firekiller15 10 Report post Posted December 30, 2011 Just upgraded my 9" today...I removed the housing put in new 3rd member and new axles along w/ new stock height 4 leaf springs. I know have a bad vibration while driving...any recommendations on a fix? I'm thinking pinion angle or drive shaft. Thanks. Quote Share this post Link to post Share on other sites
LindenBruce 27 Report post Posted December 31, 2011 Well if you changed the springs it's possible the rear end housing is not seated properly causing a pinion angle issue. Crawl back under the beast and double check everything. Did you compare the new springs with your old one to make sure they were correct? I know you said you put in a "new" center section. But is it really "new" or is it "new" as in different? Could be an issue there. Are you getting any different noises from the "new" center section? Bruce Quote Share this post Link to post Share on other sites
Mike65 476 Report post Posted December 31, 2011 Like Bruce stated check to make sure the axle housing is seated on the spring centering pins, if not get the housing down over the pins & then drive it & see if the vibration is still there. If that is ok & you still have the vibration if you still have the old center section swap it back in & see if you still have the vibration, if not that is where you problem is. Quote Share this post Link to post Share on other sites
firekiller15 10 Report post Posted December 31, 2011 The center chunk is new...new ring/pinion, bearing kit and a currie trac loc. And the springs are aftermarket, they match the OEM ones. I will try what you guys suggested, thanks. Quote Share this post Link to post Share on other sites
Powershift 19 Report post Posted December 31, 2011 Did you change the gear ratio too? If you installed lower gears, the drive shaft is spinning faster, and could be out of balance for the speed it now spins. It's an issue we dealt with in Fox Mustangs all the time. Quote Share this post Link to post Share on other sites
firekiller15 10 Report post Posted December 31, 2011 Yes I did...went from a factory 3.0 open carrier to a 3.55 w/ trac loc. Quote Share this post Link to post Share on other sites
avijay 10 Report post Posted December 31, 2011 Did you change the gear ratio too? If you installed lower gears, the drive shaft is spinning faster, and could be out of balance for the speed it now spins. It's an issue we dealt with in Fox Mustangs all the time. Same problem here at above 70mph with lower gears installed. Whats the fix on this? Quote Share this post Link to post Share on other sites
Powershift 19 Report post Posted December 31, 2011 (edited) Just get the drive shaft rebalanced. Or, buy a nice new aluminum one. The aluminum units are usually intended for high performance applications, and spun balanced to a higher rpm. Getting the stocker rebalanced is obviously cheaper though. Keep in mind too.... as mentioned, pinion angles being out of whack can also cause this issue. But, I have had really good luck with just getting driveshafts rebalanced, or replaced, when a vibration occurs after a gear change. Best of luck! Edited December 31, 2011 by Powershift Quote Share this post Link to post Share on other sites
sportsroof69 13 Report post Posted December 31, 2011 Are you feelng it at all speeds? If you are, and there wasn't anything before, I feel like you're waisting your money messing with the driveshaft. Quote Share this post Link to post Share on other sites
firekiller15 10 Report post Posted December 31, 2011 Yes I am feeling the vibration at all speeds, use to be smooth as silk prior to the swap. What is your opinion sportsroof? Quote Share this post Link to post Share on other sites
sportsroof69 13 Report post Posted December 31, 2011 Well, if you're feeling it at all speeds, I doubt it's a driveshaft. For example, if you're feeling it at 30 mph now, you're driveshaft it still spinning slower than it used to at 60 MPH. Can you drive through the vibration, or does it just continually get worse? Quote Share this post Link to post Share on other sites
Powershift 19 Report post Posted December 31, 2011 I agree, if it's at all speeds.... pinion angle sounds more like the culprit. Quote Share this post Link to post Share on other sites
avijay 10 Report post Posted January 1, 2012 Just get the drive shaft rebalanced. Or, buy a nice new aluminum one. The aluminum units are usually intended for high performance applications, and spun balanced to a higher rpm. Getting the stocker rebalanced is obviously cheaper though. Keep in mind too.... as mentioned, pinion angles being out of whack can also cause this issue. But, I have had really good luck with just getting driveshafts rebalanced, or replaced, when a vibration occurs after a gear change. Best of luck! Where's a good place to get an aluminum driveshaft?? Any suggestions? Quote Share this post Link to post Share on other sites
