Hello! I am new here and new to the autostick world!! I have a 69 that I am about to start a body off. Not a complete resto because I have different color schemes etc...Anyways, when I get between 45-50 mph and then stay the same speed there is a humming noise. It stops if I let off the gas or give it more gas. Does this sound like it is just low on gear oil? Help is appreciated. Thanks!!
Hello there!
What do the tires look like? Badly feathered/cupped/separating tires will cause a noise like the one described right about that speed. I would also check the tire pressures. Do not go off the tire pressure recommendations on the inside of the glove box door! These pressures are mostly for bias play tires that would get hot and increase in pressure and were for old style radials that were not very good. I personally recommend the rear tires be set to the max load pressure and the fronts about 2-3 psi under the max load pressure. Better tire wear, steering, gas mileage and handling will result. The ride will get slightly rougher but a slight compromise in my opinion.
Something else to check. Does it only produce the humming noise in gear while cruising that speed? If so, what gear: L, 1st, 2nd? Not sure?
Try this: Get up to speed to make the noise. While cruising at this speed, disengage the clutch by pushing down on the shifter and let off the gas. If the noise disappears, it is engine or drive train. If the noise is still there, then it is a tire, tranny differential carrier bearing or a wheel bearing. Another test: rev the engine and hold at the approximate rpm as if you were cruising an hearing the noise. If the noise is present, then it is engine or torque converter, but I would lean more to the engine. Old gear oil/low gear oil will also cause a humming noise because it has worn the bearings in the tranny.
A few things to check out. Post back with you results!
-Evan.
Thanks for the info. I have replaced the front wheel bearings recently because that was my first guess and I have no clue last time it was done. I reved up the engine to the approximately rpm and nothing but sweet german sounds. The tires are old but tread wear is fine. The noise happens in 2 and when I let off the gas it stops and when I give more gas it stops.
Hello again!
Sounds like the tranny internal bearings are worn, or the gear oil is low. Does it continue do it when you activate the clutch while it is making the noise?
-Evan.
No because once I let off the gas it then stops. I will be taking the body off pretty soon to start some work so I will check the gear oil and then take it for a ride to see if the noise is still there before I begin. Would it be better to replace the bearings or find a newer tranny?
Hello!
Well there are few choices. The noise you have sounds like it is coming from the input shaft bearings. This is somewhat normal as the transmission ages. If they are not too loud, change the gear oil and drive it. If it is sounding pretty bad, I would look for another tranny. You can send out your tranny for a rebuild, but I'm not sure where you can get your A/S tranny rebuilt where you are, where ever that is. I would take a look around for another goos used tranny and also post a wanted ad here on VWAR. I would look for a tranny that is from a bug built after August of 1970. An A/S tranny built after 8/70 will have the better 4.125:1 ring and pinion gears for lower freeway cruising RPM's. Pre 8/70 A/S tranny's like yours (and mine), will have the 4.375:1 ring and pinion gears. You can also look for an even later tranny that has a PARK position. I am not sure when they started that exactly. Someone else here on the forum can shed some light on that. I think it was late 1972 that it started. I know the 73/74 Supers had a PARK position. The choice is up to you. Were it me, I would at least try to find a 4.125:1 R&P tranny. I just purchased one for mine a few months ago. I will be doing the swap in mine as soon as some free time comes around!
Good Luck!
-Evan.
Thanks again for the info. I will definitely keep an eye on a newer tranny. As for right now it is not that big of a deal especially because I am taking it off the road for a couple months anyway. Thanks again.
Quote from: Sunday69 on 25 July 2009, 21:52
Hello! I am new here and new to the autostick world!! I have a 69 that I am about to start a body off. Not a complete resto because I have different color schemes etc...Anyways, when I get between 45-50 mph and then stay the same speed there is a humming noise. It stops if I let off the gas or give it more gas. Does this sound like it is just low on gear oil? Help is appreciated. Thanks!!
Hi
depends whether its a humming or a whine...
My original gearbox made such a racket that the radio could not be heard.
I put in a bottle of ProMar additive into the gearbox and the noise slowly went away..
anyway I did change gearboxes, and I have filled this one with Synthetic oil
and it does whine in drive 2... not loud but I can hear it with the radio off...
so, more Molydebneium disulfate to be added...
Hypoid gear oil must be used in the gearbox..
but if the gearbox isn't in use.. the oil attacks the zinc in the bronze bushes...
thats from memory.. but it does eat into the bushes if the gearbox is sitting around for a long time.
cheers
LEE
I'll look forward to seeing what sound mine makes after being sat since the late eighties.... ::)