Talk Morgan Forums Morgan Sports Cars Morgan Three Wheeler & Super 3 Timing belt trouble

Shocking, this one had been changed only a few thousand miles ago. Guess I am going to need a new one. Promptly.

What is all the hairy "tobbaco" dust in there, degredation of the belt itself I presume?

I havent changed it before, is it a fairly simple job?

This should help


http://www.talkmorgan.com/ubbthreads.php/ubb/showflat/Number/229212/Searchpage/3/Main/17438/Words/cambelt/Search/true/Re:_Cam_Belt#Post229212

I have replaced mine it took about 40 mins. The instructions above will work but you do not need to remove the crankshaft bolt and washer, only the idler pulleys. To keep the tension off the tensioner I used a piece of rope tied to the spanner and then to the indicator support, this keeps the tension off and you can then fit the belt.

Justin-time that is just in time you found out !

Do you have the washers between your belt cover to get the temperature down ?

I am currently looking into the posibility of converting the timing side of the engine to all gear drive. This would totally elliminate the belt and last the life of the engine.

Would any other owners be interested in this conversion if it proves possible and viable?

A company called Zeus used to do timing belt replacement gear kits for 200 and 300 TDi Land Rover engines around 15 years ago and I invested in one following 2 previous premature belt failures - and it was an inteference engine - despite changing belts at half the LR recommended interval. They were noisy but did the trick for nearly 100,000 miles, until they shattered and trashed the top-end of the engine for the 3rd time!

Great idea, but maybe still quite hard (and expensive) to make resilient enough I suspect.

I agree, gears would naturally be noisier than a belt but I think we could live with that.
I ran a Vincent 1000 with a Steib sidecar for 30 years and they were always known for their mechanical noise, but it was a fact that very often the noisy ones were the quickest, not that it should make any difference.
As we are aware, the engines in our M3Ws are non-interference engines, so if the gears were to fail it would not result in serious top end engine damage, and with the correct choice of gear material and heat treatment this should not be a problem.

Not all belts are of the same quality. I now only fit Gates. Interestingly Gates are standard fitment on LR now with a recommend change interval of 150,000 miles. I have just done mine at 80k and still looked like new.

Helical timing gears are a lot quieter and really a must. Velocette tried straight cut in the 50's when they introduced the M series. It was found acceptable on prototype engine but the thinner timing cover on production models forced them to use helical gears which solved the problem.

.... and when done nicely, they sure can be pretty....

Quoting Richard Wood:-
"Helical timing gears are a lot quieter and really a must. Velocette tried straight cut in the 50's when they introduced the M series. It was found acceptable on prototype engine but the thinner timing cover on production models forced them to use helical gears which solved the problem".

I know helical gears would be quieter but they also impose axial loads on the shafts and/or bearings on which they are mounted, and these loads would have to be accomodated in the design of the complete set-up.

I believe, if the timing cover (it would obviously have to be the early type without the cooling slots) were to be made oil tight by means of a gasket and provided with a filler plug, a drain plug and a level plug so that the lowest gear (i.e. the gear on the crankshaft) could be up to half it's diameter in oil, the gears would then be running in oil.

I believe this would reduce the noise to an acceptable level but this would need to be proven.

Two comments from the peanut gallery...

If the belt is OK other than the hairy edge, I would get out the propane torch and while the motor is on idle, I would singe the hairs off with the torch being careful to not burn the belt material itself. I've done this before and had no issues.

But if those are cracks in the back side of the flat belt, change it out now and move on.

As far as the gear drive goes, I was going to say the same thing about the axial load, but even with straight cut gears running oil, there would be some parasitic drag due to the oil bath and gears. That's why they put windage trays and dry sumps in race motors.

I personally think that straight cut gears on the motor would be way too noisy and would be a constant distraction from the fun of driving the M3W. Guys on small block Chevys take out the timing chains and convert to the gear cam drives mainly to make them sound like a big blower mounted up front. Yes there is probably a tenth of a hp to be gained by gears over the timing chain in the SBC, but it's about the noise. Believe me with just four gears it's way loud.

