Large Posted February 7, 2012 Report Share Posted February 7, 2012 So as the title says i have a 97 trans am with a 6 speed. I'm an over the road trucker so i dont have much time to get the car in the air and poke about. Hoping i could get some pointers from you guys/gals. First off,the car is low miles,well maintained and in excellent shape.That being said the car vibrates the faster you go,starting around 60mph.Whether you are in gear or out of gear it is fairly consistent.When do press the trottle down slightly it does go away somewhat but not completely,also when i let off completely,while in gear it shakes more than other times.I automatically assumed ujoints are bad but with the crazy rearend setup on these cars that im not used to im not sure. Second,the car seems to have a miss 3/4 of the time.has a brand new Opti and new plugs and wires,i figured i had a wire burn on the headers.At low rpm i can put it to WOT until about 2500 and then the miss starts again. When it does miss i have not even half the power i should have. Being a trucker with no free time i also need to know where i can take the car to have the work done.Be it a shop where i supply the parts or someones garage where i buy beer/pay you and help so i can learn more about these fbodies. thanks for any info you all can offer. Quote Link to comment Share on other sites More sharing options...
Richard Cranium Posted February 8, 2012 Report Share Posted February 8, 2012 Just working this through in my head. The easiest thing to start with for the vibration is tires. Might be worth getting them balanced to rule that out as a possible culprit. Also the LT1 cars came with steel drive shafts and GM had problems with balance on them. The solution was to replace them all with aluminum drive shafts. As for the miss, I've learned never to trust an Opti, even if it's new. I'm not saying it's your problem, but just because it's new doesn't mean it can't be the problem. I'm working on a miss with my LT1 Impala SS and the next step is to replace the cap and rotor again with an OEM version instead of the MSD version I bought last time. If you want to try and ignition module and coil at some point we could probably work something out on a weekend when the weather warms up a bit. Quote Link to comment Share on other sites More sharing options...
Not Brian Posted February 8, 2012 Report Share Posted February 8, 2012 Vibration with speed has always been a tire problem in my experiences. Quote Link to comment Share on other sites More sharing options...
BStowers023 Posted February 8, 2012 Report Share Posted February 8, 2012 Issue #1 - Either the tires need alignment or the driveshaft needs rebalanced. Issue #2 - Opti Spark = junk. I'm not an expert on these LT1 cars but I would possibly look into transfering to coil packs, I'm sure you can find where people have done that before. Quote Link to comment Share on other sites More sharing options...
Cordell Posted February 8, 2012 Report Share Posted February 8, 2012 Just working this through in my head. The easiest thing to start with for the vibration is tires. Might be worth getting them balanced to rule that out as a possible culprit. Also the LT1 cars came with steel drive shafts and GM had problems with balance on them. The solution was to replace them all with aluminum drive shafts. As for the miss, I've learned never to trust an Opti, even if it's new. I'm not saying it's your problem, but just because it's new doesn't mean it can't be the problem. I'm working on a miss with my LT1 Impala SS and the next step is to replace the cap and rotor again with an OEM version instead of the MSD version I bought last time. If you want to try and ignition module and coil at some point we could probably work something out on a weekend when the weather warms up a bit. Let me start by saying that Rick here has had a good bit of experience with these cars. An opti is a logical place to start looking for your miss, but without a scan tool to look at its signal you are limited to just putting on another to see if it's bad. Issue #1 - Either the tires need alignment or the driveshaft needs rebalanced. Issue #2 - Opti Spark = junk. I'm not an expert on these LT1 cars but I would possibly look into transfering to coil packs, I'm sure you can find where people have done that before. Tires don't vibrate from an alignment dumbass, they vibrate from poor wear, bad balance, or a broken belt. It sounds more like a driveline vibration which could be a few things, the driveshaft is a good place to start, but make sure the pinion isn't getting loose as I've seen this numerous times. Quote Link to comment Share on other sites More sharing options...
Large Posted February 8, 2012 Author Report Share Posted February 8, 2012 Let me start by saying that Rick here has had a good bit of experience with these cars. An opti is a logical place to start looking for your miss, but without a scan tool to look at its signal you are limited to just putting on another to see if it's bad. Tires don't vibrate from an alignment dumbass, they vibrate from poor wear, bad balance, or a broken belt. It sounds more like a driveline vibration which could be a few things, the driveshaft is a good place to start, but make sure the pinion isn't getting loose as I've seen this numerous times. I am at 99% certainty that it isn't tires,i just pulled off the stocks and swapped to C5 17fr 18rr last weekend and the issue there still remains. How would i check to see if the pinion is loose? Yank on the yolk? pull the cover? Ive never had a diff apart in my life. As far as the ignition problem goes should i just scan the car and post the results? Id really hate to drop 300 bucks on new ignition parts if i only need 1 wire. Not trying to be a tight ass,just trying to save cash for new heads/intake Quote Link to comment Share on other sites More sharing options...
