Got my vette back with several mods installed

[Skant]

Got my vette back with several mods installed (Transmission noise problem)

I'm very excited about it! My LT4 was previously totally stock..

4.11 ring and pinion (Tom's)
Borla cat-back exhaust
Breathless Air Rammer Intake
Lowered 1"


I'm nearing the end of the break-in process for the ring and pinion... it's sooo hard to baby her around and not cut loose to see what this new stuff will do.

The Borla exhaust sure growls nicely. I'm finding myself very pleased with its sound level. It has a huge resonance at 1500 RPM, but it goes away almost entirely by about 1800 RPM. Pretty quiet at 2000RPM cruise. It has the LT1 square exhaust tips on it which I'm trying to decide if I like or not... I think they look a little weird if you look inside them with two round exhaust pipes opening into the big rectangle. I might want to put the ZR1 tips on it instead. Dunno yet.

The shop was concerned that the tranmission was noisy when they took it for the break-in drives. To me, it does sound noisier than it did before. Which is odd because they didn't do anything with the tranny. My perception of it is that it's like the sound deadening material under the cup holder area has been removed. It makes the same sounds it ever did before, but it's like the barrier isn't there. If I just put a little towel over that cup holder panel, the extra sound is gone.

Now I know there's no insulation there that would have been removed, so that's kinda weird. A vague theory is that maybe the sound is being reflected by the new exhaust somehow... kind of like an echo...

But really, as I've been doing the break-in runs on the car, the gear sounds have been changing. The shop said that the new rear gears were quiet and I shouldn't hear them during break-in or afterward... but after a while I was hearing some sort of gear whine that was linked to road speed. It's a little hard to tell where it's coming from, but it sounds like the rear of the transmission. But then this and all the other sounds seem to be quietting down as it gets broken in. In fact, at this point, it seems to me like the car is sounding near normal again (or maybe I'm just getting used to the new sounds).

It's so hard to figure out if it's just me being hypersensitive or what. I know after I get a car back from the shop, I'm listening and watching so carefully for any sign of any trouble...

Anyway, I think it could be that the new ring and pinion actually is whining a bit and that's being transmitted down the drive shaft so it sounds to me like it's from the transmission. The nature of this is changing with heat level and time. And it seems like it's getting quieter. So hopefully that's just normal.

Of course, the first time I can cut loose with this thing, I suspect I'm not gonna care what it sounds like anymore. Even just babying it around, I can feel its greater desire to go... it's definately opened up.


The other part that's a little questionable right now is the lowering. The shop says they measured it as having dropped a little more than an inch. But I just measured it this morning, and it's at pretty much exactly the same height it was before. Now I expected it to be high for a few weeks since that's what happens when you pull the spring out. It needs time to settle again... and when I'd gotten a new spring before, it dropped 1.0 - 1.25 " from its initial height when I first got it back over the next weeks. So if it does that again, then that will be good. That will put it where I expect.

But the weird thing is... how is it the shop measured it as being an inch lower _now_? That's weird. Maybe because they'd already had it on the lift for a while so it was sitting high for their initial measurement or something.


So anyway... it looks like both of these quibbles are things that should settle and be fine after a while. Hopefully it will all be good. Just slightly nervous in the meantime... what if they _don't_ settle? But... this shop seems to be a real good place. So I'm not too worried yet.

 

[tntcorvette]

how I wish I had a ZF-6 and 4.09 or 4.11 gears.................

congradulations on the upgrades!

 

[Gman]

Glad to see you went with the 4:10s as one of your mods, Skant. I've been curious to see how your car responded to the gears as it's something I've been considering. Guess I'll have to wait a little longer to find out what you think. Hurry up and break them in! :L

 

[vader86]

Gears do make noise, that or the synchros can make a sound that would seem to be from the rear of the tranny.

 

[Skant]

Well, I followed the break-in procedure to the letter. It was difficult because a BMW M3 pulled up next to me at one point near the end and was really asking to be spanked. But I was good and babied her like I was supposed to.

So I've gotten to do one short drive after the break-in and cut loose a little bit now.

OMFG!

1st gear goes from 0-42mph now. And it is indeed at the limits of traction. The rear end feels buttery on the way up... the tires are slipping right around the edge of tripping the ASR. And that's not just at red line. I think the first time I went, I thought it was the rev limitter that kicked in, but it was probably the ASR... since I thought the rev limitter kicked in earlier than I expected.

