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Going 4.11

xlnt6

By xlnt6
in Driveline Workshop

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xlnt6

xlnt6

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Well, I've been driving around with 4.11 diff gears for over three months now and every day I kick myself for not doing it earlier. If cdm is still out there, I conceed your views as I now am a "believer" !!

Especially after the bigger turbo which made the boost response a bit lazier, the 4.11 recovers that low down urge nicely. I have a T56 6 speed. That provides a taller overall top gear than the 5 speed.

For driving around town and freeway driving I can't recommend it enough. I guess I'm changing gears a bit more than before, but mainly by shifting up to 6th, whereas 6th wasn't really possible til 110km. Now 100km is about 2100rpm, and the ratio works out the same as a 5 speed in 5th with 3.45 diff. Fuel economy hasn't really changed either as the top gear is still tall enough to return good economy.

BTW I had originally a 3.45 ratio then tried a temporary 3.7 ratio and finally 4.11.

Cheers

Robin.

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bcl

bcl

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I've also had the 3 diffs.

The 4.10 was also going to be better with the bigger turbo, so your comments don't surprise.

It's sort of like suddenly picking up an hefty increase in torque!

With a 3.73 diff 6th at 100kph will be about 180rpm less, so less responsive.

My opinion is that 3.90, if available, would be the best option/compromise.

Brian

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xlnt6

xlnt6

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The 4.10 was also going to be better with the bigger turbo, so your comments don't surprise.

True, and I planned to do the diff and turbo in a similar timeframe for that reason. Actually ended up with 3-4months in between, and when it finally happened, it just showed that a bigger turbo upgrade really needs to be done in conjunction with a diff change in order to get the same lower RPM seat of the pants urge as with the OEM turbo.

whats the cost of a 4.11 fitted and just the part/s?

Don't know about the cost of parts, I was given the bits and had then built into a spare 3.45 LSD by TransDiff in Thomastown for $200. The biggest cost is the fitting, as it's quite labour intensive, about 4 hours, allow $400-$500 to do the swap.

Cheers

Robin.

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stealthxr

stealthxr

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It seems like you have the complete package robin, Credit to you and car mate

Has the backlash improved over the OEM item ???? and what Gearset are you using, is it a case of just a crown & pinion swap or are there mods to be done.. I'm due for it

Thanks Pete

BTW, the box is a Going good.... just the rollover noise on idle sometimes is bit excessive, but still feels very strong it will soon be visiting Mal W for freshen up!

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xlnt6

xlnt6

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Has the backlash improved over the OEM item ???? and what Gearset are you using, is it a case of just a crown & pinion swap or are there mods to be done.. I'm due for it

Hi Pete, my original diff, while it did have a bit of backlash, didn't cause me any grief, not like I've heard others complaining about. The new diff is the same. You still get driveline clunk on take-up especially noticeable on decel at low speed. The Gearset is still a Dana set - I think ...... (they are available thru most diff shops that build / reco diffs and I've seen them advertised in a few of the mags). Yes, it was just a matter of changing the crown and pinion and having the diff shop set-up the clearances. I also took the opportunity to have the LSD tighten alittle which has helped with straight line traction and hasn't effected cornering (as far as I can tell without being on a track). Beside that nothing else has changed. Except acceleration of course !!!

BTW, the box is a Going good.... just the rollover noise on idle sometimes is bit excessive, but still feels very strong it will soon be visiting Mal W for freshen up!

Good to hear. What can Mal do to fix this problem permanently ??? As I understand a blueprint job will only address it for a while, before the noise comes back ??? Mine does it, and started doing it within 3k-5k from being brand new.

Cheersin.

Rob

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RAP1D

RAP1D

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Would you recomend the 4.11 to those of us with less power?

If it matches the T56 better like you say I might look at it for mine... Ive changed ratios on previous rides and always worked out well down low

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bcl

bcl

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If it matches the T56 better like you say I might look at it for mine... Ive changed ratios on previous rides and always worked out well down low

A point to note is that if you want to run down the 1/4 you will be slower, as you will need to use 5th gear ... will cost you up to .3 to .5 of a second.

Brian

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