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Old 03-06-2013, 10:04 PM   #1
ironjack63 OP
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What happened to 5th gear????

I finally got my '81 r100rt started today and took it on it's maiden voyage after sitting in my buddie's storage barn for 7 years. It needs more tweaking and probably needs the valves set tomorrow, but my problem is that on my 25 mile ride today I could not get the bike to shift into 5th gear. No grinding, no nothing. I found a neutral between 4th and 5th, but no 5th gear. All shifts between the first 4 up or down were pretty darn smooth for a 32 year old bike, but no 5th gear. Any ideas?
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Old 03-07-2013, 03:30 AM   #2
Rob Farmer
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Has it any whining in the other gears?

First thing to check - is it a smooth gearbox or does it have reinforcing webs?
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Old 03-07-2013, 05:24 AM   #3
AntonLargiader
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Are you sure the shift lever isn't hitting anything, or that the shift linkage is loose? Losing 5th is just about unheard of on that transmission.
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Old 03-07-2013, 06:52 AM   #4
DaveBall
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Are you certain it is the original gearbox? Somebody may have swapped in a 4 speed. Why they would do that on an RT? I have no idea. But it could have been done.
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Old 03-07-2013, 08:13 AM   #5
Bill Harris
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Continuing to grab at straws, the gearshift pattern is one down and four up-- you couldn't be skipping 1st gear?

Loose or binding shift linkage is the best idea,

(yeah, I know the shift pattern has been standardized for centuries now, but I remember the first question in the 60's when "swapping out" bikes was "what is the shift pattern?")

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Old 03-07-2013, 10:57 AM   #6
kixtand
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Had this happen on a 5 speed of unknown origin before, turned out that the shift fork was stuck on the shaft it rides on...
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Old 03-07-2013, 12:55 PM   #7
disston
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My money is on the 4 speed trannie being in a bike that should have a 5 speed. But only because it would be the most face palm worthy solution. All the other ideas are also still in the running I guess. Will we hear the solution today?
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Old 03-07-2013, 01:32 PM   #8
ironjack63 OP
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I don't believe it is a 4 speed tranny, because when I attempt to shift into 5th gear, all I get is a neutral between gears like the pawl or whatever is just short of engaging. I will look this afternoon for anything in the way of the lever, but I don't recall anything being there. The tranny is not as smooth as my new Bonneville, but it is not bad for a 32 year old bike. There is no grinding or whirring or any out of place sound to be heard going down the road, it just won't shift into 5th. More to come after another test ride.
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Old 03-07-2013, 01:38 PM   #9
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I get some very intermittent false neutrals between 4th & 5th. Doesn't happen in the other gears. But usually all gears slip right in.
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Old 03-09-2013, 06:39 AM   #10
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Quote:
Originally Posted by AntonLargiader View Post
Losing 5th is just about unheard of on that transmission.
I just took a trashed trans in trade for showing a traveler passing through town how to check/adjust valves, rebuild his carbs, etc. Aside from being really tough to turn over by hand and making nasty growling sounds when you do, it's lost 5th gear. Why are the early 80s boxes less likely to lose 5th?
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Old 03-09-2013, 08:12 AM   #11
100RT
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Let's start at the beginning, Was that the first time you have ever ridden the bike? Did it ever have a 5th gear?
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Old 03-09-2013, 08:30 AM   #12
DaveBall
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In my experience, I have not heard of nor found any airhead to lose 5th gear all by itself. Maybe in conjunction with all other gears being blown out a hole in the tranny, but otherwise?

Start at the beginning. Are you shifting 1 down and 4 up? If so, and you can't get into 5th, then check how you are shifting. These are tractor style transmissions. They can be hard to shift, until you get used to them. Shifting from 4th to 5th can be notchy, especially if the tranny has been abused in it's lifetime. When you are about to shift from 4th to 5th, put a little preload on the shifter prior to pulling in the clutch, then when you pull the clutch, give the shifter a good solid movement upwards.

If you still can't get it to go to 5th, check the tranny to see if somebody has swapped out the 5 speed for an older 4 speed. It is a fairly simple swap that somebody may have done due to blowing the original tranny, and never got around to putting in the correct one. I have heard of the odd, and very well used, 4 speed tranny having a false neutral above 4th. But that was a very abused bike.
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Old 03-09-2013, 09:23 AM   #13
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My r90 did this when I first started riding it. After three fluid changes and a lot of riding it anyway, fifth came back.

It also used to get stuck in third. No up or downshifting possible.
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Old 03-09-2013, 10:29 AM   #14
100RT
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The 81 was the first year for the new style "clutch carrier (flywheel) that includes a different clutch disc, input shaft and all related parts.

In my opinion, I wouldnt refer to it as a simple swap of parts.
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Old 03-09-2013, 02:11 PM   #15
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Quote:
Originally Posted by 100RT View Post
The 81 was the first year for the new style "clutch carrier (flywheel) that includes a different clutch disc, input shaft and all related parts.

In my opinion, I wouldnt refer to it as a simple swap of parts.
Good point RT. As profound an explanation as the older trans swap might be it is not a simple thing to do. Possible 4 speed trans very unlikely.

As KT's example suggests there is a possibility of things correcting them selves. Have you changed the gear oil in this trans? Would like to see what the stuff in there looks like. Certainly the bike can be ridden at highway speeds in 4th gear.
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