Texas_Ace

iTrader: (18)

Ok, so i finished my sub-frame swap the other day. I did the swap because i wanted the 5 lug parts from the parts car and the LSD and the bushings were MUCH better condition on the parts car.

So today i got the exahust back on. Now that i can hear i took it for another drive and i have good news and bad news.

The good is that nothing feel off or broke, The new shocks are MUCH better, ride is much improved and overall the car is tighter.

The bad is that there is a clunk from something in the rear, kinda like before with my bad diff bushings (though after removing the old sub-frame they were not that bad) but differnt now. and a whine from the diff.

The whine i think is from a worn out LSD, it looks like i might need to drop that again and pull it apart. Anyone know what kind of fluid it is supposed to use? I am going to change that first.

The clunk though i don't have a clue. If i have the car in say second gear going real slow where the car will "buck" you can clearly hear a clunking sound from the rear. same thing if i let the clutch in and out and make the car "buck". or if i go over a bump in the road.

I thought it might be the diff but if the car is sitting still and i let the clutch out with the brake on, no clunk. Before when it was the diff it would clunk anytime let the clutch out. It is possible it is the exahust hitting something but i think it is something more.

I checked allt he sub-frame mounts and they are all on and tight. Bushings are all either new or good.

Only thing i noticed that i didn't before was that when it is "bucking" and i have my hand on the shifter i can feel it pull towards the front of the car. Could i have installed the driveshaft wrong and would that cause any of this? how do you tell if it is installed right? it just slipped in and i didn't have to force anything.

So any ideas?

Stanello

iTrader: (1)

The clunking is a busted front diff mount. Basically when you put load on it, the front of the diff comes up and smacks the floor, and then smacks the subframe when it comes back down.

There's a competition version of the mount which is a bit stiffer, or you can fab up a piece of steel to use in place of the rubber part of the mount, and weld it all back together.

Also sometimes the small flange that connects the mount to the subframe breaks it's weld and comes off the subframe completely. You can just weld the flange back onto the subframe.

Texas_Ace

iTrader: (18)

Well here is the problem, My old clunk from before was indeed a busted diff monut.

No doubt about it.

This clunk though is differnt and doesn't happen DUE to the power the diff gets as far as i can tell but because the power makes the car buck.

With the old sub-frame if i let the clutch part of the way out while on the brakes it would clunk. Now if i do the same thing it won't clunk. Only clunks when the car goes over a bump or i create one by giving it power all of the sudden.

But everything is nice and tight so i can't figure what could even be clunking.

Texas_Ace

iTrader: (18)

Now for my LSD questions:

Looking at the cost of rebuilding the stock LSD from :

http://www.mazdatrix.com/G8LSD.HTM

Would be over $400 if i need to replace everything (plan for the worst hope for the best). Plus i would then have to rebuild the LSD and hope i get it right and i have never beena big fan of clutch LSD's.

So here is the option i have looking at:

http://cgi.ebay.com/ebaymotors/RX-7-...spagenameZWDVW

Yes it is ebay, yes it is cheap. But seeing as the most power it will ever see is NA + stock S4 turbo = ~200hp. And even that is not for sure, most likely it will always be NA. I think it should last plenty long enough for me, i don't drive this car THAT much anyways. Plus i just drop it in, no rebuilding :-)

So forgetting that it is an Ebay item (contrary to others, i have had VERY good luck with ebay items in the past with my other cars and other things), what do ya'll think about that?

Now as for my current diff. What fluid does it need? will i ruin anything driving on it until i can afford to get the diff above? I would like to change the fluid (partly to see if there is any metal in the old fluid) and then drive on it until i can afford the diff to replace it.

Texas_Ace

iTrader: (18)

Ok, today I got out there to do some more looking for this mystery clunking and to install a new shock.

So I jacked it up and first looked at all the fasteners for the sub-frame. Sure enough, they are all tight.

