twizted_3kgt

This just started today when I was out driving around. Loud banging from the rear of the vehicle kind of randomly, sometimes on the right side and sometimes on the left. It will usually do it after i've made a turn, straighten out, and hit the gas but not always. Or after i've stopped for longer than a few seconds, and start to go again (doesn't seem to do it if I just stop and go). It's not a continuous bang, just one loud bang, sometimes two. It's as if something is getting caught and releasing harshly.

Also when i'm turning lately, I get a nasty shudder throughout the car seemingly coming from the rear. As if the rear tires won't/don't want to spin at different speeds. And it seems to be getting worse the more I drive.

The car sat for almost a year up until about a month ago when I brought it back out for the winter months. I don't recall it having that shudder on turns last year.

The rear differential fluid was changed probably about 5k miles ago, and I looked under there briefly tonight and it doesn't look like it could have leaked out.

Am I looking at a whole new rear end here? Could it be something else?

The car is an electrical nightmare (move the muffler and all the lights shut off/on, among others), but it has always been a reliable runner. Now I don't think I should continue trying to drive it. I have a 60 mile trip I have to take Monday morning in a snow storm, don't really want to get stuck. At the same time, however, I don't want to drive my summer car in the snow (even if it is AWD).

Thanks guys.

edit: Oh yeah, might as well add this: Whenever I used to do a brake stand or a burnout, it would leave two nice and even tire marks. Well I did one burn out a couple weeks back and it left a nice one wheel peel mark, that had me puzzled. Figure it might have something to do with this?

T-rick'srod

Hey twizted, sounds ( and reads ) as if you have a smoked posi unit. If you
will remove the cover from your differential, as sure as ten dimes will buy a dollar, you'll see why you're hearing strange noises and only smoking one
tire.



"the secret of life is honesty and fair dealing...
if you can fake that, you've got it made, "
Groucho Marx

goomaan

iTrader: (2)

What rear do you have?

I just pulled the rear from my '91. I am not sure of the gear ratio but it did have a good posi unit and drum brakes.

twizted_3kgt

ugh, wish I was more familiar with these cars or rear ends in general. Posi unit = replaceable? fixable? bypassable? I won't do any work on it unless I absolutely have to since its 15* outside and I have no shop access.

I'm not sure what rear end I have, I have disc in the rear though. I'm not adverse to converting to drum though, easier brake changes.

Man, guess I better put collision back on the VR4 and go get it out from under the cover before this blizzard hits tonight.

greezemonkey

iTrader: (14)

My guess..... trans mount broken

goomaan

iTrader: (2)

Hey start there. Open the hood and place the car in gear, have someone watch to see if the unit is turning or jumping.

The posi is replacable but I would not try it myself. Some things come out cheaper and eaiser when you leave it to a pro.

twizted_3kgt

Hmmm...even though it's bucking, inside wheel hopping, and rear end clunking on turns? I really thought there might be something catching in the rim and stopping it from spinning momentarily. I'll check it out, just seems like an odd solution.

From what i've looked up on the posi change out, looks like it'll cost more than I want to put into the car in parts alone. As far as doing it myself, I don't think i'd have a problem with it, rebuild the diff, set the lash, and go pretty much?

Figures, just spent $250 on a new MAF and alternator. Ungodly list of new parts in this thing over the last 10k miles. Think i'll just take the hit and sell it for $500 as needs a rear end...depends how I feel after winter. I think i'm gonna leave it alone 'till spring. Sucks not having a garage to work in.

Pat Hall

iTrader: (31)

Banging and jerking like that is usually more the characteristic of a locker type differential. Although it'd be difficult to imagine that an 88 car would've gotten the dreaded Eaton Gov-Loc carrier. Do you know if the friction modifier additive was put in when the gear lube was changed last? Without it, a clutch type posi can have the symptoms you're describing. I also remember reading a post from a guy who had a 9 bolt posi rear that he'd switched to synthetic gear lube, and he was having similar issues. He switched back to regular gear lube with the friction modifier, and it solved the problem. The only other thing I can think of that would cause your problem would be broken teeth on the pinion or ring gear. That usually causes it to bang or jerk every few feet though. A burnt out posi unit won't cause the car to be inoperable, it just won't spin both wheels anymore.

