Forum Replies Created
-
Adam, if you are going to strip the gearbox completely I found that there were 2 vital things in my humble opinion. There may be better advice on this Forum from others but ……
1. Renew the bronze bush in the middle of the main shaft (between the output and the input shafts). Any play in this bush is likely to cause the gearbox to jump out of gear on occasions and will also put sideways stress on the helical gears (hence broken teeth)
2. On the mainshaft make sure you get the helical gear off the steel “collar” (for want of a better word) that it has been pressed onto. It was not immediately obvious to me that the “collar” was not in fact part of the gear itself. However after looking at it very carefully I realised that there are various holes into which you need to insert some hardened steel pins in order to push the gear off the collar. Some heat might be needed. When you get the gear off you will find that there are oil holes and pathways hidden underneath which have no doubt accumulated crud and carbon over the 80 years or so. The holes in mine were completely and solidly blocked. The blockage of these holes prevents any real lubrication reaching the bronze bush in the middle of the mainshaft and will cause wear to this important bit of the gearbox.
It is difficult to describe all this accurately but checking how oil can get to this bronze bush in the middle of the mainshaft should be more obvious to you when you get the gearbox apart !!
Adam, having refreshed my memory by looking at my notes this morning I suppose it could be possible to renew the seals with the gearbox “in situ” and without taking off the front and rear housings (I presume that is what you suggest in your post ?). However the shafts will be in the way and it would be very difficult to remove the old seals and put in new ones without damaging the new ones.
It would be much better to get the gearbox on to the bench and then take off the housings. However having gone that far it would probably also be a good idea to take it all apart to check the condition of the bush in the middle of the main shaft and all the vital oil holes in the helical gears. That probably really means a strip and rebuild but it is not too difficult if done carefully.Adam, do you have the latest Club 4.5 litre handbook ? There is quite a lot of detail about the G9 gearbox in there by David Hine – page 93 – including seal info.
When I rebuilt my G9 a few years ago (before David Hine had produced the revised handbook !) all the seals (and bearings) in modern form were available virtually off the shelf from my local bearing supplier.
I hope this helps.Yes, Richard Jones is the person you want. I dont think anyone else does this conversion unless anyone knows otherwise …….
Just to clarify my earlier post on 18th August and Laurence’s above. Yes it seems to be correct that with NGK there is nothing between 2 and 6 for 18mm plugs. I was not aware of this.
I have also checked with the friend I mentioned above who has the pre war BMW. He is in fact using NGK 4 not 5 !! He is using 14mm plugs with an insert not 18mm. He is doing about 50 miles to a pint of oil (burnt not leaked) and does not have a misfire !!
He drives very hard !
I think that with modern fuels we can probably use softer plugs than we thought we could !Even on coil ignition engines I think you will find that suppressed leads or plugs (R in the identity usually) will lower the intensity of the spark and should be avoided. That is unless of course you value your relationships with neighbours or family who enjoy watching television !
Just to resurrect this thread about cooling on the 4.5 engine. I had an interesting conversation at VSCC Prescott 2 weeks ago about the cooling on a Pre War 6 cylinder BMW/Bristol engine. The owner was an engineer who worked at the time for an Formula 1 team. He was not satisfied with the cooling on this engine and as he worked in F1 he had access to all the proper equipment to test flow, cooling etc properly. He told me that he ascertained that the cooling was inadequate and (just like the 6 cylinder Meadows 4.5) there was insufficient cooling to number 6 cylinder – even though this was not apparent on the normal dash mounted temperature gauge. His solution was to put all the cooling water from the water pump to the back of the head . Thus all the cooling flow went from the back of the head to the front and then into the radiator.
This does not of course mean that this is the ideal solution for all 4.5 litre cooling issues (although it worked for me – see earlier post) but it would be interesting if someone who has the knowledge, time and equipment checked whether this alternative type of cooling system is in fact a proper long term solution.
Those of you with spare socks can however rest assured as a sock (or filter) would, however, (for other reasons) still be required in the top of the radiator !!
Food for thought !!Rich, I tend to only think in terms of “hard” and “soft” so cant be exactly certain about cold and hot. Someone else will put us straight I am sure!
A hard plug ie a 7, 8 or 9 in NGK terms would be used in my experience on a higher performance engine. For instance when we ran a 2.8 Hart engine on about 12:1 compression ratio we used NGK 8s.
If your engine is fouling either from too rich mixture or oil at lower engine speeds then I would tend to go to a softer plug – more like 5 or even 4. I use NGK 6 on my 4.5 engine and have been thinking of trying 5s with this horrible modern fuel.
In my experience the Green Spark Plug Co are not only reasonably priced but also extremely helpful and knowledgeable.You may even find 6 is too “hard” with modern fuels for ordinary driving.
It seems that we can use much softer plugs than previously due to the volatility of modern fuels.
Try 5s and if it doesnt misfire at the top end you would be ok.
I have a friend who is using 4s in a 319 BMW (1936) and he drives it very hard indeed ! He says they are fine !
In my experience NGKs are very good and I would stick to those.Well done Julian. It is good to know that things are going well.
I am sure that even though you are obviously very busy your input to this Forum is appreciated by all – as long as you have enough time to do so !I dont know if it helps but I have always understood that Lagonda fitted a “Sky-Hi” jack at least on the ali bulkhead cars ie 1936 and earlier. There were different sizes of Ski-Hi jacks and I am not certain which exact size was correct for Lagondas. Probably the one which fits best !
My M45 came with a Sky-Hi and although it was only found and given to me after I collected the M45 on purchase it fitted perfectly under the original spring loaded clips on the bulkhead.Hi Laurence
Yes, I quite understand – but be careful on the first corner after swap around !
Even if you cannot do the job yourself, any competent engineering company could do the job for you I am sure. As long as the holes are drilled with the correct PCD I would not have thought that you would have any balancing problem.
Maybe you should make certain if possible that the material used for the front and rear drums is identical – drums were often made from different types and one type of material may be better than another ! Therefore your current front drums may be very efficient and your rear ones not so good.I would have thought that it was better to leave the drums where they are because all the linings and drums will now be nicely bedded in.
If you simply want lightened (ie drilled) drums on the front why dont you drill appropriate holes in the standard drums ? This is not as difficult as it sounds if you have access to a small milling machine or decent pillar drill. I have done this on a number of drums for a couple of cars (not Lagonda) and can be done with a decent (Bosch) “hole saw”. Or you could use a Mag Drill if the drum metal is sufficiently magnetic to allow the drill base to “grip”.As a matter of interest (see my earlier post above) do you have an original block or a nice new(ish) modern one ?
Surely there must be some other car which used a carbon thrust washer of the correct dimensions – or is it a very difficult size ?
Maybe something which was fitted to a lorry ??
If not quite the correct size then machine to fit as I presume you have the original Lagonda holder for the carbon washer.
Alternatively get a lump of carbon and machine one up yourself (carefully) out of the solid ??