micah

Well, I did a bunch of searching... all I found was diff upgrades and "will this fit in this" threads.. I haven't seen a thread with shiny pretty pics of the procedure. Would be nice to see that kind of thing.. So far it seems intimidating.. Or maybe just a step by step would be nice. I just need to swap from one 82 GSL to another 82 GSL. One of my diff's is whining.. the other is fine.

Here's my take on the situation.
1. drain fluid
2. remove rear cover
3. unbolt 3rd member
4. remove wheels/brakes/disks (I have disks)
5. pull axles out to release 3rd member???
6. pull 3rd member out.. replace with other 3rd member..
7. steps 1-5 in reverse.


Is that about correct? Can somebody revise? I'd like to do this this weekend if it'll only take me a couple hours. The whining is killing me.. I feel like its gonna grenade at any second. hehe.

Siraniko

iTrader: (13)

1. You should unbolt the diffy filler plug (the one on top) before the drain plug. If that plug wont come off, then how would you fill it up?

2. What rear cover are you referring to? the cover is part of the 3rd member

trochoid

iTrader: (6)

I was going to fill in the blanks and make corrections, but section 9 of the 85 FSM covers about 1/2 of what you need along with some very good diagrams.

Have you checked/changed the diff fluid recently?

A few suggestions to help you out:

Download the FSM and read Section 9.

Soak all nuts, bolts and plugs with P B Blaster 24 hours before starting.

Before you even drain the fluid, make sure you can remove the fill plug. If you can't, don't start until you find a way to remove it. Severly rusted/siezed plugs sometimes need a 3/8" shorty extension welded to the plug, then you'll need a replacement plug once you get it out. Crack the drain plug too.

Break the lug bolts loose before jacking up the car and set 2 jackstands under the axle.

Loosen the e-brake adjuster at the handle to facilitate disconnecting the cable ends from the calipers.

When you unbolt the calipers, use a coat hanger/wire to hang them off to the side until you have the flex line disconnected. Hard line will need to be carefully slipped out of the backing plate.

After caliper and bracket, remove the 3 nuts and bolts holding the axle to the housing flange.

Loosely bolt a spare spare tire or junk rim onto the axle flange. You can beat on that to pop the axles out 3-4". Otherwise, rent an axle puller.

Now is the time to inspect the axle bearings, that may be your whine.

Drop the driveshaft.

Never put a socket to the pinion flange nut unless you plan on buying a new crush tube and resetting the diff.

Unbolt an pull the diff from the front. There is no back cover, which tells me your research didn't include the FSM.

That covers the basics and a few tricks. Now you get to take pics of the swap and do a write up.

micah

I've got the FSM.. but my computer at work (which is where I am a LOT of the time reasearching this stuff) doesn't open PDF's... well. not at the moment anyways.. Should have mentioned that.

Also, my axle-experience is with jeeps.. so, there's usually a back cover.. but I'm guessing this is more like a toyota diff in that the entire front comes off instead... but, I've seen axles that had a big front member that had rear covers.. so it was a shot in the dark.

Soon as I can open pdf's.. I'll open one.. but that'll have to wait until I get home later tonight.

Thanks for the help. New to FB's, and as much as I love searching... forums are a terrible way to store data.

micah

Well, a co-worker just let me use her system to check it out.. Looks super simple... sorry for the post. This looks like an evening job assuming everything is in good shape. Will definitely pb blast 24hrs in advance... I almost always do.

I don't think its the bearings... and if it is, its probably the bearings in the rear diff assy itself.. Two different noises.. one while in drive, one while in coast.. I would imagine if it were axle bearings, it would be a pretty consistent noise and would get louder regardless of load/etc. This noise chatters and blips a bit in the slop between the mesh. My other FB doesn't have this noise.. or at least not as bad.

Correct me if I'm wrong so I can go pick up some bearings.. might as well replace them while I have this all apart.

Midwest 7's

iTrader: (4)

yea its like doing a toyota diff.

trochoid

iTrader: (6)

It wouldn't hurt to replace the axle bearings while you have them out. One glitch though, they need to be chiseled off and pressed on. Not usually a DIY replacement.

micah

Well, I've got a 12ton arbor press.... but, the press-fobs and such I don't have.

steve84GS TII

You can carefully grind the retainers until they split.They will come off easily after that.
If you have a press,then all you need is a long piece of pipe to slip over the axle and drive the new retainers on.Or take it to a local machine shop,they will usually do it quick and cheap.Its always best to do the rear bearings if you dont know how old they are.They always seem to fail at the least convenient time.

