bah, think i killed the diff in an AU3 SR

sneaky · 05-08-2008, 08:12 PM

hi guys, after a confirmation and a guestimate on price of fixing / replacing the diff in an AU3 SR falcon..

was out trying to warm the brakes tonight to see if that would fix some annoying squeaks that had been occurring for the last week or so..

anyway, what better way then to part-take in some hijinks on an empty road. anyway, long story short. car drove fine and made no noises coming home until i went to swing into the driveway, then there was an almighty creaking / groaning rubbing noise coming from the back end.

-tim

sneaky · 05-08-2008, 08:39 PM

i'm back.

a quick phone call and my brother tells me that i have killed the sun gears..

any idea on a rough price to fix? or would somewhere do an exchange for a reco diff? i'm on the central coast nsw, but can get the diff to newcastle or north sydney (i work in hornsby area)

oh, and has someone got a spare room or lounge, it's my wife's car, che is due to give birth in about 2 weeks, we already have a 12month old kid (the sr is the only one with a kid seat) and i go on the call out roster next week so i basically won't be here for the week...

-tim

atec77 · 05-08-2008, 08:49 PM

Quote:

Originally Posted by sneakypete23

i'm back.

a quick phone call and my brother tells me that i have killed the sun gears..

any idea on a rough price to fix? or would somewhere do an exchange for a reco diff? i'm on the central coast nsw, but can get the diff to newcastle or north sydney (i work in hornsby area)

oh, and has someone got a spare room or lounge, it's my wife's car, che is due to give birth in about 2 weeks, we already have a 12month old kid (the sr is the only one with a kid seat) and i go on the call out roster next week so i basically won't be here for the week...

-tim

go buy a used centre . might be 100 or 200 for a full diff dependant on source then use your brakes

sneaky · 05-08-2008, 08:56 PM

used centre you say - would this be from a wrecker or a diff place?

so hopefully i can get out of this for under $500.

and i've learnt an important lesson, no hooning in the bosses car...

EvilChief · 05-08-2008, 09:10 PM

wreckers normally send diff in complete assembly

what u mean with sun gears? the spider gears in ur centre or the crown and pinion gear?

i got a crown and pinion 3.45:1 you can have for $120

BTW replacing the carrier housing requires new shims to set the correct backlash. to avoid that you should be able to get a set of spider gears from spare parts new and "simply" rebuild ur centre with the new gears (again shims/spacers are used to set tolerances). but u will need atorque wrench, centre punches and about 2h of your time to re build centre alone.

PS: while i am rambling you can pick up new LSD centres for around $500, or a good second hand unit for 200 to 300 ... shop around ;)

sneaky · 06-08-2008, 04:47 AM

cheers evilchief. my brother is a mechanic so he has the tools and the know how, as i said above, the timeframe is my big issue. he spoke to a friend of his who is the service manager at a ford dealership, he said that because of the style of diff it would be difficult to rebuild it in the backyard (something about having to hold it open or pry it open..)

so to make it an lsd diff all i need is a new centre, which is stuffed and has to be replaced anyway, hmm...

burnz · 06-08-2008, 06:18 AM

hornsby diff's very cheap and 20,000k warranty.
$850 for an lsd any ratio.
http://www.hornsbydiffs.com.au/3.html

EvilChief · 06-08-2008, 08:22 AM

Quote:

Originally Posted by sneakypete23

cheers evilchief. my brother is a mechanic so he has the tools and the know how, as i said above, the timeframe is my big issue. he spoke to a friend of his who is the service manager at a ford dealership, he said that because of the style of diff it would be difficult to rebuild it in the backyard (something about having to hold it open or pry it open..)

so to make it an lsd diff all i need is a new centre, which is stuffed and has to be replaced anyway, hmm...

u need a good vice to torque down the crown pinion back to the carrier housing (150NM), diassembly can easily be done with rattle gun (BTW left hand bolts ;).

last time i build a diff it took me about 3h from start to finish (without gera ratio change)

sneaky · 06-08-2008, 08:51 PM

well the diff is out of the car and ready to go to the shop tomorrow morning. hopefully to be built by close of business friday..

cheers for the help, now waiting for diagnosis

-tim

EvilChief · 06-08-2008, 08:59 PM

should easily be done ... btw get carrier bearings checked while u r there ... now is the best time to change them if they need to

sneaky · 07-08-2008, 08:29 PM

diff is in the shop and pulled to bits. spoke to the dude at lunch time, he was starting to try to pull the welded planetary gears from the hemi :( hopefully he got that sorted or replaced and i should be back under the car tomorrow night trying to put the car back together.

while i'm at it i bought some rear brake pads to replace the worn ones in it.

bad news, looking under the car means that i have seen the exhaust that is rusted to bits and won't pass rego - at least i have until feb to fix it.

-tim, hoping not to encounter too many problems putting the diff back in..

sneaky · 09-08-2008, 08:26 PM

well well well. the diff is fixed and back in the car, plus i put new bendix pads in the rear. very, very happy with the service and price from coastal driveline specialists at charmhaven on the central coast. i rang them wednesday for a quote, dropped the diff off on thursday and picked it up on friday and the price was as quoted...

got some help from a mate and my wife (and dad later on) to put the diff in, we did a decent job considering none of us knew what we were doing (at least i had the benefit of actually looking under the car when i was taking it out). and now i have a rough idea of how things work under there

very rewarding to fix things yourself, just wish i didn't have to break it first and get in trouble off the boss

cheers for the help peoples

-tim

EvilChief · 10-08-2008, 10:22 AM

very good mate ... hope u didnt swap the two side shims from side to side ... that would have altered ur back lash and you would get a nice whine :p

sneaky · 10-08-2008, 12:38 PM

Quote:

Originally Posted by EvilChief

very good mate ... hope u didnt swap the two side shims from side to side ... that would have altered ur back lash and you would get a nice whine :p

as i don't know what you mean i also hope i didn't swap the side shims.. (insert embarressed / confused smily here)

only driven the car once since fitting, and that was only for about 5k's. no noises that i could hear..

-tim

EvilChief · 10-08-2008, 01:04 PM

lol there were two shims (spacers) on either side of the diff centre, which sit between the diff housing and the diff carrier outer bearing races. these are two diff seizes (thicknesses), which give the diff the offset relative to pinion and set your backlash.

sneaky · 10-08-2008, 05:33 PM

ahh, that's ok then. i just dropped the whole diff off and picked it up the next day full of oil and ready to run. so the diff man should have rebuilt it correctly

phew...

-tim

EvilChief · 10-08-2008, 08:42 PM

ah .. IRS diff