S1 monty ghia, 3.9 LSD

[kratas]

Hey guys, was just hoping for some feed back here. Took the car down to my mechanic because I noted that when changing from neutral to drive or reverse, there is a distinct lag, before a clunking engagement. Thought that the diff might need a service (notorious on the AU) so asked the bloke to check her out.

He said it was definatley a slack diff, and that it would need to be fitted with a recoed one. Gave me the number of a diff place about 20ks away from his shop, saying that he knows that the guys dont rip you off and do a decent job etc.

Onto my question. I have been toying with the idea recently of changing the diff anyway, so I figure while they are putting in the labour, I might as well change the diff ratio and also put LSD on the bad boy.

Its a series 1 fairmont ghia. 3.1 diff ratio (iirc) single pegger. With IRS. I was wondering, should I just get a swap to an XR6 LSD diff, and have the ratio changed to a 3.9. I am sick to death of the 0-50kmh 15 second foot to the floor, titanic geting out of harbour feel of the fairmont ghias long diff ratio, 4 speed slug box and damned ECU.

So, I was thinking 3.9 LSD and a 3 grand stallie. What is your opinions? will a straight swap be possible? is the ratio good? one mate said 3.9 is too short, and I should go 3.7 and another said I should go 4.11.... lol

thanks in advance

[Professor Farnsworth]

3.1? i would guess it was a 3.45 or a 3.23 at the very least.

for all round drivability, i would suggest a 3.7

[kratas]

Could not remember the ratio if you dont mind, could you advise me to the difference between a 3.7 and 3.9?

[Professor Farnsworth]

Originally Posted by The Monty

3.08 for S1 monty. Go 3.9's or 4.11's.

ahhh.. no.. the s1 au ghia has a 3.23, and the VCT got the 3.45. we're talking about the ghia here, not the fairmont.

http://www.fordforums.com.au/photos/...cat=728&page=1

Originally Posted by kratas

Could not remember the ratio if you dont mind, could you advise me to the difference between a 3.7 and 3.9?

not much at all mate. 3.9 would be good actually since your car is a VCT. It basically means for every full rotation of the rear axle, your driveshaft spins 3.9 times. The more the driveshaft turns in relation to the axle, the quicker the car will accelerate. The downside is it will rev harder on highway speeds, going from 3.23 for example to 3.7 may make it rev 400rpm higher at 100.

[The Monty]

Originally Posted by Professor Farnsworth

ahhh.. no.. the s1 au ghia has a 3.23, and the VCT got the 3.45. we're talking about the ghia here, not the fairmont.

Touch'e. Didnt read the Ghia bit, my bad, lol.

[The Monty]

3.08 for S1 monty. Go 3.9's or 4.11's.

[kratas]

So then should I go for 4.11 or will that be undriveable?

[Stattic]

if you can find 4.11s, go for it

[blueoval]

It depends on what your car is mainly used for.

For instance, do you drive spirited on the street often, or are you a daily grandpa kind of driver? Knowing how you drive could be the difference.

[Stattic]

i looked into going 3.7 myself but its not much up from 3.45 so i got talked out of it (rightly so)
i ended up buying 3.9s because i couldnt get a hold of 4.11s... probably a good thing, i might be doing more highway driving than i thought :P
from all reports, economy isnt too bad around town because the engine is revving more freely and youre not having to use much throttle to get going
i will see how i go, im still waiting for my lsd to be set up with the new gears

[kratas]

yeah, well... here is a development for you. I went to Central Diffs in Springvale, and the guy basically told me that A) My diff is NOT slack, and that I should get my transmission checked. He also stated that B) the biggest you can go in the fairmont ghia was 3.73? he said it had to be imported into the country from south africa blah blah, sounded like a load of because I told him I knew multiple people with 3.9 and even the odd 4.11 in an AU. He also talked me out of LSD because he said traction control "took care of it" and if I took traction control off and had an accident, then insurance would not pay out.

How much of this was BS and how much was accurate? P.S I was qouted 1,100 for 3.73 basically recoed diff with new ratio.... seems a bit high for my tastes

[Windsor220]

Originally Posted by kratas

How much of this was BS and how much was accurate? P.S I was qouted 1,100 for 3.73 basically recoed diff with new ratio.... seems a bit high for my tastes

Hell thats cheap. I've been ringing around places enquiring about 3.9s and all of them qouted $1800. I called one of them back today and had a chat saying that I wasnt interest in anything fancy just put the gears in and thats it. He then qouted me $1550.

The guy said he doesnt recommend me supplying my own gears as the ones you get form ebay etc are always noisy.

