noisy transmission


The old and reliable.

Golden Jubilee
Golden Jubilee

Posts: 341

Joined: Sun Nov 15, 2015 8:16 am

Post Mon Jun 03, 2019 5:19 pm

noisy transmission

The KB1 is back on the road and I forgot how loud the transmission is. Far and away the loudest I can remember. I had a 49 Dodge with a floor shift. I don’t remember it as overly noisy. On the KB 1st gear is a little loud but not bad, 2nd a bit louder and 3rd the loudest. It’s three-on-the tree. Wines like a rear end but not as heavy. I know these are farm trucks and are probably driven at slow speeds. We run it along between 40/50 mph. Running 140 gear oil.

Love the uniqueness of the truck and am hoping the loud tranny is common. What say you IH Gurus?

Golden Jubilee
Golden Jubilee

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Joined: Thu Nov 29, 2012 9:28 pm

Location: Lyman, IA

Post Mon Jun 03, 2019 5:30 pm

Re: noisy transmission

Bet it is your rear end and not the trans. A three speed will be quietest in third as the power goes straight thru from the input to the output shaft and none of the gears or shafts are sideloaded in 3rd.
Does the noise change or come and go, power on, coast, power off?
Could also be a carrier bearing if the truck has one.

Golden Jubilee
Golden Jubilee

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Joined: Thu Dec 27, 2012 12:45 pm

Location: Canada's left Coast

Post Mon Jun 03, 2019 6:35 pm

Re: noisy transmission

Those old straight cut gear transmissions are noisy. Old IHC pickups did not have any sound insulation. An automatic transmission is surprisingly noisy. Allison 545 and the GM TH475 make lots of gear noise as a loud whine There are two ways to hide the gear noise. 1) a radio. 2) ear protection and 3) insulation.
Lloyd taught me to count. Disposable foam ear plugs are the best "bang" for the money.
Gale Banks, the turbocharger guy, suggests it is important to stay with the recommended viscosity and fill volume. I do not know what viscosity is recommended for your truck. An-overfill and higher heavier viscosity adds to the parasitic loss in power and heating of the oil.
I would rather have tools I do not need than to need tools I do not have
“Never argue with stupid people, they will drag you down to their level and then beat you with experience.
Mark Twain

Golden Jubilee
Golden Jubilee

Posts: 341

Joined: Sun Nov 15, 2015 8:16 am

Post Wed Jun 05, 2019 9:33 am

Re: noisy transmission

Thanks. Food for thought. I will take it out tomorrow and try coasting in neutral and then on and off the gas? I don’t think it sounds as heavy as rear end gears. I am ruling nothing out while I search.

I rebuilt a Ford rear end and replacing the 308 gears ( I think ) with 373’s. I did the work myself and was a first time and am hoping I did it right. I followed a rebuild video of the Ford differential. I insured the ring to pinion contact was per video using yellow gear paint and that the bearings had proper shims and loads. Used a new crush washer, and also installed new axle bearings and seals. New brake shoes and drums were also installed.

I’m not ruling a bad rebuild but of course I’m hoping for better of my endeavors. In my KB1 transmission the gears are helical cut so I assume should be quiet.

I’ll repost after some more research .
Last edited by Bobby K1 on Fri Sep 06, 2019 8:09 am, edited 1 time in total.

Golden Jubilee
Golden Jubilee

Posts: 4596

Joined: Thu Nov 29, 2012 9:28 pm

Location: Lyman, IA

Post Wed Jun 05, 2019 9:52 am

Re: noisy transmission

My reason for suspecting the rear end is that you say it is noisiest in 3rd when NONE of the gearing is loaded, and the bearings and shafts only carry minimum load.
Most noisy in 2nd and I would suspect a pocket bearing or bushing between the main and input shaft, Most noise in 1st/reverse and countershaft bearing would be suspect.
Noisy in 1st and 2nd but quiet in 3rd and I would say either countershaft or main shaft bearings.
Noise changes when the clutch pedal is depressed, and I would suspect throw-out bearing. Noise when stopped in gear and pilot bearing is suspect.
A note on setting up Hypoid gearing. If you want the strongest configuration just set for best contact pattern and let it howl, but if you want quiet you have to match the setting etched on the gears at manufacture for quietest running. 90 deg gearset are still select fitted to each other and run on a fixture to determine the quietest configuration.
If replacing a known good configuration without the special tools, you can take the shim packs and settings from the old gearset to work backwards to find the baseline, then adjust the shim pack to the new gearset requirements.
Edit: are you saying this vehicle has a Ford rear end you re-ratioed? If so I would say you got the settings wrong for quietest running.

Golden Jubilee
Golden Jubilee

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Joined: Thu Nov 29, 2012 9:28 pm

Location: Lyman, IA

Post Wed Jun 05, 2019 10:27 am

Re: noisy transmission

It should be noted that "rebuilding" and "Re ratioing" are two different operations. If just replacing bearings and seals, then you can go back with the same shims in the same places and almost always will be correct.
If changing gear sets, the shim pack will almost never be the same between gear sets, and will require different packs for the new set.

Golden Jubilee
Golden Jubilee

Posts: 341

Joined: Sun Nov 15, 2015 8:16 am

Post Wed Jun 05, 2019 12:02 pm

Re: noisy transmission

Thanks CB. If I remember correctly I did refit new shims adding and removing until the pattern was correct or what I thought to be correct. In your opinion what is the best way to differentiate rear end noise from transmission noise ? Most of the time I am by myself but if necessary I can find an old car guy to do a ride around with me. If my search is unsuccessful maybe I can video it with our iPad and email it to you.