2nd gear should top out at about 65mph now. I wasn't able to _not_ burn the tires going into 2nd gear. It's 0-60mph run now is absolutely furious. It's gotta be faster on 0-60 than it was. I guess the gearing is perfect for it now.

Now this is on a cold dim day when it's been raining. The road was only recently dry... might still have a tad bit of moisture. On a warmer day, it may well be able to hold the tires (barely) through 1st. I may need to get better tires... right now it's running Goodyear HP Ultra Plus (their economy ultra performance) and the rears are getting on toward being worn out. So getting it to stick in 1st doesn't look like an unsolvable problem.

I think that's an interesting objective measure of performance increase. It was never able to break its tires loose after the initial hookup before. Therefore, it must be accelerating faster. It can't just be my imagination or the car 'seeming' more powerful just because of a louder exhaust. It's actually experiencing some difficulty now for being too fast for its own good.


Okay... on with the concern... the break-in time is theoretically over... and it seems like it's left with a whine that's particularly notable at freeway speeds. I don't know that it's changing sounds anymore... I think this is where it may stay. It's pitch changes with road speed. And it can only be heard when throttle is applied to maintain speed or increase speed (louder)... no noise on coast. It's hard to tell where it's coming from. Might be the rear of the tranny.. that's where it mostly sounds like it's coming from, but it's hard to locate. Might be the rear end. Considering the rear end is what was worked on...

I seem to remember another post where someone was complaining about something similar, and there was some solution about GM limitted slip additive or something. But I can't find it now.

I may well still be premature. I'm supposed to take it in for servicing after 800-900 miles (mostly to change the rear end fluid which will be gunk by then because of the new gear break-in). The noise may well go away during this time or after the service. During break-in, there have been times when it did fade away. I just hope it's not reaching its 'final' condition and its whiney. It is an annoying noise.

Amusingly, I was worried about the exhaust being too loud for me. And that's not bothering me at all. That's fine. The exhaust is typically louder, but it's a pleasant sound. The gear sound is unpleasant.

That's the only thing that's worrying me now.

 

[qwik-tripp]

I'm glad you are happy with the gear choice, I am purchasing a set of 4:09 gears myself. Do you have any info or parts# for speedometer calibration?

 

[garycr14]

Gear - Gas Milage

Hi,

I know it's a little too soon for you to be able to have a firm number, but what has the gear change done to your fuel economy. I am considering upgrading my rear gears, but it's a daily driver, as well as a weekend warrior so fuel consumption is a factor for me. How much have you lost?

Thanks

 

[qwik-tripp]

gary, looking to install in the next 2 weeks. do you have a 6speed if so I don't think it will affect fuel mileage at all since now 6th gear would be useable.

 

[Skant]

Re gas mileage: This is going to be dependent on what tranmission you have. I have a ZF6, and that changes 65mph cruise from 1500rpm to 1800rpm. Fuel mileage is reduced about 15%. I'll have more accurate figures to show later after I get my speedo reprogrammed and all.

For lower speeds than freeway driving, there would be no difference. In city mileage should be unaffected.

qwik-tripp: Just purchase the Hypertech Power Programmer III for your model vette. I bought mine from MidAmerica for $325. It should be here Monday. I'll let you guys know how it works, but there's no reason to believe it won't. They list support for 4.09 rear end specifically in their online instructions. (Which I think is new in the version 3 programmer)

 

[Skant]

I've had some more time to drive the car. It's cold and overcast here, but hasn't rained in a couple of days. In these conditions, my car is tripping the ASR as it goes up through 1st. I need to turn the ASR off for best acceleration. It's getting some wheel spin, but not so much that's its audible or out of control. But the rear end is buttery.

I've taken several friends for rides in it, and they all say yeah that's definately faster than it was before. There's a lot of comments that the front end of the vette lifts like crazy. It's pretty wild.


I am still concerned about the gear whining noise however. It's not subtle. I've taken some of my more mechanically savvy friends for a ride, and they all think the sound is coming from the transmission, not the rear end. That concurs with the shop's comments. And I'm inclined to agree. Though I'm confused as to why that would be... the transmission wasn't the subject of the work that was done. It doesn't seem like it could be a coincidence that this coincided with the modifications that were made.

