Gearbox fault diagnosis
Discussion
The Toyota 5 speed gearbox (from the mk1 Celica & Starlet) in my Sprite has started making a noise and I'd appreciate some help with a diagnosis.
It started on the long run to Gaydon from Hampshire a few weeks back.
After a long (relatively) high speed run of about a 100 miles I pulled off the M40 and got a nasty whine as I changed into second at the end of the slip road.
The symptoms are as follows:
- Whirring whine from general bellhousing area when moving and stationary.
- Whine only present in Neutral, R, 1 & 2. I've driven very slowly in third and cannot detect any sign.
- Whine disappears when the clutch is depressed but only once it reaches the biting point.
I've checked the oil level and added some additive but it made no difference.
My thinking is it's either the release bearing or the input shaft bearings but I can't see why either wouldn't make a noise in the higher gears.
I don't know much about the internals of gearboxes, is there any chance that the lower gears are on a different shaft?
Either way I think I know what I'm doing over Christmas!
Your thoughts would be very much appreciated.
It started on the long run to Gaydon from Hampshire a few weeks back.
After a long (relatively) high speed run of about a 100 miles I pulled off the M40 and got a nasty whine as I changed into second at the end of the slip road.
The symptoms are as follows:
- Whirring whine from general bellhousing area when moving and stationary.
- Whine only present in Neutral, R, 1 & 2. I've driven very slowly in third and cannot detect any sign.
- Whine disappears when the clutch is depressed but only once it reaches the biting point.
I've checked the oil level and added some additive but it made no difference.
My thinking is it's either the release bearing or the input shaft bearings but I can't see why either wouldn't make a noise in the higher gears.
I don't know much about the internals of gearboxes, is there any chance that the lower gears are on a different shaft?
Either way I think I know what I'm doing over Christmas!
Your thoughts would be very much appreciated.
Laygear bearing (1st gear end)?
First and Second will load up that end of the gear, 3rd is at the other end, 4th is straight through (no load) and 5th uses a different layshaft/gear?
I would have thought it was the release bearing myself but that makes a definitive noise. Laygear bearings don't really whine though, they make more of a gruff noise, but if the bearing has worn, it will cause the cogs to not run right and whine.
Pull the plug out and look for swarf. I'd have the box out if I were you, since you have to to check the release bearing anyway.
First and Second will load up that end of the gear, 3rd is at the other end, 4th is straight through (no load) and 5th uses a different layshaft/gear?
I would have thought it was the release bearing myself but that makes a definitive noise. Laygear bearings don't really whine though, they make more of a gruff noise, but if the bearing has worn, it will cause the cogs to not run right and whine.
Pull the plug out and look for swarf. I'd have the box out if I were you, since you have to to check the release bearing anyway.
love machine said:
I would have thought it was the release bearing myself but that makes a definitive noise.
Shagged release bearings tend to scream when you press the clutch pedal down (ie. when the clutch is disengaged). When the clutch pedal isn't being depressed, the release bearing isn't spinning, so you can probably rule that one out. Ultimately, the only way to be sure what is causing the noise is to strip the gearbox and inspect the internal components - it could have several causes.Gassing Station | Engines & Drivetrain | Top of Page | What's New | My Stuff