While thinking on this matter I have experienced some shuddering on a quick start on a corner which I thought to be rear wheel hop with weak leaf springs. I’m still running the large pattern mud/snow tires. Hmmmm more to think about.

Appreciate all your input

BK

Golden Jubilee
Golden Jubilee

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Joined: Thu Nov 29, 2012 9:28 pm

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Post Wed Jun 05, 2019 1:16 pm

Re: noisy transmission

You need to shim in two directions, The pinion depth is shimmed behind the rear pinion bearing, the backlash is shimmed by the carrier bearings and the tooth contact is a combination of both the pinion depth and carrier shims.
The old and new gear sets should have a + or - plus a number. This is the pinion depth setting from the std 0 setting as determined by the gear hobber. You can either use the special tools to determine the baseline setting or you can work backwards from the old gear set. If the old gear set was marked +.005 and had a .003 shim behind the pinion bearing, you know the housing baseline is +.008, A + number means the pinion is moved away from the ring gear center line (less pinion depth) and - number means the pinion is deeper in. So with the old pinion, with no shim, it would be at +.008, with .003 added behind the pinion bearing, you move the pinion in to +.005. If the new set is marked - 004, you would need a .012 shim. So a baseline of +.008 and a desired setting of -004 means you need to add .012 behind the bearing. Adding shims reduces the total number, moving the pinion in, Then you can set the backlash and check the tooth pattern. If the depth is set correct, and the backlash is in spec, the tooth pattern should be ok.
Ford makes a pinion depth gauge tool for the 8.8 T79P-4020A if the original baseline setting is not known.
90 deg gearset are one of those things that if you change one thing, it effects everything else.
When you change to a faster ratio, the pinion gear is bigger so the ring gear has to move to one side more. Sometimes this can be accomplished by shims alone, sometimes by how thick the ring gear is made and sometime it requires a different carrier, and with big changes is ratios it can require all three, other times is can be a combination of two.

Golden Jubilee
Golden Jubilee

Posts: 341

Joined: Sun Nov 15, 2015 8:16 am

Post Fri Jun 07, 2019 12:42 pm

Re: noisy transmission

OK. Yesterday I removed the differential cover to install a new one as the old one was pretty rusted .
This gave me an opportunity to examine the gears. I did not paint the ring to check the pattern but there was no silver dust and all the mating surfaces looked good.

Transmission ; at idle= with clutch pedal depressed quiet
“. “. Clutch pedal out can definitely hear the transmission rotation
While driving; starting off in first gear hear engine as expected, very little Sound from transmission
Shifting into second a definite louder rotation noise (not grinding)
Third gear continues with the same (maybe a bit louder).
Foot off the gas = louder (similar to rear end). Maybe it is but I think not.
Front shaft bearing ? Pilot bearing?
Next step is to crawl under with my stethoscope and see if I can zero in.

If I can get through the summer I plan on pulling the transmission.if nothing else I will be able find any slop .

Golden Jubilee
Golden Jubilee

Posts: 4596

Joined: Thu Nov 29, 2012 9:28 pm

Location: Lyman, IA

Post Fri Jun 07, 2019 2:52 pm

Re: noisy transmission

Without being there to hear the noise, I can only guess and make assumptions based on what you report. Main and input bearing on the trans are a possibility but because noise doesn't seam to slacken when the shafts are lightly loaded from when they are heavily loaded (3rd gear vs. 2nd gear) I tend not to think they are the problem. Less noisy in 1st vs. 2nd says the same for countershaft bearings.

I wouldn't expect "dust or particles" in the rear unless it is so badly assembled that it self destructing. That doesn't mean however that it was set to where it runs the quietest. As I said before, if all you care about is the strongest build, assemble for ideal tooth contact pattern and let it howl. This is what most racers do as they can't hear the noise over everything else.
You can have good tooth pattern and noise at the same time, when any two 90 deg gear sets are paired, there is one point where they will run the quietest. the gear mfg finds this point and etches the setting on the gears, and pairs them for life. It is why you can't just replace one gear (either the ring or pinion) in a set, you must replace them as a matched pair. The setting will be different on every set of gears.
If you want to cure the noise, do it now before the gears have many miles on them. They WILL develop a wear pattern, and once that happens it may be impossible to get rid of the noise even if re-set to the mfg setting at a later date.
Unless you "did the math" or used the special tooling to select the shim behind the rear pinion bearing, there is no way it can be set right. The chances it is correct on a guess, or with the shim from the old set is almost non existent.
This is from an old gray hair proctologist. I work at a trans shop and built many a stick, and all the rear ends, from little car units to massive tandem two speed in trucks.
Rear axle noise is telegraphed up the driveshaft and can seam like it is coming from the trans, when in fact it isn't.
If you never built a rear end before, it is hard to know what you don't know. Few people have the experience. I was lucky when I was a young "sprog" to be instructed in my 1st rear by a gray hair pushing 60. He made me do it by the book , with all the special tools, so I knew how and what I was doing and looking for.
As I said, I am not there, but my guess, based on what you are reporting, is while you have good tooth pattern, you don't have it set for quietest operation.
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