My friends suggested that it could just be something small. Like the pressure against the driveshaft is just slightly different or maybe the output shaft got moved just a little or whatever. The sounds it's making are pretty much the same as it ever made... but increased. They think that it doesn't sound terminal. It is a bit of an annoying sound. And we noted near the end of the run that it seemed to sound a tad bit quieter than it did at the beginning. Whether it just alters with heat level, or if it's really coming down with mileage, or if the volume change was just our imagination... dunno yet.

The suggestion right now seems to be to just continue to drive it and see what happens. Maybe it will just go away as things settle.

The tranny has had Red Line MTF in it for about a year. And the shop changed it again when they weren't happy about the amount of noise. I think I might have read some comments somewhere that the stock GM tranny fluid may quiet transmissions. But I don't think it's actually available.

Sooo... at the moment... I'm more relieved and more nervous. I'm a little relieved because it does seem like the sounds are not coming from the parts the shop worked on... and I've dreaded the potential of having a fight with the shop to get a botched job redone... something very unpleasant I've had happen with other (admittedly cheaper) shops before. This is my first experience with this particular shop. And it does seem like they do a good job so far. I can't link the noises to being their fault at this time, and they do seem interested in getting it taken care of. They noted their concerns about the sounds to me, not the other way around.

But I'm more nervous in that there may be something wrong with the transmission. And from what I understand, anything to do with the ZF6 is rediculously expensive. Quite possibly more expensive than I can deal with right now.

I'm fearful that I'll just have to live with this noise. And it's frankly unpleasant.

 

[Skant]

I took it for another spin today... and much of the time the bad sounds were gone. They seem to have reduced or become intermittent now. So it does seem like it's settling somehow and going away. I think.

Waiting for the other foot to fall... you know... seems too good to be true.

So I pull into a gas station to fill her up... and there's smoke coming from under my hood.

Oh boy!

Now... let me mention that I've noticed a bit of burned smell after I've driven my car since I got it back. I thought nothing of it because the car has a whole new exhaust system. I'd expect it to smell a little as it got burned in at first.

Yesterday, it seemed a little stronger, but I wasn't sure.

Today it was smoking. At first I thought 'Oh man... my transmission must have fried... that sound was terminal!'. The smoke was coming from the cats. There was fluid under the car and it was cooking off on the cats. The front of the engine is moist.

The fluid isn't antifreeze. It's more like oil. I check the oil... still at the same level it was. Odd... what could it be? I check the power steering fluid... half the resevour is gone. That's it. It's dumping power steering fluid.

Well... I guess that's better than a burnt tranny!

Geez... one concern goes away... and a new problem sprouts to take its place! Aaaiiieee!

Still... hopefully this is something simple. Would the power steering system need to be disconnected or something to access the spring for lowering? I'm guessing something happened there. So hopefully it's the kind of thing the shop will just take care of. Maybe just a loose fitting or something.


Alright. Gotta calm my jangled nerves. My car was not on fire. My transmission hasn't exploded yet. The leaking power steering fluid is probably simple. The front end does look to be settling to a lower height. And the transmission sounds seem to be going away on their own.

Calm blue ocean. Calm blue ocean.

 

[garycr14]

gary, looking to install in the next 2 weeks. do you have a 6speed if so I don't think it will affect fuel mileage at all since now 6th gear would be useable.

Qwik-Trip, Sorry to say I have an automatic, which is why the concern. Currently at 70 MPH I'm running at about 1900 rpm, I don't want to do something that will push this up to 2200 + as I know I will suffer in the fuel department. There are only 2 mod left to do on this car 1 is the rear end, the other is the torque converter.

Thanks

 

[qwik-tripp]

garycr14- if I remember right the auto trans has a lower 1st gear ratio so you can get away with less rear gear. try-www.f-body.org/gears/ they have a gear calculator that is simple to use. 3.73 may be better suited for you.

 

[garycr14]

Gears

garycr14- if I remember right the auto trans has a lower 1st gear ratio so you can get away with less rear gear. try-www.f-body.org/gears/ they have a gear calculator that is simple to use. 3.73 may be better suited for you.

Thanks for the respnoce - I was thinking either 3.73 0r 3.54, but I will check out the web site you suggested for some further insite.

