Printable Version | Subscribe | Add to Favourites
New Topic New Poll New Reply
Author: Subject: DeDion Tube Construction?
Pavel

posted on 29/1/05 at 10:17 AM Reply With Quote
DeDion Tube Construction?

I'm consideering building a dedion set up for a sierra rear end.

Most Dedion tubes are just that tubes.

Do they have to be ?

Can they be made out of RHS? something like 2" square?

regards

Pavel

View User's Profile E-Mail User View All Posts By User U2U Member
dozracing

posted on 29/1/05 at 11:15 AM Reply With Quote
Yes they can be, in fact i believe that Tiger do just that on one of theirs.

Kind regards,

Darren

PLEASE NOTE: This user is a trader who has not signed up for the LocostBuilders registration scheme. If this post is advertising a commercial product or service, please report it by clicking here.

View User's Profile E-Mail User Visit User's Homepage View All Posts By User U2U Member
Kissy

posted on 29/1/05 at 12:07 PM Reply With Quote
Try to use round tube, it not only looks better it is far stronger torsionally pound-for-pound
View User's Profile E-Mail User View All Posts By User U2U Member
Cita

posted on 29/1/05 at 12:23 PM Reply With Quote
Here we go again:tube versus RHS
View User's Profile View All Posts By User U2U Member
undecided

posted on 29/1/05 at 12:30 PM Reply With Quote
well moon cheese is a non starter so round tube much safer
View User's Profile View All Posts By User U2U Member
JoelP

posted on 29/1/05 at 12:57 PM Reply With Quote
i think kissy has worded it correctly here though, stating pound for pound rather than by size!

i would use 2inch square myself to make it easier to line up square.






View User's Profile View All Posts By User U2U Member
mangogrooveworkshop

posted on 29/1/05 at 03:57 PM Reply With Quote
round is the way
[img][/img]

View User's Profile View All Posts By User U2U Member
andylancaster3000

posted on 29/1/05 at 10:17 PM Reply With Quote
By how much are the standard sierra drive shafts too long for the book chassis. Is it possible to use the sierra drive shafts (as they come off the sierra) on a book chassis, if so how much wider is the rear end.

(Sorry if i have hi-jacked this thread!)

Andy

View User's Profile View All Posts By User U2U Member
chunkielad

posted on 29/1/05 at 10:36 PM Reply With Quote
If you use a 4" wider chassis then you can use them full size so it looks like 4" wider track!!

I would consider the square tubing as it's going to beasier to make yourself rather than trying to bend tube!

View User's Profile View All Posts By User U2U Member
craig1410

posted on 30/1/05 at 01:10 AM Reply With Quote
You don't have to bend the tube. Look at the GTS Tuning design at www.gtstuning.co.uk. They just weld the two halves of the round tube together. Personally I prefer the design that mangrove shows above as this is the same design as my own but maybe I'm biased...

Cheers,
Craig.

View User's Profile Visit User's Homepage View All Posts By User U2U Member
NS Dev

posted on 30/1/05 at 11:24 PM Reply With Quote
Round tube is no harder to accurately line up than square tube. It may give the illusion of being easier, but in either case you could do with (as a minimum) a bit of a cobbled up jig of some sort to hold everything still while you weld it up, in which case, the round is as easy as square. (and as was said above, if nothing else, round looks much better!!)

On the driveshafts subject, remember that custom made (not shortened and welded but custom made from scratch!!) shafts are only £70 each! (from GB engineering in Nantwich, for those that have missed my previous plugs for this excellent company!!....no connection!!)

View User's Profile Visit User's Homepage View All Posts By User U2U Member
Rorty

posted on 31/1/05 at 04:10 AM Reply With Quote
New billet axles are lovely and simple; you hand over your cash and you have new axles.
Welded tubular axles are fine too. Lobro (probably the largest CV and axle manufacturer in the world) sell weld axles specifically for inserting into thin wall tube.
Afterall, what's a drive shaft if not a welded tubular structure.
Granted, the torque through the axles is multiplied by the diff, but tubular axles are perfectly acceptable. Rescued attachment Lobro_weld_axle.jpg
Rescued attachment Lobro_weld_axle.jpg






Cheers, Rorty.

"Faster than a speeding Pullet".

PLEASE DON'T U2U ME IF YOU WANT A QUICK RESPONSE. TRY EMAILING ME INSTEAD!

View User's Profile E-Mail User Visit User's Homepage View All Posts By User U2U Member
britishtrident

posted on 31/1/05 at 09:16 AM Reply With Quote
Caterham also don't bend the tube -- I don't why the general layout of the Caterham tube set up isn't more widely used (litigation worries ?)

Square section is a bad idea apart from the very minor factor that by weight it isn't as efficient as round at carrying torsional loads-- the strain deformation at the end welds with square section under torsion isn't nice.

