60 Plymouth
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| posted on 11/5/11 at 02:34 PM |
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Cut down car 'box for reverse and Hi/Lo ratios
Hi again guys,
Odd one this but it's not the first time it has been discussed on this board. I'm looking at building a reverse trike BEC. Trouble with
BECs is the reverse gear. The electric reverse is about the best low cost option, but where I live I have to back up an access road, then down into my
driveway (or back up the driveway and down the access road). An electric reverse may be ok but I'm not sure. Getting out and pushing is probably
the best option but it'd be nice to at least come up with somthing more engineery. So I thought about using a car gearbox with most of the gears
removed (two forward one reverse?).
Searching around here shows a few other people have thought of it, mostly using a transaxle at the rear, but Ned mentioned an Escort gearbox (Type 9?)
being used in the trans tunnel. I'd be willing to accept the weight of a type 9 (22kg for the four speed?), not so sure about the transmission
losses. I could get the advantage of having a hi and lo ratio for town/country driving.
My concern is that by the time the engine torque has gone through the bike's own primary and gearbox, I'd be looking at over 330ft lbs of
torque (assumed a pan euro engine for now). Am I right in thinking this will do nasty things to a Type 9? Although I could live with 22kg weight
penalty of a Type 9 I'm not so keen on 50kg for somthing a Rover V8 would need.
Any other info on BECs that use a cut down car gearbox for reverse? What did ya use and how heavy was it?
Thanks for your help guys,
Conor
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blakep82
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| posted on 11/5/11 at 02:56 PM |
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just a mention, there is no 4 speed type 9. type 9s are ALL 5 speed, before you start scouring the internet for something you won't find.
but why remove half the gears? why not just leave them in? i don't think they'd do any harm in there would they?
would you need another clutch on the car box? or will both work quite happily just off the bikes clutch?
interesting idea though!
[Edited on 11/5/11 by blakep82]
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60 Plymouth
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| posted on 11/5/11 at 03:05 PM |
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I thought the earlier type 9s were four speeds and thats why the overdrive gear is housed in the tailshaft in the five speeds? Am I thinking of
another box?
One of the reasons I want to remove the additional gears is to reduce friction, since all the gears are constantly meshing there must be a loss there,
it'd also knock a few pounds off but that's less of an issue. How much this would save I don't know.
I'd like to use 4 as my top gear - since it runs straight through it might have less power loss than the other gears. Is that reasonable?
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60 Plymouth
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| posted on 11/5/11 at 03:12 PM |
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I'd only use the bike clutch. The car gearbox would be treated a lot like the hi/low ratios in a land rover, or a two speed rear axle like Ford
Ts used, selected in anticipation of the type of driving you do.
Having said that, it should still be possible to shift on the fly. Depressing the bike clutch would unhook the engine from the bike trans. Hopfully
the synchros in the car gearbox will be enough to match the two gearboxes together to allow the car-shift to be made. It won't exactly be a fast
acting gear shift, but a hell of a lot quicker than changing the rear end ratio!
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blakep82
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| posted on 11/5/11 at 03:14 PM |
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the type 9 fords first 5 speed box, based on i think the type E, which is a 4 speed box
but type 9 is only the 5 speed.
makes sense. thought it might have been handy, if using the type 9, to have the extra overdrive for better MPG, but otherwise makes sense. sounds
interesting anyways, and something i know nothing about lol. i don't like taking gearboxes apart. they never work after i've had a go at
them...
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don't write OT on a new thread title, you're creating the topic, everything you write is very much ON topic!
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stevebubs
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| posted on 11/5/11 at 03:14 PM |
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Early Genesis BECs used (I think) a Rover 200 Gearbox in a similar fashion...
[Edited on 11/5/11 by stevebubs]
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60 Plymouth
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| posted on 11/5/11 at 03:25 PM |
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It's always encouraging to know I'm not the only one foolish enough to think of stuff like this.
That makes sense about the Ford boxes. Overdrive I'm not fussed about at all - I plan to use a Goldwing final drive/brakes on the back wheel and
that's already got a tall 2.75 ratio.
A little searching seems to suggest that Type Es ain't cheap - shame. I wonder if there are any around with knackered first gears going cheap .
. . .
Any other tough-as-nails, lightish RWD four speeds about? Heck even a three speed if the top two gears are reasonable. . .
