118 replies to this topic

[Sean12]

So my project has finally begun,

I am planning on building a rwd rear engine fireblade mini. I have been lucky enough to be given a few items which has allowed me to do this project. I am a university student studying mechanical engineering and i am tying this project into my 3rd year dissertation. My project will be on chassis design so i am goin to try an come up with a space frame/chassis for the rear to hold and locate the engine. after lots and lots of research i am just about ready to start/just started lol

as above i was luckily given a few items for free, these include a mini shell with lots of supplies and a 1998 CBR 900RR Fireblade engine with 2k miles on, so fairly new. Alot of those miles where track miles so has been nicely run it, the owner (Girl Friend's dad) said they bike had just start to wear in nicely and getting to peak performance (so should be good for the mini ).

The last few weeks have been abit hectic trying to find a diff, i decided to go with a LSD for all the obvious reasons . After a long hard search and many scrap yards later i managed to aquire a Late model Sierra XR4x4 (2.0 engine) 7" LSD (god damn they are pretty rare and hard to find now lol) with a 3.92:1 ratio. I did alot of reading about LSD and there ratios and seen alot of people on hear talking about ratios and on other BEC sites, and aparently speaking to a family friend who has his own grass track engineering company said this one was meant to be good acceleration but lower top end (which suited my needs perfectly), however after lots of reading an researching it all seemed pointless, and that is because when stripping it down (can been seen further down), you remove the outer anulus gear and dont have the helical gear from the prop shaft, so surely that ratio becomes irrelevant and it doesnt matter what lsd ratio you have ? and that the new ratio is completely down to the 2 sproket sizes attached to the diff and the bike ?? (correct me if im wrong)

any who, this was the pic of the LSD before gettin it back to the garage (will post pics of the taking apart tomoro)

Attached Files

•  161020091.jpg   51.02K   54 downloads
•  16102009.jpg   51.85K   33 downloads

Edited by Sean12, 28 October 2009 - 02:50 PM.

[basher]

you may want to check what cooling the bike engine uses, as i believe zcars say you cant use an oil cooled bike engine, it needs to be water cooled as it will just overheat and seize. i think they may use oil cooling on that bike?

anyway good luck, im hoping to be doing something similar in a couple of years when im rich enough, so its always handy to see home builds popping up.

[Sean12]

Basher thanks for your heads up. As far as I am aware the fireblade is an oil to water cooled engine. I spoke to a lecturer of mine, who is a huge bike enthusiast, to confirm my thoughts an he agreed an thought it was to. But if anyone knows any better I would be greatful to hear about it. Also if it isn't oil to water, what's stopping me making it oil to water cooled using an oil to water heat exchanger then running your typical water cooled system to cool the oil? Or having an air intake on the side of the mini to pass over a larger oil cooler.

Will post the other LSD pics later when home from uni to.

laters guys

Edited by Sean12, 03 November 2009 - 01:32 PM.

[R1mini]

Fireblades are water cooled but also have a water to oil cooler typically seen as a small alloy can sitting under the oil filter can

Cheers
David

[Sean12]

Cheers David, Ye that's exactly what I thought so cooling shouldn't hopefully be a problem. I mean ab performance specialise in bike engined cars and have built 100's of bec and specialise in the carb'd blade so there must be ways of cooling them. After speaking to them they just said to make sure of using a good rad such as a 2row rad for better efficiency and to make sure if mounted in the front that the air is channelled through well an not leaking or escaping around the edges. So touch wood if all set up ok all will be fine (and cool lol). I will prob start off with a polo rad to start with then when taking to track the polo rad will no longer cope so will upgrade to a 2row rad from ab performance which is similar to polo rad but alot more efficient.

cheers

Edited by Sean12, 01 December 2009 - 08:48 PM.

[sotiris]

good luck.......
good start

we wait for news.....

[bikem1ke]

Sounds good, maybe you could incorporate your rear spaceframe into a cage for the whole car to improve torsional rigidity. A few thoughts......

