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| stomper |
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I got a EF GLi and i want to put a 3.9 LSD in it that i have arranged. Problem is that i wont be able to get a speedo gear big enough.
Here is what it says on the calculator. Speedo gear- Brown 20 Tyres - 205/65 R15 Diff - 3.08 SS i calculated it so that it is within half a KM and this is what i got. Speedo Gear - Black 23 Tyres - 205/85 R16 Diff - 3.9LSD And its just as much out with Speedo Gear - Black 23 Tyres 205/65 R17 Diff - 3.9LSD Whats going on??? What profile tyres and diff gear to have the 3.9 in?
_________________ HOLDENS go like rockets. They fall apart in stages!!! |
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| ebfairmont3.9 |
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dude why are ya worried....just get a speedo corrector to fix the speedo signal to your dash... putting in big diff gears doesnt hurt your shift points or anything...asuming your auto. just change the speed signal to the dash not the ecu and you will be fine.
_________________ 1994 ED Fairmont Champaign Gold - AU Series II Intech 4.0L - EL EFI - Thermo Fans - 4.11 LSD - Pacemaker 4480 Into Custom 3" Exhaust - Shift Kit |
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| stomper |
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ebfairmont3.9 wrote: dude why are ya worried....just get a speedo corrector to fix the speedo signal to your dash... putting in big diff gears doesnt hurt your shift points or anything...asuming your auto. just change the speed signal to the dash not the ecu and you will be fine.
Tell me more. LOL I want the 3.9 in so ill have to work this out. Ill be going manual probably at the same time.
_________________ HOLDENS go like rockets. They fall apart in stages!!! |
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| gogetta |
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ebfairmont3.9 wrote: dude why are ya worried....just get a speedo corrector to fix the speedo signal to your dash... putting in big diff gears doesnt hurt your shift points or anything...asuming your auto. just change the speed signal to the dash not the ecu and you will be fine.
thats not right because the circuit goes sender->dash->ECU so if you use a speedo corrector then the ECU will hold gears for way too long before changing....u will need 2 speedo correctors (i think)
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| green machine |
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speedo gear for 3.9's should be green and i'm not sure of the number!
_________________ custom airbox,custom intake |
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| Krytox |
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Or a police spec dash! =)
_________________ Carefree, we may not be number one, but we're up there. |
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| FordFairmont |
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Posts: 6113 Joined: 8th May 2007 |
From what ive heard, the ecu shifts gears based on road speed, so if you hook up the speedo corrector to the speedo input wire going to the cluster, then the speedo output wire will get the adjusted road speed signal to the ecu... all good !!!
Heres a doco i did on installing a jaycar speedo corrector if anyones unsure how to install..... http://www.trueblueford.com/discussion/ ... php?t=3187 (you may have to be a member to view it?) |
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| stomper |
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just had a look at them and it looks easy enough to install. Ill see what the manual box has in it first and how that goes.
_________________ HOLDENS go like rockets. They fall apart in stages!!! |
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| prydey |
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black 23 tooth is the biggest available gear but as has been mentioned, just fit a jaycar corrector. i have also heard that you may need to fit 2 although unsure on this. i have 3.9's in mine with black speedo gear and jaycar speedo corrector fitted. i don't have any trouble with hitting the limiter or gear changes but thats prolly more due to the fact that i'm running aftermarket ecu.
speedo correctors from jaycar come in kit form so you'll need to be handy with a soldering iron or know someone who is.
_________________ eb v8: low loud and fast. just how a v8 should be. i guess the big question is, is it fast enough... |
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| Steady ED |
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FordFairmont wrote: From what ive heard, the ecu shifts gears based on road speed, so if you hook up the speedo corrector to the speedo input wire going to the cluster, then the speedo output wire will get the adjusted road speed signal to the ecu... all good !!!
Heres a doco i did on installing a jaycar speedo corrector if anyones unsure how to install..... http://www.trueblueford.com/discussion/ ... php?t=3187 (you may have to be a member to view it?) You don't want the ECU to get the adjusted speedo signal, thats what makes it shift wrong. You need to supply the dash the right signal, so you see the right speed, but then modify it BACK to being wrong for the ECU.
_________________ ED XR8 Sprint - S-Trim, V500, 249rwkw |
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| Swine |
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Posts: 266 Joined: 16th Feb 2007 |
http://www.shiftkits.com.au/
give them a call, they do a dash only speed correcter. Do the auto as well and ya shift points are rooted |
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| stomper |
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SO i want the Dash Cluster to get the modified signal but the ECU to get the standard signal?
_________________ HOLDENS go like rockets. They fall apart in stages!!! |
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| FordFairmont |
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Posts: 6113 Joined: 8th May 2007 |
ive been thinking about what steady ed said and i still cant understand how it works.
I thought the ecu had to see the adjusted road speed from the speedo corrector so it changed gears earlier instead of giving it a higher speed signal (thats out from the diff change) from the cluster, i guess its not that hard to experiment with, just have to buy 2 correctors |
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| Steady ED |
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Okay, I'll explain it again.
Stock diff, stock ECU, stock speedo gear. ECU shifts 1st >2nd at 80km/h under WOT. You put 3.9s in, stock ecu, stock speedo gear. Speedo is wrong, ECU will still shift at 80km/h under WOT, but your actual speed will be only say 60. NOW, if you modify the signal, so the ECU sees the CORRECT speed (eg. 60km/h at 5000rpm as opposed to 80), it will be waiting for 80km/h to come so it can shift to 2nd. But it will never get there, it'll bounce off the limiter a few times before it figures it out or you back off and force a shift.
_________________ ED XR8 Sprint - S-Trim, V500, 249rwkw |
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| FordFairmont |
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Posts: 6113 Joined: 8th May 2007 |
Ah makes sense now, after trawling throught countless threads about this issue, what you just said was the best response and the most clear.
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