Gearbox Vibration

[HQentity]

Hello all!

Driving along today, I had quite a bit of vibration coming from the gearbox. When I slowed down, I could hear something as it spun, about 3-4 revolutions for each wheel turn in 1st. Theres no noise in neutral. The gears change fine and smooth, the vibration is linked to the engine in some way I think. When I use the clutch, it feels quite...grainy? Also when I put the clutch down, the gearstick still vibrates a lot now, like if it was still in gear? Thoughts?

[tony g]

First thing Id check is the gearbox to engine bolts are all still tight. Just go round and nip up the ones easily reachable. Other than that it could be clutch or release bearing on its way out or worse the gearbox itself. Any strange noises in reverse?

Tony

[HQentity]

That was the first thing I checked funnily enough (maybe I really am learning something from this! ), they looked finger tight across the top at least; I will have the time to properly check them tomorrow. When the engine was out in April, the release bearing felt great, along with the clutch and flywheel faces being good. Reverse is good, sometimes tricky to get into, and requiring the car to roll forward an inch or two. Really hope the gearbox is alright! The previous owner said be had it refurbished (maybe 4-5 years ago?!).

[Galileo]

Any change when coasting, foot down on the clutch? You can usually rule in/out the drivetrain or identify the area at fault i.e. prop shaft universal joint or gearbox bearing by getting up to 30mph say, and then see what changes occur when coasting in or out of different (forward) gears.

[MIG Wielder]

Hello all!

Driving along today, I had quite a bit of vibration coming from the gearbox. When I slowed down, I could hear something as it spun, about 3-4 revolutions for each wheel turn in 1st. Theres no noise in neutral.

Hi Kyle, Interesting problem. Its curious the noise is 3 - 4 times per wheel revolution. The diff; ratio is 3.63 therefore I'd be looking at propshaft and rubber doughnut. That sort of area.
Can you get some grease from a grease gun into the U.J.'s and the sliding joint at the front of the prop; just as a try-out ?
Is yours an overdrive gearbox ? I can't remember.
Probably not gearbox lay-shaft bearings though which is good news.
Worth looking at the front engine mounts as well since they are very visible. And the rear gearbox mount.
Tony.

[HQentity]

Thanks all.

Coasting with foot down on the clutch, the vibration in the gearstick is the only thing any different. Everything else runs normally with no vibration. It seems to be worst in low gears. Nothing happens in neutral pushing the car at all.

Tony - I did think that, I knew there was a 3.63 ratio for something! I will try the grease; I don't have overdrive. Will check everything tomorrow weather permitting.

[HQentity]

I've had a look at everything this morning, the gearbox mounting bolts needed tightening, but otherwise everything (mounts etc) were solid as a rock. The gearbox is full of oil. I haven't got a grease gun for the UJ's, however they were both replaced last year. Still a little squeaking when I disengage the clutch though now, which is what turns into buzzing and vibration at higher speeds. Very strange, hoping it's not engine out for gearbox access?!

[MIG Wielder]

Hi Kyle, Sounds like you've made progress anyway. If you do need to do a clutch on the Dolomite it can all be done from inside the car. The parcel shelf has to come out, the transmission tunnel has to be removed and the passenger seat, but there it all is in front of you. The propshaft bolts are all accessible as are the bell-housing bolts. Its one feature that Triumph were always good at, going back to the Herald and Vitesse.
So you can sit there in the dry ( its raining right now ) and do it all from the inside.
1850 is O.K. I seem to remember the Sprint needs the back of the sub-frame lowering
If you do want to lift the engine let me know and I'll see what I can do about the engine crane.
Tony.

[James467]

Give me a shout if you need the engine crane Kyle and Tony.

[HQentity]

Thanks again everyone as always for all the wonderful support! My biggest concern really right now is to find the problem, but if you think I need to access the gearbox from inside the car, that's definitely something I can start! I have 2 weeks off from today (talk about timing!) So would love to get it all sorted before I go back to work! I will take her for a test drive tomorrow I think, and see if theres still problems.

[HQentity]

Still rattling along this morning. It sounds occasionally like something's loose somewhere, like when you drive over a pebble and it flicks up? If you remove the transmission tunnel, can you remove the top of the gearbox and see what's going on?

[Carledo]

Still rattling along this morning. It sounds occasionally like something's loose somewhere, like when you drive over a pebble and it flicks up? If you remove the transmission tunnel, can you remove the top of the gearbox and see what's going on?

Yes you can! And what you are looking for, IMO, is chipped or broken teeth on gears.

Steve

[MIG Wielder]

Do you have the early 3-rail gearbox ? If so there is a nylon bearing at the base of the gearlever. Mine broke up on my early 1850 years ago and you could select reverse instead of first If it is wearing, the gearlever itself will feel quite floppy and loose during changes.
The important thing as Douglas Adams would say is "Don't Panic "
How about giving A.H. Motors in Dorking a ring and getting them to have a look-see. There specialism is Stags, but Dolomites have a lot of similar parts. They would certainly be able to get grease in the U.J.s and into the front sliding section to see what difference it made.
Yes, the gearbox top-cover with selectors can be removed with the transmission tunnel out but its a fiddle. I remember removing mine for some reason and the front plate dropped into the depths of the box. I had to rummage around with a magnet-on-a-stick to retrieve it.
Tony.