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The 2-Stroke Garage => Turning Wrenches => Topic started by: gargantua350 on November 27, 2024, 10:18:53 AM

Title: shift shaft upgrade
Post by: gargantua350 on November 27, 2024, 10:18:53 AM
Hello All.  I purchased the shift shaft upgrade kit and had questions on the PVC tube with set screw.  Looking at the installation pictures it looks like it tube rests right on top of the seal.  The original or oem had a washer and E clip.  The E clip prevented any excessive side to side movement.  My question(s) are:

Do I put the tube right on top of the seal with no gap?  Or do I add a gap between. Would it be better to put the washer back in so that it is between the tube and seal?

Right now I have the tube resting right on top of the seal with the shaft fully extended out. By tightening the set screw, this prevents any side to side.  Is this ok and does anybody have experience with this?

I have a 1973 RD350 but I assume it will be the same installation on the later years.



(https://i.postimg.cc/bd2D03WX/shift-shaft-seal.jpg) (https://postimg.cc/bd2D03WX)
Title: Re: shift shaft upgrade
Post by: rodneya on November 28, 2024, 03:56:21 PM
I would say no gap. or very small gap so that the shift shaft can not move inwards. I dont think the washer makes a difference
Title: Re: shift shaft upgrade
Post by: m in sc on November 28, 2024, 05:57:09 PM
i still feel this is a band-aid, at best. the actual fix is to bush the outer cover & remove shaft flex. thats what kills the seals.

id leave the washer and clip in place with a new seal in the case as well. there needs to be enough 'gap' to allow free movement (rotation) of the tube.
Title: Re: shift shaft upgrade
Post by: 1976RD400C on November 29, 2024, 05:47:14 AM
I would put the side cover on with the set screw loose and wiggle the plastic tube to check what kind of gap there is, if any, to add the washer.
Title: Re: shift shaft upgrade
Post by: gargantua350 on November 29, 2024, 09:45:55 AM
Thanks for all the suggestions guys really appreciate it.  I think in it's natural state of operation there should be a gap for relief.  Out here is ca we do alot of riding so I will report out my findings.  the true test will be an endurance/cycling type but you can only achieve that will riding time.

 
Title: Re: shift shaft upgrade
Post by: gargantua350 on December 01, 2024, 10:03:35 AM
Just an update/observation.  I inspected the black rubber seal and with no gap there are some indentations caused by the plastic tube.  I feel that over time this will wear it down if the tube is right up against it after many shifts, and may shorten the service life of the seal.  I decided to add about a .025 gap approximately and will report back.  the shifts however have improved as all the play is gone.  I am satisfied with those results. 

New top end on this motor is coming and so far its ran great in this configuration probably the best it ever ran.  This is all because of the support and great forum members.

big thx to all...
Title: Re: shift shaft upgrade
Post by: Striker1423 on December 02, 2024, 09:50:19 PM
Not to hijack the thread, but Mark do you have any bushing size suggestions?

My RD is one errant foot away from false neutrals. I have a bad habit of flicking the trans and I really have to give it a good toe up to get positive shifts.
Title: Re: shift shaft upgrade
Post by: m in sc on December 03, 2024, 07:17:00 AM
pretty sure this is what i used

https://www.mcmaster.com/6658K11/

just remember to 'recenter' the hole in the outer cover. by this i mean, measure which side was worn and how much, then file the other side the same amount. this makes a 'centered' oval. drill to 9/16" then ream to 15mm.
Title: Re: shift shaft upgrade
Post by: soonerbillz on December 07, 2024, 11:07:06 AM
Quote from: m in sc on December 03, 2024, 07:17:00 AMpretty sure this is what i used

https://www.mcmaster.com/6658K11/

just remember to 'recenter' the hole in the outer cover. by this i mean, measure which side was worn and how much, then file the other side the same amount. this makes a 'centered' oval. drill to 9/16" then ream to 15mm.

 Thank for link Mark.
 I do wonder if the bushing would ever see enough friction to actually release the oil as designed.
Title: Re: shift shaft upgrade
Post by: m in sc on December 07, 2024, 11:30:32 AM
its sees enough to oblong the case cover.. not sure but its better than 50 year old aluminum.