Ando81 2,949 Posted May 26, 2013 Hi all, I am thinking of replacing the diff in my xf sedan from 2.77 to 3.45 and wanted to put it behind my t5. The speedo is spot on at the moment as I got the gear changed to suit my 15inch rims but cannot remember the colour of it. I am hoping to fit a eb-ef lsd and from my calculations the speedo will be out about 25%. Has anyone else done a similar conversion and remember what gear to put on the speedo sender? Cheers for any help Share this post Link to post Share on other sites
MNTL.XD 3,831 Posted May 26, 2013 While on this topic, i need a question answered too if possible. What is the right colour speedo gear for a C10, 3.5 diff, 16" wheels? Any idea? Share this post Link to post Share on other sites
adrianphu123 73 Posted May 26, 2013 I have a T5 and 2.92 diff right now and its using a 19 tooth gear. i remember someone changing to a 3.45 and using a 23 tooth gear (i think) Im guessing it works out like this: 19 divide 2.92 = 6.51 6.51 multiply 3.45 = 22.45 so approximately 22 or 23 Im going to a 3.27 diff and im planning to use a 21 tooth gear: 19 divide 2.92 = 6.51 6.51 multiply 3.27 = 21.28 so approximately 21 or 22 You'd rather the speedo read a bit higher though, not sure if you'd go higher or lower tooth count for that lol i cant get my head around it. Theres a few tables in this link. http://www.ebay.com.au/itm/GENUINE-FORD-EA-EB-ED-EF-EL-SPEEDO-DRIVEN-GEAR-DRIVE-COG-SELECT-FROM-LIST-/120976451040?pt=AU_Clothing_Merchandise_Media&var&hash=item1c2ac225e0&_uhb=1 Share this post Link to post Share on other sites
adrianphu123 73 Posted May 26, 2013 So basically, Old tooth count (divide) old diff ratio (multiply) new diff ratio = new tooth count Share this post Link to post Share on other sites
Ando81 2,949 Posted May 26, 2013 Oh good work mate!! Sounds like you've got it sorted Share this post Link to post Share on other sites
MNTL.XD 3,831 Posted May 28, 2013 While on this topic, i need a question answered too if possible. What is the right colour speedo gear for a C10, 3.5 diff, 16" wheels? Any idea? Pretty surprised no-one has answered this, it has to be the most common ratio out there? Share this post Link to post Share on other sites
PRO250 1,506 Posted May 29, 2013 when you find out tell me the ute reads a fair bit out Share this post Link to post Share on other sites
n00bus m@x1mus 465 Posted May 29, 2013 The cog for 3.45s is a black 23 tooth gear... but if you have upped you wheel dia and gone to a diff cog to correct you may need to do the same here, so one up or down depending on which way you went previously. On another note does anyone know which cog I would need for 3.7s.. did they come in cortys? Share this post Link to post Share on other sites
n00bus m@x1mus 465 Posted June 6, 2013 Bumping this cause i still need to know lol Share this post Link to post Share on other sites
Tyler06 266 Posted June 6, 2013 The cog for 3.45s is a black 23 tooth gear... but if you have upped you wheel dia and gone to a diff cog to correct you may need to do the same here, so one up or down depending on which way you went previously. On another note does anyone know which cog I would need for 3.7s.. did they come in cortys? The gear in a corty wouldnt compare as they had a different box being a 4 cyl with the 3.7s im pretty sure but p100_ute ( aka tim) would know more Share this post Link to post Share on other sites
n00bus m@x1mus 465 Posted June 6, 2013 They didnt have a bw auto? Or singlerails with the 6 cyls? As long as top was 1:1 it should work out fine Share this post Link to post Share on other sites
Tyler06 266 Posted June 6, 2013 Nah the 3.7s only came in the 4 cyl manuals but they were different boxes so im not sure that the gears on the cable will help you. Share this post Link to post Share on other sites
n00bus m@x1mus 465 Posted June 6, 2013 Fair enough... what about commodores? Or even pintaras, where did these gears come from? Share this post Link to post Share on other sites
Thom 6,650 Posted June 6, 2013 Skylines and pintaras might be an option as the had 3.7, 3.89 & 4.11, don't know if the Speedo gear would interchange with a falcon gearbox ( also watch out for the teeth on the Speedo gear being "cut" the opposite direction between autos an manuals) Share this post Link to post Share on other sites