So I then started banging and pushing on everything I could to see if anything would move; nothing moved a bit.

So I then spun the tires myself to see if I could get the clunk with the car jacked up. Found the whine is indeed coming from the diff, the diff is defiantly bad, I now get to change it back with the open diff I just took out lol. But no clunking.

So I took it for a drive and the clunking is back! If I put it in second gear and at around 20mph press and then let go of the gas the car will buck and the clunking will happen. If I go over a bump it will also happen, maybe not as bad though. I am 90% sure the diff mount is fine, it could be but it acts different then my old clunk which WAS the mount.

I even had someone ride in the truck while I made the clunk and could not figure out where it is coming from.

So does ANYONE have any ideas as to what could even be clunking back there? Could it be a driveshaft installed wrong? Is that even possible? Before I drop the sub-frame again I want to have everything ready to get this car on the road.


Really need ideas.

misterstyx69

iTrader: (142)

did you install the stabilizer link on the diff?..you know that Pesky bar that you have to take off in order to drop the darn thing?..also the Mount maybe good on the front of the Diff,but did you check the Mounting Point that it goes to?...One thing that you should check is ALL mounts..Engine mounts,transmission mounts....Now,Driveshaft.you would notice if the driveshaft was "off" in one way or another.It would vibrate the car,and it would feel like a bad tire..you could try to turn the driveshaft at the diff,and bolt it Like 90 degrees from the original Bolting pattern(pop the 4 bolts,turn 90,and install again)..see if that helps,But Honestly,I am thinking it is a MOUNT or bushing problem..If you let off the gas,and then Get onto it,and the car clunks then it could be a mount problem or a Joint problem.(OH..half shafts,check them for Play..they are another question here.If they have play..Longitudinal wise and when you turn them back and forth)..anyways..I"m tryin to give ya as many things I can think of at 4 in the morning!....G'Night!

Texas_Ace

iTrader: (18)

Stablizer bar = Check, i also thought that might be it, but it is on nice and tight.

The mount on the diff, is good as far as i could test without dropping the sub-frame again. Bolts are all on and tight, the diff would not move even with a jack on the front.

Engine mounts are fine, maybe a little worn but this clunk is coming from the rear without a doubt and it didn't do this before i swapped frames.

Tranny mounts, i have not checked those, will do that later today.

I figured that the driveshaft would either be off or on, no real in between. when i am just driving alond, other then the whine from the diff, the car if perfect. So rattles or anything.

Half shafts i have not checked, but i know they looked a lot better then my old ones which were leaking.

See my problem i can't figure out what even COULD be clunking back there. much less what is clunking.

HAILERS

Loose bolts/nuts at the sublink or two control links, maybe. One of those was mentioned above. Or worn out bushings in the two.

Texas_Ace

iTrader: (18)

I will check out all of that later today, i might just drop the sub-frame again to change the diffs back and track down the clunk at the same time.

Rexpelagi

So it sounds like you pulled the stock subframe and diff, and you replaced them with a different subframe and an LSD type diff.

If this is correct, what fluid did you put in your LSD (I know you are asking about what you should put in)?

Texas_Ace

iTrader: (18)

Yes, i have a GXL parts car with 5 lug and lsd that i and swapping parts from.

I didn't put any fluid in the diff, I saw no reason to do it before i swapped it over and then took it for a test drive and found that it is bad and not worth fixing.

Rexpelagi

Did you verify that there was adequate fluid in the differential? I'd definitely want to change it regardless because old fluid could be causing your gear whine.

Texas_Ace

iTrader: (18)

No, i never cheacked it, once i knew it was bad i didn't want to waste anymore time on it. Just put the open back in and get an LSD for it later.

But might as well check it out, though at this point if it is empty i am sure the diff is long gone anyways.

Texas_Ace

iTrader: (18)

Ok, well i have some good news finally!