85irocz355tpi

Hey if you want to sell it next spring i'll buy it from you. I've always wanted a thirdgen firebird for my coll. Or if you want I have a 10 bolt with disc brakes and a 9 bolt with discs I could sell you make me an offer. I'd prefer to keep the 9 bolt though. The 9 bolt has a posi the 10 bolt has a one wheel peel.
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I'd check the trans mount before making any rash decisions though. Jack the car up and crawl under it and lift on the tailshaft of the tranny. If it moves up it's broke and it should only cost around 20 bux for a new one.

a1990camarors

The shortest reply on the post by Greezmonkey is probably the right one. lol check your tranny mount first this is the most commen cause of this problem of shuddering and banging when u hit the gas and its alot alot less expensive place too start then ur Rear end. If that doesnt fix the problem then concentrate on ur Differential at the worst ull have too get a rear end out of a junkyard but they dont hurt the wallet too much so dont worry about. IMO i would just pull everything inside the housing and replace with top end posi unit and some moser axles lol thats a bit more expensive thou lol. Start with ur tranny mount first thou.

twizted_3kgt

Well that sounds like some good news. I'll definitely try to get some garage time at my buddies house where there's heat and get under there. Now that I think of it, the other day I did run over some pretty hard ice that scraped the whole underside of the car, could've busted the mount. If theres nothing there, I might as well pull the diff. cover off and see whats going on in there as well.

Pat Hall - I definitely put the friction modifier in there when I changed the diff. fluid last.

Thanks guys, you've given me hope!

edit: Now that I think of it more, everytime I went over a bump it would do it as well. This is making more and more sense.

goomaan

iTrader: (2)

Fix the easy stuff first then see what happens. Don't throw in the towel yet.

zee28

I had a clank/bang and found my end link to sway had broke and it popped loudly evrytime I turned.might wanna check them also.

Nater2491

iTrader: (1)

did he say it drums were easier than calipers????????

twizted_3kgt

When the caliper bolts haven't been touched in probably 10 years and theres a tiny access area...yeah i'd much rather pop a few springs off.

pwt

sound like your missing a tooth on one of your spiders

twizted_3kgt

Ok guys, read the above for the problem. Here's what's inside:



I don't know what that is. I'm used to seeing spider gears. All I know is a bunch of shiney metallic gear oil drained out with some small chunks of metal here and there. I started taking it apart, but couldn't figure out how to get the axles out. So how do I get the axles out? Are they locked in near the wheels? or am I just missing the pin/clip that holds them inside the diff? Also whats the cheapest way to fix this?

After some searching, i've found I just need to remove the 4 nuts behind the rotors and slide hammer them out, right?

Pat Hall

iTrader: (31)

Correct, on a 9 bolt rear the axles are held in at the ends of the axle tubes by 4 bolts. And yeah, you'll probably need a slide hammer style axle puller to get them out. Sounds like you definitely need to pull the carrier out and inspect things further. Just make sure to keep your carrier shims and your bearing caps in order so that they go back in the same way they came out. If your carrier ends up being toast, there's been a couple of them listed in the classifieds on here recently.

twizted_3kgt

Thanks for the reply, i've got my eyes set on one from eBay which i'm going to buy just in case. I'm pretty sure it's toast from what I can see through the little peep hole there, which was bare jagged metal.

The carrier shims are the only part that I don't fully understand what I have to do to install them correctly. I read the thread "everything I know about the 9 bolt", but got lost at that part. Maybe it will make more sense to me once I have it out.