Your losing the engine weight from the front what are you going to do about making the suspension work again and getting the weight distrubution back to 60:40 or close to that? Why not front engine rear wheel drive as it's different and hardly anyone has done it before so would be more of a technical project to make your dissertation really stand out from the crowd and get you a decent result. I guess dissertations are just copying other peoples work these days though, not creating something new and exciting.

What are you going to do about rear suspension? Independent or not? You need to think about adding brakes to the rear too, maybe inboard brakes.

How are you going to reverse and meet the new regulations about mechanical reverse?

[Sean12]

hi mike (and dave lol) thought it might be you, trying to ask complicated questions !! Nice try guys

but anyway, the space frame will incorporate a cage for the whole car, as seen in most rear bike engined mini's for rigidity and stregth and would be crazy not to.

the weight distribution will never be 60-40 as your well aware, however all other ancillaries (such as radiator, fuel tank etc...) will be placed in the front to add as much weight up front to help aid the weight distribution problem, along with the correct suspension set up and chassis design.

the suspension will be independant suspension incorporating coil overs to be set up to the desire settings. The rear brakes will be converted to disk (from somethin like a saxo vtr or pug etc...)

i will not be using a mechanical reverse as the car will not need one to be SVA'd. The car will have an electric reversed using a flywheel and starter motor, powered by a foot switch.

Edited by Sean12, 03 November 2009 - 01:38 PM.

[Sean12]

as promised yesterday more pics of the taking apart of the lsd, firstly it was taken out of its casing....

 lsd1.jpg   33.43K   24 downloads
 lsd2.jpg   35.86K   47 downloads
 lsd3.jpg   41.96K   41 downloads

Then fiddle around removing the angular roller bearings etc...

 lsd4.jpg   55.08K   36 downloads

To leave the diff ready for the casing and new bearings.

 lsd5.jpg   50.39K   47 downloads

The LSD is being sent off tomoro to have the casing made and the sprockets made up. a viewing hole arrangement will be done in the casing to access the circlips inside the diff holding in the output shafts and to check an change oil. oil seals an o-rings will be needed to create perfect seal. will update when the progress has been done on that.

should be getting the shell soon to start body work and cutting out the back end, and i am currenly working on a 3D CAD model frame so will post pics when complete.

and finally a picture of the engine being used (yes the lower casing will be replaced to get rid of scuff mark lol)

 Engine1.jpg   69.39K   73 downloads


Sean

Edited by Sean12, 03 November 2009 - 02:27 PM.

[Monte Busa]

...is it just me, or does this look like an open diff, not an LSD?

 lsd2.jpg   35.86K   47 downloads

[gizmo]

sure looks like an open diff to me

[R1mini]

It's lsd, the finned bit to the left is the viscous unit

Cheers
David

Edited by R1mini, 28 October 2009 - 09:59 AM.

[Sean12]

As david said, the part on the left is the Vicous part.

As you can see, it has a split down the flange on the left hand side, if you were to undo the bolts holding them together you would find a chamber full of interleaved metal disks in a vicous silicon fluid. the left hand output shaft has a longer spline than the right and that is because under the large flange on the left there are two sets of splines next to each other, one connected to the planetry gears and the other restricted by the viscous chamber locking it in place, creating the limited slip.

This type of LSD could be classed as a kind of hydraulic type i guess as opposed to the typical mechanical. It is probably the best type for a car application i feel as the slip is not so mechanical an not so snappy, giving an instant loss of power, it is more gradual because of the viscous fluid and the slip is alot smoother. Its abit more forgiving i guess

Edited by Sean12, 28 October 2009 - 12:11 PM.

[Sean12]

hey guys,

just out of interest do any of you guys know the final weight of your finished stripped out BE minis?


Cheers

[Rosslin Racing]

hey guys,

just out of interest do any of you guys know the final weight of your finished stripped out BE minis?


Cheers

this is a good question I wanted to weigh mine but i have not finished gutting it yet, ( too much to do at work right now)