T80 transmission noise?

hi Guys,

I have finally got my T80 from its previous owner. it is a1985 reg with 12K miles on the clock and judging by the overall condition , it has been well looked after.( I did post a pic of it a few months ago - silver finish)
I have been checking it over doing all the sensible things, oil, tyres ,brakes etc On the bench the  engine/gearbox and electrics all checks out and it runs well.
This morning I took it out on the road for a 5 mile spin just to get familiar with it.
All was well but I noticed more transmission noise on the over run especially in top gear. Is that to be expected with the shaft drive system although I suspect more of a gearbox noise ?
On the stand the drive shaft system spins quietly in the forward direction but noisier running backwards which I would expect to a certain degree.

There will be more road testing but I thought I would just ask for comments.

steve9e wrote:hi Guys,

I have finally got my T80 from its previous owner. it is a1985 reg with 12K miles on the clock and judging by the overall condition , it has been well looked after.( I did post a pic of it a few months ago - silver finish)
I have been checking it over doing all the sensible things, oil, tyres ,brakes etc On the bench the  engine/gearbox and electrics all checks out and it runs well.
This morning I took it out on the road for a 5 mile spin just to get familiar with it.
All was well but I noticed more transmission noise on the over run especially in top gear. Is that to be expected with the shaft drive system although I suspect more of a gearbox noise ?
On the stand the drive shaft system spins quietly in the forward direction but noisier running backwards which I would expect to a certain degree.

There will be more road testing but I thought I would just ask for comments.

It would be wise to dismantle the rear drive unit and re grease it. The grease tends to dry out after a long period and does not lubricate the teeth. Use Castrol Speerol EPL-2 (a liquid grease) https://www.castrol.com/en_gb/united-kingdom/products/off-road/grease/spheerol-epl-2.html
Also worth changing engine/gearbox oil standard SAE 10/40 motor oil

hi John,

Thanks for the advice . My bike had been stood for over a year at least so your comments make sense.
Looking at the paintwork around the bevel housing etc there is no sign of the original paintwork being disturbed so it may be "original" grease.

I noticed that Yamaha specified grease which surprised me ( my Moto Guzzis and BMW used oil) so liquid grease seems a better bet. Did you use the same quantity as Yamaha recommended ?

I have used 10/40 in the engine anyway.

Thanks again

Steve

Yes about 120 grams or 125 ml (1/4 of a 500ml tub) so enough in tub to do 4 drives.

Hi John

The plot thickens !

Crown wheel is in a bad state , lumps out of 4 teeth at least !!! pinion looks OK but I would replace as a set.

I reckon since it was nearly full of fresh Red/Brown grease someone has been at it.
Although the silver paint was pristine I notice one of the housing bolts was not torqued up, but they had done a good paint job.
However that's life I have fixed a lot worse.
This bike came to me from a good friend who bought it nearly 2 years ago and never used it, so the bird will have well and truly flown?

Any sensible suppliers in the UK who might have a set, worth trying ?

Cheers    

There is a new old stock crown wheel on eBay https://www.ebay.co.uk/itm/YAMAHA-T80-TOWNMATE-C-1986-GENUINE-NOS-DRIVE-SHAFT-RING-GEAR-29F-46110-00-/352344630800 for £48.90

New parts are no longer available from Yamaha and last published prices were Pinion £98.86 and Crown wheel £151.79
https://www.fowlersparts.co.uk/parts/3974491/t80-2fl-1986-999-a/drive-shaft

There is also a secondhand complete used rear unit standing at £14.99 with no bids yet and 6 days to go https://www.ebay.co.uk/itm/yamaha-townmate-80-drive-shaft-good-con/132633999471?hash=item1ee19a386f:g:DCMAAOSw8MdbBdlp
but obviously you take a chance with that. May be as bad as yours inside.

hi john

I located a supplier in Greece with a Yamaha set raising the final ratio slightly for £125 plus carriage which hopefully solves the problem.
The overall condition of the bike is so good I think it is worth the extra cost, but beggars cannot be choosers sometimes.

