lightspear27
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| posted on 12/9/06 at 07:22 AM |
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Bike engine + car gearbox
Hello,
This has certainly been discussed before and can seem stupid for some of you ...
... but I did not found a thread about that.
Here we go ...
Are there suitable ratios in a car gearbox to use it with a bike engine and box? If there are suitable ratios you could use low gearing for track use,
acceleration, B roads, ... and high gearing for quiet cruising or highway ... plus the reverse.
You could choose your gearing using the car gearbox and then use the sequential bike gearbox.
In a front engined rwd kit car you could use a "standard" rwd box or a transaxle with a built in diff for better weight distribution.
In a front engined fwd car, or in a mid engined one, you could use a fwd car gearbox.
Yes, you add the weight and complexity of a second gearbox but there is no more need for an unreliable reverse gearbox + diff.
I have not checked the ratios in car gearboxes so this is pure theory but it could make a bike engined car more usable ... track weapon and road
cruiser at the same time.
Am I a complete dreaming stupid or is there some potential in this idea?
What's your opinion?
I remember of the Pell Genesis ... I think it used to have a car gearbox in with some gears missing in addition to the bike gearbox ???
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G.Man
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| posted on 12/9/06 at 07:29 AM |
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By adding the car gearbox, you will pretty much negate the main advantage of the bike engined car...
Power to weight...
I believe there is a reverse box available that allows you to change the ratio of input to output, i would expect that to be a better idea...
One that allows you to quick swap ratios would be awesome
Opinions are like backsides..
Everyone has one, nobody wants to hear it and only other peoples stink!
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lightspear27
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| posted on 12/9/06 at 07:43 AM |
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is a car gearbox so much heavier than a reverse box + differential ?
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lightspear27
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| posted on 12/9/06 at 07:43 AM |
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prices are to be considered too !
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procomp
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| posted on 12/9/06 at 07:59 AM |
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Hi two sets of wheel and tyre would do the same trick 13"-15" 15's with road tyres and the 13's with track tyres.
Altho this will not allow for the sudden erge to have the lower ratios whilst out for a quiet drive.
cheers matt
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Coose
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| posted on 12/9/06 at 08:00 AM |
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quote:
Originally posted by lightspear27
is a car gearbox so much heavier than a reverse box + differential ?
You would also need a diff with a car gearbox, so yes is the answer! I really wouldn't bother with reverse anyway - I have coped fine for the
last 4000 miles without it! You just think a bit more in advance and jump out and push if you really need to. It's no great hardship, believe
me!
Knowing how volatile reverse boxes *can* be (I'm not saying all are as some people have been lucky) and how much of a weight increase a car
'box would make, I totally agree with G-man in that it would negate the reason for going bike-engined in the first place!
Spin 'er off Well...
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Coose
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| posted on 12/9/06 at 08:02 AM |
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p.s. - My R1 on 13's with a 3.54 diff is geared for just under 125mph and gets to a ton (on private land of course) before you can blink! What
more do you need?
Spin 'er off Well...
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smart51
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| posted on 12/9/06 at 08:07 AM |
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An overdrive box could be usefull. 6 gears on a bike's normal transmission give good acceleration but, because BEC gearing is lower than bike
gearing, motorway speeds are a bit revvy.
A box a bit like a reverse box that would reduce the revs by 15% would be quite usefull. It would be just like having a switch that swapped a 3.62
diff for a 3.14.
I find with my R1 BEC that there is very little difference between 5th and 6th and not too much between 4th and 5th. The most ideal solution would be
to swap 5th and 6th gears in the box for slightly taller ratios. It probably wouldn't be more expensive than trying to get a car gearbox to fit
to a bike engine's box.
It would be a nice trick if you could do it.
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Minicooper
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| posted on 12/9/06 at 08:11 AM |
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http://www.transworks.biz/minidiff.html
That's exactly what these people have done, they have stripped the box down to the single forward gear and the reverse to save weight
They have a two speed version in development not lowcost but shows the idea can be made to work
I looked into this a while back and found for instance a typical 5 speed fwd gearbox to weigh about 42kgs, now if you add up all the things that are
used in a chain drive diff the weight penalty was about 20kg against a chain driven sierra diff and about 15kgs against a chain driven sierra diff
with an electric reverse
Using the sierra rwd gearbox will add a lot more weight more like 35kgs, but I doubt you could tell going around a track
Anyway that's my worthless opinion
Cheers
David
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ReMan
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| posted on 12/9/06 at 08:33 AM |
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Another option is Smurfitt, who do a lovely rear diff with variable ratios and a built in reverse.
About £4000 I think, but it does have shiney anodised bits
http://www.muffettgears.co.uk/muffett-motorsport.html
[Edited on 12/9/06 by ReMan]
www.plusnine.co.uk
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JoelP
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| posted on 12/9/06 at 08:54 AM |
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the chain drive one is an excellent option, 18kgs including reverse!
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Peteff
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| posted on 12/9/06 at 08:59 AM |
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I wonder if they'd knock us a tenner off if we ordered in bulk. They do look a nice compact solution though and the range of final drives is
good.
yours, Pete
I went into the RSPCA office the other day. It was so small you could hardly swing a cat in there.
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zilspeed
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| posted on 12/9/06 at 09:06 AM |
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Having thought about this a few yearsd back (honest), I reckon a gearbox from an older RWD car would be the way to go on this - Morris Minor / ford 4
speed / Vauxhall viva.
Thes boxes can be reasonably light and are very compact.
Drive onto the input shaft wouldn;t be a problem either. (using machined friction plate centres).
This all sound very heath robinson, but it makes sense to me - honest.
