Transaxle Noises - Advice Needed

[Riff Raff]

Background:
I recently got my Mango up and running. It has a 67 big nut transaxle and a 1600. I got the transaxle locally and it was in unknown condition.
PPO resealed it, re booted it, did the brakes, and was going to install it in his bus, then sold the bus and transaxle to the guy I got the transaxle from.
I filled the RGB's with 80W 90(they were almost full) and the centre section, which was almost empty before test driving. No evidence of any leaks.
Initially I thought it was an RGB growl, but the noise is not a constant growl and seems to go from not bad to real bad for a while (15 seconds) and then not too bad again. The noise itself is difficult to describe, but sounds like bearings starting to go bad intermittently. No bad noises with just the engine running.
I had the bus out for a drive yesterday, part highway and part city, and when I got home, I shot the running gear with a temp gun. Engine oil was 90C, drivers RGB was 36C, passenger RGB was 31C, both axle tubes were 25C, but the centre section was 55C. Ambient was about 15C.
The centre section seemed far warmer than I thought it should have been, and it was that hot all the way from the bell housing to the nose cone.

Questions: Does the 5 C temp differential between the two RGB's suggest a bearing may be going bad on the warmer side?
Does a temp of 55C plus the varying noises suggest the centre section has serious problems?

Any other diagnoses I can do to try to narrow down the issue before I pull the transaxle?
Coast down a hill in neutral with engine off?
Drain all three sections and inspect the oil?
Thanks
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[slow36hp]

i would check the oil before any more driving also couldn't hurt to pull the drums and inspect the brakes make sure you dont have a spring off whick can make a horrid intermittent screeching sound
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[Campy]

If it were a "whining" sound, you might think that it was in the drive pinion but it is more of a growling sound?
The first thing that you should do is to drive the bus for a while, then return home and drain the gear oil from the transaxle. You need the oil to be warm so most of the contaminents will still be mixed up in the oil and will go out with the gear oil. After draining the oil, carefully look for specks of metal.
The center section had almost no gear oil in it then, without draining it, you added gear oil? You should have drained it, then checked the gear oil for contaminents; if you saw no contaminents, then put all new gear oil into the centersection. It makes me wonder if the transaxle were used when there was very little oil in the center section. If so, that would spell disaster for the bearings.
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[Riff Raff]

Thanks for the advice.
A couple further clarifications. The noise, at it's worst, sounds like a front wheel bearing gone bad - kind of a high pitched growl. Noises telegraph so much in the bus that it is hard to tell where the noise is coming from.
It goes from bad to not too bad and kinda oscillates.
I can't hear it at all in first, but I can in second, third and fourth.
Trans shifts smooth and doesn't pop out of gear
There were new boots on the axles and fresh gasket sealant on the nose cone, so I thought that the centre section had been drained to keep leakage at a minimum when doing those repairs - thats why I wasn't all that concerned about it. Perhaps I should have been.
When I first drove the bus after getting it roadworthy, there were no distressing sounds at all. That lasted about ten miles and then, all of a sudden, it started kinda growling.
I read as many threads as I could on transaxles going bad and thought it sounded like an RGB bearing, but I'm not so sure now.

I guess I'll run it around the block a couple times to stir up the oil and drain all three sections and see what I can see.
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The greatest obstacle to discovery is not ignorance, but the illusion of knowledge
- Daniel Boorstin

[Campy]

You need to determine if it is a bearing in a RGB or in the transmission (front main shaft and pinion shaft). Also, there is a large bearing for the ring gear in the differential. When you disassemble the RGBs, you can check out the bearings to see if there are any bad ones. If they are all good, then you know what your next step is...
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[Riff Raff]

I drained all the oil from the transaxle.
There are lots of brass specs in all three reservoirs, lots of brass specs.
In the centre section, the drain plug had a LOT of metal fur on it and a couple of metal chunks - about 1mm x 1mm x 3mm.

This doesn't look good for the centre section does it?
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[Campy]

There is a ball bearing on the pinion gear side of the pinion shaft and, on the pinion shaft and the drive shaft (front main shaft), there is a needle cage for each gear; fourth gear on each shaft has an inner race for each needle bearing.
If you coasted the bus and listened for a noise it would narrow it down as to what happened. If the noise only occurred when driving the bus, the ring gear and pinion gear adjustment is too tight and/or the pinion bearings are bad.
If it is noisy when driving and coasting the bus, the pinion bearings are bad, an axle shaft bearing could be bad, or the ring and pinion gears are bad. It could be all three. Did most of the crap come out of the transmission or the differential side of the case?
It is time to order a rebuilt center section. If you can, think about getting a 1967 center section. Remove the snap rings and remove the side gear and the thrust washer from each side for use on the rebuilt center section (if they are not too worn, especially on the inside where the fulcrum plates go, and there are no cracks). Re-use the fulcrum plates if they are in good shape.
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[quartermilecamel]

transaxle rebuild time. Drive it till you cant stand it, assuming you dont have the money to rebuild it now. Rebuild as soon as possable or just drive it. Ive now had 3 transaxles rebuilt. One from chirco to get the bus rolling initially in 1995, again in 1996 and again in 2008. Never let your transaxle fluid go low...period. A simple fluid check will keep your transaxle happy for a long time. The low fluid is what kept killing my transaxles due to a nose cone leak.
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[Campy]