I will report what happens next to the forum?

cheers

Looks like you are getting a T50 gear set. The T50 one is 3.3:1 whereas the T80 one is almost exactly 3:1 reduction.
If so your bike will be sightly under geared, OK in hilly terrain but not so good on the flat, will reduce top speed to about 40mph.
Note the gears were not sold in matched pairs, but individual items. So if your pinion and its inner bearing are OK then just the large (crown wheel) would be OK. The inner bearing is part of the pinion and shaft assy, the outer bearing can be replaced.

hi John,

The gear set I am getting is a rare 3.078 ; 1 so it is slightly higher than standard T80 3.166 : 1. It is not a  T50. It apears I have got the last one? the chap in Greece ( Ninos Technoshop ) was very helpful he reckons spares are hard to find over there also. ( parts are on the way)

It is an interesting point about the standard pinion, I will remember that although hopefully I will not get the same problem again once fixed ?

I have noticed that the bearings are KOYO and the numbers do not tally with anything I can see and I assume some are specials.Even KOYO cannot identify them and my usual bearing suppliers.
The one on the pinion looks like a 6204 which is pretty standard but the ones on the crown wheel seem special  60/28RK & 60/280. I have not checked them with a mic, just curious ? They all feel good and a new one will come with the new pinion.
cheers - Steve  


I got a new set of decals from the USA Discontinued Decals - they look well and their service was excellent

hi John,

I just realised what I said about ratios - the one I am getting is a LOWER ratio ( 3.078 : 1) which should slightly increase speed over the standard T80.( 3.166 : 1) the history behind this version would be ineresting no doubt, we shall see as it appears to be in a Yamaha box?
Touch of brain fade I am afraid we shall see if it makes much difference as my impression was that the gearbox ratios were on a bit of the low side. icenicam review of the bike made a similar comment I think.
cheers

hi Jw

I received the crown wheel and pinion set from Greece which was a brand new Yamaha Part but rare. Aparently, some were sold to Russia ?

Pinion

The new pinion was a different ratio than the standard T80 but a direct replacement fit. It  uprates  the overall gearing slightly ( see previous post)

Crown Wheel

The compared with the standard crown wheel at a glance looked the same except :

On the standard gear there is a boss cast in the gear which pulls up onto the right hand bearing  on the outside, The new wheel does not have this boss , so a distance piece has to be fitted to the shaft to mimic the standard. The bearing fit is the same.
On the left hand (brake side) both have identical splines 28 mm dia, however the new shaft is 30mm dia and has to be ground down to take a 28mm bearing and a boss machined in to locate the crown wheel exactly as the standard.

It looks as if the new crown wheel bearing size on that side were different or beefed up to take a bigger diameter bearing assembly.

However time will tell. Road testing will start next week and hopefully it will take part in the Coast to Coast Run up in the North East, later this month.
An interesting excercise but good machine shop facilities will be needed. The supplier was not aware of the differences and had sold a number of these and the differences were not easy to spot unless you know what to look for - I do now.

cheers  

Steve  

Strange that Yamaha made different sizes, I wonder if the are from a quad bike, but looking at the diagram for an 80cc Raptor Quad there is a long drive shaft attached to the crown wheel (No 16 in diagram) https://www.bikebandit.com/oem-parts/2002-yamaha-raptor-80-yfm80wp-drive-shaft/o/m145737sch251397

Hopefully you have someone who can do machining, but other buyers may not, and have effectively bought parts that they cant use. Particularly when they have come from abroad and will cost a lot in postage to return them, assuming seller will refund the money. A real case of buyer beware

Hi JW

Crown wheel - the one I had to modify is identical in length and dimensions with the standard T80, basically it was only the addition of a simple collar at the back of the gear. but the splined side needed access to a suface grinder to reduce the 30 mm down to 28 mm. for the original bearing fit

The quad bike unit is nothing like the T80 unit.

As I have the Yamaha package box still I will see if I can identify exactly which model it was intended for?

cheers

Steve

hi Jw

The bike is now road legal and goes very well. The new rear gear is very smooth and quiet ( both ways) so I look forward to giving it more severe tests in the Durham Dales.

I checked the Yamaha reference on the box which is 560-02-20800   T80(2). This reference appears on the internet under T80, but I cannot track down a parts list with  this reference directly linked to the T80 or similar equivalent. Unfortunately the pic on the internet is angled so that you cannot see the crown wheel shaft clearly.

Cheers

The part number on the UK parts list https://www.fowlersparts.co.uk/parts/3974529/t80-2fl-1986-999-b/drive-shaft is 29F-46110-00 for the T80 and T50

Hi JW

yes I went through all the usual parts lists, I reckon it is a pattern part for a non Yamaha bike, but someone will know just out of curiousity.I will find out eventually and at least I am on the road.

Cheers