Possible stupid question but..

[JonB]

.. while I have the gearbox out of the car, can I clean the old gunk off the insides using a solvent?

Probably asked before, but I see lots of nice black gear oil coating the interior (and the case interior walls have lots of black crud on them too). I could fill it with solvents and spin the gears a bit to remove all of that old crap, then let it dry and add some fresh oil. Plan, or potential disaster? I'm not about to attempt disassembly!

[elanfan1]

Use an engine flush it should do the job without risk of any damage.

[SENC]

Don't be scared of disassembly - was actually quite simple and gives you the chance to check all of the bearings. The only part I didn't disassemble was the reverse idler.

[JonB]

SENC, that way lies madness (of the "While I'm in there" variety).

Don't I need special tools?

[69S4]

SENC, that way lies madness (of the "While I'm in there" variety).

Don't I need special tools?

That's been my worry as well. The gearbox is the only part of my Elan I've never taken to bits. Plenty of motorcycle boxes but I've left the car alone on the basis I probably couldn't do much anyway without either special tools or knowledge. Now however it's showing signs of needing some tlc - 3rd gear is getting noisy and once or twice it's jumped out of 1st on the overrun. So am I just a snowflake mechanic or is 'fools jump in where angels fear to tread' a good principle to follow for gearboxes?

[Mick6186]

A word of warning!!
When rebuilding my 130/5 I flushed the insides of the gearbox with a poweful solvent then put the top cover back on but didn't refill with oil (doh).
A few weeks later topped up with oil then noticed the gear change had become Very stiff.
Out came the engine & gearbox again to discover the selector rods had a coating of surface rust and were binding where they passed through the ally casing. Stripped & cleaned and it was fine, but a lot of work.
I assume the degreaser had done a fantastic job and left the shiny surface of the selector rods open to condensation and rust in my chilly garage
Mick

[JonB]

Thanks for that Mick!

I figured something like that might happen if I didn't immediately refill with oil and turn the gears a bit to get them coated. You must have been gutted to see all that rust!

[rgh0]

Personally i would flush with a low cost mineral gear oil of the original specification and then drain and then fill and drain with the synthetic oil I was going to use and then do a final refill with synthetic oil.

I would not use a solvent as i would be worried of leaving amounts of solvent in places where it could cause bearing damage on startup. Maybe I am over worried but I just dont like having anything near bearings except lubricating oil unless i can fully dissemble them and ensure they are dried, cleaned and relubricated

cheers
Rohan

[Chris]

Yes, you need special tools like dummy shafts for assembly, slide hammer and horse shoe for disassembly . If you decide to pull it apart make sure you have the correct dummy shafts before starting. It is not a difficult job if you have done it before, but it can be a bugger first time.

[MarkDa]

Jon
I'm in the if it ain't broke don't fix it camp.
If the gear oil came out clean then why do you want to loosen up whatever is fairly firmly attached to the casing?
If you can be sure of getting it all off and out then carry on.
Rohan's advice on flushing requires the box to be in situ so you can get the oil circulating to pick up whatever it's going to and be warm enough to flow easily and carry the 'debris' out.
What's the availability of parts like if you were to take it apart?
Put it back in and flush it if you feel you have to do something!

[2cams70]

Best to rebuild if it's showing signs of noise or dropping out of gear. You can get away with no special tools to rebuild the gearbox. You may need (or best to) have access to a press to replace the input shaft bearing. You don't need a dummy layshaft for the cluster gear needle rollers. Just stick them and the thrust washers in with grease. Before you lay the cluster gear in the bottom of the case loop a piece of string around it at both ends. Once the mainshaft is in you can then lift it into alignment using the pieces of string and carefully slide the layshaft in.
You don't need a special tool to extract the reverse idler either. It's usually not necessary to remove the reverse idler unless the gear teeth are very chipped in any case. The reverse idler shaft itself is not normally a very tight fit in the case and can be extracted by screwing in a long bolt and carefully tapping the underside of the head using a drift and hammer.
One strong recommendation though is to buy the best quality circlip pliers you can afford. It will pay dividends in ease of disassembly of the mainshaft and preventing circlips springing out of their grooves never to be seen again!

[JonB]

Well, I've rinsed it with petrol and got a fair old measure of gunk out. Wicked up the puddle left over at the bottom of the casing and let it dry out a bit. Then poured some Redline MTX on the top gear shaft and selector mechanism and spent some time turning the output shaft in all gears. Teeth look much cleaner now, and the box is turning easier. Gearshift feels better and that's without any Vince Reynard magic. I'll let it sit a while and turn it over periodically. Hopefully that will shift any left over petrol in the bearings.

I don't think it needs a rebuild as there is no more noise than expected and it doesn't drop out of gear. Removing dirt is just a maintenance thing which I hope will lead to a longer life (the gearbox, not me!)

The reason for fiddling with it is to try and get a better gearchange. So far, so good.

[MarkDa]

Glad to hear that you are having some success improving the operation.
Have you removed and cleaned up the selector mechanism?

[JonB]

Glad to hear that you are having some success improving the operation.
Have you removed and cleaned up the selector mechanism?

Hi Mark
Which part of it? Everything in the main part of the box (including selectors) is clean, but the selector parts under the gearstick are still a bit grubby. I've put some redline in there and worked it and I think it is OK. Have the stick mods to do now...

[2cams70]

If you have the top cover off it's easy to inspect the condition of the synchro rings, There should be a fair size gap between the face of the ring and the corresponding gear it engages with when you push the ring toward the gear with a finger or gently with a screwdriver. If not the inner cone of the ring is worn allowing the ring to move close to the gear. The friction it has available to correctly synchronize the gear speeds during engagement is reduced in that case and it's best to renew them.
Also check the dog teeth on all the gears for wear or chipping. On high mileage boxes it's common to see a lot of wear on the side of the dogs that transmit the drive torque particularly on the main input drive gear. I usually assess this area in particular as evidence of how much mileage an unknown condition secondhand gearbox has covered.