flak monkey
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| posted on 14/6/10 at 09:43 AM |
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lsd or not?
not sure to do. I have a 3.62 lsd which I was going to fit, but would rather keep the existing 3.92 ratio.
so should I fit a 3.92 diff for bolt on shafts, or rebuild a 3.92 lsd or go for 3.62 lsd and keep it simple?
with the new wheels and tyres I can put all the power down in second gear without spinning the wheels with the existing 3.92 open diff and 2 people up
and hard cornering the car is totally neutral handling.
any opinions/experiences?
david
[Edited on 14/6/10 by flak monkey]
[Edited on 14/6/10 by flak monkey]
Sera
http://www.motosera.com
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graememk
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| posted on 14/6/10 at 10:06 AM |
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I'd put the pinto back in and build a westfield, using your new engine and shiney bits.
I have a LSD and if i was building again i dont think i would build using the ford LSD but maybe use the quaife.
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imp paul
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| posted on 14/6/10 at 10:07 AM |
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hi Dave i feel you should re build to make a 3.92 lsd as so you dont end up spinning 1 wheel up some of the time also it would be better to drive
with lsd 
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tomgregory2000
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| posted on 14/6/10 at 10:09 AM |
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funny this as i was out in mine yesterday with the new wheels and tyres fitted for the first time, i have a 3.92 lsd and it would spin up in 1st 2nd
and 3rd with the old tyres but now i have bigger tyres on the rear is has had the same affect as changing the diff ratio so now i get less wheel spin
in 1st but a bit slower acceleration but lower cruising revs, i was going to fit my 3.62 before my change of tyres but now i dont need to BUT a am
greatful for having the LSD otherwise i would just sit there spinning up one of the wheels as i try to go forward.
btw i am running 275/40/17 kumko v70 in med compound on the rears
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imp paul
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| posted on 14/6/10 at 10:14 AM |
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lol its funny when you see that happen 1 wheel going mental
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v8kid
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| posted on 14/6/10 at 10:24 AM |
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David,
In my opinion if you can boot it coming out of a tight corner without loosing it you don't need a lsd or bigger tyres.
If it spins the inside wheel you need a lsd.
In between is a grey area. I found a lsd gave me understeer going into the corner slowing me down but I was able to get on the power sooner coming out
of the corner. Overall it was faster but more difficult to drive.
Sorry if that is not much help!
Cheers
David
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hobbsy
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| posted on 14/6/10 at 11:24 AM |
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I fitted a Quaife LSD to my R1 Fury and it made a massive difference coming out of corners (no more spinning one wheel).
Its taken a while to build the confidence to do it but you really can get on the loud pedal early.
It also helps with my lack of reverse but its not always popular if done in a residential area 
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Ivan
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| posted on 14/6/10 at 12:35 PM |
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Comparing my Cobra to others I seem to have a lot more directional stability on pull off without a limited slip diff and not much more wheel spin than
those using one as they often end up with the tail sliding down the road camber and occasionally gripping when the car is facing the wrong way. Most
of the Cobras that have mounted Curbs or penetrated garden walls that I know of had LSD's. 
In terms of quarter mile times there's not much in it with amateur drivers and setups but they do however seem to have an advantage out of
corners.
So I believe the open diff is safer for normal use with non-expert drivers and the LSD an advantage to those who can set it up properly and get the
most out of it. The LSD also has some bragging rights but then you have that in buckets full with your setup 
[Edited on 14/6/10 by Ivan]
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flak monkey
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| posted on 14/6/10 at 05:34 PM |
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Thanks for the input
The car is fine in a straight line with 2 up as it is, not sure what its like around the corners when pushed hard as I am still learning the limits of
it. I know its nice and controllable now and you can push a lot harder.
I was planning to change to a 3.62 as I had no traction in a straight line with the old tyres - but yesterdays run out highlighted that its perfectly
controllable with the open 3.92 in a straight line now so I would prefer to keep that ratio to maintain the acceleration and the cruising RPM isnt
silly as it is (3000rpm @ 60mph). Infact I suprised myself with just how much acceleration and grip there is now. What its like with one person in and
90kg lighter I dont know yet...
Maybe I will leave it as it is for the rest of the year and make a decision then. I was just itching to get the rear brakes changed over
Sera
http://www.motosera.com
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NS Dev
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| posted on 15/6/10 at 04:58 PM |
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I have a 3.62 lsd and, iirc, a touch less power to weight than you (200hp 540kg in mine) and as you have said with yours, I have absolutely no
traction issues at all on 195 50 15 Yoko A048R's
I also have a 3.92 diff and I plan to put the cwp onto my lsd at some point!
As for which is best, if it doesn't seem to lose grip (good test is bumpy b roads where grip comes and goes on one wheel and the other, I know
there are a lot of good roads that fit that description a touch south from your place, around north norfolk! ) then don't bother with the
lsd.
I would be willing to bet it will be fine everywhere except when booting it hard on bumpy stuff, and the "shimmying" revs when it does
that can soon annoy you into wanting a lsd......
Retro RWD is the way forward...........automotive fabrication, car restoration, sheetmetal work, engine conversion
retro car restoration and tuning
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flak monkey
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| posted on 15/6/10 at 06:50 PM |
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Thanks Nat, kind of confirms what I was thinking. I have 270bhp and hopefully similar weight to you now.
I think the absolute best would be a 3.92 LSD - I do have a couple of 3.92 diffs, one of which is missing the back, but may be ok with a thorough
cleaning out.
Just need to make a tool to undo the bearing housings now!
It does spin one wheel up on bumpy roads when driving hard, which is a little annoying!
Sera
http://www.motosera.com
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NS Dev
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| posted on 16/6/10 at 09:50 PM |
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270hp, baahhhhh
dammit must find time to upgrade mine!!!
I reckon you are about bang on the most useable power at that. 250 to 270 hp must be about the most you can use really properly in a 550kg car,
certainly fun I take it!!!
Must say I do find mine a tad sluggish now!
Retro RWD is the way forward...........automotive fabrication, car restoration, sheetmetal work, engine conversion
retro car restoration and tuning
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flak monkey
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| posted on 17/6/10 at 07:48 AM |
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Yes its definately all usable and lots of low down grunt as well.
Tran-x diff on the way if I can cobble together the parts.
David
Sera
http://www.motosera.com
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