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Main : Mechanical : Engine Holey Crossmember

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Holey Crossmember
Holey CrossmemberPopular
SubmitterddgonzalMore Photos from ddgonzal   Last Update2009/2/23 5:15    Tell a friendTell a friend
Hits2927  Comments21    0.00 (0 votes)0.00 (0 votes)
cut it out

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The comments are owned by the poster. We aren't responsible for their content.

Poster Thread
hotrocket
Posted: 2009/2/23 22:21  Updated: 2009/2/23 22:21
No life (a.k.a. DattoMaster)
Joined: 2007/12/20
From: Nyngan, nsw Australia
Posts: 2376
 Re: Holey Crossmember
interrogative would be lost there...would it not

Poster Thread
ddgonzal
Posted: 2009/2/23 22:54  Updated: 2009/2/23 22:54
Moderator
Joined: 2001/5/3
From: 48 North
Posts: 31599
 Re: Holey Crossmember
Are you asking a question, or is yours also a subtle pun?

Poster Thread
Mildman
Posted: 2009/2/23 23:15  Updated: 2009/2/23 23:15
No life (a.k.a. DattoMaster)
Joined: 2003/9/2
From: SE Melbourne
Posts: 3195
 Re: Holey Crossmember
Have you done all that cutting as a weight saving exercise?

How did you decide it would still be strong enough to handle the load of the engine?

Poster Thread
SomeDAT
Posted: 2009/2/24 0:03  Updated: 2009/2/24 0:03
Just can't stay away
Joined: 2007/4/23
From: Sydney, Sutherland Shire
Posts: 86
 Re: Holey Crossmember
what is the main advantage of this?

Poster Thread
ddgonzal
Posted: 2009/2/24 2:37  Updated: 2009/2/24 2:37
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Joined: 2001/5/3
From: 48 North
Posts: 31599
 Re: Holey Crossmember
1/3 less weight, and still the same strength. You don't need to be a rocket scientist to figure out where to cut, this is old procedure and well known in racing community.

Poster Thread
PIGDOG
Posted: 2009/2/24 2:43  Updated: 2009/2/24 2:43
No life (a.k.a. DattoMaster)
Joined: 2004/10/28
From: Geelong, Vic
Posts: 6184
 Re: Holey Crossmember
it does have additional bracing added to it to make up for some loss of strength from the holes

Poster Thread
hotrocket
Posted: 2009/2/24 3:01  Updated: 2009/2/24 3:01
No life (a.k.a. DattoMaster)
Joined: 2007/12/20
From: Nyngan, nsw Australia
Posts: 2376
 Re: Holey Crossmember
Quote:
it does have additional bracing added to it to make up for some loss of strength from the holes


it does on the ends (see pic), i no what you mean by adding braces.....but whats the point there trying to lose weight,..lol

my opinion is why why they weigh nothing anyways...

Poster Thread
PIGDOG
Posted: 2009/2/24 3:18  Updated: 2009/2/24 3:18
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From: Geelong, Vic
Posts: 6184
 Re: Holey Crossmember
working on "every little bit counts" no doubt

looks pretty cool though

EDIT, just found more bracing

has the extra bits underneath, has the braces inside the crossmember near the ends and has bracing at the back of the mounts

Poster Thread
ddgonzal
Posted: 2009/2/24 5:59  Updated: 2009/2/24 5:59
Moderator
Joined: 2001/5/3
From: 48 North
Posts: 31599
 Re: Holey Crossmember
This full-on Datsun 1200 racing coupe weighs less than a stocker. The best ones can do 210 kph with 1300cc.

Poster Thread
hotrocket
Posted: 2009/2/24 6:03  Updated: 2009/2/24 6:03
No life (a.k.a. DattoMaster)
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From: Nyngan, nsw Australia
Posts: 2376
 Re: Holey Crossmember
CRIKEY...it be floating at that speed

Poster Thread
1200rallycar
Posted: 2009/2/24 6:03  Updated: 2009/2/24 6:03
No life (a.k.a. DattoMaster)
Joined: 2002/3/20
From: Melbourne, Australia
Posts: 8221
 Re: Holey Crossmember
i've got a good one for you thinkers...

decreasing the weight of components that are below the centre of gravity of your car actually increases the height of the centre gravity of your car..

im sure that effect is cancelled by the weight reduction itself buts its kind of an oxymoron

probably more something to worry about when building a 4x4 and worrying about it rolling over

Poster Thread
ddgonzal
Posted: 2009/2/24 6:12  Updated: 2009/2/24 6:12
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Joined: 2001/5/3
From: 48 North
Posts: 31599
 Re: Holey Crossmember
Interesting comment, and I'm sure you're right.