View User's Profile View All Posts By User U2U Member
andkilde

posted on 31/1/05 at 02:12 PM Reply With Quote
quote:
Originally posted by Rorty
Lobro (probably the largest CV and axle manufacturer in the world) sell weld axles specifically for inserting into thin wall tube.


Ooh!

Those are snazzy. Do you know of any suppliers that stocks these Rorty? Or are they only available to the auto manufacturers in quantity?

Cheers, Ted

View User's Profile E-Mail User Visit User's Homepage View All Posts By User U2U Member
Bob C

posted on 31/1/05 at 03:41 PM Reply With Quote
>>Square section is a bad idea apart from the very minor factor that by weight it isn't as efficient as round at carrying torsional loads-- the strain deformation at the end welds with square section under torsion isn't nice.

Ah but the only torsional load down the dedion tube is brake imbalance.
Square on the other hand is better at resisting bending, so should perhaps be preferred??? (I might be wrong here.....)
I agree make the damn thing straight if you can - MUST be better!
Cheers
Bob
PS in a recent thread on the round v square subject, someone posted that same wall thickness square had same bending strength as round IIRC - that feels wrong to me. I'll test some 3/4 by 16g next chance I get.

View User's Profile Visit User's Homepage View All Posts By User U2U Member
flak monkey

posted on 31/1/05 at 03:48 PM Reply With Quote
'Ere we go again...Square is stiffer in both bending and torsion than round as it has a higher second moment of area (polar second moment of area for tortion) (more material further from the neutral axis).

But when/if square fails it will do so suddenly due to the corners being stress raisers. So it will also fail earlier (at a lower load) than round, but the deflection up to that load will be much less.

You can make a dedion tube from RHS. For the same failure strength it will be heavier, but a lot stiffer.

Think that makes sense,
David





Sera

http://www.motosera.com

View User's Profile Visit User's Homepage View All Posts By User U2U Member
cymtriks

posted on 31/1/05 at 08:08 PM Reply With Quote
If your car is light weight then you could try 2.25-14gauge which someone reported (was it Rorty?) as being used on a light weight home made seven clone.

The original Escort axle is about 2.5 inches and again I recall someone stating that it was less than 10 gauge in wall thickness.

I think Caterham use a 2.5 inch tube. I think La Bala uses a 3 inch 16 gauge tube.

If I was doing it I'd use a 2.5 inch 14 gauge tube. This will be very slightly heavier than the 2.25 inch tube but is much stronger and it is easier to weld than 16 gauge.

Tube strength and stiffness has more to do with tube size than with wall thickness so don't kid yourself that a thick walled small tube will be as strong as a bigger tube with a thinner wall.

Regarding links I'll suggest a Satchell link with the top links as in the book but with lower links running from the lower rear corners of the transmission tunnel to the outer ends of the Deon tube. The lower link mounts on the tube should allow a link angle of 30 degrees minimum to the axle line. So if the link goes out from the tunnel corner by 20 inches it'll need to go back by about 11.5 inches minimum.

Satchell links are simpler, lighter and cheaper than five link designs and do not require a welded wishbone as in the Caterham design. They can also handle a lot of power.

View User's Profile View All Posts By User U2U Member
Rorty

posted on 31/1/05 at 09:08 PM Reply With Quote
quote:
Originally posted by andkilde
Those are snazzy. Do you know of any suppliers that stocks these Rorty? Or are they only available to the auto manufacturers in quantity?

Cheers, Ted

They are a standard catalogue item for all sizes of CVs and should be available through any Lobro retailer. The part # will start with 0616 and then the relevant joint size after that.
I've used them for some fairly high horsepower cars, but frankly, with all the torque a BEC puts out, a cut-and-shut tubular axle made from a standard solid axle is fine.
I have cut the ends of solid axles off so I could drill the centres out to 10mm (from both ends), and then welded them into some tube. Nice and light (also marginally helps spin up for better throttle response) and plenty strong enough if done properly.
Even though axles don't spin as quickly as a prop shaft, it's important to ensure they're reasonably well balanced if they're welded. I normally check them for run out after they've been welded, and if they're visibly out, I'll nudge them in a press a couple of times to straighten them. It's not very scientific, but it's all that's required.
I've never had an axle fail since I crudely welded some Imp axles with an arc welder in my early teens.





Cheers, Rorty.

"Faster than a speeding Pullet".

PLEASE DON'T U2U ME IF YOU WANT A QUICK RESPONSE. TRY EMAILING ME INSTEAD!

View User's Profile E-Mail User Visit User's Homepage View All Posts By User U2U Member

New Topic New Poll New Reply


go to top






Website design and SEO by Studio Montage

All content © 2001-16 LocostBuilders. Reproduction prohibited
Opinions expressed in public posts are those of the author and do not necessarily represent
the views of other users or any member of the LocostBuilders team.
Running XMB 1.8 Partagium [© 2002 XMB Group] on Apache under CentOS Linux
Founded, built and operated by ChrisW.