Hi,

Help wanted for a novice! I've now got the Ron Champion book and want to give it a go, even though I dont know much about cars!

I want to build a bike engined locost, preferably getting most bits from a single sierra donor if possible. So many questions, where to start? Sorry if these questions have been asked loads of times before!

1. Can the sierra front hubs and steering rack be used? I think I read somewhere about widening the frame by 100mm or something? Are there plans anywhere for frame and wishbone mods (I plan to make the frame myself)?

2. I've seen plans for mods to take a sierra rear suspension on the Locost Car Club website (http://www.locostcarclub.co.uk) Has anyone used them, any comments on the mods?

3. With a bike engine (I plan to use a zzr1100 motor) will a sierra diff be a suitable ratio? Do sierras all have the same ratio or does it vary between models?

4. From reading the book, I understand that the splined output shaft from a car gearbox is about 4inches long, along which the propshaft moves slightly with rear suspension movement. The drive shaft for the front sprocket on a motorbike engine is much shorter, so is it not very risky to use this to drive the cars propshaft?

Thanks for any help/advice!

If you want to use the running gear from the sierra look at a Gts locost .

http://www.gtscougar.freeserve.co.uk/

Darrens chassis is very close to Ron's the extra 17 cm ish is taken up with the suspension using dedion on the back and a wider track front..It does mean donor bits are cheap....You do not have to make the chassis wider to use the bits...The rack may be a differant matter....

A standard Sierra 3.62 diff should be ok and easy to find, although a 3.34 would be ideal.
You'll also need a modified prop shaft with a centre bearing.
Pat...

The front hubs and uprights can be used with a bit if machining and a "mushroom" insert.

You can go for an independent rear suspension setup with the Sierra rear but it's much easier to do as
Big_wasa says above and use a de-dion set up.

Both the above will have the diff mounted to the chassis so there is no movement affecting the
prop other than in any mounting bushes which is v small. Hence the spline length is (AFAIK) irrelavant.

Searching (search button at top of page) the threads will reveal several discussion regarding these issues.

Cheers

Hi Sammy

I'm building an MK Indy, which uses Sierra running gear and an ZZR1100 engine. I don't know about chassis mods for independant rear suspension but I'm sure they are out there.

I used the following from the 1.6l donor, front hubs, disc brakes, steering rack (which MK shortened), steering column and switches, lower steering link (which MK lengthened), prop shaft, diff, drive shafts, rear drums, master cylinder and steering wheel.

Sold the rest on ebay / to scrappy and made my money back.

The ZZR is a good choice of engine, being cheaper to source than Blades, R1, Busa's and the later ZXR12, but with a useful amount of power, torque. You can also change the ZZR sump for a GPZ900 sump which will help minimize either bonnet projection or increase the ground clearance.

As regards the diff ratio, I'm using a standard 3.62, but if you can get a 3.34 it might give you slightly higher top speed and more relaxed motorway cruising. Although I should be able to do 70mph at about 6500 rpm with 13" wheels.

Do a search for the Gearcalc spreadsheet, which allows you to play around with different variables, engines, diffs and wheel / tyre sizes.

1st Gear 11.5K RPM = 44mph
2nd Gear 11.5K RPM = 61mph
3rd Gear 11.5K RPM = 77mph
4th Gear 11.5K RPM = 92mph
5th Gear 11.5K RPM = 106mph
6th Gear 11.5K RPM = 119mph

I've been in a few 7's and maxing out at about 120mph doesn't worry me. Partly because they're not very aerodynamic and partly because there aren't really that many opportunities to go that fast.

Hope that helps.

Cheers

Mike

[Edited on 18/5/05 by Guinness]