Help needed understanding older Isle of Man TT classes?

Hi everyone,  I wonder if someone can help me understand what these older TT classes were?  Whilst reading about Mike Hailwood at the 1979 IOM,  it mentioned about him narrowly missing out on victory in the "Classic TT".  Problem is, if you try and google IOM Classic TT all you get is the modern "Classic meeting" and not the original class.  The official IOM TT website gives very comprehensive results from every category in every year but no explanation as to what they were! 

So using 1979 as an example, the classes were:-  Formula One,  Sidecar (self explanatory)  Senior TT,  Junior 250 TT,  Formula two TT,  Formula Three TT   and Classic TT? 

Any help would be appreciated. 

Formula 1 - Bikes that complied with FIM TT Formula 1 rules, basically 1000cc four strokes in special chassis and up to 500cc 2 strokes in special chassis. The engines had to be based on current production road engines but the chassis etc was free choice.

Formula 2 and Formula 3 same philosophy as F1

F2 - 4 strokes up tp 600cc, 2 strokes up to 350cc (many of the 2 strokes were lightly modified TZ Yamahas using LC cylinders)  

F3 - 4 strokes up to 400cc and two strokes up to 250cc (viz 250 TZ instead of 350 TZ). Another successful F3 was the 350cc single cylinder Aermacchi Ala'Doro which as it was based on a road bike qualified without any modifications.

Note - the early 73-80 TZ were based on the RD road bikes with similar engine/frame configurations but upgraded for racing and water cooled. The liquid cooled LC Yamaha introduced in the late 70s meant that the F2, F3 bikes could run TZised LC motors including dry clutches etc.  

Senior - Up to 1000cc  

Senior - open up to 1000cc (big 4 cylinder 4 strokes), TZ750 2 strokes, RG500 two strokes and any other combination 

Junior 250cc - Two strokes (mainly) up to 250cc, but when the 350s became obsolescent (350 Yamaha TZ etc) they were allowed alongside the 250s (after '81 I think)

Senior Classic - 500 cc racing machines prior to 1968 (I think that was the cutoff date) - 2 strokes nota allowed

Junior Classic -  350 cc racing machines prior to 1968 (I think that was the cutoff date)

Lightweight Classic - 250 cc racing machines prior to 1972 (I think that was the cutoff date)

The cuttoff dates exactly for the Classic I am not sure of (never raced this type of bike apart from a brief stint on a 350 Aermachi Mettise in 1972)

Some info anyway.

Good explanation, Tony, but the 1979 "Classic TT" was another TT-F1 race with a bigger purse (like today's Senior TT is another Superbike race, isn't it?) - George won on his F1 Honda, beating Hailwood on the '78 Grand Prix Suzuki with which he won the Senior earlier in the week.

Edited by Michael Ferner, 11 June 2022 - 17:07.

Michael: Of course you are correct. I was forgetting that.

I still see Alex quite regularly.

THE 'Classic' races did not appear until later and held at the MGP.

The TT race classes seemed never to be the same from one year to the next in that period.

Edited by tonyed, 12 June 2022 - 03:22.

Thank you to both of you for your replies,  particularly for the classic explanation. I should have mentioned in my original post that the article I read said that Hailwood was on a Suzuki, so I had an idea that it wasn't a race for "classic bikes"  which is what made me curious in the first place.  As a side question, when did the class format as we know it today start? as I seem to remember a "light weight TT" and a 125 class at some point?

Are you familiar with https://www.iomtt.com/tt-database

The current format seems to have been introduced in 2010

There was an electric bike race - 1 lap up until this year - no loss in my opinion

The 250 cc Lightweight race last appeared in 2002 

The 125cc Ultra Lightweight class in 2003

Then it all became production based until the reintroduction of the 250s in 2013 as the Formula 2 Classic and then 2016 as the Lightweight Classic TT

Now we have the 'shopping bike class' the Supertwins which was introduced as the Lightweight TT. Started off as a 'cheap class' but has 'progressed' to another expensive class with factory manufactured specialised machines.    

That's right.  Motocourse 1979-80 lists it as the "Schweppes Classic Race: 1000 cc"

The final leaderboard for the race was populated by 1000, 750, 500 and 350cc machinery.