Couple of different questions...

[MrBluGruv]

I think I have a pretty good idea of the answers, but I wanted some second opinions from a more experienced crowd.

Firstly, an exhaust question: Let's say I did a full exhaust, headers all the way back with the exception of mufflers, 2.5" piping all the way but the muffler inlet and outlet are about 2.25" from being on the stock exhaust before the rest. Will that translate into a serious drop in power vs. getting a new pair of mufflers with 2.5" in and out or will it be negligible?


Secondly, rear diff question: For a while now, whenever I turn my vehicle while in motion at any speed really, I hearing kind of a humming/whining/rubbing-a-wet-finger-against-the-inside-of-a-drinking-glass sound, with the volume of the sound increasing with the degree angle of the turn and also it seems to be more noticeable after driving for a while and especially now with the high temps during mid-day. Do I just need to have the fluid exchanged and/or friction modifier added, or is there a serious possibility that this is indicative of more serious problems? Or something else altogether like there isn't enough here to say? If need be, I'm sure I can try to capture the sound on camera but it may not come out very clearly.


I really appreciate anything you folks can tell me. :)

[musclemerc]

Just an opinion on the exhaust. If your going 2.5" pipe all the way then I think you know you need to swap to 2.5" mufflers. I will also add I hope it's mandrel bent and not crush bent. If it's crush bent then just keep the stock back half and the mufflers as they are.

[MrBluGruv]

Yeh, I was afraid of that, but it's not really the price part that bothers me the most, I've found a muffler that I think sounds REALLY good on my car now, and I'm afraid it'll be hard to find another set in that diameter. :(

[musclemerc]

Then do a mid pipe swap and be done. There is really not a need to swap to 2.5" on the back half on a N/A MM. There will be no additional gains for the extra work involved. This has been well documented over the years

[MrBluGruv]

Even if headers are involved?

[LeoVampire]

It sounds like it could be one of 2 things.

Either the limited slip lock up is not functioning properly due to the clutches going or what not because it is only on the turns you said that you hear anything.

Or a remote possability that the outer axle shaft bearings or the axle shafts where they sit on the bearings is worn in a way where it would only be noticable in a turn type situation. But this is more of a remote chance problem vs the limited slip lock up being the issue.

Sugestion would be to pull the rear end cover and do a good inspection of the fluid and the lock up and pull the fill plug to see what is on the magnet for material.

Again all of this is a guess as it is hard to judge without hearing things for yourself or being able to look @ the car personaly.

[musclemerc]

Yep! Even with headers. Do you know how many guy's are running LT's with the stock H pipe? Alot... Both Kooks and SW sell a kit that bolts straight to the stock 1-7/8" H pipe... Unbelievable but true. Do a search and gather some info, it's all here.

[justbob]

I just changed GusPech750's clutchs in the rear because the guy who changed his rear oil didn't add friction modifier. His car made the exact noise you describe....

[MrBluGruv]

Thanks for the insight LEO, what makes me really nervous is basically the rear end was completely rebuilt for a gear swap back in May, so ALL those parts should be fresh. A few weeks after the install I had the magnet checked and there was barely any shavings on it, but that's probably been about two months ago. I'm gonna schedule an appointment with the shop that did the install to check it within the next week or so.


I could totally believe it about the exhaust musclemerc, this car never ceases to amaze me with what doesn't and doesn't make or affect power. :P As I'm sure you remember I've been tossing back and forth on exhaust work, and I figured I'd do it all if I was going to do it at all, but if long-tubes with stock h-pipe back is almost exactly as efficient as long-tubes with fully-custom exhaust piping (given an N/A setup) I guess that's gonna be the most cost effective solution in the long run after all. Thank you. :)

[MrBluGruv]

I just changed GusPech750's clutchs in the rear because the guy who changed his rear oil didn't add friction modifier. His car made the exact noise you describe....

