Diff gears

sphell · 18-06-2005, 07:05 PM

I'll be getting some 3.89 diff gears from a Skyline tomorrow. Just wondering if anyone has any tips on fitting them to the 3.23 Borg Warner diff I have now.

I spoke to Bass_Crazy and he said just to play around with the shims until it all sits right. Otherwise it'll make noise.

Anything else to look out for?

Cheers
Doug.

stockstandard · 18-06-2005, 07:09 PM

No advice to offer sorry, but considering how many people are running econo-gear ratios like me what are the chances of taking a few pics while your at it. I wouldnt mind attempting a gear swap myself.

niko · 18-06-2005, 07:19 PM

ferntree gully selling a 3.9 complete lsd for $650

Damo · 18-06-2005, 07:25 PM

no advice sorry Doug, but good luck with it. I think SiLenCeR has fitted 3.5 skyline gears to his diff. Where are you getting the gears from ?

Sox · 18-06-2005, 10:13 PM

Gear swaps are easy.

Make sure the pinion is bloody tight, you can swing off the nut, a lot more than you'd imagine. If it whines on de-acceleration, it's not tight enough.

You only want a bees dick of backlash, as someone else said, you'll need to play with shims.

Be careful you don't break the shims as you belt the crownwheel back in (yes, you need to belt it).

Rick.

galapogos01 · 19-06-2005, 01:10 AM

love to see pics.

i didnt think 3.89/3.91s would fit into a 3.23 housing?

NC_Steve · 19-06-2005, 01:22 AM

I have gone through all this before with the fitting of 4.11s to my Fairlane. And in my opinion it is best left to the professionals if you want a reliable diff. There is alot of shimming involved to set it up properly. There are shims that are behind bearing cups that are pressed into the housing. And you will probably need new bearings pressed onto the pinion shaft as the bearings are a different size. And did I mention all the shimming involved?! You don't belt the crownwheel/hemisphere back in. You need a special tool that spreads the diff housing apart to get the hemi in and out. That's why the diff has those two holes on the housing, on each side of the rear cover.

Walkinshaw · 19-06-2005, 02:42 AM

I have also been of the opinion that 3.7, 3.9, 4.1 CWP's wont fit in 3.23:1 housings, but they will in 3.08:1 housings. This may or may not be the case

galapogos01 · 19-06-2005, 09:21 AM

well the diff joint that fitted my 3.9s was pretty convinced that was the case. i now have an EL 3.08 housing in my EF Fairmont.

Sox · 19-06-2005, 09:23 AM

Quote:

Originally Posted by NC_Steve

I have gone through all this before with the fitting of 4.11s to my Fairlane. And in my opinion it is best left to the professionals if you want a reliable diff. There is alot of shimming involved to set it up properly. There are shims that are behind bearing cups that are pressed into the housing. And you will probably need new bearings pressed onto the pinion shaft as the bearings are a different size. And did I mention all the shimming involved?! You don't belt the crownwheel/hemisphere back in. You need a special tool that spreads the diff housing apart to get the hemi in and out. That's why the diff has those two holes on the housing, on each side of the rear cover.

Not everyone has a diff spreader, and they are not needed anyway. I've done more of these diffs than I care to name, and I've never used a spreader.

So long as you use a soft hammer, or a lump of hardwood between a metal hammer, it will be fine.

I haven't had a diff fail on me yet.

And BTW, the shimming is not at all difficult, and bearings are easy enough to change, though if you can't do it, most workshops will for a few dollars..

Rick.

INJECTED_250 · 19-06-2005, 11:02 AM

But, alot of the shims need to be changed.. all you will have is a few shims that are all varying sizes and chances are these sizes arnt going to be ythe right ones the diff places have shim grinders/ surfaces to get it perfect. Unless u think youre bench grinder can do a better job leave it to the experts. AND you dont do the pinion up as tight as you can, . It depends if its a shimmed pinion spacer or a crush type spacer. If you do the crush ones up as tight as you can u will kill the pinion bearings in no time as there only spose to have a certain amount of preload on the bearing... ..... If you do it ya self HAVE fun.. BUT for the money it costs to get a pro to do it around $200 why put up with a noisy diff

Sox · 19-06-2005, 04:14 PM

Quote:

Originally Posted by INJECTED_250

But, alot of the shims need to be changed.. all you will have is a few shims that are all varying sizes and chances are these sizes arnt going to be ythe right ones the diff places have shim grinders/ surfaces to get it perfect. Unless u think youre bench grinder can do a better job leave it to the experts. AND you dont do the pinion up as tight as you can, . It depends if its a shimmed pinion spacer or a crush type spacer. If you do the crush ones up as tight as you can u will kill the pinion bearings in no time as there only spose to have a certain amount of preload on the bearing... ..... If you do it ya self HAVE fun.. BUT for the money it costs to get a pro to do it around $200 why put up with a noisy diff

What a surprise, you don't agree with me......

