2nd gearbox option (and other driveline questions) for a motorcycle streamliner

[superleggera]

Looking at options for running a secondary gearbox for a motorcycle powered streamliner project.  Have a bunch of information via vendors and sales people, etc -- but curious what is actually "working" out there and successfully on the Salt Flats.



Four items for discussion for this thread:

1) options for secondary sequential gearbox setup to get about @145mph worth of additional ratios beyond primary engine gearbox.

2) Primary engine output (gearbox) to secondary gearbox:
    a)  chain drive with sprockets
    b)  belt drive with sprockets
    c)  geared drive setup (encased)

3) rear drive itself:
    a)  chain drive
    b)  belt drive

4) Cush drive requirements?  I've hearing of people not using one and allowing tire/salt slippage to resolve -- thoughts?

note: NOT going to get into clutch / slipper clutches, etc in this post itself -- will do upcoming.

[Interested Observer]

“Parts that aren’t there can’t break” ...or absorb horsepower.
Why do you need two gearboxes?

[panic]

The extra box is because the spread between 1st and high gear in the stocker is not wide enough to provide good acceleration at start, good RPM drops, and close ratio into high gear?
1. is the stock shift into high gear close enough for your power band?
2. have you examined all the alternate gear sets for the box, including mix-n-match for choices never offered (as done with the A10 box)?
3. JM2¢, but the 1-2 shift is relatively irrelevant, so you can use a high numerical 1st gear (viz., big RPM drop on the 1-2) to get away with tall sprocket gearing.
4. which end of the range will have (a) gear(s) added: above 1st or after high? The difference is pretty big: above 1st can be a really big "granny", but a new "last" must be at least as close as the stock high gear RPM drop.

[Anvil*]

Unless you are going to split gears like a semi-truck, it would be best to get the first set of gears close enough to run through the set while still within your power band. Basically start with your high gear and work down. Your new first may seem closer to your old third gear if the powerband is narrow.

Most push or tow to a speed where the streamliner engine can take over. If it really had to be from a standing start... Well that would be again working the spacing with your powerband down to a gear you can slip the clutch and maybe use a hand push from a helper to get rolling. You would want to get to the same speed your push vehicle would have and go direct on that extra trans. It will cost horsepower.

Before you get too far, figure out your approximate horsepower and total vehicle weight. Can the existing primary, clutch, and gearbox handle that horsepower at that load. It is really easy to take that 340 pound street-fighter and load it well over 600 to 800 pounds, so your race engine is now towing a small trailer down the salt.

Another suggestion for a first-time build on a motorcycle streamliner. Start with a mildly-tuned engine and concentrate on everything else on the vehicle. It has to make a number of passes under observation with increasing speeds. The record-breaking engine should be swapped in after rather than spend it's short life a low speeds, or worse, delaying those in between runs before qualifying as you fight engine problems. There will be enough other things going wrong.

[superleggera]

I can go into detail ala gear chart -vs- rpm dropoff later if needed.  Given the initial powerband / displacement utilized, we are going to use a close ratio gearbox (vs wide ratio).  Perk is better acceleration in higher gears.

Per push/tow -- that is a given to about 40+mph to lesson clutch slippage required.  (using a motorcycle dry clutch setup, a dead stop start under acceleration would be foolish obviously)  All shifts of the motorcycle gearbox are sequential with ignition cut-out to facilitate when under power.

2nd gearbox (2 or 3 speed?) -- for low-speed MPH acceleration where aerodynamics (or shift time delay or wider RPM dropoff) aren't going to hurt us.

Engine?  Initially we are going to run the smaller engine on GAS.  Essentially a standard roadrace engine setup that could run a regular road race season with minimal maintenance and we are very comfortable with years of experience.  LOTS of things need to be sorted as per tech inspection, licensing, observation trials, aerodynamics, chassis angle, crew logistics, chassis/suspension, electronics, cooling system, etc -- stupid silly to put a crazy engine tune into it when nothing else is proven.  I'm figuring this setup for the first two+ years at minimum.  Then upgrading to FUEL setup and optimize/learn.  Later options are turbocharging/FUEL and displacement -- but only after the initial setup is competitive.  Small steps -- I figure it's at least a 5yr project at minimum or longer given a motorcycle streamliner.

Trick is making sure the cockpit/chassis/bodywork will encompass the changes later as needed.  After visiting with Sam Wheeler (really smart guy) and seeing the total revamp of his streamliner in process now, I'd rather make sure we don't have to repeat his current sequence with squeezing in a 2nd gearbox into an existing space it wasn't planned for along with other mods he is  making.  Prefer to design once and optimize for many years later as our comfort levels and experience grows.

[Dean Los Angeles]

Is anyone running a dual gearbox on a motorcycle?

The high dollar choice would be to split the PTO to two gearboxes and run like the F1 teams. Take off on the first clutch and gearbox in 1st gear, swap clutches to the second gearbox that is in second gear, shift the first gearbox from 1st to 3rd  . . .

Suzuki ran the RP68 road racing 3 cylinder 50cc with a 14 speed gearbox.


Help us out here. What class are you running. Give us some specs on the engine. Desmosedici GP12? 

[Glen]

I think Derick McLeish has run one at Elmo on one of his strange motorcycles. Might check with him.

[superleggera]

Help us out here. What class are you running. Give us some specs on the engine. Desmosedici GP12? 

Initially with a 749cc on gas.  Racebike via rear wheel dyno is 132hp and 63lbs torque.  Very conservative setup.  Later can do various displacements (500, 650 and 999cc) within the same engine case configuration / mounting.  

