropping the differential pan and doing a visual inspection of the teeth looking at the wear pattern first. Then you’d check the backlash with a dial indicator. Last you’d using some marking paste to see the actual tooth pattern.

Lots of you tube videos about setting up ring and pinions. It’s similar across on differentials.

If you find the backlash is out of spec, I’d caution against tightening it up if you find it loose.

Also, when ring and pinions are setup, you are basically trying to hit the quiet spot. You could miss the sweet spot and the ring and pinion would be fine. So, fresh fluid and drive it. Maybe a higher viscosity lube than stock. 140WT? See if the noise changes.

[purtypitcher]

[SoquelDude]

[MarkWard]

You could bypass the cooler with a short loop of hose. Without me taking notes of what and when, the most efficient way to change the gear oil if it was not performed after break in, is to drop the pan. If I had an automatic, I’d weld in drain bungs for both pans.

So, if you are unsure if the break in oil was removed, best to do it now. Take a picture of the teeth on the ring gear. Try to get both the front and back of a tooth and post it up. Use the lubricant the builder recommends. I have to wonder if the warranty is transferable and what the mileage is.

If you aren’t comfortable, you’ll need to find a local shop to do the investigation and worse case they would remove it and ship to the builder.

As I said earlier, if the builder missed the sweet pinion depth, but got the bearing preloads and backlash correct, it could hum along for miles without incidence. If bearings are prematurely wearing for a number of reasons, they should get louder over time.

[purtypitcher]

[purtypitcher]

[MarkWard]

I have a square cut 4th gear. It whines enough my wife can hear it. After a long day at highway speeds, our ears are ringing. It’s more obvious at slower speeds. At highway speeds the other noises mask it from being audible, but it still affects our hearing.

I mention this, only because we have thousands of miles on it. Since this is an aftermarket gear to solve another weakness in the 4 speed, it doesn’t mentally bother us. It seems if something was wrong with yours, it would be a problem by now.

Changing both fluids would give you an idea if something is prematurely wearing and give you fresh lubricants.

[purtypitcher]

[MarkWard]

The quietness actually comes from proper pinion depth. After the depth is set, you adjust backlash.

I said early on, I wouldn’t recommend resetting backlash on gears that have mileage on them. It could actually create a problem.

That said, backlash is something that can be checked. If it is out of spec, you have some information you don’t have. Same is true of changing the pinion depth after the fact and does require some disassembly to measure and swap in shims. Changing the depth after the gears have bedded in could be worse.

So, if your tech doesn’t have a dial indicator, you could probably by a Chinese one with a magnetic base for them. Not to change it but measure only. A picture or 2 of both sides of the ring gear teeth post them up and we might have some
comments.

But not to sound repetitive. You only want the visuals. Don’t attempt to change anything till you report back.