The 3rd member swap is simple.....No hidden dangers or special tools required.

micah

I got the 3rd members out of both cars (doner and daily driver)... I'm going to do the 3rd member swap first, then if that doesn't fix it (and probably in the near future anyways) I'll do the axle bearings. The 3rd member swap really was easy.

mjm4jc

Trochoid,

Can you explain your statement below?

"Never put a socket to the pinion flange nut unless you plan on buying a new crush tube and resetting the diff."

Thanks,

Mike

trochoid

iTrader: (6)

Sure, though Steve can give a better explaination than I can. It all has to do with the preload and back lash of the R&P gears. Once back lash is set, then the crush tube flange and the rest of the parts are torqued to spec. The crush tube is a single use part that, well, crushes when torqued.

If you you loosen the flange nut, you lose that 'set' and probably won't get it tightened back to the correct point.

If any of this is incorrect, someone please correct me.

mjm4jc

Thanks friend, now I know what you mean.

Mike

trochoid

iTrader: (6)

You're welcome. Had I known this thread was going to get archived, I would have gone into more detail and posted pics, lol.

steve84GS TII

Heres a link in case you really wanna get technical and see some pics of the discussed parts......

https://www.rx7club.com/1st-gen-archive-71/drivetrain-how-rebuild-your-lsd-711948/


Basically,its impossible to reset the pinion bearing preload once the differential and ring gear are installed.The crush sleeve allows for controlled,retainable torquing of the pinion nut in order to set preload on the tapered bearings.The sleeve is actually reusable,but only in situations where its current crushed spec is within that needed for a given set of bearings and housing/gears.
The slightest amount of turning of the nut will increase the bearing preload exponentially,which is why you must torque and check many times when setting the pinion.But with the diff installed in the car,there is no way to spin the pinion and check the drag without interference from the ring,diff and axles.

notveryhappyjack

iTrader: (4)

steve or tro can you explain how to properly set the backlash? My turbo car uses a T2 flange, so any factory diff I get will need the pinion nut removed, the flanges swaped , Them the pinion nut put back in the right spot. How can I make sure that it is set right? I'm a little confused and looking for my 3rd diff in the last 100 miles.

notveryhappyjack

iTrader: (4)

wow, I think that link solved most my questions.

steve84GS TII

Thats what its there for.
If you have any questions during the diff setup,let me know......

trochoid

iTrader: (6)

3rd diff in 100 miles? Care to explain that. If you're tearing up your diff due to too much power, it's time to upgrade to an 8.8 If you don't want to do that and have to keep changing the diff out as an unmolested unit, it would be cheaper to change the flange on the driveshaft so you don't have to swap the pinion flange and have the backlash/preload reset each time.

I take it you're pushing over 350 hp, doing lots of drag launches or most likely both. I had a driveshaft made for kenn chan so he could mate his TII swap to the stock diff. He's pushing around 300 hp, iirc and hasn't torn up his diff, yet.

Steve, thanks again for clarifying my semi-educated post.

micah

Well. 3rd member swap went well... kinda..

Now around right hand turns, I get this dreadful grinding/rubbing noise... only on right hand turns... what should I be looking at?

trochoid

iTrader: (6)

Check that the axles are fully seated, then check the brake pads/calipers/rotors and shields. If all of those are good, it may be a bearing, but unlikely.

micah

Could it be the LSD binding in one direction? I'm pretty sure the axles are seated.. can they be not seated all the way but still bolted in?

trochoid

iTrader: (6)

It's the bolts that seat the bearings in the housing. If the clearance is tight, they may not pull down to fully seat, then it's time to assist that with a bfh on the end of the axle. Can't see the diff binding when turning in one direction and not the other.

micah

Cool, well, I'll take a bfh to it tonight to see if it goes in a little more.. then I'll re-torque the bolts.

notveryhappyjack

iTrader: (4)

tro, I was unaware that removing the pinion nut would ruin the backlash (never been inside the diff before, learned a lot) I swaped in one without knowing that and hit it with the impact gun until it was tight, too tight and broke it really fast.
Anyway, I found a great diff shop (built the diff for team falken S13.5 drift machine pushing 400hp and 375 tq at the wheels) and that is who I plan on having set my back lash and everything for me. All I ned to do is pull it and bring it in and let them do their thang pulling all the inside goodies out and rebuilding it.