Overdrive 5th gear

I had the same problem. Measured and went by year on Mike's chart for my '83SK that called for the smaller hole but guess what? Would not fit. Had to use the earlier version with the bigger hole. On the upside Mike did exchange for free (no restocking or other BS charges) I think the moral of the story is you never know until you try?
 
Gefest. Hello there, I kinda agree with twomany, why? Sales? I didn't change mine, mainly because my mating gear was in great condition. If the dogs are worn, then I would buy the new one. I will say that the 81 mating gear was much beefier than the 72.
Not to repeat myself, but I bought an 81 trans on eBay, (it was in great condition), for $40 and put it in my 72. I also added the taller 5th gear. Mine works great.
I strongly recommend that you carefully inspect the shifting forks. My center one was bent. Too much power shifting in my 20's.
Good luck! :bike:
 
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Maybe this 'mating' gear needs clarification. Here's the MikesXS listing:

http://www.mikesxs.net/product/05-0857.html

05-0857.jpg


The listing shows this to be the opposing 22-tooth 5th slider that rides on the final output shaft, as part # 256-17251-04. It's gearteeth will be in constant mesh with the OverDrive gear that's on the (driving) mainshaft. It's these gearteeth that are in question.

Note that with the -04 suffix, this would be the revised later gear that only works on '77-up output shafts. Also, this gear slides to engage 2nd and 3rd gears. As such, it has nothing to do with the advertised 5th gear engagement dogs.

The 20-tooth 3rd (driving/spindle) slider gear, on the (driving) mainshaft, part # 256-17131-0x, is adjacent to the Overdrive 5th gear, and contains the engaging dogs that have a history of wear and breakage.

Here's a pic of the transmission layout:

View attachment 54332
 
Well, I bought a pair of gears from Mikesxs...
and I saw the difference
Part #05-0857
Left - stock, Right - Mikesxs
ac6e0ba16db491f509f2849b86e8c0ce.jpg

35160580f24fccc3a55fea4dd3d15528.jpg



in the rest the same

Part #05-0869
Left - stock, Right - Mikesxs

8dd9a9a4616b50943febfa2a109e97ce.jpg

55e13f3fcd174f2750c91a89605b6a1c.jpg

75e6bf62e5381bbe68f4513b6a8d0ca1.jpg


Now what worries me
I said before:
Gefest said:
Good day, I want to change the transmission of 5th Mike, Mike has 2 versions of the gear, I measured a shaft it's 24,94mm(0.982")
I Have XS650 SJ 1982.
Mike says this year will approach Part #05-0870
Main shaft 0.975 mm ONLY
0.979 inches or 24.82 mm (Hole diameter)
But this is not true, I have larger shaft it"s 24.94mm(0.982") not 0.975 or 0.979 like Mike says.
It turns out, the need for my gear from 73-77 Part #05-0869 ???
Click to expand...

Part #05-0870 24.82 mm (Hole diameter)from Mikesxs will not sit down on the shaft, is too small
Part #05-0869 25 mm (Hole diameter) what we need

but when I installed, I found the backlash, It is very small compared with the flow, but there is


This is OK?
Part #05-0870 24.82 mm (Hole diameter)should not sit, Part #05-0869 25 mm (Hole diameter) must be OK... a small backlash is possible? Can I install it?
 
Great pics, Gefest! And, good video of the gear/shaft fit.

It appears that the MikesXS gear does indeed have an extra 0.025mm - 0.050mm diametrical clearance. Other folks have run with that clearance without issue.

But, my personal preference would be to get the smaller gear, and grind its ID to match the original's closer clearance. And, most importantly, grind it to be concentric with the gearteeth, not the original bore.

But, what is really concerning, is your close-up pic of that new OverDrive 5th's slot walls. They look straight, as though they're not undercut. And, that's the concern over several member's reports of the transmission jumping out of gear...

OD-5th-Undercutting.jpg
 
so it's been 3 months since I first posted in this thread and I just got round to measuring my shaft today.

I had a struggle getting the circlip off at first because my only pliers are for internal clips. Nevertheless I could see enough shaft bearing surface to get the tips of my vernier jaws on to measure. It came it at .979

Not being happy with the accuracy of this I persevered with the clip and got it off. Measuring again I got .982

Now here's why I think the .979 measurement came about improper use of measuring tool. If you use the vernier jaws at the tip and push the thumb slide hard enough you will get a smaller reading than it is due to the caliper giving a little.
Ideally the part should be in the root of the vernier jaws and instead of pushing the slide over with the thumb squeeze the jaws together either side of where they contact the part being measured, it keeps the jaw surfaces square and the reading true.

So according to my ruler* I have .982 shaft with .984 gear as stock on my '77 with early trans...
EDIT: which means, like Gefest, I need part 0870 with 25mm hole. heiden's claim this to be for '78 to '83 bikes. so do I trust the description of "'78 to '83" or "25mm"?
 
