Second gear dramas (another one!)

[drworm]

Hi guys
I have a problem with second gear 'slipping' out and back in when accelerating. I understand this is reasonably common.
Luckily I work in a decent machine shop as a toolmaker, so have access to milling machines etc.
I am curious about undercutting the gears, or just recutting them square again if they are not too far gone.
I realise to take the engine out special sockets are required so I will machine some up tommorow after a few measurements. Any SA guys will be welcome to borrow them.
If anyone would like to share their knowledge/experiences I would be very grateful.
So far I have established I should be replacing the shift fork, and inspecting/replacing/remachinnig the gears. Any other tips?
Thanks guys
Ben

[Maj]

Fork and probably shaft, there are hd shafts available, last ones i had came from Pete
if it hasn't been going on for long you can do the shift forks through the cover behind the sprocket
quite fiddley but can save many hours

Do you have a disposable 1/4" carbide burr & bearing blue , the gears are bloody hard, as you would expect,
you need a fairly square corner and a bit more angle in the back cut than they have std, so on drive they pull together not drive apart..
I have a roadranger with a similar problem in top and wondering if i can just cut them

[GRUNTMAX]

Dr Worm,

The 2 forks on mine-OK, the 1, worn well below specs.
Like Maj sort of says, the stock shift shafts are shitty tubes that flex too much. If ya work in a machineshop, you could make your own, or just buy "billet shift shafts" . Just happened to have this handy & schnitz racing or alpha-sports sells those the tools. If your going to pull the gearbox apart, may as well fit a high ratio 5th n 6th Gear, low ratio 1st gear, heavy duty output shaft. Up 2 teeth on the front sprocket, down 1 at the back.
Don't spend too much money
[attachment=9414]
Don't forget the gaskets.

[heavensdoor]

Thanks GRUNTMAX looks handy information for gear box rebuild.

Dr Worm,

The 2 forks on mine-OK, the 1, worn well below specs.
Like Maj sort of says, the stock shift shafts are shitty tubes that flex too much. If ya work in a machineshop, you could make your own, or just buy "billet shift shafts" . Just happened to have this handy & schnitz racing or alpha-sports sells those the tools. If your going to pull the gearbox apart, may as well fit a high ratio 5th n 6th Gear, low ratio 1st gear, heavy duty output shaft. Up 2 teeth on the front sprocket, down 1 at the back.
Don't spend too much money

Don't forget the gaskets.

[Camel]

TUNGSTEN carbide burr! Carbide gets shot to shit too quick. But I've found an even better way. A compound table, a swivel angle plate and a 4" grinder fitted with a 1mm thick cutting disk. Make a mount for the grinder, and another for the gear (I use a spare shaft), adjust the position of the gear using the swivel plate and compound table. Just get your angles right and drive the gear to the grinder, does beautiful undercuts. Then, (this is crucial), as Maj alludes to, use bearing/prussian blue to check all the mating surfaces have even contact.

BTW, some will say you don't need to use billet shift shafts. Well that's fucken bullshit. They flex like you wouldn't believe, I've pulled apart Busa boxes where the box is jammed and the shafts are still bowed by the jammed fork. Move the fork over with a gentle lever and the shaft flexes back to its original straight position. Tool steel/billet shafts fix that problem once and for all. They also help prevent the shaft holes in your cases from 'barrelling' due to repeated excessive flexing.

Wear eye protection and have fun.

'Safety First' Camel

[GRUNTMAX]

Or, you could just stick it in a box & freight it. They designed & built aircraft especially for your Busa Gearbox

http://www.fastbygast.com/Catagories/Pro...ssions.asp

Doesn't weigh that much.

[Legend]

TUNGSTEN carbide burr! Carbide gets shot to shit too quick. But I've found an even better way. A compound table, a swivel angle plate and a 4" grinder fitted with a 1mm thick cutting disk. Make a mount for the grinder, and another for the gear (I use a spare shaft), adjust the position of the gear using the swivel plate and compound table. Just get your angles right and drive the gear to the grinder, does beautiful undercuts. Then, (this is crucial), as Maj alludes to, use bearing/prussian blue to check all the mating surfaces have even contact.

BTW, some will say you don't need to use billet shift shafts. Well that's fucken bullshit. They flex like you wouldn't believe, I've pulled apart Busa boxes where the box is jammed and the shafts are still bowed by the jammed fork. Move the fork over with a gentle lever and the shaft flexes back to its original straight position. Tool steel/billet shafts fix that problem once and for all. They also help prevent the shaft holes in your cases from 'barrelling' due to repeated excessive flexing.