 

[Skant]

More updates on how this is going...

The leak turned out to be in the power steering pressure hoses. Cost me some $$$ to get those replaced. I don't think it's a coincidence that these gave out when the shop worked on my car, but I also don't beileve it's the shop's fault. They must have been about ready to go, and just a little flexing from going onto a lift or being pushed a little while they worked on the spring made it let go.

The transmission sounds have returned to normal except on the freeway. It's making a warbling whiny noise when it's crusing about 65-70 mph and up. This miight be getting better, too. It was originally all the time starting at exactly 65mph. Now it seems to start at nearly 70mph and tends to go away during decel or accel... it happens specifically at maintaining speed.

So it may yet just go away on its own, but I'm becoming less and less hopeful as time goes on. To me, this sounds like a bearing noise, not a gear whine. The gear whine sounds from before died down already. It's pitch varies directly with road speed... so I'm thinking that it may be a bearing on the output shaft from the transmission that's going out.

So what's up with this happening the moment I have 4.10 gears installed? Well, I'm fairly convinced it wasn't anything the shop did wrong. I think the changed rearend just made issues in the tranny apparent. The rearend itself doesn't seem to be exhibiting any maladies at all. It looks like the shop did a very good job.

I had mentioned that initially it sounded like the same gear whining sounds the tranny made before but much louder. I'm theorizing that while the rear end is being broken in, it's very tight. So it literally takes more power to turn it. So the additional noise level was the noise level of the transmission as if it were under acceleration. Thus why it sounds the same to me at cruise, but louder. And that's come back to pretty much normal now. So I'm not too worried about that.

But this other thing that I think is a bearing noise? Well, if a bearing is going bad... any sort of changes can make it switch between quiet and a variety of noises. Going to a different rear gear certainly qualifies. The output shaft has probably moved a little.. the balance is slightly different... whatever.

At least, these are my theories. I'm still hoping this other noise will just go away on its own. It's a very annoying noise, and it's loud enough that playing my stereo doesn't squelch it.


So... if it is a bearing going bad... what are the remedies? I presume there are at least two bearings on the output shaft of the tranny... does it make sense to just replace those? Or are we talking about a whole rebuild here ($$$$!!!!). The car has 50k miles on it.

I don't even know that the sound is a bad bearing. That's just what it sounds like to me. But I'm not a mechanic. I just note that it sounds a lot like when the bearings on my computer cooling fans are going out.

I'm feeling kinda depressed about my car at the moment. It's fast as heck now... but it's annoying to drive on the freeway just because of the sound. I don't _want_ to drive it.

 

[Skant]

Btw... re: gas mileage with the 4.11's... I got 25mpg driving from San Jose to Hayward with the new gears. And I wasn't babying it around. It would have gotten 25-28mpg under the same conditions before. So at the moment, it's looking to me like the gears may have dropped the gas mileage less than I thought. Or... well, actually... the improved exhaust and intake probably offset the gas mileage loss from the rear end.

In the end, I don't seem to have lost much gas mileage on the freeway at all.

 

[jhong321]

Can you tell me where did you get you rear end gears changed at?

thanks

 

[Moonunit 451]

I'm very excited about it! My LT4 was previously totally stock..

4.11 ring and pinion (Tom's)
Borla cat-back exhaust
Breathless Air Rammer Intake
Lowered 1"

Congrats Skant! I love my Borla's :cool The square tips grow on ya after a while Although the ZR-1's are very cool as well.

Sorry to see you're having issues I hope things settle down and it's nothing serious. You must be close to getting the rear fluids changed and perhaps all will be well Think +

 

[Skant]

jhong321: Northstar Automotive in Mountain View.

Moonunit 451: I didn't much appreciate the square tips until they'd been in long enough for the insides to turn black. Now they look quite nice, I think. I keep the outside parts of the tips polished.

As for the problems... right now my car is in the shop having the transmission rebuilt to the tune of $3500. It looks like it was actually a preexisting problem in the tranny. The 4.11 gearing just brought the warbling whine part of it down from a higher speed to freeway driving range. Where it started at 65mph after the installation, it would have started at 90mph before...

- Skant

 

[Moonunit 451]

Aw man, I'm sorry to hear that Skant It never seems to end with these things :cry