TY175 with DT175? forks and odd front wheel

[David Lahey]

I bought a TY175 a while ago that came with a DT175 motor, odd forks and front wheel. This posting is about changing the front end back to TY175.
The forks had less travel than TY175 forks and the action wasn't very nice, so I rebuilt some TY175 forks and fitted them. The backing plate brake torque attachment on the odd backing plate was a slot type that fitted the odd forks, so I tidied up an old TY twinshock backing plate that miraculously fitted the odd front wheel.
I have included comparison photos of the fork internals in case anyone is interested.

[David Lahey]

And here it is with the TY front end (and still the odd front wheel)

The other photo shows the odd backing plate in case anyone recognises what it is.

Maybe a bit of history might help with this too - the bike came from known bike fiddler Noel Pearce from Townsville

[Warren]

David
Is the brake plate supposed to be painted or should they be polished?

[David Lahey]

TY brake plates are painted (silver) to keep them looking pretty for longer than if they were bare magnesium.
The mystery brake plate in the photo is also magnesium. Does anyone know what Yamaha it is from? The wheel rim has a manufacturer's date of July 1982 if that is any use.

[trialsmutha]

unlike the rear hub, the front hub on ty,s are commen to quite a few yamaha models including a few road models with tin rims [19,s i think].mainly used in the early 70,s .it also stayed with a few of the cheaper models in later years.that 82 rim in your pic david could be a dt as you say or even a ag model. few years back i came across a few brand new road wheels with these hubs.all in all its good for us blokes cause front hubs are easy to come by! if you look inside it will have the code 248 which is the code for an AT1. the first model to use this hub. backing plates however were differant. hope this helps.

[David Lahey]

Thanks Adam I didn't realise that hub was so commonly used.
The backing plate still has me stumped because there is nothing to drive a speedo from on the hub or the backing plate. Maybe it's a backing plate off a kids bike like an RT100 or TTR90 that doesn't have a speedo - but why would they use magnesium on a bike like that?
Thinking about this reminded me that we must have come close to TYs having the same hubs as YZs and MXs, because in the film that Yamaha made about Mick Andrews riding the SSDT in 1973, Mick's bike being put through scrutineering for the SSDT has YZ pattern hubs (and fork sliders), but in the scenes shot soon after the SSDT, the hubs are normal TY items. Another thing I noticed is that the prototype he rode in the 1973 SSDT has a bulbous mag cover like an A model but no fancy symbols on it (ie a sand cast part), but the later bike (still in 1973) has a TY250 BCDE flat-type magneto cover. We didn't get the later magneto cover till the B model (late 1974).

[trialsmutha]

mick had some pretty trick gear thats for sure! did you notice that there is no oil pump cover on that ow? yam works bikes always have trick sandcast hubs,i remeber steve gall saying that the works hubs on his ow were that big and heavy that he ran std yz465 wheels instead.looked real good but not that great.mate of mine owned the bike for awhile and seeing the original hubs up close, and some of the high tech stuff of the day was amazing! the hand made parts look real crude and i lot of the ideas are still used today in modern bikes [more refined of coarse].i guess that works bikes are the pioneers for all those that follow. i gotta admit i love factory rides,OW,s. RC,s.RH,s.and RN,s.KXsr,s just to name a few.first time i seen the sandcast cases on my 325 beamish it made my works bike senses tingle......

[Tee-Why]

Just having read comments on "Works" bikes in Classic Dirt Bike Magazine, its not all what it seems. Some riders had different levels of factory support, some sponsored riders bikes were only factory replicas and were offered only some trick parts, many a bike was a well prep'ed stock bike, and the rider made the difference.

Thing is if you have access to the Yamaha parts bin being a sponsored rider, a lot of bits can be found to adapt or found to be of some advantage. The YZ465 front brakes were double leading shoe also.

BTW David, do you have any use for those DT forks now? I would gladly take the inner tubes particularly (or complete if you prefer) off your hands, my project DT175C has badly rusted and pitted tubes.

Cheers, Roger

[Hagsta]

Mystery Solved - I was talking to the "Known Bike Fiddler" this morning who said the bikes originally came from Chris Noon in Townsville. KBF's fading memory says the forks and backing plate are AT1 or CT1 (pre DT) and the rim is early YZ. The extended cable retainer was made up to accept the longer lever which came from his secret supply of Yamaha "Bucket Road Racer" stock.

[trialsmutha]

the bikes i were refering to were the " deal real" not replicas and not tricked stockys!, gall and landerman rode real ow,s here in oz. anthony gunter rode a genuine rh that was flown in for mr mx then taken back after the race! my cousin trevor williams had real kx380sr raced it in the mr mx series he was backed by kawasaki they flew the bike in but he owned it, he later sold it off to local farmer! this bike has since be found too! i still have the spare barrel of mike landermans ow. totallay diffarant to any yz bolt pattern and stud size.only the top guys got the you beaut stuff and even those bike were ridden buy a few riders.trev,s SR380 was ridden half the season by gassen galyon moiser in the states before he got it.