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+--- Thread: Excessive transmission noise in car. (/showthread.php?tid=2834)
Excessive transmission noise in car. - Roger - 23-05-2019
Since completing my renovation and driving the car for the first time I found it to be excessively noisy.
I jumped to the conclusion that it was rear axle/diff so dismantled and checked, all things looked good.
It was still the same noise so fitted new Cw & Pinion etc. All to no avail just the same sound.
An A7 friend accompanied me in the car recently and described the sound as being very “rough grating” but probably not the back axle. The sound is possibly transmitted into the body by the torque tube socket which may be too tight also very close to and possibly touching the bodywork. How tight should this be?
Transmission is Hardy Spicer and in good condition.
Where else could the cause of this annoying sound be originating from.
The car is 1933 RP box.
Roger
RE: Excessive transmission noise in car. - "Slack Alice" Simon - 23-05-2019
Fabric coupling hitting the handbrake?
RE: Excessive transmission noise in car. - Roger - 23-05-2019
Thanks for your reply.
No I fixed that one a while ago.
This is constant when driving less so on overrun, it happens in all gears, more noticeable the higher the speed. It sounds like a gearbox with no oil in it would (not that I ever have done).
Roger
RE: Excessive transmission noise in car. - Reckless Rat - 23-05-2019
A 33 Box should have a 4 speed crash box, which are usually pretty sturdy. Has it been fitted with a later synchromesh one as they are not... A crash box has a big nut on the forward end of the gearbox cover.
![[Image: Gearbox%202.jpg]](http://austin7club.org/Gearbox%202.jpg)
The lateer synchro boxes do suffer wear in the layshaft due to worn thrust washers. This could be the source of your noise.
RE: Excessive transmission noise in car. - Howard Wright - 23-05-2019
Hi Roger
I had a terrible grating noise on my 36 special which turned out to be the flywheel cover touching the starter ring gear. Also be aware that noise generated at one end of the car often appears to come from the other! (That from someone who is tone deaf and wears hearing aids!!!)
Cheers
Howard
RE: Excessive transmission noise in car. - Roger - 23-05-2019
The original box had lost it’s speedo drive gear so was replaced with a 4speed synchro box, not a good move then.
The sound is more from the rear of the car, but that may be very misleading.
I have not checked the gearbox, what is the most likely problem area?
Roger
RE: Excessive transmission noise in car. - Bob Culver - 23-05-2019
It is hard to imagine noise originating in the torque tube ball joints but these must move freely thru range or there is risk of breakage.Likely not be acheivable without a slight knock when drive reverses etc.
As you have observed the metal to metal contacts transfer noise.
Noise level is high but few other cars have the gearbox directly exposed in the cab!
RE: Excessive transmission noise in car. - Roger - 23-05-2019
Hi Howard,
It sounds more like a dry gear mesh noise. It’s very difficult to describe without miss Leading.
Roger
RE: Excessive transmission noise in car. - Reckless Rat - 23-05-2019
Is there actually any oil in the gearbox? the level should be 1/2" below the filler plug threads. SAE30 or 25W/50
RE: Excessive transmission noise in car. - Roger - 23-05-2019
Thanks Bob,
My thoughts are:-
1) Gearbox
2) transmission shaft
3) rear axle
As sources of the sound, travelling at say 30/35 mph it is very distracting but pleasant when foot is lifted off accelerator.
Roger
Yes, plenty of oil, just under filler plug..
And 140 in diff.
Roger