I think i tracked down the clunking. It suddenly hit me when i was pulling it out of the driveway to remove the sub-frame again that the sound seemed to be right next to me in the tranny area.

So i jacked it up and checked ALL of the bushings and everything ya'll have suggested. EVERYTHING was fine, EXCEPT the tranny.

I put a jack under it and put a little pressure on it, and it moved without a hickup, kept jacking and it kept moving. So it is looking like i have bad tranny mounts. which is good because if it was not that then i didn't have a clue what it could be.

The tranny should not move with a jack under it righT? at least not much and not easy? the gear shfit would move about 1 - 2 inches before i got resistance which i think was the body.

So i let it down and drove it again with this in mind, and the sound does want to play tricks on you, even knowing what i did it still sounded like it was coming from the rear but after a little bit i am now 90% sure it is the tranny that is causing the problem.

So now new questions.

Where do i get tranny mounts for cheap? and how hard is it to change them out?

Seeing as i don't really care about the LSD i have in there now, will anything bad happen to my car other then the LSD blowing up if i drive it like it is?

And what fluid should i put in it? i plan to go pick some up in a few mins after i replace my radiator.

Rexpelagi

I picked up some Royal Purple for mine. The repair manual (the one that is stickied at the top of the 2nd gen section) calls out a certain weight, but you just need to make sure you have something in there for the fact that it is an LSD. The Royal Purple stuff I got was meant for LSDs, but you can also just get a friction modifier designed for LSDs and a regular gear oil I believe. The only trick with that is there's really no science behind how much of the modifier you should add (as far as I know), although it might have a rough mixture on the bottle.

Texas_Ace

iTrader: (18)

Ok, took it for a drive down to pepboys today to pick up some diff fluid. Picked up 2 bottles of royal purple and i will put that in tomorrow.

Otherwise though with me now knoing what the clunk is everything else seems pretty normal.

So i think i will just run with the LSD that is in there now until it blows, by then i should hopfully be able to afford a new LSD to install in the open diff i have.

Rexpelagi

As long as you got the right weight and it has the limited slip additive that should be good. I hope that helps.

Texas_Ace

iTrader: (18)

I got 75w140, since i am in Texas the little thicker oil won't hurt anything but should help the whine.

And yes it says it is for LSD diffs.

Boost or Bust

iTrader: (1)

Idunno I think 75w140 might be too much. You should probably look at the FSM. I believe it recommends 80w90.

Texas_Ace

iTrader: (18)

You are right but as said i am in Texas where the temp is 100+ most of the time and int he winter i will be driving my truck most of the time since it is just more comfertable.

Here most people use thicker oil then normal. Either way the LSD is already gone, the worst i can do is kill it all the way faster. Though the thicker oil should make it quiter and last longer.

RETed

If you don't get that clunk fixed, I would check the "front" mounts on the subframe.
This is the big nut (19mm?) that's on the front furthest corners which have the extra bracket that secures on the chassis itself.
I had this problem when doing my front diff mount, and the clunk only appeared when one side was unloaded and loaded - think off-camber turn.
Talking to a friend who did numerous diff mounts, he said that the front corners can sometimes hang and not tighten all the way down.
You need to loosen each corner and retighten as much as you can!


-Ted

Texas_Ace

iTrader: (18)

Well i know the actual bushings are fine as they are brand new delrin bushings.

Though them getting hung is a real possiblilty. Will check that while i have it jacked up tomorrow to do the diff fluid.

Texas_Ace

iTrader: (18)

Ok, so i changed the diff fluid today.

Now correct me if i am wrong but when drining the diff metal coming out in the fluid is a bad thing right?

The fluid was half superfine metal and there was also some metal chunks from something. So yeah, this diff is gone.

It seems a little quiter and smoother with the new fluid but i know i am on borrowed time with it. I plan to just use it until it pops then by that time hopfully be able to afford another LSD, I would love a KAZZ but doubt i will have the $$$.