In the M3W there would be a few more than just four gears.

Again just an outsider's opinion.

I would suggest you contact Matts Machine Shop in South Wales to get a new belt, they are certainly cheaper than Morgan. Ask about the modification kit for the crankshaft drive pulley, bolt and idlers at the same time. If it doesn't already have it, the front cover should have the gasket removed and spacers fitted to give some cooling airflow, also slots in the front cover. The "snake skin" debris in cam belt case area is the release agent from belt manufacture and is normal. Not seen a "hairy" belt like that before, looks like you may have got it just before failure? With all the mods done, Morgan say the belt life is 30,000 miles.

What makes MMC so certain that with the increased ventilation the belt life could be expected to be 30,000 miles.

This can only be an assumption on their part because this figure has yet to be proven.

With regard to the noise Dan I think you may have a vakid point.

Having said that, most british bikes had gears for their camshaft drives and as far as I know, Velocette were the only manufacturer to go to helical timing gears and from memoery I do not think anybody complianed about the noise from the timings sides of engines made by other manufacturers.
(Velocette were always a bit un-conventional, you only have to look at their clutches to see that).
The Vincent had 6 straight cut gears in the timing case and all but the last one (which drove the magneto) were steel.
The majority of the mechanical noise produced by the Vincent twin engine was caused by the strange cantilever cam followers that they had.

Dan states that the noise of timing gears would detract from the pleasure of driving the M3W.
I do not think this would be a major problem as it would be inaudible over the screaming bevel boxes.

I can't hear the stage 1 exhaust over the BB once its warm so I would worry about the gear noise you should be fine

Maybe you should include Moto Guzzi as well although I'm sure I could find others. I appreciate the axial load issue but in a former life I sold many helical gear conversion kits based on that of the OE V7 Sport model (see below), to owners of later models that were fitted with a timing chain. It was assumed this was on the grounds of cost saving. We never had any load issues, indeed I road nearly 100,000 miles on one bike fitted with these gears and without issue, although the original design was to accommodate such.



The lower gear drives the oil pump.

Good one there...

Concerning the use of helical timing gears and Richard's initial reference to the Velocette, I merely stated that as far as I was aware most british bikes had gear driven camshafts and that Velocette were the only manufacturer (to my knowledge) using helical gears.

I have no doubt that Richard (given time) could find many other examples of non-british bikes with helical timing gears.

I can only bow to Richards vast knowledge of motorcycles which is obviously far superior to my own.

Sorry I genuinely didn't mean to offend

Just defending an earlier post I made.

I am sorry but having had the rear end of my M3W severely smashed at the beginning of this week, I am just a little touchy.

I just thnk it would be feasible and I have started to lay it out in AutoCad. I have also bought a spare camshaft support plate, camshaft pulley and crankshaft pulley from Matts Machine Shop to get the dimensions of hole centres, pulley bores and angular positions of keyways etc.

Despite the various doubters I will still look into the possibility of doing this gear conversion as long as the cost is not too prohibitive.

Well.. You have the extra time now...

If you decide to go ahead might it be worth considering lubrication of gears simply by using oil leaking past camshafts rather than a dedicated pool of oil, which may cause drag?

It's a while since I've worked on Guzzi engines but from memory the timing gears illustrated in earlier post, received lubrication in that manner since the was no camshaft oil seal. The dribble of oil then made its way via gears to bottom of chamber where it drained back into the sump via holes you can see.

A recent warranty job to cure leaking camshaft seals on my car indicates there is oil behind, so removing them may achieve the purpose, although not the double lip crank seal which may be holding back some oil pressure. Anyway just a thought.

Thank you Richard for your comments on the lubrication of the gears.

The arrangement I envisage will have 3 idlers, i.e. 1 between the crankshaft and the inlet camshaft and the remaining 2 would replace the current rollers that sit above the camshafts.

