Author Topic: A7SS Gearbox  (Read 4332 times)

Offline Mosin

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A7SS Gearbox
« on: 06.07. 2009 12:07 »
I have now covered about ten miles on my A7SS, but for the life of me I can only seem to find three gears in the box! The speedo doesn't seem to be working very well and is not accurate and I have mostly been riding down very narrow country lanes where it can be difficult to guage exactly what speed I am doing, so it is not easy to tell what gears I am getting. I have checked the gearbox oil and that is fine and the clutch etc seems to be working well, but the box is still very clunky, only allowing me to drop from what I think is second, down through neutral to first when the engine is running very slowly. My instinct is that I am not getting top as The engine seems very revvy when I am in the highest gear I can find, but without getting out onto a main road, it is difficult to be sure. Especially since I have never ridden an A7SS before and have nothing to compare it to. Unfortunately, My bike does not have an MOT and the nearest test centre is 25 miles away and I'd rather not ride this without top gear! Hmmm.

Any suggestions for things to check would be most welcome. 
1960 A7 Shooting Star
1959 D3 Bantam
1994 Triumph Trident 900

North West England

Online RichardL

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Re: A7SS Gearbox
« Reply #1 on: 06.07. 2009 13:31 »
Mosin,

At the risk of horribly underestimating your experience, I apologize in advance, however, it sounds like you are starting out in 2nd gear (down one stop from neutral), which would explain slow engine on take-off. First gear is upward from neutral (sorry if this is way beneath your understanding). Depending on the chain sprockets on the engine and gearbox, 4th gear (1:1 ratio) can feel like a rather low gear for the open road. My 4th gear is a bit like this. I am yet to try real road speeds of 65+ mph, as my engine is yet to complete the break-in period. If your gearbox has "Sc" stamped on top, it is a scrambles type and 1st, 2nd and 3rd gears are lower ratios than a standard gearbox.

All of the above said, there may be a problem in your gearbox which might, from your story, be recognized by someone having more experinece than I.

Well, now, I'm just guessing and others will put me in my place for my "misguided ideas," but it also sounds to me like, either, your shift pedal is on backwards or you have a rear-set shifter cam plate (inside the gearbox) with a front-set pedal.

Boys, straighten us out!

The discussion got me thinking again about ratios, so, I went looking for this chart in our fourm.  http://www.a7a10.net/forum/index.php?action=dlattach;topic=325.0;attach=465;image

Part of the point is how great the forum is in keeping our precious information resources. I went to the search tab and entered "gearbox chart" and "Match All Words" and, presto, there it is!

Regards,

Richard L.
Plan on signing up for the world-wide 2017 DISTINGUISHED GENTLEMAN'S RIDE on September 30, 2018. Watch website at https://www.gentlemansride.com for details.

Offline Goldy

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Re: A7SS Gearbox
« Reply #2 on: 06.07. 2009 17:02 »
The gears on my machine were difficult to engage after re build. I found that I had the cam plate plunger screwed in too far. I kept unscrewing it half tun at a time with the bike on the stand, until the gears selected more easy. Might be worn checking.
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Offline MikeN

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Re: A7SS Gearbox
« Reply #3 on: 06.07. 2009 20:56 »
Mosin,
 Here are 2 rather obvious questions.
a) ,has this g/box just been rebuilt and
 b) Are the timing marks on the quadrant aligned correctly ?
 As described in the Haynes manual.
Mike

Offline roadrocket

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Re: A7SS Gearbox
« Reply #4 on: 06.07. 2009 21:36 »
Hello

I have just spent a long time sorting my box, and just to put a very hard earned piece of information forward, my box would not shift correctly with the two dots aligned, but rather with the one on the quadrant one notch down. Took many test fits to figure out... Now everything is sweet again.

Otto in Denmark
Otto in Denmark

Offline Mosin

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Re: A7SS Gearbox
« Reply #5 on: 10.07. 2009 22:00 »
OK, Thanks for all the tips guys. I have now had the A7 out on the open road and am now convinced that it is top gear which I cannot find. I am selecting first ok (one notch up from neutral) and then dropping down into second, then down again into third, but after that I am hitting a stop. The engine runs beautifully up to about 50/55 in the highest get I can find (which I think is third), but then it runs out of power, is revving like mad, and is crying out for another gear.

I decided to have a look at the Cam plate plunger as it seemed the easiest thing to start with, but both it and its locking nut are siezed absolutely solid and they are not the easiest things to get at. I am at a serious risk of rounding off the corners if I apply any more force to them. Something which I don't want to do.

MY gearbox has "STD" stamped into the top of it. I assume that this means it is a standard box.

I do not know if the gearbox has been rebuilt or not as I bought the bike on ebay and got very little information about it. But it is increasingly looking as though the gearbox is going to have to come out of it while I investigate things further (and also free up the siezed Cam plate plunger). I have never taken a box out of a bike before.

