Printable Version | Subscribe | Add to Favourites
New Topic New Reply
Author: Subject: Does this need more bracing ?
big_wasa

posted on 7/5/06 at 02:44 PM Reply With Quote
Does this need more bracing ?

Showing a mate a few photos of progress on the new chassis and he felt I need more bracing. I have beefed up O3 to 50x25x2mm and its a live axle car so no diff hanging from it ect


What do you guys think ?

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

posted on 7/5/06 at 02:57 PM Reply With Quote
Can do if you like.

Not really necessary as that part of the car isnt that structural... The axle loads go through the tubes where the trailing arms mount. In a live axle car theres pretty much no load on the bulkhead.





Sera

http://www.motosera.com

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

posted on 7/5/06 at 03:17 PM Reply With Quote
In my pic below I think A will add more strength to the trailing arm bracket tubes, B will add more strength to the rear of the chassis, along with a fully braced rollbar and I put the tubes in at C but I hadn't doubled up the tubes between the rollbar base plates like you have so probably unecessary in your case but certainly a belts and braces approach. I was concerned about the single top rail twisting under the weight of two people as that rail takes most of the forces in a heavy braking/accident scenario.

Ned. Rescued attachment chassis.jpg
Rescued attachment chassis.jpg






beware, I've got yellow skin

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

posted on 7/5/06 at 03:17 PM Reply With Quote
i did but then my diffs hanging off it
View User's Profile E-Mail User View All Posts By User U2U Member
britishtrident

posted on 7/5/06 at 03:31 PM Reply With Quote
Yes -- "union jack" style
View User's Profile View All Posts By User U2U Member
Kissy

posted on 7/5/06 at 04:26 PM Reply With Quote
The 50x25 was overkill IMHO. The diagonals you propose are useful as they contribute significantly to the torsional stiffness of the chassis
View User's Profile E-Mail User View All Posts By User U2U Member
DIY Si

posted on 7/5/06 at 04:50 PM Reply With Quote
Could you put a steel bulkhead in? It's what I'll probably end up doing. But even then I have another box structure hanging on the back of the tunnel to hold my diff up so no real need for extra bracing.
View User's Profile E-Mail User View All Posts By User U2U Member
JoelP

posted on 7/5/06 at 05:05 PM Reply With Quote
i would add a 19mm round bar, in 20g. Next to no weight but pretty effective as it's in tension and compression if the bulkhead was to ever try folding up. But if you intend to panel it, which i suppose you have to, then either welded steel or bonded and riveted ally will be more than adequate.
View User's Profile View All Posts By User U2U Member
zilspeed

posted on 7/5/06 at 05:57 PM Reply With Quote
Nice neat looking work.

I know that adds nothing to the thread, but it needed saying

Bones V. Soon






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

posted on 7/5/06 at 06:14 PM Reply With Quote
quote:
Originally posted by big_wasa
Showing a mate a few photos of progress on the new chassis and he felt I need more bracing. I have beefed up O3 to 50x25x2mm and its a live axle car so no diff hanging from it ect


What do you guys think ?


I put the extra diagonals into my chassis. My thoughts were that in the event of a roll the rear bulkhead would be carrying a lot of force and you wouldn't want it to lozenge. I also have the vertical members going to the top tube as I am using Cobra hoops so the 'O' bar needs extra support in the middle.

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

posted on 7/5/06 at 06:48 PM Reply With Quote
quote:
Originally posted by zilspeed
Nice neat looking work.

I know that adds nothing to the thread, but it needed saying

Bones V. Soon



Thanks, ive updated my archive a bit with a few more pics.


Im going to bond and rivett an alloy floor hence the 30x3mm stringers to take the seats.


Thanks for the input chaps

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

posted on 7/5/06 at 08:08 PM Reply With Quote
quote:
Originally posted by flak monkey
In a live axle car theres pretty much no load on the bulkhead.


Erm..... apart from all the suspension loads which go straight up into the corners of that bulkhead!! Stiffness of the rear bulkhead is vital to the torsional rigidity of the car, live or irs. Without it it's an open box - floppy. I'd put the tubes in.

Liam

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

posted on 7/5/06 at 08:13 PM Reply With Quote
Yup, but those loads are vertical only. The two angled rear tubes, and the side tubes of the rear bulkhead will take these loads as they are purely in tension.

Of course adding in 2 tubes will increase the stiffness of the chassis, as nothing beats a properly triangulated stucture. But the tubes are not 100% necessary, especially with that huge tube running across the back anyway. My original answer was on a neccessity basis rather than anythign else.

Makes little difference. Depends if you are bothered about another kilo on the weight...

David





Sera

http://www.motosera.com

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

posted on 7/5/06 at 08:25 PM Reply With Quote
Load might be vertical, but when it's only on one side, i.e. any one wheel bump or corner, it will act to lozenge the rear bulkhead, and the whole chassis. A chassis without a torsionally stiff rear bulkead will flex horribly under hard cornering.

Of course you could take the american approach - "if we put enough big horizontal bars in we dont need triangulation!" . I never said that chassis needs those bars but any triangulation is an elegant way of increasing the efficiency of the structure. Loosing that unnecessary 2"x1" bar and adding the diagonals instead would have resulted in a chassis the same weight and much more stiff.

Liam

[Edited on 7/5/06 by Liam]

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

New Topic 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.