EasyJimbo
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| posted on 16/4/09 at 06:50 PM |
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Diff help for a beginner
Hi Guys
I need some help, I am trying to work out what diff I should buy for my MK indy project. I am going to be running a blade engine and want to
concentrate more on acceleration rather than top speed, what diff would be best? Also I see there are 7 and 7.5 diffs whats the difference and which
type do I need?
thanks
James
be gentle I am new to all this :-)
blog: http://mkjimbo-mkindybuild.blogspot.com/
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daniel mason
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| posted on 16/4/09 at 06:58 PM |
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a 3.62 lsd could be an option. the 3.38 is more common and more expensive as it gives a higher top speed!
not sure what top speed with 3.62 will be with a blade engine but someone will be around soon with more advice than i can give
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mads
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| posted on 16/4/09 at 07:00 PM |
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Hi James,
Did you not sell your kit in the end then?
As for diff, you'll need the 7" one as AFAIK that is the one MK build the mounts for on their chassis.
As for which ratio, if it is the acceleration you want then you want a higher ratio if possible e.g. 3.62:1 (someone correct me if i'm wrong).
But out of interest, why are you concentrating on the acceleration? You do realise you will lose top end speed because of it?
edit: corrected what I said. got it wrong way round.
[Edited on 16/4/09 by mads]
We gain knowledge faster than we do wisdom!
Life is not a journey to the grave with the intention of arriving safely in a pretty and well-preserved body, but rather to skid in
sideways, thoroughly used, totally worn out and loudly proclaiming... "f*ck, what a trip!"
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EasyJimbo
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| posted on 16/4/09 at 07:04 PM |
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Thanks for the replies so far, yes I am now not selling the kit and forging ahead. I get it in 3 weeks time.
be gentle I am new to all this :-)
blog: http://mkjimbo-mkindybuild.blogspot.com/
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EasyJimbo
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| posted on 16/4/09 at 07:08 PM |
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Found this one on ebay, any thoughts?
http://cgi.ebay.co.uk/SIERRA-XR4X4-3-62-COSWORTH-4X4-LIMITED-SLIP-DIFF-7-INCH_W0QQitemZ220387743025QQcmdZViewItemQQptZUK_CarsParts_Vehicles_CarParts_S
M?hash=item220387743025&_trksid=p3911.c0.m14&_trkparms=72%3A1683%7C66%3A2%7C65%3A12%7C39%3A1%7C240%3A1318
J
be gentle I am new to all this :-)
blog: http://mkjimbo-mkindybuild.blogspot.com/
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mookaloid
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| posted on 16/4/09 at 07:14 PM |
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quote:
Originally posted by EasyJimbo
Found this one on ebay, any thoughts?
http://cgi.ebay.co.uk/SIERRA-XR4X4-3-62-COSWORTH-4X4-LIMITED-SLIP-DIFF-7-INCH_W0QQitemZ220387743025QQcmdZViewItemQQptZUK_CarsParts_Vehicles_CarParts_S
M?hash=item220387743025&_trksid=p3911.c0.m14&_trkparms=72%3A1683%7C66%3A2%7C65%3A12%7C39%3A1%7C240%3A1318
J
Very very expensive 
"That thing you're thinking - it wont be that."
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jacko
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| posted on 16/4/09 at 07:24 PM |
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Keep looking i only payed £40 for mine
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mark chandler
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| posted on 16/4/09 at 07:25 PM |
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I have a 918 blade engine, 185/60/13 tyres and 3.62 LSD diff.
The car will hit 12,500 rpm in top , so the gearing is ideal as top RPM = top speed.
If I had a higher diff the car would not max out but be nicer on the road, lower may help acceleration, the car can spin the rear wheels in first if I
boot it (with grippy yoko 048 tyres) so maybe not!
My car is very light, I estimate no more that 400kg, a MK may be a little heavier.
At Lydden hill, a short course the gearing is pretty much perfect as I can get into 6th on the straight.
NB/ the LSD makes a difference on the track, if I follow similar cars without you can see the inside wheel spinning up, IMHO well worth the extra £100
notes even if it is well worn like mine.
Regards Mark
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tomgregory2000
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| posted on 16/4/09 at 07:38 PM |
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quote:
Originally posted by EasyJimbo
Found this one on ebay, any thoughts?
http://cgi.ebay.co.uk/SIERRA-XR4X4-3-62-COSWORTH-4X4-LIMITED-SLIP-DIFF-7-INCH_W0QQitemZ220387743025QQcmdZViewItemQQptZUK_CarsParts_Vehicles_CarParts_S
M?hash=item220387743025&_trksid=p3911.c0.m14&_trkparms=72%3A1683%7C66%3A2%7C65%3A12%7C39%3A1%7C240%3A1318
J
Cant you get a whole sierra for that?
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eznfrank
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| posted on 16/4/09 at 07:50 PM |
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I'm pretty sure the guy selling that diff used to be called Sierra Shack and he sold me a LSD for about £80 IIRC.
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ReMan
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| posted on 16/4/09 at 08:22 PM |
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Mines 893 motor , 3.62 diff and 195/50/15's
This equates to EXACTLY 1000 RPM per 10mph in 6th.
So top speed is 100mph at 10,000rpm and then on to what you want to call your redline
OK its a bit low for motorway speed, but a good all round gearing IMHO
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motorcycle_mayhem
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| posted on 17/4/09 at 08:28 AM |
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My 893 was great all-round on a 3.38 running 205/60/13.
Viscous Sierra 7" pretty much my favourite, lovely progressive diff. Had a 7.5" at some point, it was available, no real difference,
except I had to shave a bit off the casing to get it in.
GSXR's go better with a 3.21 (Freeloader), essential when on 21-22" dia. 13" slicks.
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