Slabz

hey guys. i've been searching the forums for info about putting an R31 skyline diff into my XF but i haven't found answers to all my questions.

i've got a 4.1 carby XF with a borg warner 4-spd manual box and 2.92 single spinner diff. i wanna change my diff ratio for more take off (and hopefully wheel spin). i know my economy is going to go out the window but i don't really give a shit, i wanna get an e-series 5-spd manual later on to fix this problem

my mate has an R31 manual skyline with the 3.7 diff and he's going to change it over to a 4.11 ratio from r31 pinny. i'm wanna score his 3.7 ratio off him and whack it in my car but i need to know a few things:

1. can i just bolt the 3.7 crownwheel onto my centre and whack the pinion that goes with the 3.7 into my diff (creating a 3.7 single spinner with 25 spline axels)

2. can i do this myself of is it insanely hard so i should get a shop to do it

3. if my centre is the wrong offset or something do i need a spacer or what other diff centres are available that will let me do this

this car isn't anything special, so i don't want big flashy thousand dollar ideas, i just wanna keep it really cheap. the reasons i'm picking 3.7 is because i wanna go to the extreme with changing diff ratios so the difference is really obvious plus i can get it cheap from my mate (and i kno the diff isnt screwed). that way i kno which one to pick for my next car (hopefully a 302/351 xd/xe).

rollin posted this in this thread: http://fordforums.com/showthread.php?t=70332

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deankdx

i didn't read that other thread, but... the gears should fit you're housing, i wouldn't recommend you fit it yourself, i'm mechanically minded but diffs aren't easy. a diff joint would probably charge say $300 ish? single spinner 3.7 will wheel spin like crazy and if you spin 1 wheel for long enough(trust me it doesn't take long to be long enough) you will blow up the centre quickly,
fOrD mAn Xf has just got his converted to lsd and a ratio change, cant remember how much he supplied to diff joint but it was a fair price for what he got done, i think he's going to fit it over easter. perhaps if you pm him he'll pass on his experience

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""not in full control of vehicle" officer? did you not see those perfect figure 8s!

Slabz

bugga. i didnt really wanna pay some1 else to do my diff, i wanna be cheap and do it myself. wot would be a better ratio that will still wheel spin on demand (from a str8 gas carbied 4.1 4-spd) but wont explode?

can i do it myself if i change to whole centre (dont go unbolting crownwheels) or is it the shimming and aligning the pinion and crownwheel that is hard?

if it cant be done, i'll just get the whole diff from the wreckers (it'd be cheaper then paying a shop to fit my ratio)

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deankdx

you've got 2 other options, if you'xe got a XD you could look for a XG/XH ute or E series wagon XR6/XR8 lsd diff 3.45 would be the lowest factory ratio, they all have leaf speings, you'll have to get the brake lines modified(late ones are metric) and hand brake will need mods good luck.
if you have an XE/XF you can fit E series XR6/XR8 sedan diff with the same above brake mods,
either way the diff will cost probably as much a s paying someone to do yours, and E series and MY XG uteLSD is not as tight as you'd want for hooning. the one i recently got converted(ratio change to 3.45 and LSD rebiuld cost $650) is tight as and squeels the tyres on tight U turns.
for a cheap LSD you could get a fairlane diff from ZJ leaf spring or ZK/ZL for coil springs, 2.77 and 2.92 are the only ratio std, probably cost $150ish.
a GOOD 250 crossflow(i've had heaps) will still hoon quite well with a 2.92 especially with a manual. if you've got a bigger cam 3.23 would be a minimum i'd be looking for probably 3.45 happy medium and 3.7 will scream on the highway

its very hard to do on the cheap

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""not in full control of vehicle" officer? did you not see those perfect figure 8s!

fOrD mAn Xf

Yeah mate, actually put the diff in on friday, it was a bit of work, defentley a 2 man job as you really have to hold the diff in place with jacks and jack it up. I have 3:23:1 LSD 4 pinion diff (which is 5 times stronger than a conventional diff) that cost me $650 to get done, but it was a full rebuild and comes with a 12 month warranty. everything goes good, axles slid in good, and it makes no sound at all. I have taken it for a test drive, but I can't accelerate fast in it or exceed 75km/h in it as I have to run it in (see below) but I can automatically feel the difference it has made, just keeping low, i dont need to accelerate as much to get it moving.

like dean said, you have a number of options, but changing the gear sets etc. from diff to diff i would not try, the teeth have to line up exactly, I have seen what the guy at the diff shop had to line up, and he spent a bit of time lining them up, and thats with the knowledge and the tools. you can find plenty of 2:92:1lsd complete diffs, or use a EA "s-pac" diff, which are 3:23:1 lsd, i was considering this option, but i didnt want to muck around.....its not really that hard, its just the hand brake line has to be exchanged and i think the brakes have to as well....can't remember?

i knew nothing about all this diff business (i still have more to learn) but deankdx has really helped out and provided very, very useful information, so i would defenetely listen to him;-)

Heres what I have to do for the "run-in" with the new diff:

"All reconditioned and repaired diffs must be "run in" for 1000km at a speed not exceeding 75kph and must not be subject to trips over 50KM, misuse or abuse. New bearings are pre loaded and generate very high temperatures.

Slabz

deankdx and ford man xf, thanks a bunch for your help. i think i'll go get a complete 3.23 diff from an XF (or 3.5 if i can) or an EA and i'll probably stick with a single spinner because my car kinda lacks in the power department.

thanks again guys.
Slabz

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rorycollett

get the old shims outa the r31 diff and remember wich side they came from(put a tag on them or something) and wak it all in and it will be ok, just check the teeth mesh properly.