bnickel 10,004 Report post Posted January 1, 2012 try pulling the shaft and rotating it 180 degress and reinstall it. sometimes that will help cure vibrations such as you describe. FTI.....one thing about balancing a mustang driveshaft, though, is that most early models stangs have a 2 piece driveshaft. I know it may look like one piece but in most cases what you have is sort of a shaft within a shaft and only vulcanized rubber connecting the two of them. if you have one of these it will be quite obvious by closely examining the differential end. if you have one of these types of shafts they cannot be rebalanced, the only option is having a new one made for the car. most of the high performance stangs got a one piece shaft, Boss 302, 428cj, 351c 4v possibly the 390 but i'm not 100% sure on that one. the 69 351's all got the 2 piece unit as did all 302 2v, six cylinders, 289's on 68-older, etc. so unless you have a big block car it's very likely you have the 2 piece shaft. Quote Share this post Link to post Share on other sites
Fordrevhead 29 Report post Posted January 2, 2012 I would def try the 180 pinion switch as you could have done that when changing the gears. Regarding the rubber 2 piece sleeved driveshafts not sure if there was specific vehicle combos these were used on but have seen it on a 68 years ago. I have heard they tried it for 2-3 years. Its obvious by size but also u can see the rubber liner. Quote Share this post Link to post Share on other sites
FoMoCo1969 10 Report post Posted January 4, 2012 sorta same prob here, car is smooth as silk till 65mph anything over feels like the car is going to come apart. tried two sets of wheels, I do have a custom aluminum driveshaft, but I'm not 100% sure on driveshaft/ pinion angle. I installed an AOD trans and built my own trans. crossmember. Quote Share this post Link to post Share on other sites
Fordrevhead 29 Report post Posted January 4, 2012 IMO, even a lot of the people that know how to set pinion angle omit checking the transmission to driveshaft angle. There is a joint on both ends and you can run between 1 and 3 degrees but they should also be set equal. If you change engine height, transmissions, crossmembers, rear ends, etc. you have to check this. The suspension also has to be loaded which if you are mocking up your driveline on a shell is not exactly accurate to begin with. Get a magnetic protractor. No cheap magnets, as they may not be too accurate after they hit the floor a few times. Quote Share this post Link to post Share on other sites
stangme428 33 Report post Posted January 4, 2012 my buddies have laughed at me due to me being very anal about my drive shaft angle .... this is why i am trying to make sure its within spec... too much money involved to have the rear seal or anything come apart at speed worse case... i still have yet to order my drive shaft... i want to measure it again under load before i order. Quote Share this post Link to post Share on other sites
BuckeyeDemon 211 Report post Posted January 4, 2012 the 69 351's all got the 2 piece unit as did all 302 2v, six cylinders, 289's on 68-older, etc. so unless you have a big block car it's very likely you have the 2 piece shaft. not to get off topic, but are you sure? my 69 351W doesn't look like a two piece. the stripe codes matched what my car was supposed to have (according to an MCA judge anyways). Quote Share this post Link to post Share on other sites
Fordrevhead 29 Report post Posted January 4, 2012 Yeah, I would like a definitive source on this as well. I have only ever seen it on a 68 personally, with a 302 auto. My belief was that they were used on the higher revving small block automatics unsure of start year and phase out year. Perhaps what bnickel said was correct except for the auto only disclaimer? Quote Share this post Link to post Share on other sites
1969 Mach1 14 Report post Posted January 4, 2012 I doubt your pinion angle has changed much, if any, from what it was before. Is it something silly, like one of the new axles is not straight? Does the driveshaft slip into the transmission output shaft the same distance as before? Quote Share this post Link to post Share on other sites
bnickel 10,004 Report post Posted January 5, 2012 not to get off topic, but are you sure? my 69 351W doesn't look like a two piece. the stripe codes matched what my car was supposed to have (according to an MCA judge anyways). ya know, i did say most!!!! LOL.......both my GT and my Cougar had the rubber 2 piece shaft originally. the Cougar still has it's original one and the Mustang now has the one piece shaft from my old 70 cougar that had a 351c 2v and FMX trans, BTW, both 69 Cougar and the GT both have 351w and FMX as well. so it's quite possible that they were only used on auto trans cars and not manual trans cars. I think 69 may have been the last year for the 2 piece unit, because as i said the 70 cougar had a one piece. Quote Share this post Link to post Share on other sites
Pakrat 1,043 Report post Posted January 5, 2012 I can't say for sure that mine is original but considering how just about every other thing on it was I have to believe this was too and my 302 3 spd had a 2 piece shaft FWIW. Quote Share this post Link to post Share on other sites
avijay 10 Report post Posted January 5, 2012 not to get off topic, but are you sure? my 69 351W doesn't look like a two piece. the stripe codes matched what my car was supposed to have (according to an MCA judge anyways). Buckeye, Can I ask you where you got that new driveshaft from? Quote Share this post Link to post Share on other sites
BuckeyeDemon 211 Report post Posted January 5, 2012 Buckeye, Can I ask you where you got that new driveshaft from? Mark Williams Enterprises. It's 3.5", aluminum w/bonded ends. Quote Share this post Link to post Share on other sites