I remember when I had the gear swap and diff rebuild done, I asked him about that sort of thing because I read a lot of opinions about gear oil + FM vs. synthetic gear oil WITH FM, but I don't remember what he said he was gonna use. I think he was leaning towards royal purple. One thing I can say for sure though is that as of yet the posi-trac still works like a champ.

[LeoVampire]

When the car is in the air a tech with a keen ear and he should also be able to feel what might be causing the problem with moving parts manualy.

Plus having someone holding one of the wheels while turning the other to isolate what might be happening.

But it takes someone with experience to recognize the sounds and feel to start isolating the problem and a quiet spot when loooking for it.

Then you pull the cover and start to inspect and try to narrow it down.

Yes I remeber your having the rear end done but maybe a lack of friction modifier or something not perfectly set inside of the rear end can cause a slowly growing problem.

[justbob]

I left too small piles of equal rubber in my garage with Guspech's car prior to opening the rear. He just wanted them changed out because of mileage. Sounded HORRIBLE on tight turns. It took a few weeks after the oil change for the noise to start.

[MrBluGruv]

I left too small piles of equal rubber in my garage with Guspech's car prior to opening the rear. He just wanted them changed out because of mileage. Sounded HORRIBLE on tight turns. It took a few weeks after the oil change for the noise to start.
Sounds about right. :(

Well at least I should be armed with information now.

This may seem a silly question, but do you guys think I ought to press hard for him to cover any expenses if things are damaged and need repair?

[LeoVampire]

Sounds about right. :(

Well at least I should be armed with information now.

This may seem a silly question, but do you guys think I ought to press hard for him to cover any expenses if things are damaged and need repair?

If he provded all the parts and labor and you have little milage on all of it yes I think he should be partly if not totaly responsable depending on what is going on.

[Zack]

Lidio ran 11.40's years ago with stock exhaust right down to the manifolds.
If you are staying NA, remove 2 cats and leave the rest alone.

[MrBluGruv]

The thing is I'm not entirely sure if I'll ever run forced induction on the car, and probably won't to be honest. I want to, but not sure if I'll ever be able to. I'd love to at least get more power than I have now, something closer to the 300whp number at least.

*edit: ok I re-read what you said, so I guess the n/a comments on my point are a little redundant to your point. But would a long-tube exhaust system REALLY not get me power to the point where it's completely not worth it? Like I said, I've seen some guys running up to nearly 300whp and some a hair over, I'd like to get to that point. Cheaply is a bonus, but an understood unlikely possibility.

[MrBluGruv]

K update, took the car into the shop yesterday, had my U/D pulleys finally installed and got the rear-end inspected.

Before I dropped the car off, took the mechanic for a ride around the block to try and replicate the noise problem. His initial idea was that it may have been a rear brake issue but that he would check the rear end as well. Final result was he found that there was no problem with the brakes, and he added friction modifier to the rear-end (the ticket said something to the effect of "limited-slip lubricant", so I'm actually going to call him today to try to get details about things more than his front desk person had). They told me that if the problem persists that I should come back in a bit, like a week or two, and they would tear it apart and look at it again. I noticed right off the bat pulling out of the parking lot that what they put in made zero difference, the noise was still there. They didn't charge me for anything but the friction modifier though.

Now my question is this:
After friction modifier is put in, will it take some time for it to work in? Or should I notice the difference right away? I'm getting the feeling like I'm gonna be taking it back to the shop for a teardown inspection.

Also too, I was wondering, is it at all possible that given the fact I used the HD cobra clutches and stronger S-spring, the diff will just make racket? I don't think I've ever read it anywhere, but some older mechanics I know have been telling me that these locking diffs do make some noise, but even so I didn't think it'd make a terrible lot even if it did.

[LeoVampire]

K update, took the car into the shop yesterday, had my U/D pulleys finally installed and got the rear-end inspected.