Wear eye protection and have fun.

'Safety First' Camel

I dont use billet shift shafts so I guess I must talk bullshit.

If all is working well within the gearbox then why would you need them? lots of busa's have 100,000ks without being touched, once you take the motor out of a bike and put it in a car chassis is when you find the weak link or create weak links in the busa motor. Billet shift shalfs will cover up the problem of the shift forks not holding up to the abuse. The gearbox is under way more stress in a car or big tyre dragbike then in a "normal" busa configuration.

I agree that the billet shafts would be a lot stronger than the stock shalfts but dont agree that you have to have them.

Thats my opinon , if you think I talk bullshit then thats your opinon.

Leonard.

[drworm]

Thanks for the input guys. Will be pulling engine out probably late next week or early week after.
Will keep all updated on progress.
I will machine some billet shift shafts while I am at it. Can't hurt. Pretty lucky as I can do all the machine work and get paid for it!

[GRUNTMAX]

You must work for the Government

[drworm]

You must work for the Government

Ha!
Nah man, dont need to worry about me!
I work at Holden.

[Camel]

Legend,

no mate, I don't think you talk bullshit. I agree, many Busas with 100,000 plus km have no problems with their flexi shafts. But I'd rather bend a shift fork than damage my cases. So if the engine is coming apart I fit the billet shafts just to be on the safe side.

drworm, to further clarify my previous post, you'll need a small tungsten carbide burr to undercut the blind window in the 2nd driven gear. I couldn't get a small enough burr for my die grinder but dremel make one that does the job beautifully.

Before:


In progress:


In progress because all the dogs need to be identical in order to distribute drive forces equally.

Here's the dimensions of the mount for the gear to be bolted to a swivel plate:


Camel

[drworm]

Thanks Camel, your a champ.
I realise the driven gear pockets are going to be the most difficult. Thanks for the pics and detail.
I will take some of my progress when the time comes.
I will be grinding the male drive dogs, I have access to some very nice tool and cutter grinders and equiptment.
I will give milling the pockets in the driven gear a go, can use a 5 axis mill, and secretly go through a few cutters! See what happens, if it works will make it heaps easier.
Any particular angle? I was going to measure the others and figure it out that way.

While on gearbox issues, has anyone tried the Factory Pro Shift Star? Sort of interested.

[Haerera]

I have made all the sockets/necessary to remove engine and also access to range of carbide burrs / if you need em gis a call - Philfy -SA

Thanks Camel, your a champ.
I realise the driven gear pockets are going to be the most difficult. Thanks for the pics and detail.
I will take some of my progress when the time comes.
I will be grinding the male drive dogs, I have access to some very nice tool and cutter grinders and equiptment.
I will give milling the pockets in the driven gear a go, can use a 5 axis mill, and secretly go through a few cutters! See what happens, if it works will make it heaps easier.
Any particular angle? I was going to measure the others and figure it out that way.

While on gearbox issues, has anyone tried the Factory Pro Shift Star? Sort of interested.

[drworm]

I have made all the sockets/necessary to remove engine and also access to range of carbide burrs / if you need em gis a call - Philfy -SA

Thanks for that dude, but I will make my own anyway, gives me something interesting to do at work!
Have to hook up for a ride once all sorted!
Cheers

[drworm]

Late update,
All complete and running as it should.
Man the engine is heavy, almost busted my back with no helpers!
I found the shift fork was rooted, and the shaft was bent a fair bit, 0.18mm total indicator, so that was replaced with a precision ground case hardened shaft, for the reasonable sum of $8.
If anyone wants to get one, Linear Bearings cut precision ground shaft to size, not sure though if I got a mates rates price, but would still be way cheaper than other options. It is 14 diameter, which I was surprised they kept in stock.

The actual undercutting process was easier than expected, and a solid carbide 6mm endmill did it perfectly, in a pretty decent CNC machine centre though. The cutter was a bit worn, but not as bad as I would have thought.

Great to get back on the Busa, spent a week riding my dads FJ1200 around, and although its not a bad bike, couldnt wait to get off it! That throttle didnt really do anything!

One thing I didnt notice at the start, but noticed in time, is that the clutch basket also needs to be removed to get to the GPS, so I also knocked up a clutch holder tool as well.

If anyone wants to borrow the tools, I am happy to let ya, even if you want to pay for postage I will send them off, but I'm sure you could find someone local if you try!