Diff
Author
Discussion

snookes

Original Poster:

262 posts

309 months

Tuesday 28th January 2014
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Shortly to have diff refurbished
Btr 3:45 out of a cerb running LS2
Question is do I change the final drive ratio to a 3:23/3:07
Or leave the 3:45 in?
Thoughts and opinions please and has anyone gone the same route?
Thanks
Anthony

rigga

8,805 posts

227 months

Tuesday 28th January 2014
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Brummmie might be the one fir this .....

RichardD

3,608 posts

271 months

Tuesday 28th January 2014
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What output is the LS2?

A 3.45 diff gives better in gear acceleration than something like a taller 3.08.

But a 3.08 can turn extra torque into roadspeed and make a really powerful car quicker through the gears due to less wheelspin in lower gears and time wasted changing gear.

Brummmie has the 3.08 because with the amount of power his car has, a normal diff gives more acceleration in 1st than there is grip. (This is still the case in 2nd, on a track day, with slicks hehe)

I'd say :-

with a 400/420bhp engine stick with 3.45.
If you have 450-480 bhp decide based on your preference.
With more than 500bhp go for a 3.08 smile.

snookes

Original Poster:

262 posts

309 months

Tuesday 28th January 2014
quotequote all
RichardD said:
What output is the LS2?

A 3.45 diff gives better in gear acceleration than something like a taller 3.08.

But a 3.08 can turn extra torque into roadspeed and make a really powerful car quicker through the gears due to less wheelspin in lower gears and time wasted changing gear.

Brummmie has the 3.08 because with the amount of power his car has, a normal diff gives more acceleration in 1st than there is grip. (This is still the case in 2nd, on a track day, with slicks hehe)

I'd say :-

with a 400/420bhp engine stick with 3.45.
If you have 450-480 bhp decide based on your preference.
With more than 500bhp go for a 3.08 smile.
Thanks
460 bhp and 470 ft/lb

RichardD

3,608 posts

271 months

Tuesday 28th January 2014
quotequote all
snookes said:
Thanks
460 bhp and 470 ft/lb
Do you know your peak power rpm? (I'd guess at fairly close to 5500).

Maximum gear speeds (mph) should be fairly close to :-
3.45 :47,71,100,132,178
3.08 :53,80,113,148,188

As before the normal diff will give more acceleration in gear, and the top speed would be limited by the redline (that was with 6500), but a 3.08 unit would allow the car to reach its true top speed limited by power. Plus have lower revs on the motorway.

(On a 1/4 mile the 3.08 is better too, so less grunt doesn't mean less acceleration though the gears).

Up to you smile

330p4

668 posts

256 months

Tuesday 28th January 2014
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With all that torque i would go with the 3.08
Ian

snookes

Original Poster:

262 posts

309 months

Wednesday 29th January 2014
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Thanks for the input guys
I'll have a word with brummie and make up my mind
Cheers
Anthony

flyingdutchie

870 posts

220 months

Wednesday 29th January 2014
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Brummie wil say 3.08. I have a 3.08 also. I want to know how it all works with the T56 in. Did check the oil os the diff. Itlooked a little grey. Metal. It doens't make noise, but it was supplied by someone from who i wouldn't buy a nut from anymore. First the gearbox and then working to the back. Hope the driveshafts are strong enough for the ls2.