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small sports chassis weight

Posted: Fri Jan 04, 2013 5:31 pm
by scimjim
CNHSS1 wrote:Dunno if you have a scale suitable, but could you weigh a chassis? Maybe a spring type susepnded from an engine crane?
FINALLY managed to do this today and the results are:

non-galv: 97.5 Kg (minor bits fitted - 2 x CVH rubber engine mounts, 3 x rubber diff mounts, 4 x door hinges, bump stops)

galv: 105.3 Kg (only bump stops fitted) - edit, note below - this is a retro-galv without Ti engine mounts.

it was a real struggle, so only accurate to within a couple of Kg either way.

Re: small sports chassis weight

Posted: Fri Jan 04, 2013 7:19 pm
by Alan SS1
Jim

Two Questions
1 is the non galv one ferrous oxide free?? :-)
2 how many weight savings are in above non galv!!
Make that three Qs
3 how much weld on non galv!

Seriously 7 or 8kg is fair bit extra from the Zn :shock: (or did Reliant increase the overall gauge of the later chassis with the need for the Ti)

Re: small sports chassis weight

Posted: Fri Jan 04, 2013 7:25 pm
by Roger Pennington
Alan SS1 wrote: Seriously 7 or 8kg is fair bit extra from the Zn :shock: (or did Reliant increase the overall gauge of the later chassis with the need for the Ti)
I don't know if there were any change to the gauge, but the galv chassis did come with both engine mounts, which presumably would add a bit to the weight?

Re: small sports chassis weight

Posted: Fri Jan 04, 2013 7:27 pm
by scimjim
Good point about the galv one being ferrous free - it's actually a Reliant retro-fit item and I can guarantee there is some internal corrosion because someone has bodged the earthing point and it cracked, so I ripped it out and can see inside (will try and take some pics later) - it does however mean that it doesn't have the additional Ti engine mounts.

sorry - don't understand Q2 :oops:

the non-galv has been repaired (poorly) along the sills and a few inches up the A/B posts both sides as well as the NS bend where they crack by the exhaust downpipe.

Galvanising is generally accepted to add 7 or 8% weight to a chassis - the above works out to exactly 8% I think the gauge is identical.

Re: small sports chassis weight

Posted: Fri Jan 04, 2013 7:28 pm
by tony.idle
scimjim wrote:
it was a real struggle, so only accurate to within a couple of Kg either way.
The time honoured method is to hold the spring balance in one hand and lift up & hook the item to be weighed onto it with the other. Where's the struggle? :mrgreen: :mrgreen:

Re: small sports chassis weight

Posted: Fri Jan 04, 2013 7:33 pm
by scimjim
a spring balance would have been a start Tony :-)

turns out that the scale on the sheep pen outside, is an integral part, so I couldn't use that - as it was a rare day that I had an assistant that could lift a chassis (I don't want to kill poor Chris off :-)), we used the digital bathroom scales (that I bought to weigh everything as I took it off G97 and lightened). Although apparently good for 150 Kg, we obviously had to balance the chassis quite accurately to get a figure :-)

Re: small sports chassis weight

Posted: Fri Jan 04, 2013 7:38 pm
by Alan SS1
Jim
sorry Q2 :oops: toooo tangential
what I meant was how many fresh air sections were there (as in sections of sill that you can poke fingers through)
if it is any consolation the 'remains' of mine weighed in at around 100kg at local breakers yard, that was with fresh air and offset by the extra weight from corrosion. what EOL form? :wink:

bathroom scales 150kg jeeze thats > 350 lb that ??? Stone :shock:
USA bathroom scales? :wink:


PS I have a DIFF reinforcing plate here if it is required approx 2mm thick mild steel and plastic coated (well most of it is)

Re: small sports chassis weight

Posted: Fri Jan 04, 2013 7:58 pm
by scimjim
ah - the sills had been repaired - only small holes showing but it was repaired without removing or cutting the tub, so the top inner joint isn't actually welded :shock:

It's from the car that I bought to repair G97 when DJ rolled it. The chassis turned out to be much better than advertised (I only paid £75 :-)) and I got a pair of QRG galv sills with a free car I collected a few weeks later :-)

I have one of those diff mounting repair plates too :-)

http://www.scimitarweb.co.uk/sgwrs/view ... diff+crack

Re: small sports chassis weight

Posted: Fri Jan 04, 2013 8:29 pm
by CNHSS1
Great work Jim, i owe you a pint or 4 next time we meet!

Did it have the front shock mounting coss beam?

By the time you add the front armature, rear armature and largely unstructural tub, ill bet you will double the 100kg.

A Locost 7type is about 75kg, and a race spec 7type (Caterham superlight/bec westfield etc) 65 kg

Re: small sports chassis weight

Posted: Fri Jan 04, 2013 9:35 pm
by scimjim
no crossmember, no brake pipes, nothing unless listed.

Rear armature is 8Kg, Front armature is 15Kg, Headlights inc motors etc are 9.6 Kg the pair, 6.8 Kg for the standard CVH rad and fan (inc crossbar) - there's 40 Kg straight away! I reckon I've got that down to 10Kg on G97?

nearly all of the weight of the tub is in the windscreen and surround as you know, I will weigh a body tub sometime too, guesstimate (from lifting it off the chassis today) is around 45 Kg :-)

Re: small sports chassis weight

Posted: Fri Jan 04, 2013 9:36 pm
by scimmy_man
non-galv: 97.5 Kg

sounds heavy, I remember picking one up at the factory, and asking why they didnt galv them, this would be very early in production life.

Re: small sports chassis weight

Posted: Sat Jan 05, 2013 12:41 am
by tony.idle
scimjim wrote:a spring balance would have been a start Tony :-)

turns out that the scale on the sheep pen outside, is an integral part, so I couldn't use that - as it was a rare day that I had an assistant that could lift a chassis (I don't want to kill poor Chris off :-)), we used the digital bathroom scales (that I bought to weigh everything as I took it off G97 and lightened). Although apparently good for 150 Kg, we obviously had to balance the chassis quite accurately to get a figure :-)
A friend bought a set of (what we assumed were) sheep pen scales at an agricultural auction. He was going to use them to measure hovercraft thrust. It turned out that the (numeric) scale was meaningless - apparently because there must have been a lever ratio between sheep & scales.

Re: small sports chassis weight

Posted: Sat Jan 05, 2013 11:41 pm
by scimjim
Front crossmember is 2.3Kg

Bare body tub is 43.1Kg - over 20Kg of that is the windscreen and surround.

Pedal box inc servo & MC is 7.5Kg

Re: small sports chassis weight

Posted: Sun Jan 06, 2013 12:01 pm
by b.c.flat hat
Just had a thought Jim, did CH ask you t'weigh him as well! All this talk of "bare body", "tub" and the like derailed my train o' thought!
Or 'as 'e got weight shift ideas for the peddler!

Re: small sports chassis weight

Posted: Sun Jan 06, 2013 1:48 pm
by Roger Pennington
For info, thread now stickied :)