Lagondaforum » Other » Drive train

adamgentilli	Jan 12, 2017 6:56 pm
Subject: Re: G9 gearbox Well Bill. You are now on my shoulder! Gearbox is out and the internals look in very good order with no broken teeth or play apparent and no cracks in the casing. So I do not propose to take it all to pieces this time and will simply replace the oil seals. However, I have discovered a cracked silentbloc housing, which is now in two pieces, on the rear bearing housing. I propose to attempt a repair and have also asked LMB for the price of a new casting. Tin hat on! My question is whether I can remove the rear housing, without dismantling the internals. I do have the latest book but David is not too specific on partial repairs. It would be too much to ask that it might, having removed the speedo gubbins, just pull off with the bearing in situ. Any advice or comments gratefully received.

adamgentilli

Jan 12, 2017 6:56 pm

Subject: Re: G9 gearbox

Well Bill. You are now on my shoulder! Gearbox is out and the internals look in very good order with no broken teeth or play apparent and no cracks in the casing. So I do not propose to take it all to pieces this time and will simply replace the oil seals. However, I have discovered a cracked silentbloc housing, which is now in two pieces, on the rear bearing housing. I propose to attempt a repair and have also asked LMB for the price of a new casting. Tin hat on! My question is whether I can remove the rear housing, without dismantling the internals. I do have the latest book but David is not too specific on partial repairs. It would be too much to ask that it might, having removed the speedo gubbins, just pull off with the bearing in situ. Any advice or comments gratefully received.

Colin M34	Jan 13, 2017 10:44 am
Subject: Re: G9 gearbox Hello Adam I suggest you have a word with Alan Brown, He still has some G9 bits and as always is very helpful. Colin

Colin M34

Jan 13, 2017 10:44 am

Subject: Re: G9 gearbox

Hello Adam

I suggest you have a word with Alan Brown, He still has some G9 bits and as always is very helpful.

Colin

adamgentilli	Jan 13, 2017 11:40 am
Subject: Re: G9 gearbox Thanks Colin, will do.

adamgentilli

Jan 13, 2017 11:40 am

Subject: Re: G9 gearbox

Thanks Colin, will do.

bill	Jan 13, 2017 12:28 pm
Subject: Re: G9 gearbox For the benefit of others : - Adam, I have spoke to you but you should be ok to get the rear housing out. However, mine was very difficult. It needed a bit of heat on the aluminium housing and gentle prising with a knife edge tapped into the gap. If you can face it, go further and inspect the bush hidden between the input shaft and the output shaft. If this does not get much lubrication it will, I think then cause the 2 shafts to "wobble" leading to possible breakage of the helical teeth.

bill

Jan 13, 2017 12:28 pm

Subject: Re: G9 gearbox

For the benefit of others : - Adam, I have spoke to you but you should be ok to get the rear housing out. However, mine was very difficult. It needed a bit of heat on the aluminium housing and gentle prising with a knife edge tapped into the gap.
If you can face it, go further and inspect the bush hidden between the input shaft and the output shaft. If this does not get much lubrication it will, I think then cause the 2 shafts to "wobble" leading to possible breakage of the helical teeth.

Julian	Jan 14, 2017 11:12 am
Subject: Re: G9 gearbox Morning Adam, My advice would be to go all the way now you are this far. At least as far as stripping the main and input shafts. A crack in any of these castings can be welded, I have done many but they do need carefull preparation first as they are usually a bit oil soaked. Good luck and feel free to phone and ask anything, I know these boxes very very well. Best regards, Julian +32 489712608

Julian

Jan 14, 2017 11:12 am

Subject: Re: G9 gearbox

Morning Adam,

My advice would be to go all the way now you are this far.
At least as far as stripping the main and input shafts.
A crack in any of these castings can be welded, I have done many but they do need carefull preparation first as they are usually a bit oil soaked.

Good luck and feel free to phone and ask anything, I know these boxes very very well.

