C/R DT1 gearbox

[ji107]

Does anyone know if there are any gears/shafts that can be used to make a DT1 gearbox close ratio?

[Lozza]

What are the ratios' now and what ratio's do you want? No good closing up the box without closing(tightening ) up the power band.

[ji107]

1st  2.533
2nd 1.789
3rd  1.304
4th  1.000
5th  0.55

I believe that this is a "station" dt1 hence the ratios are different to STD.

Powerband will be tightened up considerably

[ji107]

On checking ratios, my 1st and 2nd, with 3rd, 4thand 5th from a std dt1 would probably be reasonable
1st  2.533
2nd  1.789
3rd  1.211
4th  1.000
5th  0.615

[Lozza]

First to 4th aren't to bad, gap from 4th to 5th is diabolical. Rendering it basicaly useless.Shaft centre to centre distances will govern ratio options, but wouldn't bother with replacing anything else bar 5th about 0.89-0.92 should work a treat.

[ji107]

I buggered up the figures, got confused with 5th, should read 0.766 which would make it a lot better.
Looks like it is a DT2 box

[jimg1au]

HI
i have a spare std dt360a gearbox set

[ji107]

Is that different from DT2/RT2 ?

[firko]

Jims gearbox won't fit but can be made to fit with a bit of work. It ain't worth it though.
Look for a DT2/RT2MX or YZ250/360 A&B close ratio trans. Good luck. What's a ''station'' DT1?

[ji107]

Don't know how true it is, Iv'e been told that Yamaha made slightly different models for the Aust cattle stations, designated by having. a "S" stamped on the front of the cases. Suposedly different gearbox and comp.
Gearbox part hasn't proved right!!  Sdt DT2 ratios

[mx250]

Don't know how true it is, Iv'e been told that Yamaha made slightly different models for the Aust cattle stations, designated by having. a "S" stamped on the front of the cases. Suposedly different gearbox and comp.
Gearbox part hasn't proved right!!  Sdt DT2 ratios

I have heard of a DT1 'Station', it was a version of the DT specifically set up as an outback Ag bike. I can't remember the specifics but a change to the gearbox was one of the differences. I think it had a lower first gear to dodge along behind cattle etc.  The other differences were pretty minor I think; maybe bigger/better air cleaner, bigger 'footprint' for the side stand, carry rack for 'Rover' .

[JC]

Std DT2/3 (& later DT1) 5th (.766) is 23.4% gap from 4th, which is OK for the trailie (it gives an effect like an overdrive in a car) but useless for racing. DT2M/RT2M is close to 20% (.793) which is nearly passable. YZ is about 14% (.857). All use 1.00 4th gear IIRC

[crossedup2]

I just picked up all the parts for a AT1 MX close ratio box from US. You can find the part numbers from the Yamaha site and do the search. I did have a quick look at the RT/DT stuff and they seem to have most if not all the gears. There are a couple of different ratios on some of the gears so you better pick the right ones.

The AT box cost about $140 US. plus postage and is ready a to be slipped in. Not sure what the RT/DT box would be worth in total but the ones I looked at seemed about the same price I paid.

Good Luck

Peter

[Freakshow]

Im prity sure the white DT pre 70 at Canberra nats was a Station, your right in that there are a few out there, also has the s on the barrell too from the one i have seen, looks prity much like an Ag DT1, and yes the gearbox had a long end and a short end, think it was made up to fill a hole in the product range and off load the last of the series 1 type units.

[ChrisACT]

Stock DT1 ratios are:

2.231
1.624
1.211
1.000
0.826

Stock DT2 ratios are:

2.533
1.789
1.304
1.000
0.766

DT2MX ratios are:

2.25
1.65
1.26
1.00
0.79

For my DT3 road bike I have bought 2nd and 3rd gears from a DT2MX and I'm going to run that with 1st, 4th and 5th from a DT1 box.

So I end up with:

2.231
1.65
1.26
1.000
0.826

It's reasonably close , closer than the DT2 ratios anyway but has a more even spread of ratios than the stock DT1 box.