Cordell Posted February 8, 2012 Report Share Posted February 8, 2012 I am at 99% certainty that it isn't tires,i just pulled off the stocks and swapped to C5 17fr 18rr last weekend and the issue there still remains. How would i check to see if the pinion is loose? Yank on the yolk? pull the cover? Ive never had a diff apart in my life. As far as the ignition problem goes should i just scan the car and post the results? Id really hate to drop 300 bucks on new ignition parts if i only need 1 wire. Not trying to be a tight ass,just trying to save cash for new heads/intake Yeah just shake the yoke up and down like you'd be checking for loose u-joints, it would be fairly obvious. If you have access to watch the counts on a scan tool from the opti that is what I'd do, otherwise checking for damage on the wires would be a good start as well. Either one could cause a miss. Quote Link to comment Share on other sites More sharing options...
Large Posted February 8, 2012 Author Report Share Posted February 8, 2012 Just working this through in my head. The easiest thing to start with for the vibration is tires. Might be worth getting them balanced to rule that out as a possible culprit. Also the LT1 cars came with steel drive shafts and GM had problems with balance on them. The solution was to replace them all with aluminum drive shafts. As for the miss, I've learned never to trust an Opti, even if it's new. I'm not saying it's your problem, but just because it's new doesn't mean it can't be the problem. I'm working on a miss with my LT1 Impala SS and the next step is to replace the cap and rotor again with an OEM version instead of the MSD version I bought last time. If you want to try and ignition module and coil at some point we could probably work something out on a weekend when the weather warms up a bit. Rick i'd be open to trying that if we could do it on a day before the beginning of March. Quote Link to comment Share on other sites More sharing options...
hpfiend Posted February 8, 2012 Report Share Posted February 8, 2012 but make sure the pinion isn't getting loose as I've seen this numerous times. This is what I was going to say... check for damage to the pinion seal and extra play... Quote Link to comment Share on other sites More sharing options...
Large Posted February 8, 2012 Author Report Share Posted February 8, 2012 ....and if there IS play? What does that mean in terms of what is worn/broken,and forgive me for being such a needy twat,where should i get the parts and what all parts should be needed? I'm only asking this now so the next time im in town for a few hours i can try and bust out a quick repair. Quote Link to comment Share on other sites More sharing options...
Richard Cranium Posted February 8, 2012 Report Share Posted February 8, 2012 I know enough about rear ends that I don't screw around inside them. Wait, are we talking cars here? To me, if there is play in the pinion I'm taking mine to a shop who knows what the hell they are doing. The consequences of getting the setup wrong vs. my chances of doing the job right aren't good. If it's not the pinion and it's not tires, then I would say drive shaft. If you want I have an aluminum drive shaft available. We can try swapping it onto your car and if it fixes the problem I'll sell it to you for what I paid for it. I still say it would be worth it to get a quick balance done on the tires just to make sure. I'm not sure what my schedule is going to be like for the rest of the month. I'm trying to get my Education Administration internship done right now for my masters degree. I have to turn in my portfolio at the end of March, so I'm trying to get it done this month so I can turn it in early. If I turn it in early and there is a problem I have time to fix it before the final submission deadline. I'm with you on not throwing expensive parts at a problem looking for a solution. If you can get access to a scan tool that's great. Otherwise the system is pretty simple. Opti, wires, coil, ICM. You mentioned the Opti was brand new. Where did you get it, and what brand is it. These cars are notorious for shitting out aftermarket Optis. My camaro is on it's second MSD opti, and like I said I'm about to junk the cap and rotor we put on the impala for OEM. Quote Link to comment Share on other sites More sharing options...
Cordell Posted February 8, 2012 Report Share Posted February 8, 2012 ....and if there IS play? What does that mean in terms of what is worn/broken,and forgive me for being such a needy twat,where should i get the parts and what all parts should be needed? I'm only asking this now so the next time im in town for a few hours i can try and bust out a quick repair. If there is play in the pinion, the rear end needs rebuilt. New bearings and races are a must, and the gears would have to be inspected to make sure they don't have bad wear. If I were you I'd take Rick up on that driveshaft. Quote Link to comment Share on other sites More sharing options...
