Plenty for a locost imho...
If you are running smaller circumference tyres you will need a lower ratio of 3.38 or 3.14..
3.38 or 3.14 LSD's are VERY rare and expensive, so you will probably end up with an open diff..
Just got my Yamaha Fazer 1000 engined Velocity back from Holeshot Racing of Bradford (who by the way are moving to Ireland two weeks from now)...
A dyno-jet kit, racing airbox/filter, and rolling road session gave me a 16bhp increase - I'll well chuffed with that!
One comment passed to me was that they presumed I was getting through the gears quickly.
I smiled with delight as I thought I was just being stupid. Apparently my top speed on the rolling road was only 105-110mph. I now realise why I was
hitting the rev limit at Cadwell last week.
Sure enough, the differential is geared quite low. I'm told it's a standard Ford 3.92:1. This is presumably a little too low for a BEC?
Please any of you BEC briggade suggest the best replacement, and what kind of money we're looking at? There are a few Sierra ones on eBay at the
moment.
Even better, does anyone have one for sale or sitting unused?
Any help much appreciated
Kyle, Leeds
Hi,
You may find this thread useful. Sierra 3.62 or 3.38 (if you can find one at a
decent price) seem to be the ones to use in a BEC.
HTH
Ed
[Edited on 10/2/07 by esn163]
sounds like you need the rocking horse poo of sierra diffs 3,14
Depends what size wheels your running, and what you want from the car 3.92 will be very busy. 3.62 with 15" wheels is ok, fairly common and come
with LSD. 3.38 is a good alround safe bet, but you might have to wait a while for one to come up (usually open diffs). You can also get 3.14 open
diffs, but they're like the holy grail, and command silly money. It also depends on the reduction gearing of your particular engine, theres an
excell spreadsheet kicking around somewhere that calculates top speed with different ratios.
Al.
Originally posted by The Great Fandango
Just got my Yamaha Fazer 1000 engined Velocity back from Holeshot Racing of Bradford (who by the way are moving to Ireland two weeks from now)...
A dyno-jet kit, racing airbox/filter, and rolling road session gave me a 16bhp increase - I'll well chuffed with that!
One comment passed to me was that they presumed I was getting through the gears quickly.
I smiled with delight as I thought I was just being stupid. Apparently my top speed on the rolling road was only 105-110mph. I now realise why I was
hitting the rev limit at Cadwell last week.
Sure enough, the differential is geared quite low. I'm told it's a standard Ford 3.92:1. This is presumably a little too low for a BEC?
Please any of you BEC briggade suggest the best replacement, and what kind of money we're looking at? There are a few Sierra ones on eBay at the
moment.
Even better, does anyone have one for sale or sitting unused?
Any help much appreciated
Kyle, Leeds
If you current setup is permanent (wheels, tyre sizes etc) and a 3.92:1 diff ratio gives you 107mph then a 3.38 diff should give you 124mph. This
should give you much better cruising.
BTW If my maths is wrong someone let me know!!!
I'd try that before searching for a 3.14 - they cost a fortune!
All the best
Ali
PS
Holeshot Racing of Bradford (who by the way are moving to Ireland two weeks from now)...
I'd heard about this - didn't really believe it - somewhere in Co Down - anyone have any more info?
I am running 3.62 LSD with 205/50 15 tyres which gears mine to about 130mph..
Plenty for a locost imho...
If you are running smaller circumference tyres you will need a lower ratio of 3.38 or 3.14..
3.38 or 3.14 LSD's are VERY rare and expensive, so you will probably end up with an open diff..
I sold a 3.38 ( befor i knew the true cost) for £100 to AB performance a year ago, he gets his diffs stripped of the crown wheel and pinion and puts
them on a LSD.
Its the crown wheel and pinon that you want, once you have that then with the right money you can have any ratio built with a LSD.
Reversing boxes for BEC's will give you a ratio step up instead of searching for the elusive 3.38 and 3.14.
Just out of interest then, what will a 3.38 diff, 'Busa and 15/16" wheels give me in return??
If anyone has a 3:38 that they want rid of please let me know...
try this..
Thanks for that, but I only have XL viewer so cant change anything!
Ill have a dig around and see if I can come up with the full XL....
have a look at this one instead, i've changed the diff setting.
You could download OpenOffice... that should accept it and its free....
On my ST1100 BEC I've got 14" wheels with a 3.9 diff. Top wack 118mph (calculated) @ 8500rpm. That's okay for me. Keeps the
acceleration rapid but giving a rpm of 5k for national speed limit (about the same as my Micra!!).... I can see why supernutter screamer BEC drivers
might want a long diff for motorway cruising... Anything above 5k for any period of time might be a PITA (then again, I'm building an intercom /
mp3 device so I'd just turn up the volume!!).. MPG- that's a different story....
Cheers bud! Informative! Any chance of doing one more with 16" wheels??
Pretty please??
Programme doesn't have a 16" setting, if you can work out what the circumference would be (of the tyre that is) i can input it in manually...
Ah! Ok, no worries! Dont actually no what the profile would be yet, so cant do the maths!
I guess 16's will make the theoretical acceleration a little slower and the top end a little more? Aerodynamics, (or lack of!), aside that is!!
That's correct, not sure how much difference you'd notice though...i was told not to go too big on the diameter as it upsets the handling. W*stfield's megabusa's run 13" as standard. I'm running 15's.
The Dax will take up to 17's, I like the look, but dont want the wieght!
So may well end up with 15's. However If i feel extravigant I may go for Dymags, in which case Ill fit 16's!
Ive amended the spreadsheet linked in my avatar to include some bling wheels sizes up to 17"
I don't really know what the prefered tyre sizes would be but I chose sizes that seemed to be quite commonly available from BlackCircles etc, and
small enough sizes that (relatively) won't look too ridiculous on a BEC :p
Chris
[Edited on 11/2/07 by ChrisGamlin]
quote:
Originally posted by snapper
Reversing boxes for BEC's will give you a ratio step up instead of searching for the elusive 3.38 and 3.14.
The spreadsheet originates from about 5-6 years ago and as it was originally written by Simon Ranson who owned the yellow ZCars twin ZX9 Tiger, I
strongly suspect that the step-up ratio relates to the twin engine'd car which had a transfer box to link the two engines together and also had a
step-up ratio, so no good for a single engine install.
I could be wrong but the Allens and possibly Quaife are the only boxes I seem to recall with a mention of a step-up in gearing.
Arse!
Quaife don't appear to do one (their reverse box is direct drive according to their website), Allens have stopped selling them, Nova Racing
don't reply to enquiries and the Z-Cars overdrive is not suitable!
You would have thought that there was a good market for these things. Everybody's scrambling around paying fortunes for 3.14 and 3.38 diffs and
then having to pay more for them to be rebuilt with LSD internals. The reverse box would pay for itself if it came with a suitable step-up ratio.
I did try ringing Nova Racing but it was constantly engaged. I will try again and, for the benefit of those that are interested, let you know
Marc
Seems everybody is finding difficulty getting hold of a 3.38. I must have been very lucky without realising it!
Paid a tenner! 
quote:
Originally posted by iiyama
Seems everybody is finding difficulty getting hold of a 3.38. I must have been very lucky without realising it!
Paid a tenner!
Probably wont stay Ford internals anyway. Thinking about a Quaife ATB.
oooh there goes the £10 budget, nice tho
Budget?? Whats that then??? 
r1 car with 16 " wheels and a 3.62 diff
122mph bang on