Pat Hall

iTrader: (31)

You might be getting the carrier shims confused with shims used to tighten up the posi cones. That article you were reading talks about shimming up the cones to help fix a slipping unit. The only thing you really need to know about the carrier shims is that they need to be put back in the same place, in other words, the left ones back on the left side, and the right ones back on the right side, when you put the carrier back in. Even if you end up replacing the carrier with another used one, which it probably sounds like you're gonna have to, just swap your ring gear to the new carrier, and put the same shims back in. It should still be pretty close to the correct backlash that way.

twizted_3kgt

Yeah I must have been mixed up the two, thanks. I'm having a little trouble finding them in the classifieds, how much do they usually go for?

Pat Hall

iTrader: (31)

I'd say average price is usually $125-$150 from the ones I've seen listed. The last one I noticed was a low mileage, 3.27 geared unit for like $125 shipped if I remember right. 89irocz355 was the guy. He parts out tons of 3rd gens in the classifieds. Correction, it's actually cheaper than that. I found the ad. Here's the link: https://www.thirdgen.org/forums/engi...bolt-posi.html

twizted_3kgt

Thanks for that, I PM'd him.

Which brings me to my next question, are the 2-series and 3-series carriers interchangable?

Pat Hall

iTrader: (31)

Totally interchangeable. You really need to figure out which ratio you have in there right now, if you haven't already. Reason being, is that if you already have the 3.27 ratio, all you'll have to do is bolt your original ring gear to the new carrier. Ring and pinion gears are a matched set, so you must use either your ring/pinion together, or the new ring/pinion together. It'd really be a plus if you already have the same ratio because you won't have to disturb the pinion gear. Of course, if you end up having the 2.77 ratio, it'd be worth it to swap out everything and upgrade to 3.27. One note on interchangeability, you can't use a 2.77 ratio ring/pinion with the 3 series carrier.

twizted_3kgt

Well my option code sticker isn't where it should be, so I guess i'll have to wait for a nice day to get under there and count. Hopefully this weekend.

twizted_3kgt

Thanks Pat for all your help. I bought that carrier you linked to and put it in today. Turns out I have a 3.27 ratio, I found out after I took it out (which was an hour long battle with the 2 driver-side caliper bolts which were very badly seized and pre-stripped for me, a torch would have been nice). I forgot it was printed right on it..oh well.

Unfortunately I ran out of time to find new caliper bolts, plus I want to replace the calipers, pads, and e-brake cables (I turned the rotors today), so i'll have to find those before I can put it back together and test drive it. Hopefully i'll have the parts by this weekend so I can finish it up.

Just wanted to say thanks!

But I do have one question, the carrier shims (?), the ones that go on both sides of the carrier...whats the preferred method of getting those in? Because I just tapped them in with the plastic handle of a screwdriver and a mallet. That's the only thing that worried me, I kept them on the same side they came out of though.

Pat Hall

iTrader: (31)

Hey no problem. Glad I could help you out! Your carrier shims should be fine. The only time you really have a problem with them is if they're really hard to drive in, and you're using something hard and sharp, like a chisel for instance, to hammer them in. If they get broke or bent, then you've got problems. Make sure all your ring gear bolts are torqued evenly to about 45 ft. lbs. I put a couple of drops of red loctite on each bolt, then start tightening them in a criss-cross pattern. Once they're all tight, I'll go around a couple more times to make sure they're all torqued even. You did put your old ring gear on the new carrier right? You can probably slide on the loctite if you didn't use any. As long as all the bolts are torqued properly, they shouldn't back out. You'll have to post up once you get everything done and let us know if it all worked out.

twizted_3kgt

Well I got it back together today...mostly. Advance gave me the wrong e-brake cables so I did a lot of R&R'ing of them for no reason, hopefully they'll take them back now and give me the right ones. Aside from that it drives nicely again. Brakes could use some bleeding, but i'm thinking of running all new lines since they look a little too rusted for my liking anyway. I'm halfway sold on doing a total restore of it instead of selling it as was my previous plan. But again, thanks to all that helped!

eXistenZ9431

reading this article acctually just helped me.... im having sort of the same problem with the BW 9 bolt rear.... this site is awesome thanks guys