Large Posted February 9, 2012 Author Report Share Posted February 9, 2012 From what I've read that aluminum driveshaft is a direct replacement.being such a big upgrade I'd likely buy it anyways. Now, let's say worst case scenario I have to have the rear end rebuilt, where should I take it to have that work done? And even if it is only u joints I'dfor sure buy that shaft you have Rick, how are the joints in it? The opti is an OEM unit recently installed by the cars previous owner. Quote Link to comment Share on other sites More sharing options...
Richard Cranium Posted February 9, 2012 Report Share Posted February 9, 2012 The shaft has stock U-joints, They were fine when I pulled the shaft last summer to swap in an inland empire shaft. It's been sitting in the corner of my garage since, so I have no reason to believe they aren't still fine. The only reason I swapped was I assumed I would trash a stock drive shaft with the new setup and the eventual shot of nitrous. I've not had work done there, but I've heard good things about Columbus Joint and Clutch I think is their name. Scott and other guys can probably give better input than me. If the Opti is truly an OEM piece, then I guess I would start looking elsewhere. I'm not a fan of hanging parts, but the only other pieces in the puzzle then are the coil and the ICM. The ICM is the more expensive of the two at around $100. You can get them from a dealer, and I just checked summit and they carry them. The coil is only around $30 and is easy to swap. PCM Opti Wires Plugs ICM Coil I think that is the whole ignition system. Might be worth it to start pulling parts, cleaning them off and giving them a good visual inspection and look for damaged connectors, split wires, etc... Just an idea. The Opti will suck because the water pump has to come off. A really good resource for these cars is a website a guy by the handle of shoebox put together. shbox.com has about everything you could ever want to know about LT1 F-body cars. Quote Link to comment Share on other sites More sharing options...
Cordell Posted February 9, 2012 Report Share Posted February 9, 2012 I can't ever give good advice on where to go because I always do it myself. Making my living as a technician I won't let anyone else work on my shit. I never feel comfortable working on a 10 bolt in an f-body because they won't stand up to any abuse if they are put together perfect, so I refuse to build one if it isn't going in my personal car. Quote Link to comment Share on other sites More sharing options...
Green Bastard Posted February 9, 2012 Report Share Posted February 9, 2012 Just a thought, have you pulled the spark plugs to look at them, it's possible one has a cracked insulator that could cause a short, for a couple bucks apiece it prolly wouldn't hurt to replace them anyhow... If its anything like my camaro you have to get under the car to replace the back two, when I first got my car it was only running on six of eight cylinders because whomever owned the car before me did a tune up and was too lazy to change the back two plugs Quote Link to comment Share on other sites More sharing options...
Richard Cranium Posted February 9, 2012 Report Share Posted February 9, 2012 Just a thought, have you pulled the spark plugs to look at them, it's possible one has a cracked insulator that could cause a short, for a couple bucks apiece it prolly wouldn't hurt to replace them anyhow... If its anything like my camaro you have to get under the car to replace the back two, when I first got my car it was only running on six of eight cylinders because whomever owned the car before me did a tune up and was too lazy to change the back two plugs Not a bad thought. I bought mine on Ebay, but you can get a socket that should help. It's a standard spark plug socket, but it's been cut so it's not a deep well socket any more and the square drive has been drilled out. You can slip it over the plug and the plug will extend through the back of the socket. Then put a wrench/gear wrench on the flats and back the plug out. Quote Link to comment Share on other sites More sharing options...
Large Posted February 10, 2012 Author Report Share Posted February 10, 2012 Ill get the car up on stands on the street in front of the house this weekend (funnnnnn) and start wrenching on it.thanks to all you guys for the input on the problems ive got,ill post again when ive got some new info. Rick im gonna send you a pm about that shaft. Quote Link to comment Share on other sites More sharing options...
Large Posted February 13, 2012 Author Report Share Posted February 13, 2012 So,heres my update. I bought a 98-02 aluminum driveshaft from Rick who was kind enough to meet up with me at Jegs this weekend and school me on these cars a bit while in the freezing cold.Thanks again Rick. That being said,i didn't get the shaft in.It was just downright too damn cold this weekend,but on my way to polaris the car stopped missing for a few miles and i was able to run up to "65" mph with absolutely no vibration,on...or off the throttle,which leads me to believe there is no drivetrain problem whatsoever. Shortly before my exit the miss started again,resulting in bad vibration again. Ive had a few vehicles in my life with ignition issues but never had one shake like i'm running 100mph with a flat tire before now. It's very strange,and the car tear down starts this coming weekend,rain or shine. any ideas? Quote Link to comment Share on other sites More sharing options...
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