I have a 1981 Vauxhall Chevette & am currently re-furbing the gearbox. The main shaft has a worm gear (which drives the speedo) in front of the bearing I wish to replace. I am beginning to think it was put on hot then shrunk into place & applying heat with my blow torch does not help. I am thinking of hiring a pipe freezing machine to freeze the shaft then use my blow torch & see if I can get it off that way but wondered if that might damage the structure of the shaft. Has anyone any knowledge of doing this sort of thing. Thanks.
removing shrunk on gear
- Thread starter jj4091
- Start date
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EddieM
Induction heater may remedy.
Is this worm gear preventing you form withdrawing the mainshaft so you can change the bearing?
Like the ring gears of old it could be shrunk on, and it's not usually a good thing to heat the teeth directly.....it always needed oxy gear to get things hot enough though.
John
Like the ring gears of old it could be shrunk on, and it's not usually a good thing to heat the teeth directly.....it always needed oxy gear to get things hot enough though.
John
I have the mainshaft out the gear is just stopping me getting the bearing off. I thought a combination of the 2 might enable removal of the gear. There is only another plastic worm gear running off it to drive the speedo cable so I don't think I need to worry about softening the teeth but I was worried about freezing the shaft.
Induction heater? I'll have to google that. Thanks
Induction heater? I'll have to google that. Thanks
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EddieM
Hire one, they are very expensive, but it's more effective than oxy, though that is a good shout.
I served my apprenticeship in a Vauxhall main dealer and rebuilt a fair few of these boxes. I think we pressed the rear bearing off with a hydraulic press and that took the speedo drive gear off with it. We put them back on by warming them up and tapping them on to the shaft with a hollow tube of the correct diameter. Mind you, I’m going back 40 years or more so my memory might be all wrong!
Edit: Look here at 0.40 - looks like you press the gear off as well.
Edit: Look here at 0.40 - looks like you press the gear off as well.
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Thanks for that Motman I think that might make things a lot easier to get local access to a press than the freezing or heating tools.
I never thought of googling Viva instead of Chevette.
Your memory is impressive by the way
I never thought of googling Viva instead of Chevette.
Your memory is impressive by the way
I've also stripped many of these but, not for 40 years. I also remember pressing the bearing off.
If I remember rightly, there is a big circlip with lugs, kind of like a horseshoe. We used to squash an old aerial, put the two lugs into the squashed part, and that would hold the circlip until the shaft was back in the housing. When you pull off the aerial, the circlip pops into the groove in the housing. Also, we used to put the aluminium tailshaft housing into a sink full of hot water for 5 minutes before trying to put the shaft back in. This expanded the aluminium just enough to let the bearing pop in with no fuss.
If I remember rightly, there is a big circlip with lugs, kind of like a horseshoe. We used to squash an old aerial, put the two lugs into the squashed part, and that would hold the circlip until the shaft was back in the housing. When you pull off the aerial, the circlip pops into the groove in the housing. Also, we used to put the aluminium tailshaft housing into a sink full of hot water for 5 minutes before trying to put the shaft back in. This expanded the aluminium just enough to let the bearing pop in with no fuss.
Yes I struggled a little with the circlip until I made a tool from an old Flymo blade spanner & then it was easy to just tap out the shaft from the housing. It's been one challenge after another but what I lack in knowledge is made up for with plenty of patience.
Thanks to Motman & Stivino I managed to complete the gearbox refurb. I replaced all the bearings & needle rolls & found no wear on any other components or broken teeth & it's now ready to go back in.
However I have now hit a brick wall as far as getting the engine running properly before I fit the box.
The problem seems to be that it misfires or begins to judder when the engine revs are low. Starts first time & ticks over fine, revs freely. OK when accelerating & all times the engine is loaded, it just starts when I take my foot off on flat ground & there is no load on the engine.
I've done all the suggestions in the Haynes manual without success. Gapped the plugs (which were ok ) checked advance & ****** unit by sucking on the pipe, set the timing, compression on each cylinder is 140 PSI. I haven't changed the coil as I can't see how it would not effect running at other times. Th only thing I have noticed that I thought was strange is that when I first started to investigate the fault I filled the carb damper with 3 in 1 oil ( which did not make any difference ) & today after about 120miles the oil in the damper seems to have dropped a lot, although there is still some there.
Hope one of you guys can help again. Thanks Forgot to mention the mixture is perfect
However I have now hit a brick wall as far as getting the engine running properly before I fit the box.
The problem seems to be that it misfires or begins to judder when the engine revs are low. Starts first time & ticks over fine, revs freely. OK when accelerating & all times the engine is loaded, it just starts when I take my foot off on flat ground & there is no load on the engine.
I've done all the suggestions in the Haynes manual without success. Gapped the plugs (which were ok ) checked advance & ****** unit by sucking on the pipe, set the timing, compression on each cylinder is 140 PSI. I haven't changed the coil as I can't see how it would not effect running at other times. Th only thing I have noticed that I thought was strange is that when I first started to investigate the fault I filled the carb damper with 3 in 1 oil ( which did not make any difference ) & today after about 120miles the oil in the damper seems to have dropped a lot, although there is still some there.
Hope one of you guys can help again. Thanks Forgot to mention the mixture is perfect
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You have checked the carb diaphragm haven’t you?
With the air filter off, can you hear a slight 'popping' under acceleration that sounds like a valve not seating properly? A common fault on those was the inlet manifold burning through. If you take it off and turn it upside down, you will see two large holes (inlet) and two small holes. The small holes are for exhaust gasses to heat the inlet manifold. They often burn straight through to the inlet introducing exhaust gasses into the engine that gives you running problems. When upside down, just fill one of the small holes up with water. If it comes out of the other small hole it’s fine, if it disappears and comes out of either of the inlet holes, the manifold needs replacing.
With the air filter off, can you hear a slight 'popping' under acceleration that sounds like a valve not seating properly? A common fault on those was the inlet manifold burning through. If you take it off and turn it upside down, you will see two large holes (inlet) and two small holes. The small holes are for exhaust gasses to heat the inlet manifold. They often burn straight through to the inlet introducing exhaust gasses into the engine that gives you running problems. When upside down, just fill one of the small holes up with water. If it comes out of the other small hole it’s fine, if it disappears and comes out of either of the inlet holes, the manifold needs replacing.
The engine was recently completely rebuilt, big ends, rebore, valve seats etc. & I did the carb at the same time & am pretty sure the diaphragm is ok but II did wonder if that is where the dash pot oil is going. I will have to check the inlet manifold as that is something I have never heard of. Thanks.
Has this one got a Stromberg carb then?
Re the misfire, run the engine in the dark, looking for sparks from the HT leads.
John
Re the misfire, run the engine in the dark, looking for sparks from the HT leads.
John
Yes it is a Sromberg carb, I don't think it is a spark issue as everything is relatively new. Having said that I did fit one of those electronic ignition kits & had to revert back to points as it did not perform well. Wouldn't the electrical side break down more under load though? I'm thinking it's some sort of fueling issue though because of the fact that it happens when it does.
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