Best regards,
Julian

+32 489712608

adamgentilli	Jan 14, 2017 11:56 am
Subject: Re: G9 gearbox Thank you Julian, The rear casting is now off with no problems and I will take it to a TIG welder next week. Too much mass for my Mapp gas! The front horns were moving nicely, but only because of the input shaft movement. I shall reapply myself to that end and carry on with the full job.

adamgentilli

Jan 14, 2017 11:56 am

Subject: Re: G9 gearbox

Thank you Julian, The rear casting is now off with no problems and I will take it to a TIG welder next week. Too much mass for my Mapp gas!
The front horns were moving nicely, but only because of the input shaft movement. I shall reapply myself to that end and carry on with the full job.

Julian	Jan 14, 2017 12:15 pm
Subject: Re: G9 gearbox Great Adam, As Bill has said, the input / main shaft Spiggot bearing is very important, it should be moving on both internal and external surfaces but should have minimal play. The club have them in stock I believe, T8 and G9 use the same bearing. Regards, Julian

Julian

Jan 14, 2017 12:15 pm

Subject: Re: G9 gearbox

Great Adam,

As Bill has said, the input / main shaft Spiggot bearing is very important, it should be moving on both internal and external surfaces but should have minimal play. The club have them in stock I believe, T8 and G9 use the same bearing.

Regards,
Julian

adamgentilli	Jan 19, 2017 11:16 am
Subject: Re: G9 gearbox Very happy to report that the gearbox is all apart and appears to be in excellent condition. No broken teeth, bronze bush fitting well, no blockages in the oil hole feeds to this and no apparent bearing wear. I guess it was well restored before my tenure! On the instructions of the previous owner, I have always filled with gear oil, perhaps this has been helpful. On dismantling I noticed that only jointing compound, no gasket, was used on the bearing holder and front/rear casting faces. Red hematite was used, I would use Blue Hylomar unless there are any other suggestions?

adamgentilli

Jan 19, 2017 11:16 am

Subject: Re: G9 gearbox

Very happy to report that the gearbox is all apart and appears to be in excellent condition. No broken teeth, bronze bush fitting well, no blockages in the oil hole feeds to this and no apparent bearing wear. I guess it was well restored before my tenure! On the instructions of the previous owner, I have always filled with gear oil, perhaps this has been helpful. On dismantling I noticed that only jointing compound, no gasket, was used on the bearing holder and front/rear casting faces. Red hematite was used, I would use Blue Hylomar unless there are any other suggestions?

bill	Jan 19, 2017 3:12 pm
Subject: Re: G9 gearbox Well done Adam ! I am sure Blue Hymolar is fine or a very good quality silicone ? If you dont have a magnet in the drain plug now would be a good time to fit one ?

bill

Jan 19, 2017 3:12 pm

Subject: Re: G9 gearbox

Well done Adam !
I am sure Blue Hymolar is fine or a very good quality silicone ?
If you dont have a magnet in the drain plug now would be a good time to fit one ?

Colin M34	Jan 19, 2017 7:47 pm
Subject: Re: G9 gearbox Regarding sealant, I quite like Wellseal and there is quite a good debate on the web at http://www.model-engineer.co.uk/forums/postings.asp?th=99081 I agree with the sentiments here. I keep most types of sealants to hand, including the wonderful loctite pipe sealer but if in doubt, it's Wellseal for me. I like to wear thin surgical gloves when I use it and spread it around with thin plant label sticks which can be found in pound shops. Thanks for your useful advice Julian. Colin

Colin M34

Jan 19, 2017 7:47 pm

Subject: Re: G9 gearbox

Regarding sealant, I quite like Wellseal and there is quite a good debate on the web at http://www.model-engineer.co.uk/forums/postings.asp?th=99081 I agree with the sentiments here.

I keep most types of sealants to hand, including the wonderful loctite pipe sealer but if in doubt, it's Wellseal for me. I like to wear thin surgical gloves when I use it and spread it around with thin plant label sticks which can be found in pound shops.

Thanks for your useful advice Julian.

Colin