Author Topic: 75 rd125b crank seals  (Read 565 times)

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Offline LargeOwl

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75 rd125b crank seals
« on: March 07, 2018, 01:04:21 PM »
So i have replaced the stator side crank seal and all went well. Now i am moving on to the transmission side. My question is do i have to dissasemble the clutch or can i just remove the nut an take the basket off "loaded"? Is there any thing else i should know before attempting it.... 

Offline davecumbria

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Re: 75 rd125b crank seals
« Reply #1 on: March 07, 2018, 10:37:41 PM »
I guess some might say you don't have to remove the clutch basket to replace the crank seal, just the nut of the final drive. Its not something I've had to do as I've always had the motor stripped to rebuild the crank.

If the clutch basket  has to be removed its always best to remove the plates to get batter access, but they can be removed in one go (which keep them in the correct order!)
Growing old is inevitable, growing up is optional

Offline Barnett

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Re: 75 rd125b crank seals
« Reply #2 on: March 08, 2018, 10:02:35 PM »
I guess some might say you don't have to remove the clutch basket to replace the crank seal, just the nut of the final drive. Its not something I've had to do as I've always had the motor stripped to rebuild the crank.

If the clutch basket  has to be removed its always best to remove the plates to get batter access, but they can be removed in one go (which keep them in the correct order!)

+1 on the above.

I would remove clutch as (1) it gives you the chance to inspect it for wear and damage " while your in there" (2) gives you much more room to do the seal (3) easy to do if you have the neccesary tools, air impact gun works a treat for removing the clutch hub nut, hold with gloved hand.
The downside would only be, you need propper clutch holding tool, torque wrench, new bevile washer. Incidently you will need one for end of crank as well, they are the same.
Loosen crank primary first, tighten last after refitting clutch assy.

If removing clutch watch out for the number and location of the large washers behind both drum and hub, they do vary in type, thickness and location depending on model year as do the number and location of the clutch plates! Dont overtighten clutch spring bolts, nip up only.

The right side seal should have a seal retainer as per left side, mine was missing when stripped down so made one. Early models didnt have them on the right, if you have the two holes in the casing it should be fitted.

Only drive seals in level with outside of casing / housing, no further. Half fill seal void between lips with gen purpose grease on installation. If you feel so inclinded worth replacing little rubber o ring fitted between crankshaft and spacer bush, when fitting bush chamfered end faces crank, some bushes are chamfered both ends though.
Yamaha 1974 RD125 (AS3) nearly finished!
Kawasaki 1977 z650 B1 being ridden
Yamaha 1972/3 U.S. early RD350 in bits

Offline LargeOwl

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Re: 75 rd125b crank seals
« Reply #3 on: March 09, 2018, 05:43:33 PM »
Thank you. Do you know the part number for the washers i will need? 
« Last Edit: March 09, 2018, 05:52:52 PM by LargeOwl »

Offline Barnett

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Re: 75 rd125b crank seals
« Reply #4 on: March 10, 2018, 12:20:45 PM »
Origional no was 164-16119-00 replaced by 90208-12800-09 readily available esp in the u.s.
Bevile spring washer.
Yamaha 1974 RD125 (AS3) nearly finished!
Kawasaki 1977 z650 B1 being ridden
Yamaha 1972/3 U.S. early RD350 in bits

Offline LargeOwl

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Re: 75 rd125b crank seals
« Reply #5 on: March 10, 2018, 03:37:17 PM »
Thanks...so i took it all apart and good thing i did. The cutches were in the wrong order the thrust bearing was mis aligned and crushed. The o rings on the crank and behind the clutch were missing. Im not sure on the clutch o ring where exactly should it be? Also can where can i source those o rings? Good news is the seal went in nicely.

Offline Barnett

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Re: 75 rd125b crank seals
« Reply #6 on: March 10, 2018, 09:11:17 PM »
Oh dear, looks like sticky fingers have been in there and messing about with things they shouldn't!
You had better check everything out in there, have you got a parts manual and service or shop manual? Not sure if they are on this forum, need to have a look, otherwise you can download parts manual and all sorts of interesting stuff, pictures etc from yamaparts. http://www.yamaparts.com/manuals/
The european and us rd125s are very similar but be aware some bits will be different, lots of info in the states as it was a popular little bike, sites such as partzilla, boats.net etc. in the u.s. Have on line parts lists. For parts you should be spoilt for choice over there! Pick a big yam dealer or one of the specialist sites that know these old machines, e.g. H V Cycle. Climer manual is quite good for the u.s. Models of the little yams.

Part number for crank o ring is 93210-18023 or its new number 93210-180A6-00
There is one on the clutch but its much larger and fits on the outside of the basket, i.e. Between the primary driven gear and the basket, its just a shock absorber type thing not a seal, part number 132-16369-00. I assume you dont mean the rubber rings that fit between the steel plates and the friction plates? There are 5 of these I think, not strictly necessary and un obtainable, but if you have them and they are good, use them.
The thrust washer and bearing behind the inner clutch hub come as a pair, the parts manual will detail two part numbers but this is wrong. For the pair, i.e. Washer and roller bearing washer the part number is, 93341-22302-00.
Yamaha 1974 RD125 (AS3) nearly finished!
Kawasaki 1977 z650 B1 being ridden
Yamaha 1972/3 U.S. early RD350 in bits

Offline LargeOwl

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Re: 75 rd125b crank seals
« Reply #7 on: March 12, 2018, 08:00:10 PM »
Thank you i ordered the thrust bearing and washer now just looking for the the o rings i appreciate your help a lot an i will update my progress when i can.

Offline LargeOwl

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Re: 75 rd125b crank seals
« Reply #8 on: March 12, 2018, 10:51:21 PM »
Another thing i am wondering if the primary gear on the crank is on correctly. It fits on either way but one side is beveled, does the beveled side face out or in it looks like it faces out in the picture.
« Last Edit: March 12, 2018, 11:44:43 PM by LargeOwl »

Offline Barnett

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Re: 75 rd125b crank seals
« Reply #9 on: March 13, 2018, 10:17:25 PM »
Never thought of that, I always fit with lash number on the outside, will it go on the otherway round? Thought not possible, never thought to try!
Yamaha 1974 RD125 (AS3) nearly finished!
Kawasaki 1977 z650 B1 being ridden
Yamaha 1972/3 U.S. early RD350 in bits