Gear box noise and primary gear bearing fixation
Posted: Tue Jun 07, 2022 7:19 pm
I thought our little Singer could not surprise me with anything anymore and yet she did just last week!
Only two weeks ago Johan and his wife Annejuuk drove her from the Netherlands to our holiday house in Umbria (Italy) crossing the Alps and several mountain passes amongst which the famous Stelvio pass. This trip of over 1700km she completed without any complaints other than a little strange noise coming apparently from the gearbox and the occasional popping out of third gear when going downhill on engine breaking.
Last week my wife and I did some amazing trips thru the Umbrian hills covering at least another 400km. During these trips the noise from the gearbox got worse to a point that it made me worry a bit as also the popping out of gear got worse. I decided to pull the gearbox out for a quick check. Upon dismantling I noticed that the primary gear bearing had been turning in its housing as it had a very shinny outer ring. The bearing itself was not in a too bad condition but also not perfect so I decided to replace the bearing (We always carry our p2p spare and tool kit with us so I had a spare at hand). During reassembly I noted that the amount that this bearing protrudes out of the gearbox housing is less than the depth of inprint in the bellhousing. As a result of this the primary gear assembly can move back and forward about half of a mm (about 0,04 of an inch!) This seems way too much for me I would even expect that the bellhousing would press this bearing with a certain load into to gearbox casing to keep it from spinning in the housing.
My question is: should there be any shims mounted at the bellhouse side of this bearing or sort of a spring plate, like I now is used on Riley gearboxes of the same era, to give this bearing a certain pre load and keep it steady in the gearbox housing?
For now I made up three shims out of a tin can (these are 0,25mm thick) so the bellhouse is pushing the bearing in its place. (I came up with this number as I know that 0,3mm is used on several bearings inside a classic mini’s gearbox as e pre-load.
After having everything assembled again we took her for a spin again only to find out that it did not cure our problem, the noise is still there and she still pops out of gear during descends (on steep down hills >10%).
At this moment I think that the two problems are related and are caused by too much play in the bronze bush bearing inside the first motion shaft as well as too much play in the bronze bearing inside the crankshaft. (I know the first one can cause popping out of gear during descends)
The rattling noise starts at 50km/hr (31 ml/hr?) when cruising at a steady speed on a flat road. At higher steady speeds the noise gets worse and the frequency rises with the rpm. When lifting the throttle the noise completely disappears. During acceleration above 50km/hr the noise is still there but only at higher speeds and way less apparent. When driving in third gear at a steady speed the noise also starts at 50km/hr but has a higher frequency.
My second question is: is there anything else that I should be looking at that could cause the rattling noise?
Sorry for the lengthy text
With kind regards,
Will van Gemert
Only two weeks ago Johan and his wife Annejuuk drove her from the Netherlands to our holiday house in Umbria (Italy) crossing the Alps and several mountain passes amongst which the famous Stelvio pass. This trip of over 1700km she completed without any complaints other than a little strange noise coming apparently from the gearbox and the occasional popping out of third gear when going downhill on engine breaking.
Last week my wife and I did some amazing trips thru the Umbrian hills covering at least another 400km. During these trips the noise from the gearbox got worse to a point that it made me worry a bit as also the popping out of gear got worse. I decided to pull the gearbox out for a quick check. Upon dismantling I noticed that the primary gear bearing had been turning in its housing as it had a very shinny outer ring. The bearing itself was not in a too bad condition but also not perfect so I decided to replace the bearing (We always carry our p2p spare and tool kit with us so I had a spare at hand). During reassembly I noted that the amount that this bearing protrudes out of the gearbox housing is less than the depth of inprint in the bellhousing. As a result of this the primary gear assembly can move back and forward about half of a mm (about 0,04 of an inch!) This seems way too much for me I would even expect that the bellhousing would press this bearing with a certain load into to gearbox casing to keep it from spinning in the housing.
My question is: should there be any shims mounted at the bellhouse side of this bearing or sort of a spring plate, like I now is used on Riley gearboxes of the same era, to give this bearing a certain pre load and keep it steady in the gearbox housing?
For now I made up three shims out of a tin can (these are 0,25mm thick) so the bellhouse is pushing the bearing in its place. (I came up with this number as I know that 0,3mm is used on several bearings inside a classic mini’s gearbox as e pre-load.
After having everything assembled again we took her for a spin again only to find out that it did not cure our problem, the noise is still there and she still pops out of gear during descends (on steep down hills >10%).
At this moment I think that the two problems are related and are caused by too much play in the bronze bush bearing inside the first motion shaft as well as too much play in the bronze bearing inside the crankshaft. (I know the first one can cause popping out of gear during descends)
The rattling noise starts at 50km/hr (31 ml/hr?) when cruising at a steady speed on a flat road. At higher steady speeds the noise gets worse and the frequency rises with the rpm. When lifting the throttle the noise completely disappears. During acceleration above 50km/hr the noise is still there but only at higher speeds and way less apparent. When driving in third gear at a steady speed the noise also starts at 50km/hr but has a higher frequency.
My second question is: is there anything else that I should be looking at that could cause the rattling noise?
Sorry for the lengthy text
With kind regards,
Will van Gemert