If it were my bus, I wouldn't drive it. Remove that sucker and begin dismantling the RGBs, and check them and the axles out. If needed, you can re-build the RGBS while you wait to get a re-built center section.
Remember to always drain the gear oil out of a transaxle after you get it. If you had drained what oil was left in it, you would have seen the debris and known not to install it in the bus.
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[Riff Raff]

Thanks for the insight Campy.
Both the drain plugs from the trans and diff had lots of metal fur and metal chunks, although the biggest chunk was trans side. It also seemed that there were more brass flecks in the trans side, but I didn't do a thorough count of them.
It's looking like the RGB's are probably good and the entire problem is with the centre section.
It's nice to have a better idea as to where the problem is anyways.

I already can't stand the noise, so I won't be driving the bus until it's fixed.
Interestingly, I had the bus on jack stands and was running it in gear to see if I could hear where the noises were. Noises that were barely perceptable outside the bus were very noticable inside the bus. Seems to be lots of noise transmission through the mounts and then the whole bus amplifying the sound much like an acoustic guitar does.
_________________
The greatest obstacle to discovery is not ignorance, but the illusion of knowledge
- Daniel Boorstin

[Campy]

Make sure that you check out all of the bearings while the RGB cases are split. If the stub axles are 46mm, each inner case has the big plug on the inner side of the inner case half, which would have to be removed in order to examine the inner stub axle bearing. If you have rebuilt later model RGBs, then you know what it is. Maybe I missed it but are your RGBs big stub axle?
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[Riff Raff]

It's a 67 transaxle in the Mango, so it's a big nut.
I am leaning towards getting a Rancho centre section so i don't have to worry if the next used one I put in is going to crater on me as well. A bit higher geared R&P would be helpful as well, and that's easy to get with a rebuilt centre section.

Fortunately, a guy I'm friends with in town carries Rancho trans and has a shop with all the right pullers to do RGB's, so I've got some good fortune that way.
I've read a lot about the RGB's and the differences between the big and small nut boxes, but I've never had to dive into one.
Educating oneself on a subject is always a good thing, but nothing substitutes for getting in there and actually doing it!

Cover me - I'm going in.
_________________
The greatest obstacle to discovery is not ignorance, but the illusion of knowledge
- Daniel Boorstin

[Campy]

Yeah, I mentioned a 1967 center section, earlier (bigger bell housing).
Rancho Performance used to have complete rebuilt transaxles (with RGBs) for about $650 plus shipping. You never know what "skimping" they do at these transmission-rebuiding businesses, though, so I would always rebuild the RGBs, myself, to be sure that better quality bearings were used and all used bearings replaced, if there were any doubt; also, you can make sure that you install good axles (shovel end), side gears, axle tubes (dish end), and fulcrum plates. by doing it yourself. That way you will know that they are in good shape.
At some of these rebuild places, sometimes they will be low on used parts and use what they have left. It happened to me at Transform before the old fart, without telling me, retired. He knew that he was going to retire so he probably did not have many used parts left. The "freeway flyer" bus transaxle that I bought from him lasted all of six miles; fine specks of metal came out with the gear oil. Since he had retired and closed the transaxle side of the company, there was no warranty.
Finding a reputable transaxle-rebuilder that doesn't skimp is another story.
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[Dave24]

[ozark23]

my new to me 65 DC has some major trans whine.....here is an audio file of the noise in 3rd and 4th gear
Trying to figure out if it is RGB noise, throwoutbearing, or trans is done....shifts perfectly in all gears, no slips, no grinding....
give it a listen and let me know what you think

THX

Link

[Clara]

yup, it's in the trans---
If stepping on the clutch makes the whine goes away, that means it is not the throw out bearing. The TO bearing is in use when you step on the clutch.
(If the whine appears when you step on the clutch, it is the t o bearing.)

From what I understand it's a bad bearing in the tranny making that whine.

My advice is plan a rebuild.
If/ When the noise is too annoying to drive, get it re buildt.
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[ozark23]

[2Pack]

I had this happen recently, but mine was making more of a growling sound. Touching the clutch pedal lightly, not even enough to hit the friction point, caused the sound to go away. I read on the forums that indicates a main shaft (AKA input shaft) bearing going bad. The trans builder I used later said the same thing. Edit: if you are pushing the clutch all the way in to change the noise then it's probably something different.
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[BarryL]

It sounds like the pinion bearing to me. Is it the same noise giving it gas as letting off gas?

[ozark23]