2b_pablo
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| posted on 25/10/07 at 09:10 AM |
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what diff for BEC?
just curious as to what diff lads use for a BEC? Im guessing its not the big heavy sierra diff most of us CEC lads use?
cheers
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mike smith1
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| posted on 25/10/07 at 09:12 AM |
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Certainly is, some people have used the Landrover Freelander Diff.
Mainly the Sierra Diff
Mike
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graememk
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| posted on 25/10/07 at 09:13 AM |
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i still think a robin hood is to weighty for a bec mate.
i know my old one was to weighty for a cec.
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2b_pablo
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| posted on 25/10/07 at 09:13 AM |
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ah ok cool 
thanks for that, trying to cost up a BEC build here in my head into a new chassis
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matt_claydon
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| posted on 25/10/07 at 09:13 AM |
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Same diff, although most look for 'faster' ratios like 3.38 or 3.14 (gold dust) due to the rev / gearing characteristics of the bike
engine.
[Edited on 25/10/07 by matt_claydon]
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2b_pablo
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| posted on 25/10/07 at 09:14 AM |
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quote:
Originally posted by graememk
i still think a robin hood is to weighty for a bec mate.
i know my old one was to weighty for a cec.
would be a sell and rebuild mate.
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smart51
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| posted on 25/10/07 at 09:40 AM |
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I have a sierra 3.62 diff in mine and for the road it is OK. 1st is a nice fast gear. 6th will take me up to 120 MPH at the red line.
The problems are that 70 MPH is at 6800 RPM in top and peak power at 103 MPH. On the track it seems slow above about 105 / 110.
A 3.38 or 3.14 diff will be no quicker or slower accelerating over all but will be slower in each gear. You'll need more revs to pull away and
acceleration in 1st will be about 10% (3.30) or 15% (3.14) slower. 6th gear is much more like it though. Revs will be 10 or 15% lower and peak power
speed 10 or 15% higher. Top speed will be higher too.
If you want to do 100 MPH+ on the track or do lots of motorway cruising, you need a lower ratio diff. Otherwise, don't bother.
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2b_pablo
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| posted on 25/10/07 at 09:42 AM |
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100mph on track would be sufficient
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Howlor
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| posted on 25/10/07 at 10:13 AM |
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You'll be wooped every 5 minutes though!
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twybrow
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| posted on 25/10/07 at 10:54 AM |
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I will be using the RS200 axle (3.54 open diff).
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Jubal
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| posted on 25/10/07 at 11:03 AM |
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quote:
Originally posted by 2b_pablo
100mph on track would be sufficient
It won't. Unless the car is woefully underpowered you'll need to be geared for more than that or you'll be banging the limiter on
every long straight.
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2b_pablo
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| posted on 25/10/07 at 11:08 AM |
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its fine for the track I use, currently hitting 85/90 in the hood.
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smart51
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| posted on 25/10/07 at 11:12 AM |
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quote:
Originally posted by 2b_pablo
100mph on track would be sufficient
I was hitting 115 MPH at Cadwell park and 120 at Mallory. Cadwell was only 115 because All I could manage up the hill was 110 - because the car was
beyond peak power.
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fesycresy
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| posted on 25/10/07 at 11:40 AM |
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In my opinion it depends on the engine.
An R1 with a 3.62 is fine - topping out at 120ish but I love the acceleration (got used to it now and could do with more).
A new ZX10 on the other hand would be a nightmare with a 3.62, bigrich did some calcs and he uses a freelander.
HTH.
-----------------------------------------------------------------------------------------------------
The sooner you fall behind, the more time you'll have to catch up.
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Hellfire
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| posted on 25/10/07 at 11:52 AM |
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Yep, like fesycresy says 'it depends on the engine'
Phil
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NS Dev
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| posted on 25/10/07 at 12:39 PM |
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It does indeed, but from my CEC point of view, although "much over 100" isn't much use in a 7 as its not much fun for any length of
time, my car gets to that sort of speed from standstill in around 8 secs so its not like you'll never need it!!!
Retro RWD is the way forward...........automotive fabrication, car restoration, sheetmetal work, engine conversion
retro car restoration and tuning
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