[Stattic]

recoed diffs can be gotten for cheaper but its not that expensive i guess, are they fitting it as well? and yes, it is rubbish that you cant get shorter than 3.73
thats probably all they have in stock! 3.9 and 4.11 diff gears do not come from south africa, they come from old skylines and pintaras that can be found all over the country

HERE IS WHAT I WAS TOLD... from the diff place that my mechanic deals with
someone has gone to most of the major wreckers in victoria and used a hot axe to cut out all the diff centres that had all the popular diff gears, 4.11, 3.9, 3.7 etc etc and thats why most of the diff places cant get hold of gears they dont have
its a likely story, ive rang around to alot of places recently chasing diff gears and those who didnt have them couldnt get them and those who had some left were reluctant to sell them, they only wanted them for customers who were getting a job done

[kratas]

yeah, the guy at the diff place mentioned getting 4.11s from a pintara, but said that you are likely to just blow the diff, especially if you put work into them, because they come from a 4cyl?

[Stattic]

Originally Posted by kratas

yeah, the guy at the diff place mentioned getting 4.11s from a pintara, but said that you are likely to just blow the diff, especially if you put work into them, because they come from a 4cyl?

oh.my.god.
thats the dumbest thing ive ever heard
its just as strong as any 3.08, 3.23 or 3.45 that came with any au you can find, it is a borg warner gear set just like any other
one diff place down here tried to tell me they didnt fit in the AU and that they wanted 500 bucks to make a special adaptor on top of the price they were asking to set up the lsd

[The Monty]

Originally Posted by Stattic

oh.my.god.
thats the dumbest thing ive ever heard
its just as strong as any 3.08, 3.23 or 3.45 that came with any au you can find, it is a borg warner gear set just like any other
one diff place down here tried to tell me they didnt fit in the AU and that they wanted 500 bucks to make a special adaptor on top of the price they were asking to set up the lsd

4.11's from early skylines and pinto's do require the diff to be modified to fit.
In saying that, they will be fine, can be very whiney, ricer gears are notorious for it.

[Stattic]

Originally Posted by The Monty

4.11's from early skylines and pinto's do require the diff to be modified to fit.
In saying that, they will be fine, can be very whiney, ricer gears are notorious for it.

i dont think its worth that kind of money
the ones i bought seem to be new gears that have been used a bit, they look like they have done barely any kms

[Professor Farnsworth]

i never get tired of the total BS some people try to feed you. Go somewhere else, shop around. where are you from, vic?

[madmelon]

If traction control did all that, why does anyone have a limited slip diff? Why would the factory waste money offering it?

[grandpa_spec_F6]

4.11's are fine but you best keep clear of the highway, friend had them in his v8, deadly when city driving (traffic light battles etc) however on the highway it sucked fuel like no tomorrow

[blackers10]

clunky diff = worn and just needs re lapping to rid it off this(aka realignment of the gears so the teeth mesh smoothly

If I remember correctly the AU diff needs mods to fit 4.11s

the difference in revs between the 3.9 and 4.11 isnt all that much so just go the 3.9s(or what ever the monty is running in is.. seems to be a good combo for street strip and highway (he does alot of all 3)

the IRS diffs are typically 3.45 (at least in VCT fairlanes and you would think they would have the highest highway gearing of them all....

[DW260]

Seems funny the amount of crap people get fed from mechanics. It's almost enough to make you throw your hands up and revert to purchasing and driving a sleeping-tablet, like a Toyota Camry, whenever the warranty expires...

I had my diff rebuilt earlier this year with 3.9's by a reputable shop in Canberra, who flat-out refuses to use recycled gears from Japanese cars. He had a whole host of brand-new gears sitting on the elevated storage area in his workshop. So I don't think they can be that hard to get.

He charged me ~$1500 for the whole job. Included new wheel bearings, LSD cones, new gears, oil, labour and dropped me off at work then came and picked me up from work at the end of the day. Rather nice young chap, with one apprentice with only enough room to work on one vehicle at a time.

Made a reasonable difference too. Only problem is the speedo is 10% out at all speeds, but that's not without its benefits. You have an auto, so I'd be inclined to go with 4.11's, but factor in a custom tune so they can diddle with the transmission settings for the lock-up torque converter.

[The Monty]

My Diff was $450, which had just been rebuilt. Fitting was $220, including an inspection and fluid. This was second hand though, so new prices would obviously be higher. My diff is only generally whiney after a big night at the drags, but are generally ok. Having a 3 uinch usually helps with covering the noise, lol.

[The Monty]

Do you expect them to look old and chipped? Of course they are going to look good. You would have no idea of the condition of them until you get them checked out properly.

[Stattic]

i would have no idea, hey? FYI i have had them checked out properly

[Professor Farnsworth]

settle down ladies we're all friends here

[The Monty]

Not really. Im sick of the childish crap every time I correct him when he uses wrong info. Im trying to help, Im just adding my bit. Theres no need to get deffensive Stattic every time someone doesnt 100% agree with you. Thats why everyone bars you from there MSN. Wake up and realise that some people here actually know what they are talking about. Its not third hand and fourth hand info that we are relaying on to people, its first hand information.

[Stattic]

if youve got an issue you can take it to PM because im sick of every thread i post in turning into an argument because you troll every thing i say

[frd906]

like monty said, he is only helping you

[Stattic]

oh my god keep out of it if anyone here needs help its you

there was a REASON i said for PMs because im sick of threads turning sour