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blakep82
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| posted on 11/5/11 at 03:27 PM |
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have a look here and see if anything suits 
http://www.burtonpower.com/tuning-guides.html
________________________
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don't write OT on a new thread title, you're creating the topic, everything you write is very much ON topic!
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TQ_uk
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| posted on 11/5/11 at 03:59 PM |
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I seem to recall theres a guy in NZ running a Hayabusa engine in a Toyota Starlet retaining the car gearbox in addition.
He'd got a simple setup where the original clutch pedal also pushed down on a bike clutch lever to disengage both clutches on gear changes.
Will see if I can find a link....
Linky
[Edited on 11/5/11 by TQ_uk]
Better link to original forum
[Edited on 11/5/11 by TQ_uk]
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Doctor Derek Doctors
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| posted on 11/5/11 at 04:43 PM |
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Seems like a decent idea, but why use an old (and increasingly rare) Ford Gearbox if you're not using a Ford Engine? There are probaly millions
of newer and lighter gearbox's sitting in scrapyards around the country.
Anything that doesn't have a built in Diff will do? Something from a BMW? MX5?
Or you could even use an Audi Transaxle from a FWD Audi and then you would have the diff included as well. I bet it would quite easily go were the
diff sits in a '7'
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mark chandler
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| posted on 11/5/11 at 04:48 PM |
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Its the toque in the gears that would kill the box, you could use a weedy little box and leave in 4th (if straight through) to good effect, run it in
reverse and you have 3 overdrive cogs.
Suzuki sj410 have little boxes, once you hack off the bell housing, first motion shaft towards the axle and away you go.
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zilspeed
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| posted on 11/5/11 at 05:07 PM |
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Pic from the link to the Starlet further up the thread.
I got Andy to waterjet me a drive plate to suit the spline on a ford box and standard four bolt drivshaft pattern to do just this thing.
If you read the thread above, the builder has nothing but praise for this reverse setup.
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To the right of the slave is the front driveshaft this bolts to the bike sprocket which we turned into a 4 bolt flange just like a diff pinion. The
front driveshaft takes a very short and very angular route to a standard toyota k40 gearbox with the bell housing cut off and mounted further back in
the car, the driveshaft has a starlet clutch hub inside it to drive the input shaft, it also has a couple of bearings so that the shaft can slide on
the snout the clutch release bearing normally does, this allows for any movement between the engine and the k40 box. We run this gearbox in 4th gear
all the time except when we use it for reverse, 4th is 1:1 ratio so its just like a straight through driveshaft.
From here its just a shortend driveshaft to the nissan diff.
You can buy a quaife reverse box but i couldnt afford one and had an excess of starlet boxes so thought we'd give this a try first, so far its
without a doubt proven itself which is pretty impressive when you consider its getting fed output shaft torque after the busa g/box and when its in
6th its pulling engine revs!!!!
Here's the closeup.
[Edited on 11/5/11 by zilspeed]
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60 Plymouth
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 posted on 11/5/11 at 05:13 PM |
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Hi Guys,
Thanks for the replies. I picked the Ford box for its weight (22kg) - to register the reverse trike as a motorcycle I have to keep it under 450kg
unladen. Alternative boxes are certainly an option.
Finding small, lightweight boxes designed for a rear wheel drive seems to be difficult though, most of the modern front engine rear wheel drive cars
seem to be a lot heavier (I'd be delighted to be corrected on this ) , and the Ford boxes are fairly well catered for by kit car guys and
retro Ford enthusiasts, so they have been what I have looked at.
I am aware of the Suzuki gearboxes, I have looked at the engines too, they are very light weight but I have a limited choice of rear end ratios
(basically 2.75 if I use a Honda GL1800 final drive, any other final drive and mounting wheels, designing swingarms, fitting brakes all becomes
complicated). Ihaven't considered the MX5 gearbox though.
That tall rear end ratio is one of the reasons I was looking at an 'under drive' type option. Does running the box back to front have any
structural advantages to running it the right way round? I guess there's usually more torque at the propshaft than there is at the clutch.
If I was to get a box with an overdrive top ratio, and run that backwards (to get the under-drive type ratio) would that have similar strength
advantages? Not as strong as running it straight through presumeably.
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60 Plymouth
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| posted on 11/5/11 at 05:22 PM |
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That Starlet's a fantastic thread - couldn't get the pictures up whilst I was at work.
Another advantage of that set up looks to be the ease of swapping motors out, so you could sling any bike engine straight into it with very little
modification and not even have to perfectly align the propshaft.