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so heiden's only sell one part for this, the 0870:
http://www.heidentuning.com/p/28/21.../#05-0870-gear-5th-overdrive-25mm-inside-diam

heiden's 0870 they claim it's 25mm bore .984" and fits 78 to 84

and mike's sells 2
mike's 0870 is claimed to be 24.82mm .979" and fits 78 to 84

mike's 0869 is claimed to be 25mm bore .984" and fits 73 to 77

I know I want .984" 25mm bore so which am I supposed to buy? Gefest has returned his 0869 piece from mike's which was claimed to be 25mm .0984"
Mike's website says to measure before ordering but none of these websites agree on size and part#.
I've read this thread backwards and forwards a few times trying to pick out the details and still ain't sure of what's what and what's wrong.
EDIT: Perhaps twomany's last post says it all. buy the big one and have a bit of slop or buy other and open it up.
 
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TLCbobber said:
... buy the big one and have a bit of slop or buy other and open it up...
Click to expand...

I think that Gefest's strategy is the latter, buy the smaller one and regrind the ID to get the closer clearance found in the OEM original.

Word of caution about calipers (especially the budget versions). Many have a 'varying' accuracy of greater than 0.001", meaning that at one point on the dial the measurement is accurate, and at the other side, can be more than 0.001" off. You would need a set of standards to find the pattern of this variance, and mark corrections on your caliper.

Myself, I'll use my calibrated calipers for general (+/- 0.001" or +/-0.002") work. But for precision fitments, I'll use micrometers that have been calibrated to my standards.

I zoomed-in on Heiden's picture of his OD 5th, and couldn't see any evidence of backcutting in the slots. I wonder what his opinion on that would be...
 
Thanks TwoMany, yeah my verniers probably aren't the best... cheapish digital ones I figured they'd be good enough to sort this out.

What do you make of heiden selling #0870 as a 25mm bore whereas mike sells #0870 as 24.82mm? Mike's #0869 matches heiden's #0870... but why? Suppose I could buy heiden's 0870 play or no play, and deal with it when it comes... or buy mike's 0870 and know it would need opening up. I'd just rather not have the play Gefest encountered. too tired for this shit now, it's way past my bedtime and it's doing my head in.
 
TLCbobber said:
...What do you make of ...?
Click to expand...

Well, I really don't know. I'm mostly just providing sideshow entertainment here.

If I had a box of those gears in front of me, and a set of go/no-go gauges for testing, I wouldn't be surprised to find various diameters. I'd also wonder if some, or none, have been backcut. Then there's the gearteeth. Haven't explored that yet. We all know how, nowadays, quality control has been dumped into the customer's lap. For now, you fellows buying this stuff are our best feedback...
 
well that's the problem, one is either too big or too small. now your option is to enlarge hole to fit to your satisfaction with suitable clearance rather than have one that is too loose like #0869.

I remember a comment made by Hugh of HHB where he said every one he's ever ordered has been too small and required machining to fit... so it is my assertion that he orders the small one as a matter of course and machines it to fit later transmissions on later bikes and also fits later transmisission to early bikes as matter of course... so no wonder every one he's ordered has been too small and needed machining. kinda left us that one to figure out ourselves lol... "gotta keep some secrets" :O)

I mean if he can throw in a later trans then he probably does and puts on #0870 with machined hole to fit right... which is probably the best course of action as I understand it. I mean he flat out refused to offer a machining service for this even though people would have paid for it lol.
 
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xsjohn said:
2. Lowering the R/S hotter cylinder temperature will reduce the cylinder temperatures like 20+ degrees ...........
Click to expand...

what does this mean? I'm guessing it means "lowering the [right side] cylinder temps [which are hotter than the left side] will reduce overall cylinder temps 20+ degrees"
How is that accomplished, beyond air dam wings on the front down tubes and an oil cooler in line with the oil tube in front of the engine? Is there some other way to magically drop 20 degrees in cylinder temps?
 
Muckroot said:
what does this mean? I'm guessing it means "lowering the [right side] cylinder temps [which are hotter than the left side] will reduce overall cylinder temps 20+ degrees"
How is that accomplished, beyond air dam wings on the front down tubes and an oil cooler in line with the oil tube in front of the engine? Is there some other way to magically drop 20 degrees in cylinder temps?
Click to expand...
Nevermind, edit, I have no idea how to drop tem by 20.
 
This was a fun journey down memory lane.

I'm running a rebuilt '81 engine in my '77, picked it up in a parts bundle a half dozen years ago or so. It's still in the break-in phase. Provenance is unknown aside from it was rebuilt and it came from New Hampshire or Vermont, went to South Jersey and I got it from there.
OK
The '77 is stock gearing 17/34 with the 18" rear wheel.
Total different animal from my old '83.
Today I was out cruising 55mph @ 3500 rpm. I've cranked her up to 70mph @around 4000 rpm with plenty of twist left on the throttle. I don't want to go faster....lol.
I haven't been trying to find 6th gear like on other 650 engines and have no desire to throw the 18/32 sprocket combo or any variable combo on as long as she runs like this.
I did find Petes spreadsheet in the body of this thread and now I wonder if the 5th od gear was installed.
I'm not going to break the engine down to find out...... something about lookin' in horses mouths or sumpin'.
Speedo clock is the zero to 140, tach is a tach.
 

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