Shims can had from a wrecker for a few dollars, he already knew he needed a handful of shims.

And the pinion does get tightened up a hell of a lot, those bearings do actually have a lot of preload and you will be surprised how much you need to swing off it.
The crush washer always 'relaxes' on removal anyway, if in doubt, you can fit a thin shim behind it to crush a frag further.

Rick.

mcflux · 19-06-2005, 04:26 PM

(slightly off-topic) what exactly is a shim? Could somebody please explain this to me?

I'm guessing they're like small, thin wafers which are placed in specific areas to make sure that certain components sit in the right position and can't travel, and so they're balanced if moving, etc etc.

Am I on the right track?

-Dave-

Sox · 19-06-2005, 04:43 PM

Quote:

Originally Posted by Ghia5L

(slightly off-topic) what exactly is a shim? Could somebody please explain this to me?

I'm guessing they're like small, thin wafers which are placed in specific areas to make sure that certain components sit in the right position and can't travel, and so they're balanced if moving, etc etc.

Am I on the right track?

-Dave-

Shims are available in varying thickness to allow for differences in manufacturing tolerances.

They can range from small thin wafers, to thick washer like items (and thicker).

Rick.

galapogos01 · 19-06-2005, 06:04 PM

is it just me, or is it a bit odd that the guy normally telling us only professionals can come up with cam and exhaust packages to suit an engine is now telling us to bash in diff gears with a hammer?

Sox · 19-06-2005, 06:18 PM

Quote:

Originally Posted by galapogos01

is it just me,

It's just you.

:

Quote:

or is it a bit odd that the guy normally telling us only professionals can come up with cam and exhaust packages to suit an engine

I never said anything of the sort.
I've said the professionals you're referring to are the best drive-in drive-out service available for that particular engine.
Do try to keep up.

sleep:

Quote:

is now telling us to bash in diff gears with a hammer?

Yep, do whatever works, without doing any harm.

Do some time in a mechanical workshop and see how things are done, you may be surprised.

Have you anything else constructive to add, or you just want to stir?

:

Rick.

galapogos01 · 19-06-2005, 06:34 PM

im not here to stir, but your comment was a little amusing. im not the one who has their finger stuck up their *** on that particular issue.

at any rate, im happy with my 3.9s, and they werent bashed in with a hammer.

Jason

Sox · 19-06-2005, 06:42 PM

Quote:

Originally Posted by galapogos01

im not here to stir, but your comment was a little amusing. im not the one who has their finger stuck up their *** on that particular issue.

Nah, my finger ain't up my bum, the proof is in the pudding.
If you're interested in that particular issue, my old XH produced 175rwkw today at the Intune dyno up here.
Most impressed with the old girl.

Quote:

at any rate, im happy with my 3.9s, and they werent bashed in with a hammer.

That's great, so long as you're happy.....

Rick.

sphell · 19-06-2005, 07:08 PM

Well i went to the wreckers today....that was a lot of fun spending 2hrs under a skyline lying in stinky diff oil trying to get that bloody pinion bolt undone. We couldn't lock the diff properly to undo the bolt cause someone had taken off the brake calipers. We tried using two panhard rods jammed inbetween the wheel studs but even with the breaker bar I still couldn't undo it. So I cracked the sh*ts and dropped the whole diff out, jammed a tyre lever and a big *** bolt into the rear of the housing so it locked it up against the casing, then put a pole over the breaker bar for extra leverage then FINALLY it came lose.

Thanks for everyone's help and suggestions. From dismantling it, it doesn't look like rocket science. There isn't exactly a huge amount of parts in there. Hopefully it'll be pretty straight foward.

Qwikcorty · 19-06-2005, 07:22 PM

i built a 3.45 diff out of a ea housing and xe centre with adaptor to suit 2.92+ gears and also shimmed it up. It whined a fair bit, but lasted a year of abuse lol.

INJECTED_250 · 19-06-2005, 08:54 PM

and nope Galapogos01 its not just u... Cose diff places do drive in packages as well..