One of these Coupes has the battery in the regular place, but right down on the frame horn, about 6" lower than normal position -- which makes sense if you want lower CG. Awesome, most awesome photo gallery: http://blogs.yahoo.co.jp - sato

Poster Thread
wolki101
Posted: 2009/2/24 6:16  Updated: 2009/2/24 6:16
Home away from home
Joined: 2006/11/18
From: ACT Aus
Posts: 940
 Re: Holey Crossmember
so dd you don't think this will lose any of the strength by cutting these holes? why would datsun have left them there then? and why is there still metal in there? why didn't they just cut whole sections out encompassing where the holes are and also the metal that's between the circles?

re reading my post it sounds very much like i'm having a massive dig at you but please understand that i'm genuinely interested as to why? no hard feelings

Poster Thread
1200rallycar
Posted: 2009/2/24 6:24  Updated: 2009/2/24 6:24
No life (a.k.a. DattoMaster)
Joined: 2002/3/20
From: Melbourne, Australia
Posts: 8221
 Re: Holey Crossmember
there can be a fair bit of engineering behind these things...

they have increased stiffness in many places and probably not weakend it too much with the holes (although many small can be better than a few large like this)

a circular hole does not concentrate stresses as it has no corners, so they can be quite effective

as for datsun.... the additional machining costs would probably rule it out (although maybe they wouldnt be very high in mass production situation if included in design from start).. and why take any risks like that when building a cheap economy box

Poster Thread
PIGDOG
Posted: 2009/2/24 6:27  Updated: 2009/2/24 6:27
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From: Geelong, Vic
Posts: 6184
 Re: Holey Crossmember
they wouldnt have been there from factory as they had no real need to make the car lighter. where as in a race car you want to do everything you can to make the car more competitive

Poster Thread
ddgonzal
Posted: 2009/2/24 6:36  Updated: 2009/2/24 6:36
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Joined: 2001/5/3
From: 48 North
Posts: 31599
 Re: Holey Crossmember
Yes, exactly. Instead of $5 to make a crossmember, if Nissan drilled all those holes it would be $20 per crossmember -- or some such similar figures. Then the Datsun 1200 would not have been the least-expensive car on the market 1971.

Poster Thread
PIGDOG
Posted: 2009/2/24 6:46  Updated: 2009/2/24 6:46
No life (a.k.a. DattoMaster)
Joined: 2004/10/28
From: Geelong, Vic
Posts: 6184
 Re: Holey Crossmember
just looked through the link you posted dd, i wish i had a race car like that
pitty the time line is backwards though, the car started off all finished and nice then kept getting worse. i ddnt know what was going on

Poster Thread
clyons8
Posted: 2009/2/24 6:54  Updated: 2009/2/24 6:54
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From: East New Britain, Papua New Guinea
Posts: 6981
 Re: Holey Crossmember
It may alter the centre of gravity, but if you concentrate your "weight reduction" to specific locations of the vehicle wouldn't you also concentrate the centre of gravity at the same time?

Or put the centre of gravity to a more specific axis? Making the car behave in a manner that the driver would prefer. Or put the CG in a position easier for the driver to work with?

Poster Thread
ROConnor
Posted: 2009/2/24 6:57  Updated: 2009/2/24 6:57
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From: Melbourne, Oz
Posts: 2029
 Re: Holey Crossmember
Had a look through that link DD and farout! that thing is amaseing!!! Fill'n my head full of Ideas!

Poster Thread
LittleFireyOne
Posted: 2009/2/24 9:23  Updated: 2009/2/24 9:23
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From: Townsville, Qld
Posts: 2964
 Re: Holey Crossmember
Finally, I was imaging what it'd be like to raise the exhaust in line with the floor

edit: just figured out why I cant load the pic, it's got some sneaky racer anti-hotlinking stuuff on it

Poster Thread
revhead001
Posted: 2009/2/24 10:39  Updated: 2009/2/24 10:39
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Joined: 2008/3/15
From: Melbourne
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 Re: Holey Crossmember
Peter Brock did the same thing in the late 1960's in his Austin A40 powered up with a holden 6. 50mm holes all over the car which stood up to many hillclimbs and races over a couple of seasons.

Poster Thread
wolki101
Posted: 2009/2/24 11:44  Updated: 2009/2/24 11:44
Home away from home
Joined: 2006/11/18
From: ACT Aus
Posts: 940
 Re: Holey Crossmember
hey just looking through that link, is that big cut and remodeling of the left strut tower just to clear that big airbox?