Before I dropped the car off, took the mechanic for a ride around the block to try and replicate the noise problem. His initial idea was that it may have been a rear brake issue but that he would check the rear end as well. Final result was he found that there was no problem with the brakes, and he added friction modifier to the rear-end (the ticket said something to the effect of "limited-slip lubricant", so I'm actually going to call him today to try to get details about things more than his front desk person had). They told me that if the problem persists that I should come back in a bit, like a week or two, and they would tear it apart and look at it again. I noticed right off the bat pulling out of the parking lot that what they put in made zero difference, the noise was still there. They didn't charge me for anything but the friction modifier though.

Now my question is this:
After friction modifier is put in, will it take some time for it to work in? Or should I notice the difference right away? I'm getting the feeling like I'm gonna be taking it back to the shop for a teardown inspection.

Also too, I was wondering, is it at all possible that given the fact I used the HD cobra clutches and stronger S-spring, the diff will just make racket? I don't think I've ever read it anywhere, but some older mechanics I know have been telling me that these locking diffs do make some noise, but even so I didn't think it'd make a terrible lot even if it did.

yes some diff lockers make more noise than others but if this has not been something you have heard from the start when it was all installed then this is a problem just starting to come around.

It can take friction modifier to work it's way into play in the clutches seeing there is so little of it vs the gear oil normaly. This is why I add 2 bottles of it when I do a drain and fill in a rear end that needs it.

But it is hard to believe nothing was noticed on the megnetic drain plug or @ the bottom of the rear end case if there was undo wear and tear going on because of the lack of modifier in the fluid.

Give it a little bit of time to work it's self in and see what happens if it is not solved bring it back.

[MrBluGruv]

Well, it didn't really take that long for the problem to appear. It's a really long story, kinda going back to when I had the problem with the clunking feeling under braking in the rear end. Since then I'd had a brake job done and the rear-end rebuilt, then the brakes checked again. Long of the short of it, it was I'd say within a week of the install of the gears that I really started to notice the noise issue. I think this evening or tomorrow I'm gonna find a big parking lot and do what the guy recommended before the work by doing some really really tight turns and circles to try and massage the clutches with the fluid.

Side note: the U/D pulleys brought back out the chirpy noise from my alternator. I'm really starting to dislike the alternators with this car. :( At least this is a problem that I know and know isn't a problem for once.

[MrBluGruv]

OK, haven't had time to do the tight turn test for the rear end yet, but I have noticed that the squeeking in my alternator has gotten exponentially worse by the day, to the point where anything above idle makes it go crazy somewhere between a loud cricket noise and a constant loud whistle. I'm thinking it's time for a new alternator, cause this exact thing happened to me last summer, but is there anything else I should check or look for before I drop the money on ANOTHER one?

[musclemerc]

are you sure it not the tensioner or the idler pully?

[MrBluGruv]

Almost completely positive, the sound is exactly identical to a year ago, and the mechanic had showed me that the sound was coming from the alternator by spinning the pulley with his hand. I'm taking it in to the shop this morning, I started up the car and it make all kinds of noise just idling, it's gone beyond crickets chirping noise to an almost grinding noise so I'm pretty sure it's very quickly on its way out the door. Unless he says otherwise, I'm gonna ask my mechanic about changing the alternator and putting a new serpentine in cause (sadly) I'm not entirely sure when, if ever, I changed it.

I really can't figure why it started going downhill all of the sudden, except that it had something to do with the changes from swapping to the U/D pulleys, I guess that was enough to push my alternator beyond what it was only OK at before.

[musclemerc]

Pully's actually put less stress on the alt. It spins slower

I hope you get it fixed.

[MrBluGruv]

Got the car back from the shop this afternoon. It was indeed the clutching pulley on the alternator, spinning it freely by hand you could feel a grinding sensation, I'll upload a vid I shot this morning of right before I limped the car to the shop a little later on this evening. Also replaced the serpentine with one that was a tad shorter. The tensioner had been set to its tightest position and it was still a little shaky, so we figured the smaller belt was in order. Runs great so far. One problem down, now just gotta figure out the rear end issue and I'll be golden...