YZ, IT, TT rear axle dimensions

[James P]

I'm trying to find out whether one of these rear axles will be of any use to me:

1W6-25381-00 - 1977-1980 IT250/400/425
2K8-25381-00 - 1978-1979 YZ250/400, 1979-1981 TT500

As far as I can tell, the two are practically identical, but the 1W6 axle has the pressed-in L-shaped "tag" so you only need one spanner to tighten or loosen the axle nut. If anyone has either of these types handy:

Is the shaft 17mm diameter?
What is the length of the shaft, including the thread (but not including the head)?
What is the length of the thread only?
What does the axle weigh?
Is the axle hollow?

If the dimensions suit my purpose, I'd be interested in buying one of these, so please let me know whether you have one available for sale!

Thanks & regards,
James

[mick25]

Yes they are 17mm but not hollow the TT ones
The TT ones have two different types etc lengths I have them but i will have to measure them tomorrow.
I’ve done the same as you finding the right one , I found a couple of RM axles that were hollow and 17mm and were the right length etc and lighter but now I am second guessing this after one of my solid axles was hard to remove from the wheel checked it and it was bent and I brought this axle brand new .

[LWC82PE]

I was certain that 78 YZ and TT500 axles were 17mm and hollow. Any 17mm and hollow RM axle would be from a full floater . Nothing twinshock  suzuki is hollow all the way through.

[mick25]

You are right Lwc , the TT ones are hollow only small hollow hole , the one I bent was a DR500 solid axle my mistake .
Yes the Rm ones I got from eBay were NOS ones with part numbers full floater .

[James P]

Thanks for the info so far. I have briefly investigated 17mm axles from Full Floater RM models and found the following:

64711-14600 - 1984 RM250/500E
64711-14610 - 1985 RM250F
64711-00B00 - 1986 RM250G

As far as I can tell, earlier Full Floater models used 15mm axles, while later ones used 20mm axles.

My research has suggested that the 1984-86 RM250s had hollow axles, but I'm not 100% sure.

Mick; Can you confirm any of the above relating to RM axles?
Is there any consensus on whether the specified YZ, IT and/or TT axles are completely hollow?

Regards,
James

[James P]

I have discovered based on information supplied (and followed up with further research) that 1974-78 YZ250s (also 1976-78 YZ400s) used the 431-25381-00 rear axle, which has been confirmed as hollow all the way through. It is 253mm long (not including head), of which the thread is 20mm length. It weighs 380g. It has been suggested that the 2K8 axle is slightly longer for use with an aluminium swing arm.

Although the 431 axle may suit my requirements, it may also not be quite long enough. Just about everything on Ebay (i.e. all the 431/1W6/2K8 Yamaha axles) is located in USA and the prices for axle & postage are not cheap enough to take a chance. I haven't yet confirmed whether any of the 1984-86 RM250 axles are completely hollow and I still don't know their pertinent dimensions (other than 17mm diameter). Prices of RM axles are also not low enough to take a chance!

The research continues...

Regards,
James

[mick25]

James I sent you a pm on RM axle sizes etc

[James P]

James I sent you a pm on RM axle sizes etc

Thanks to info from Mick, I have narrowed down the search a little more. I now know that at least one of the RM axles (64711-14610 or 64711-00B00) will suit my application.

Regards,
James

[James P]

I think I've sorted myself out for axles. Although Ebay offered several options, all of them were rather too pricey to take a chance...and possibly discover they were too long or too short. Although many of the axles themselves were reasonably priced, none were listed in Australia, meaning that postage (from USA) would often cost more than the axle .
I wondered whether it may be worth the 140km-or-so round trip to visit the ever accommodating Mark Collins at The Motorcycle Wreckers, North Richmond. Luckily it was !

Mark has two large plastic tubs full of axles - they took a while to search through, but I came up trumps. I found about half-a-dozen hollow rear axles with dimensions which looked like they would work. After narrowing down the field, I came away with three rear axles (one of them NOS) and three front axles, all for about the same price as the cheapest secondhand rear axle I could find on Ebay...and that's before adding the postage cost!

I'm not sure exactly what the NOS axle is, as the part number tag was missing. I think it is one of the RM250 ones (64711-14610 or 64711-00B00); 17mm diameter, 270mm long (not including head), about 30mm thread length and weighing about 350g. The zinc-plated finish is almost as-new, so I can use it as it is.

Thanks to those who have kindly assisted in my research so far .

Regards,
James