Desmosedici 999cc V-4?  If someone had a spare, I'd be willing to talk.  There are some internal problems within though -- my engine guy has rebuilt quite a few already and spare parts aren't readily available. (and almost nothing via the aftermarket industry)

Our goal is to be the fastest Ducati (powered) motorcycle -- at least a moral victory.  Once you eat/live and breathe Ducati's like many of us do here -- you can't get it out of your system.  Hopefully we can get into the record book eventually with a bunch of hard work and passion for what we are doing.

note: Pointless chasing the 1001cc+ classes -- the Hayabusa is in a different league and completely rewritten the rulebook.  Zero interest in running one of those or trying to compete against it.  I'd rather have the music of Pavarotti or an italian mistress with their unique melodic voice singing across the Salt Flats instead...

[Peter Jack]

Well said Mark. Have fun with it. There are lots of people running on the salt chasing speeds for only their own satisfaction. Records that may occur are only a bonus. 

Pete

[Anvil*]

Looking at numbers a bit...Assuming a 749cc 6-speed geared for say 260mph with peak horsepower at 10,000 RPM
6th is 23/24  ~.958:1
1st is 37/15  ~2.466:1  At 40 mph you would be lugging at 3960 RPM, that seems fine, just be kind to the clutch.

Shifting at 10,000 RPM the drops look like:
2nd   7154 RPM @ 101mph
3rd    7933 RPM @ 141 mph
4th    8441 RPM @ 178 mph
5th    8829 RPM @ 210 mph
6th    9184 RPM @ 239 mph

This does ignore wheel slip which increases with speed even on a good day and speed loss during shifts.

Anyway, the way you check is jst looking at the gearbox, peak rpm, and calculating a constant where gearbox output RPM times your constant equals the speed you've geared for.

So in 6th 10,000 x 1/.958 = 10,434.78      260/10,434.78 => .0249167...
In 5th 10,000 x 1/1.0434 = 9583.333        9583.333 x .0249167 = 238.78 mph
9583.333 out in 6th  9583.333 x .958.. = 9184.02.. RPM

Easiest to set up a spreadsheet and run through all 6 and then look at your starting RPM.

Looks like you can start with the gears you have IMO (even if you had enough horsepower to gear for 260mph).

[Koncretekid]

Quaife in England manufacture new transmissions for Nortons.  As they are separate units from the motor, they would be fairly easy to hook up.  Although not made for 200 horsepower, they can probably handle quite a bit of torque.  Once in high gear, the output sprocket is locked to the input/mainshaft, so should be pretty reliable. Normally a clutch is hung on the input end of the mainshaft, but I'm sure you could just adapt a sprocket of your choice and use the Ducati clutch. 1st gear would be around 1:2, so should give you all the reduction you want.

Just thinking outloud here, but can you really push a motocycle streamliner to 40 mph?

Tom

[dw230]

A quick glance at the rulebook shows a record in a 750cc class for Ducati at 186+.

DW

[Jon]

Hi superlegra

Interesting project, good luck with it.

I've never ridden a bike with 2 gearboxes but I have driven some older twin stick trucks (2 manual boxes with a gearstick for each), the easy bit is changing the secondary, the hard bit is getting the primary back to first at the same time. Unless you split first main 4 or 5 times with the joey which will give you a heap of gears down low and large gaps up high.

IMHO if you are pushing hard against the air in top low it is going to be quite a mission to get a sequential shift gearbox down through 5 gears back to first when you go to high on the Joey, if you can successfully do it I think you may wash off a fair bit of speed that you then need to regain.

IF I was going to run a Joey box (I'm not)I would be using it to pull off the mark in first low up to a speed that the bike can pull first proper, shift the Joey once into direct and then just work my way through the main box. This way you are only shifting 1 box at a time and the Joey that will IMHO will most likely be a driveline fuse spends most of it's time in direct.

I would be looking for a box similar to concret kid mentioned that locks input and main on direct, probably check out what the Harley drag guys are running, they put some big hp through smallish boxes and have good traction so must be using something solid.

All just my unproven opinion, I will be watching with interest.

Cheers
jon




As you say Sam Wheeler is a smart guy, what is he using if you can share?

[Anvil*]

*snip*
Just thinking outloud here, but can you really push a motocycle streamliner to 40 mph?

Tom

Tows and pushes are allowed for the streamliners, but I believe most of the specifics fall under the general grey area of doing so safely and without an unusual delay to the other participants. They don't want push vehicles running down course or digging grooves trying for a big push. So, something good to bring up at the rookie meeting since you want the starter and observers to be happy. Bring your push/pull driver too.  
If you check out the SCTA website there is a link to a pdf on rookie orientation, medical forms, tech inspection form, and such.

If you run Bud Trials, the AMA has it's own rules as does the FIA if you are going for a world record.

Mmmm, there where some check-lists about too.  Sorry, someone will know where to look (senior moment I guess).
----
Opps, my bad, four wheels:  J/GS  218.100 (tracked down your intro, though one wheel shown in the sketch).

Geared for 230 mph  That's 4476 RPM at 40 mph. The shifts are easier, but there is even more weight.

You would think same torque and horsepower input, but the fun starts when the wheels slip then grabs and the vehicle's weight acts harshly on metal bits. New things have a way of finding their weakness, much more so with a heavy foot.  

[wobblywalrus]

Baker Drivetrain in USA makes some strong trannys for Harleys.  They make a 6-speed.