Is it relatively straightforward? Does the engine also need to come out? Is there anything in particular that I need to know before I start? Is there anything else I can try before I resort to removing the box from the bike?
1960 A7 Shooting Star
1959 D3 Bantam
1994 Triumph Trident 900

North West England

Offline MikeN

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Re: A7SS Gearbox
« Reply #6 on: 10.07. 2009 23:43 »
Mosin,
  You can examine the contents of the gearbox without removing it ,or the engine.
 You can pull most of the internals out from the r/h side.If you want to remove the mainshaft or get to the sprocket and main bearing then you will have to remove the primary (l/h)drive side .Chain-case clutch and chain etc.
 It is straightfoward.Follow the directions in your manual.
Mike

Online trevinoz

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Re: A7SS Gearbox
« Reply #7 on: 11.07. 2009 01:15 »
I would look at the "timing" as Otto mentions. The lining up of the dots is a little hit and miss.
Take the outer cover off and try to select the gears with a screwdriver or some type of lever and see what you get. If the box is out one tooth you will find that the selector fouls the slot in the inner cover and will not move far enough to select top gear.
Trev.

Offline Mosin

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Re: A7SS Gearbox
« Reply #8 on: 11.07. 2009 16:00 »
Well I opened up the gearbox this afternoon, as suggested, and found the mark on the quadrant to be miles off the mark on the casing. Assuming that I had found the problem I lined them up perfectly, reassembled the lot, filled it with oil and took the bike for a spin. Hey-presto, I now have only TWO useable gears! Second and Third. Once it's cooled down a bit, I'll try it as Otto suggests with the quadrant one notch down and see what happens. Why is nothing ever simple?
1960 A7 Shooting Star
1959 D3 Bantam
1994 Triumph Trident 900

North West England

Offline roadrocket

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Re: A7SS Gearbox
« Reply #9 on: 11.07. 2009 16:38 »
This is how the dot alignment looks on my box when gears are indexed correctly:

Otto in Denmark

Offline LJ.

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Re: A7SS Gearbox
« Reply #10 on: 11.07. 2009 17:23 »
Quote
Why is nothing ever simple?

Mosin... It is simple!........... when you know how! I almost guarantee that when you get this sorted, you'll know for next time and probably will be advising the next person who has your problem.  *smile*
Ride Safely Lads! LJ.
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Offline a10gf

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Re: A7SS Gearbox
« Reply #11 on: 11.07. 2009 18:41 »
Quote
Hey-presto, I now have only TWO useable gears!

Ahhh, nothing compares to the joys of owning and restoring old machinery  *smile*

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Offline Mosin

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Re: A7SS Gearbox
« Reply #12 on: 11.07. 2009 19:43 »
Having now dissassembled and reassembled the b*%^&y thing about fifteen times today, I finally took it out for a spin. The gearbox was jumping all over the place, particularly out of gear, and the clutch for some reason started slipping like mad, but I am pretty certain that at various times on the ride I managed to attain all four gears; A first! Unfortunately before I was able to set up the clutch and try it again, my wife reminded me that I have a 10 month old baby who hadn't seen me all day....

Oh well, I'll have another look at it tomorrow...
1960 A7 Shooting Star
1959 D3 Bantam
1994 Triumph Trident 900

North West England

Offline roadrocket

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Re: A7SS Gearbox
« Reply #13 on: 11.07. 2009 21:03 »
I would suggest the boring but thorough way; take the whole box out, and take it all apart, to inspect the gears. It is easier to check new settings when the box is in a vice also. Then you know what you have. You can get gearbox parts fairly easily on eBay. I know what you're going through! I was there a month ago, but the stuff does work when assembled correctly. If all bushings are worn it would add to the general malfunction of things, but this can be fixed by simple replacement - even if it is a lot of work.

Otto in Denmark
Otto in Denmark

Offline Mosin

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Re: A7SS Gearbox
« Reply #14 on: 12.07. 2009 19:05 »
Success! (in part).

Well, I now finally have all four gears, plus neutral, selecting very positively and all is looking good (This was finally achieved by positioning the mark on the quadrant two notches above the mark on the casing). Anyway, delighted with myself, I put the whole thing back to gether and went for a spin only to find that the clutch has suddenly started slipping like mad as soon as it is under any load at all. This is something which it never did when I only has three gears. I tried backing it off on the adjuster tight to the point where it was actually dragging as I was stationary and in gear with the lever held right in, but it was still slipping under load. Sorry for being a pain, but can anyone offer any explanation for this, and more significantly, any possible solutions?

Many thanks

Simon
1960 A7 Shooting Star
1959 D3 Bantam
1994 Triumph Trident 900

North West England