I intend to run these idlers on needle roller bearings mounted on fixed spindles, the outer ends of which will have an "outrigger plate" that supports their outer ends, (similar to the Vincent set-up).

The idler spindles would have an oil hole down the centre to feed oil to the needle rollers and this would be provided by an oil feed to each spindle, mounted in the timing cover and fed by a small jet in a line tee'd off the oil pipe returning the scavanged oil to the tank.

I believe that I am correct in saying that the oil pump scavanges oil from the camshaft cavity and not from the sump.
If this is the case and the timing cover is made oil tight, then possibly a hole could be made low down in the camshaft support plate to allow any oil building up in the timing cover to drain across into the camshaft cavity ready for returning to the tank. This drain hole would be below the crankshaft gear and therefore excessive oil drag would not be a problem and the gears would be lubricated by oil exiting from the idler needle rollers.

What do you think of this arrangement?

Sounds good, the needle rollers shouldn't need too much oil. Ironically I was just musing over your proposed mod and scribbled a layout to check for correct rotation. I came up with exactly the same for a gear wheel count of seven.

Since this would (maybe) allow you to use existing idler pivots, is this what you intend?

Is it possible I wonder if S & S originally designed engine with geared timing as an option.

Not sure where scavenge pump sucks from - where the most oil is I guess.

Because of the size constraints and the size of the gears I intend to use, the centres of the 2 upper idlers do not quite fall on the same centres as the existing tapped holes for the roller spindles.

There is however, sufficient meat in the bosses on the support plate for them to be drilled and tapped slightly off centre for the idler spindles.

The central idler between the crankshaft and the inlet camshaft will run on a spindle this is mounted in the area currently occupied by the spring tensioner device. The plate is tapped 7/8" UNF (14 T.P.I.) and i have made up a threaded plug to fit this thread which I have loctited and pinned in place. This plug will then also be drilled and tapped to take the idler spindle.

Note:- As the idlers will all be running anti-clockwise, they will all be screwed in using a left hand thread so that the natural tendency is to always tighten them up when the engine is running.

You have certainly put a lot of thought into this. Regarding exhaust cam idler location is there any leeway there since you don't need a specific number of teeth? Maybe you could be cunning here and arrange for hunting teeth by having an extra one, and so even out wear as per Velocette practice, although timing marks only align every x numbers of rotation then.

BTW had a look at exploded diagram of X wedge engine. It appears that the bottom of camshaft chamber is higher than that of crankcase. This would leave a certain amount of oil in bottom of crankcase if the scavenge suction point is in the former, but this may be by design. I note there is a magnetic drain plug in sump as well.

What I have never heard it explanation, however speculative, of why these belts seem to be fine when these engines are used in a motorcycle frame, yet they seem to have a very short life when used in the Morgan. You would think with the engine sitting up front and that time in case exposed to the wind that if anything it would be running cooler than it would be sitting out the side of an air cooled motorcycle. I don't know if any of the armchair Engineers here on the board have an idea about the actual cause of these failures.

I don't think the cam belt problems with the S&S X Wedge engine are restricted to the M3W installation, there have been problems in bikes as well I believe. Just off back to my armchair now.


http://www.bigdogbiker.com/threads/another-x-wedge-cam-belt-shreds.40080/

Absolutely correct, even Hesketh have had to put a vent into the cam belt area to provide some more cooling.

That's was my question too ( see previous post ) which I asked Justin Time.
Did you had the spacers between the belt cover to get some ventilation ?????

Sorry for my late response, I have put the spacers in.



I have also spent some time with a 3D scanner, and now have an accurate model of the S&S casing, I hope to get some time this week to come up with a vented solution. I can save the CAD file in most flavours, for anyone else if they require it.




My belt arrived a few moments ago too, S&S manufactured.

I imagine some careful work with a cutting tool on a Dremel would provide the front cooling slots as on latest covers.

does anybody have pics of the updated cover?

Here maybe.

Looks like latest to me , plus has a large slot in bottom face !