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franky
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| posted on 11/5/11 at 05:46 PM |
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I'm pretty sure the type 9 is a damn lot heavier than 22kg too.
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60 Plymouth
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| posted on 11/5/11 at 05:48 PM |
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I think I was referring to the Type E. Type 9s are apparently at about 34kg, what I thought was the 4 speed version is 22kg. I'll try and find
the link for it.
Suzuki Samurai trans is apparently 27kg.
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Liam
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| posted on 11/5/11 at 07:45 PM |
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I'm sure it would work fine as in that Starlet. I personally prefer the elegance of Doctor Derek Doctors' idea of using a
renault/audi/subaru transaxle though. Diff and box in one unit will save overall weight, not require a large tunnel, and avoid needing two propshafts.
Win!
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Doctor Derek Doctors
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| posted on 11/5/11 at 08:10 PM |
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quote:
Originally posted by Liam
I'm sure it would work fine as in that Starlet. I personally prefer the elegance of Doctor Derek Doctors' idea of using a
renault/audi/subaru transaxle though. Diff and box in one unit will save overall weight, not require a large tunnel, and avoid needing two propshafts.
Win!
And people didn't believe that I work in F1.............
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60 Plymouth
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| posted on 11/5/11 at 08:45 PM |
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I fully agree that a transaxle would be a much better option, allowing fully independent rear suspension and better weight distribution. Using an
Alpha box you could stick inboard disk brakes at the back and reduce unsprung weight even further.
The only downside is that it's not as applicable a single wheel at the back.
I did consider using a belt drive from a transaxle (either two belts or a locked diff but it either widens the car, lengthens the car, and definately
makes it more expensive.
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zilspeed
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| posted on 11/5/11 at 08:53 PM |
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It's a heavy lump of a thing is a Passat box.
I remember a long time ago a bloke called Neil Gammie used to race a Westfield up here.
It had a crossflow driving a Hewland MK9 mounted at the back like normal.
This would have had the prop running at full speed.
I understand that the ease of ratio changing along with weight distribution were the main attractions.
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owelly
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| posted on 11/5/11 at 09:05 PM |
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I've been working on a dumper and it has a reversing gearbox sandwiched between the bellhousing and main gearbox. Something similer would suit
your needs if you have the time to do a bit of twebbing for info. Basically, it's a box with a reverse shaft mounted to one side. It uses a dog
gear to drive the dumper forward but when the reverse lever is tugged, the dog disengages the mainshaft and the dog gear engages the reverse shaft
wich then drives the other end of the main shaft but in reverse. If that makes any sense?? I fairly small unit but very tough.
http://www.ppcmag.co.uk
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60 Plymouth
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| posted on 12/5/11 at 07:35 AM |
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Hi Owelly,
That sounds interesting, mind me asking what the make of dumper is? How heavy is it (the dumper)?
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TQ_uk
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| posted on 12/5/11 at 08:26 AM |
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quote:
Originally posted by owelly
I've been working on a dumper and it has a reversing gearbox sandwiched between the bellhousing and main gearbox. Something similer would suit
your needs if you have the time to do a bit of twebbing for info. Basically, it's a box with a reverse shaft mounted to one side. It uses a dog
gear to drive the dumper forward but when the reverse lever is tugged, the dog disengages the mainshaft and the dog gear engages the reverse shaft
wich then drives the other end of the main shaft but in reverse. If that makes any sense?? I fairly small unit but very tough.
Isn't that essentially the same method as the available reverse boxes (MNR/Quaife/Westfield etc)?
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60 Plymouth
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| posted on 12/5/11 at 06:44 PM |
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Basically the same yeah, but cheaper, and with a possible overdrive. Also, if/when it breaks,haul it out and sling another in for cheap.
Downside is weight. If I wasn't so tight fisted, I'd probably go for a Quaife style reversing box.
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TQ_uk
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| posted on 13/5/11 at 10:23 AM |
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quote:
Originally posted by 60 Plymouth
Basically the same yeah, but cheaper, and with a possible overdrive. Also, if/when it breaks,haul it out and sling another in for cheap.
Downside is weight. If I wasn't so tight fisted, I'd probably go for a Quaife style reversing box.
Don't worry, I've often thought along similar lines, like fitting a bike engine to a VW (beetle) transaxle in a lightweight buggy for
example.
Here's a post with some views on electric vs
mechanical
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