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lightspear27
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| posted on 12/9/06 at 09:14 AM |
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I was thinking more at fwd gearboxes (in mid engined rwd kit cars) with built in diff or transaxles (to be put in the rear for mid engined or front
engined rwd cars) with built in diff.
I do not think a bike engine and box + rwd box (type 9) + diff is a good idea! Too much weight as said before ... perhaps! But if you use a transaxle
in the back and the engine in the front you could achieve a good weight distribution.
And a 15-20 Kg weight penalty is not a problem for me ... especially if the car has to be used on the road. Also remember that lightweight is
important but what is more important is to have the weight in the right place. I prefer a car 50 kg heavier but with a good weight distribution for
traction and handling!
Also ...
It's not really locost related but some lightweight fwd kitcars (Midas for example) could perform well with a bike engine and I see the car
gearbox as an "easy" way to install it. With a short shaft between engine and car gearbox. I do not really like chain driven
arrangements.
I know we are talking of very different things (fwd and rwd kitcars) and that sevens are the cars to have on this site ... I am just trying to get
different advices from different peoples ;-)
I also think the car gearbox can be a cheaper solution than the diff + reverse (mechanical or electric) solution ... and certainly more reliable.
Yes some peoples want a reverse on their kitcar ... it's 21st century you know?! And if your car is not intended for trackdays only ... and if
you want to make more than 2000 miles in it in a year ... on the open roads ... you'll agree you need a reverse.
I know our cars are "toys" but I like to use my toys to go to work in the center of the city, to use carparks, and sometimes be stuck in
traffic ... so a reverse is a "must have" for me.
Do 15-20 kg justify the extra expense of an "unreliable" reverse box? Or the extra work for installing an electric reverse?
I understand lots of kit car builders sell their cars before reaching 10 000 miles. Can you say you lived with the car when you have only done 5-6000
miles in it. The guy that has to live with the car will want a reverse ... just my opinion! Just my opinion?
Well, I think it's a good solution for some people with some kind of use in mind for their cars ... not for other peoples with other goals.
And it's an answer to some BEC detractors!
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cossey
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| posted on 12/9/06 at 09:44 AM |
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the muffett diff is more like £2000 not £4000 and is a very nice piece of kit but its more than twice what i payed for my reverse box and
quaife/freelander diff.
using a transaxle might be a way of doing it but it would be quite hard to find enough room for it at the back. the audi ones arent that heavy though
(45kg) so with 1st/2nd/3rd stripped out they arent that much heavier than a sierra/reverse box combo (35kg vs 30kg)
most of the mechanical reverse boxes are reliable if you get one of the later ones, both the quaife and the nova racing ones suffered from breather
problems and a dodgy batch of chains on the early nova boxes but i havent heard of any of the recent ones going wrong.
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cossey
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| posted on 12/9/06 at 09:46 AM |
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quote:
Originally posted by lightspear27
And a 15-20 Kg weight penalty is not a problem for me ... especially if the car has to be used on the road. Also remember that lightweight is
important but what is more important is to have the weight in the right place. I prefer a car 50 kg heavier but with a good weight distribution for
traction and handling!
most becs are already very close to 50/50 and are even rear heavy with a driver in them.
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ned
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| posted on 12/9/06 at 09:55 AM |
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my friend has done this. he fitted a 4 speed escort box to his fury to act as a reversing box and to be able to step down/up the gearing to the rear
axle.
he runs the gearbox backwards to be able to alter the gearing, he can run it in 3rd to lower the revs when cruising but uses 4th most of the time. He
is on his second box as he had some issues with the way he mounted the box in the runnel and the bearing housing he machined up to support the input
shaft moved, he recons it runs best in 4th as it's straight through the gearbox rather than running through the gears all the time. reverse
works well though.
got a couple of pics in my archive, but none of it finished..
Ned.
http://www.locostbuilders.co.uk/upload/IMG_1708b.jpg
http://www.locostbuilders.co.uk/upload/IMG_1709b.jpg
got a couple of video's of it running at http://www.putfile.com/nedc
[Edited on 12/9/06 by ned]
beware, I've got yellow skin
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G.Man
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| posted on 12/9/06 at 11:21 AM |
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Ladies
Do it the right way...
http://www.allensperformance.co.uk/gearboxes-and-couplings.htm
Opinions are like backsides..
Everyone has one, nobody wants to hear it and only other peoples stink!
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lightspear27
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| posted on 12/9/06 at 11:40 AM |
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thank you all for the replies and advice ... lots of interesting info on this site.
Ned,
do you have more info about the busa fury? 0-60? top speed? weight? tried it around a track?
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ned
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| posted on 12/9/06 at 11:56 AM |
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no idea on the stats of my mates fury, he converted it from xflow to busa for a fun road toy (he has 2 race cars) i can vouch for it being very quick,
doubt he's ever pushed the top speed to be honest but it certainly pulls like a train! Don't know if he's weighed it but can't
be as heavysteve bub's zetec fury and that is well under 600kg iirc.
Ned.
beware, I've got yellow skin
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lightspear27
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| posted on 12/9/06 at 12:09 PM |
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thank you Ned,
It certainly involves lots of work to modify a chassis in order to accept a transaxle in place of the rear diff but it should be lighter and
"technicaly simpler" than the bike engine-bike gearbox-car gearbox-diff arrangement.
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mark chandler
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| posted on 12/9/06 at 01:55 PM |
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Old Alfa's used to run dedion rear end with gearbox and diff combined. I think they also ran a prop rather than torque tube to join the
engine.
I,d be more inclined to source a small light 4 speed box and reverse. Old sipple cars like rover 90's and relient robins have very small
gearboxes.
Regards Mark
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