RD250/400 Transmission

[mavguy]

Is the RD250 and RD400 tranny the same? Especially  the clutch hub spline placement?
I don't  think that is correct but still need some confirmation. Could it be true for UK or Euro.models?

Thanks

[mavguy]

BUMP. Urgent.

[jmendoza]

RD250 has a different primary gear on the crank, different ring gear on the Clutch basket, and hub and  a different input shaft. The splines may be the same but the length of them is different due to the depth of the clutch assembly.

I know you can swap tranny parts between the DS-7, R5, RD250 and RD350, but not the RD400. 

[SUPERTUNE]

Is the RD250 and RD400 tranny the same? Especially  the clutch hub spline placement?
I don't  think that is correct but still need some confirmation. Could it be true for UK or Euro.models?

Thanks

No, 1st through 3rd ratios are the same but a 400 has a much closer ratio for 4th, 5th and 6th.
400's use a 6 spline so they do use a different splines from the earlier 250/350 models on both the clutch hub and drive sprocket.
Euro make no difference with 400's when they came out in '76.
Chuck.
P.S. Email me or pm me if you have questions...

[Jspooner]

Is the OP maybe asking about the later euro and UK 250s. Not sure what years they made them but I'm thinking they were during the same years of the 400 that we had. Did those 250s maybe have the same trans as the 400s. Seems to me I've read that somewhere.

[teazer]

Pretty sure that JSpooner is right.

Unless we're talking early RD250 into a 400 or t'other way around.  Primary gearing is different on 400 than a 250.  If you still need an answer let me know and I'll dig out parts lists and see what they say.

[SoCal250]

The 2R8 & 2R9 EU models used the same trans parts. I think the same may be true for the 3M3/3M4 Oceania models as well.

[mavguy]

Actually  my issue is with the clutch inner hub and the splines. From what I hear , the no. of splines seem to be the same on both RD250 and 400 and hub swappable......

[Jspooner]

Actually  my issue is with the clutch inner hub and the splines. From what I hear , the no. of splines seem to be the same on both RD250 and 400 and hub swappable......

Not on what was available in the US they aren't the same. For an RD400 trans you need an RD400 inner clutch hub if working with US issue stuff. A little more info of what you have might help the experts on here tell you what will work.

[mavguy]

Here is a UK listing.....splines atleast seem to be the same.


https://www.ebay.co.uk/itm/73-75-Yamaha-RD250-RD350-complete-transmission-shaft-and-gear-set-assembly-C-D/133024304920?hash=item1ef8ddcf18:g:kboAAOSwJxRctcf9

[Jspooner]

I actually think those are the same as RD400. That listing is wrong tho. An RD250C is not the same as 73-75 RD250. Do a little research............

[mavguy]

I actually think those are the same as RD400. That listing is wrong tho. An RD250C is not the same as 73-75 RD250. Do a little research............

https://www.ebay.co.uk/itm/Yamaha-GEARBOX-GEARS-RD250-RD400-E-and-F-2r8-2r9/264717242435?hash=item3da2609043:g:WwkAAOSwfDVeq933


https://www.ebay.co.uk/itm/Yamaha-RD-250-LC-4L1-Transmission-complete-56608770/283444278361?_trkparms=aid%3D111001%26algo%3DREC.SEED%26ao%3D1%26asc%3D20160908105057%26meid%3Db2ee9460ee01401e884324e45ea6587e%26pid%3D100675%26rk%3D3%26rkt%3D15%26mehot%3Dnone%26sd%3D264717242435%26itm%3D283444278361%26pmt%3D1%26noa%3D1%26pg%3D2380057%26brand%3DYamaha&_trksid=p2380057.c100675.m4236&_trkparms=pageci%3A016fe49b-919b-11ea-97b4-74dbd180c0ae%7Cparentrq%3Af737a6da1710a99481694d6affb0b2e5%7Ciid%3A1

[Jspooner]

Like I said, do some research, but I'm pretty sure the 2R8 will work for you with the right pieces but the 4L1 won't, it's for an LC.

[SoCal250]

I wouldn't believe anything from an Ebay listing. That first listing is a perfect example. Ebay is full of misinformation, dumbasses, and people just looking to make a buck(or pound) to unload stuff.  As Joe suggested, do your research and make your purchase on facts and valid data.   

[mavguy]

I agree and I did do my research. So the RD250 2R8 has the same splines/ clutch inner hub as a 400 but different gear ratio, correct? Its just that main shaft splines have got me confused