Justin guess I'm missing something. I see a neat profile of the cover (gasket?). How will this let air circulate the belt chamber? Many of the guys simply stack washers a 1/2 to 3/8" stack, much more and the bolts don't reach. I did the washers and fashioned a scoop in the bottom of the cover. Anybody out there that has used spacers had timing belt failure?

The spacer washers that S&S fit are about 2.5mm thick. I cannot see how your neat CAD profile will improve the ventilation over the washers. To achieve the current S&S style ventilation solution, Dremel or abrafile the slots in the front casing (as in Richards photo link) plus the cut out in the lower part of the cover. As you are doing all this it would be a good idea to do the modified crankshaft drive gear, bolt and idlers at the same time. That's an expensive cam belt, I hope it lasts a full 30,000 miles!

Sorry chaps, its not a product, its simply the profile of the cover gasket area, that you could use in your own CAD package, to design a vented product.

I did yesterday manage to change my timing belt, it was a tough to get on the sprockets, even with the idlers removed. Sore thumbs today.

However, I did think of this a moment ago.

Stainless steel metal powder sintered microporous filter material

I honestly don't think just porous material for the gasket will achieve anything like the cooling airflow needed. The current cover provides air forced into cover and exiting in space created by proud mounting points in lieu of washers used previously, plus aperture at bottom of cover which serves as drain as well.

Moto Guzzi provided solution to similarly located alternator rotor. A plastic cover had extended vent/drain at the bottom. This created low pressure area behind, in turn creating airflow inside cover via a spacer between cover and crankcase with a lip in the profile that didn't allow direct water ingress.

Maybe you could create something similar with your CAD profile but would still need to add the cooling slots to an earlier type cover.

Hi there... my belt gave up yesterday on the way back from Greece... 800km from home.

I just ordered a belt from Matt's Machine Shop with super-super fast delivery and now I need to find a place to drop the broken animal.

I hope Harley-D or Victory can do the job and that I can join the Chantilly Art & Elegance event this Sunday !

I have 12000km and so far 1 ECU changed.

Hi Chaps I am new to the forum and have a interesting understanding of this fault. Would people be interested in a gear driven conversion as I have a finished design and would happily let someone test it on their engine. I am strongly against the mods that have been suggested and put forward by the engine builders as they leave the belt open to the elements and on a m3w the slots are right at he front so not good. I have been involved with this engine until recently and I am happy to support where i can whether is be 3d models or additional information.

I know that some have discussed this prior, but my concerns would be lubrication for the gears.

What do you do about that? Possible to tap into an oil feed passage and then drive a hole in the bottom of the belt chamber back into the cam oil scavenging area?

Quote PeterSurrey:-
"Hi Chaps I am new to the forum and have a interesting understanding of this fault. Would people be interested in a gear driven conversion as I have a finished design and would happily let someone test it on their engine. I am strongly against the mods that have been suggested and put forward by the engine builders as they leave the belt open to the elements and on a m3w the slots are right at he front so not good. I have been involved with this engine until recently and I am happy to support where i can whether is be 3d models or additional information".

I have also been looking into a timing gear conversion which if satisfactory, would last the life of the car.
I have created some drawings in AutoCad and started cutting metal.
if you want to discus this further please send me a PM.

Regards
Keith

Your post alludes to the fact that you know a lot more about the issues with this engine, are able to elaborate ?

I have experience with these engines as well as designing and manufacturing components for them. Im not able to share my findings because I dont feel it is right of fair for the companies involved. I am 100% confident that the spacing the cover off is a dangerous game to play especially with m3w having face on slots. The route of gear driven cam is a must in my mind for the engine in this application. For motorcycle however a vented cover is acceptable as they normally do much fewer miles and normally only in the dry. The cover on the Hesketh as mentioned earlier combats the water ingress because it uses low pressure air currents to circulate air. This could be achieved on the m3w and I do have designs for that purpose but again they are untested. I am a Mechanical Design Engineer having worked in Automotive and engine design.

As clear as mud, then..