n00bus m@x1mus 465 Posted June 7, 2013 Choice ill check them out. Im pretty sure these would be corty gears but if im not going to find a bw box in a corty then i guess im searching for anything that would adapt. Just read that AUs had 3.7s?? What models would that be? XRs or maybe the TE50s? Im also going to fit an ultralite dash some time soon so if im stuck could i possibly just run the 3.45 gear ive got here and them tune the speedo to suit? Share this post Link to post Share on other sites
XF347 205 Posted June 7, 2013 Pretty surprised no-one has answered this, it has to be the most common ratio out there? http://mustangpartstech.com/SpeedometerGears.html I have a C10 with 3.55's aswell, according to this you need a 20 tooth gear. 1 MNTL.XD reacted to this Share this post Link to post Share on other sites
n00bus m@x1mus 465 Posted June 7, 2013 Thats not correct with our gear boxs but. The factory driven gear for an xr6 with 3.45s is a black 23 tooth gear. 3.27s were a purple 21 and green 19 was for 2.77s. Share this post Link to post Share on other sites
XF347 205 Posted June 7, 2013 Ye sorry Noobus that was for MNTL.XD, he stated earlier he has a C10 and 3.5 gears. 1 MNTL.XD reacted to this Share this post Link to post Share on other sites
NZXD 2,328 Posted June 7, 2013 I have the gear out of an AU xr6 btr auto for my single rail as running the 3.45 ratio, the gear is grey and has 22N EA on it. The btr auto has the spline cut the opposite direction to the c4/6 autos. 1 Thom reacted to this Share this post Link to post Share on other sites
Wezza 13 Posted September 6, 2013 Does anyone know what colour i need for a XD V8 running a C4, 2.77 diff and 215/60r14? I cant seem to get an answer anywhere, not even Ford have that combo on their records and no chart i have found has helped. The diff was changed from drum to disk before i bought it which i am assuming is where the difference was. Any help is greatly appreciated as nowhere i can find can give me a definitive answer. Not exactly swimming in money so i want to get it right the first time LOL. Share this post Link to post Share on other sites
NZXD 2,328 Posted September 7, 2013 I'll have a look in my XD book, it has all the ratios and gear box combos etc Share this post Link to post Share on other sites
NZXD 2,328 Posted September 7, 2013 Does anyone know what colour i need for a XD V8 running a C4, 2.77 diff and 215/60r14? I cant seem to get an answer anywhere, not even Ford have that combo on their records and no chart i have found has helped. The diff was changed from drum to disk before i bought it which i am assuming is where the difference was. Any help is greatly appreciated as nowhere i can find can give me a definitive answer. Not exactly swimming in money so i want to get it right the first time LOL. Hey mate, just checked my ford XD repair manual, it states the only XD with the 2.77 was the 351 clev with FMX, with 205/70/14 tyres ran the orange 20 tooth Speedo gear. Share this post Link to post Share on other sites
Wezza 13 Posted September 7, 2013 Yeah thats the trouble im finding. I dont think the diff was out of an XD and im not even sure if the gearbox is original either. Both of which make it more difficault. Is it possible to work it out manually at all? Share this post Link to post Share on other sites
Ando81 2,949 Posted September 7, 2013 Mate I have a diagram at home, cannot remember where i got it but it says all xd xe xf falcons with 2.77 diffs and 3 speed auto and 3 or 4 speed manuals need to use 18 tooth purple gear. I assume that this is going on the drive ratio of Borg Warner autos like 35 or 40 boxes. You would need to check the drive ratio of a c4 compared to a bw35 auto. Hope this helps mate. Sent from my iPhone using Tapatalk - now Free Share this post Link to post Share on other sites
Wezza 13 Posted September 7, 2013 Cheers mate. Ill look at that. I have heard that also but nowhere seems to mention the C4. Share this post Link to post Share on other sites