bimbleuk
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| posted on 20/5/09 at 06:43 PM |
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Sierra diffs 3kg weight difference
I wasn't expecting this but when I moved two Sierra diffs one was obviously heavier.
Both 7" diffs but the 3.62 has small input shafts. The other is a 3.92 diff with larger input sockets but no Lobro adapters in place. So I would
have guessed quite similar in weight.
3.62 diff weighed 18kg and the 3.92 diff weighed 21kg. Both emptied of oil but 3kg difference. Now if you take into account the smaller diameter
driveshafts with no Lobro adapters that's got to be a good 5kgs difference just there?
May not seem significant to some but to save that sort of weight on my car elsewhere would require much thinner body work or an alloy gearbox casing.
Both quite expensive options in comparison.
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Hellfire
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| posted on 20/5/09 at 06:52 PM |
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Trouble is though, the ratio of your diff is dependent upon which engine you're running. Simply swapping the 3.62 for a 3.92 to save 5kg will
also mean sacrificing top end speed.
It is interesting to know the weight difference though........
Phil
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jollygreengiant
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| posted on 20/5/09 at 07:02 PM |
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The weight difference is probably, mostly, just in the drive flanges.
Beware of the Goldfish in the tulip mines. The ONLY defence against them is smoking peanut butter sandwiches.
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Steve Hignett
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| posted on 20/5/09 at 07:04 PM |
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I fitted the lighter diff and lighter shafts on my car. For lightness by the way, in case that wasn't so clear...
I struggled to find the smaller shafts though, and it ended up costing me a lot in the end...
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bimbleuk
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| posted on 20/5/09 at 07:26 PM |
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quote:
Originally posted by Hellfire
Trouble is though, the ratio of your diff is dependent upon which engine you're running. Simply swapping the 3.62 for a 3.92 to save 5kg will
also mean sacrificing top end speed.
It is interesting to know the weight difference though........
Phil
I also have a 3.92 with the smaller shafts so I'm lucky to have the choice. I'm assuming this 3.92 would also be 18kg but I'll check
out of curiosity when I remove it this weekend.
As for the smaller driveshafts they are available as exchange units from parts suppliers. At least that's how I got the ones fitted to my
car.
[Edited on 20-5-09 by bimbleuk]
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snapper
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| posted on 20/5/09 at 09:55 PM |
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3Kg is not a lot but i understand trying to loose weight every where you can but don't start throwing money at 3Kg if you have a heavy battery
or a steel gearbox or heavy wheels.
Look at the whole picture before getting blinkered over one thing, I speak from experience.
By the way a few tins of slimfast is supposed to save that much weight in a few weeks
I eat to survive
I drink to forget
I breath to pi55 my ex wife off (and now my ex partner)
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Steve Hignett
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| posted on 20/5/09 at 10:01 PM |
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I know you aren't specifically referring to me - but I didn't have a heavy battery/steel gbox/heavy wheels etc.
I pretty much went all out on my car to reduce weight as much as possible. The only time I drew the line were when it didn't make financial
sense to do so (for eg - I'd already spent money on upgrading to lightened sierra discs for the rear, so couldn't justify to then spending
money again going to wilwoods etc)
Whilst building the first time round though, I did cut down every one of my bolts to 1.5 threads past the nut to reduce weight. I know it's
totally anal, and it didn't pay off straight away until I started replacing a lot of my body panels with CF. But it all adds up and I was happy
to put that sort of dedication toward my first build!
 
quote:
Originally posted by snapper
3Kg is not a lot but i understand trying to loose weight every where you can but don't start throwing money at 3Kg if you have a heavy battery
or a steel gearbox or heavy wheels.
Look at the whole picture before getting blinkered over one thing, I speak from experience.
By the way a few tins of slimfast is supposed to save that much weight in a few weeks
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bimbleuk
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| posted on 21/5/09 at 07:20 AM |
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The way I look at it that's a 20% weight saving on one component be it a fairly large one. So as already mentioned it only becomes significant
when the all parts are taken in to consideration.
If I were to go on a weight saving crusade then I'd start with a BEC anyway and neither of these diffs are ideal to start with. Oh well I just
wondered why people kept quoting different weights for the Sierra diffs and now I know!
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MikeRJ
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| posted on 21/5/09 at 09:28 AM |
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quote:
Originally posted by snapper
By the way a few tins of slimfast is supposed to save that much weight in a few weeks
I drank a whole tin to wash down my daily bucket of KFC for a few weeks and it didn't seem to work?
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motorcycle_mayhem
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| posted on 21/5/09 at 10:25 AM |
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Don't focus on the one thing, as he says...
I had the 7.5" viscous Sierra in a GSXR750 BEC (diff weight probably not so far off the engine weight!), wasn't too slow.
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