Hi all..

I've finally got place to build, so I'm flat out in ProE cobbling together a potential chassis layout...

I'm designing a common chassis for a build of 3 cars (there are 3 of us) aiming towards mid-engined BEC's that have a couple of "body-shell alternatives.
power-wise, we're planning on using a sierra diff mated - obviously using a flexible coupling - to the output of an R1 or Hay-bus 'box. (or similar..)

Here's the bit where I get to my main reason for writing...
Does anybody happen to have a model of
a) a Sierra Diff (or even a 2 d sketch with accurate(ish) dimesions)
b) an R1 lump.

I'm currently designing around the Hayabusa model that I have on the (possibly misguided belief) that it's physically the biggest of the options.


I'll start a build topic on it as soon as I start to get closer to reality. )

Thanks for any help you guys can Offer,

Nick

Better to use a chain diff if the engine is going at the back.

...Depending on what you want to achieve in the way of future engine applications, 4wd set-ups, component layout, and Exhaust routing... and tank positioning etc..

..and usable "luggage space" *Nick hides from the abuse*

[Edited on 17/6/07 by nick baker]

A chain diff will be smaller than a Sierra diff and coupling.

And if you decide to use a proper engine in the future a transaxle is the way to go...

Hi Again... thanks for your concern, I know what layout I want, and I know why.

I know a chain-driven Diff is a) lighter and b) mechanically advantageous
I'm also aware that the total length of the installation will be reduced, but that is not one of my goals. A smart and simple Layout however IS.... And in this particular case a longitudinal positioning is my goal. Lack of Chain wear and added stress on the Bike 'box output bearings are merely bonuses.

"Proper engines" aren't in my sights. Ever.

If it will help to stop you from worrying, we can happily assume I'm running a "Standard BEC" locost layout... and am still looking for the dimensions..

Thanks again,

Nick.

Try here, some are a bit basic but dimensions are acurate

http://www.locost7.info/mirror/other.php

I do have some CAD files about Sierra diff. Not sure their quality or exactness. But anyway you can have them later today.
(collected them in hope that I can someday learn CAD and use them, but seems that my brain is not built for 3D).

That would be absolutely outstanding. Thanks.

I did try the site recommended, but sadly didn't find anything of much use

Has anyone got a rough weight on the diff?

Cheers,

Nick
.. back at work after a weekend's ProE work

I did weigh my 7 inch sierra diffs, which I now don't have anymore, an open sierra diff I think from memory was 20kgs, the lsd diff was 28kgs with flanges

I was looking into this very idea for my mini, but the main thing for me was the height of the outputs on the diff, even with just four inches clearance on the sump using R1 engine and no exhaust running underneath either. 12 inches was the height to the centre of the diff outputs was 12" using a freelander diff and 13" using a sierra diff, I would need to use 17" wheels to keep the droop on my driveshafts to a sensible angle

I have included a picture of an R1 temp fitted using a flexible coupling to the freelander diff to show you and idea of the height of the outputs

Cheers
David
Rescued attachment Coupling.jpg

Dont recall which one contains diff, but you will find it. I hope you will share finished drawings with rest of us. Have fun.

http://www.filefactory.com/file/bcfb5f/

http://www.filefactory.com/file/0ad6a8/

Thanks Guys.

David: That is one hell of a good point. I've been lining up the 'Busa model I have and the Diff- alignment seems totally feasable... however the R1's output seems rather a large amount higher than the 'Busa's.

Do you happen to have the output to bottom of sump measurement available?

This could be a seriously limiting factor... though i do have more room available than you would have done in the mini: I rekon i have around 40cm between diff input and 'box output to play with.

Macintosh: Thanks for the files.. Sadly they're exactly the same one as were available on the other page. I think i'll just nip off to the Scrappy and like under a sierra with a tape measure for a while

The picture shows the R1 and freelander diff, the space under the sump is about 7 inches at that height the diff outputs where 15 inches, I just subtracted 3 inches off the sump height and took the same amount of the diff output height, giving me 4 inches sump clearance with 12 inches to the centre of the diff outputs.

That means the output to bottom of sump measurement is 8 inches which I have double checked just now

The R1 is one of the shallowest to the bottom of the sump, the busa is another 1.5 deeper

The sierra diff has the diff outputs above the centre line by 1 inch so that gives a diff output of 13" at a sump clearance of 4 inches using the R1 engine

For me in a mini with wheels no bigger than 13 inches and the narrow track it was just to much, which is a pity I was looking forward to not using a chain no matter what other people say

If your car is bigger then with the bigger wheels and the car is wider will both make the droop on the driveshafts I think acceptable

Cheers
David

[Edited on 18/6/07 by Minicooper]

*Nick sits and smiles happily*

I'm aiming directly for 17" wheels, and the 'busa model I have gives me a 190.5mm sump-drive center. I'm not looking for more active travel than 50mm.. obviously with more droop when totally un-weighted.

I'll also be pushing the diff back a little to give myself more room for CV-jointed link between 'box and diff... just incase it's needed.

Glad to hear the R1 has a lower output than the rest: it's our engine of choice, and a better clearance would make it more worth while.

Thanks for all the help!!

EDIT: and I agree... getting away from the chain is a very desirable goal


[Edited on 18/6/07 by nick baker]

I have got some solidworks models that I did myself - can you import them? Mountings & inputs/outputs are not too bad on 'em, say good to a few mm.
There was a really good R1 s/w model (which I might have) if you're interested.
Bob

Funny you should mention it Bob, I think I found a few shots your models on a web-page you set up to document your locost... and I was thinking "Darn.. if only I could get in contact with him.."

ProE supports many formats, but exporting files as IGES / IGS files would be the best if possible. IF you're not capable right now, I have friends who'll be able to run the conversion, so the solid-works files would be really appreciated anyway!

I spent a fair bit of tie last night trying to make myself believe that a chain-drive would be advantageous.. and I woke up today with a splitting headache. Coincidence? Maybe...