1972 t500 gearbox mod T3 service bulletin.

[Paulreade]

Hi, I am looking at a purchase in the uk of a mint T500 with apparently genuine 9k miles. I have put the point to the dealer has the gearbox mod been carried out to allow 1400cc of oil. I suspect it hasn't. my Q are:
Is there any stats on when the failure starts I.e what sort of mileage
If 1400cc of oil was placed without the mod what would be the consequences ?
Is this mod critical and should it be done without delay
Is the mod difficult - I assume engine out, full strip down ? And would you then advise all new seals etc

I ask as I have no idea of these bikes and this is a nostalgic purchase to keep this lovely motorcycle running and in good hands, I want to do the right thing !.
Any advice appreciated.
Regards
Paul

[Zunspec4]

Hi Paul,

I would not get in too much in a tiz concerning the "oil dam" mod. 4th & 5th gears can get dry of oil without it and the 1400cc of oil if you do a lot of steady cruising in those gears (motorway stuff). In normal blasting around the streets it is unlikely to cause too much of a problem. Ask if the crankcases have 1400cc cast into them near the oil filler, if they do you have no problem. There will also be no problem using 1400cc of oil if they have 1200cc on the cases. To install the "oil dam" mod it is an engine out and split the cases operation. Not a big job at the end of the day, the T500 engine is pretty simple.

In summary - The mod is not critical but good to do if you have too. If you intend to do 10,000 miles/year touring, yes get it done. If you just enjoy going for a ride in the local area on a sunny day you will be OK.

Cheers Geoff

[Paulreade]

Encouraging news Geoff. The dealer is going to discuss the mod with his boss on Monday as to whether they do it or not. The sales manager believes they should. The bike if purchased will probably only do a 1000 pa at most so it sounds like it won't be much of a problem. Thanks for your input

[Zunspec4]

Hi Paul,

Get them to do it if they are willing, it is the best "engineering" solution. Of course they might find it has already been done but you cannot check without splitting the cases.

When the engine is apart it would also be best practice to change out the crank seals. Easy to do on the outer bearings but replacing the centre bearing seals will require the crank to be stripped and re-built.

Cheers Geoff

[argo1974]

Paul,

1) You can check the mod when you unscrew the crankcase breather and look straight down into the case. This is difficult with the engine still in the frame though. A person with experience can feel with screwdriver if rubber oil dam is there or not.
2) You'll have the crank seals replaced anyway after these years despite of the low miles. Splitting the cases twice is not a good idea. Suzuki used inferior seals back then. You will find better seals even on Russian or Eastern European bikes from the era.
3) With bad crank seals, the transmission will suffer from damage with or without oil mod. When the gears start whining, they are already beyond repair.
4) With bad trans, the center crank bearing is subject to premature wear since it's lubricated with transmission oil.
5) Generally spoken, you can fill in 2 liter transmission oil and forget the oil mod. This will cause little more clutch drag, about 5 percent. I've tested it excessively with transparent tubes attached to the engine.
6) Transmissions are mostly toast on bikes with inadequate transmission oils (ATF, engine oils) or on bikes driven hard over long distances. SAE 80 GL4+ or GL5 transmission oil is good choice.
7) As goes to statistics, on my 6 early bikes (1200cc oil) the gears were still OK after 10 to 12 thousand miles while they were junk on bikes I bought with 35+ thousand miles. All my spare engines I've collected over the years - 7 or 8 of them - come with transmission damage.

My advice, get a discount from the dealer and have the engine gone through by a T500 specialist.

Regards,
Argo

[Paulreade]

Cheers guys, the dealer has agreed to do the mod, the issue of crank seals remains a Q I have with him. If he will do it, I will have the bike if he won't I will probably decline. I have asked if there is any test you can do to confirm if the seals are good or not ( sorry engines are not my expertise). Another piece of advice that I received was to use EP 90 gear oil ?.
Look forward to any comments on available tests and gear oil spec ?
Regards
Paul

[m in sc]

does anybody have a link to the mod? im in the middle of doing up a 72 myself and the search function was kind of useless. thanks.

btw.. Hi guys! been a while

[ConnerVT]

Bulletin T-3

LINK

[m in sc]

thanks

[Paulreade]

Hi Argo
Thanks for the info. I have moved ahead with this purchase ( subject to hearing it run next week) I have got a bigger discount from them so an engineered solution may be the way forward.
In the intim if the gears / engine sound ok - they are doing a service on it before it's released - as regards oil spec and quantity should I ask them to deviate from what the book says perhaps ? Can you advise - it's a 1972 model.
Also I may look to purchase the oil dam kit and seals - where is best to source and does anyone know a ' knowledgable t500 engineer' in the uk preferably Nw England ?
Best regards
Paul