smythge

I have new extension housing, new control arms and shocks.

fisher2985

anyone else notice that we all have 4.10's. but i had the same vibration with 3.73's thats why i changed em. i thought that was my problem.

cliffyk

As you lower the gear (higher numeric ratio) the driveshaft spins faster at any speed.

With 3.27:1 gears the driveshaft is spinning 3060 rpm at 70 mph; with 3.73s it's turning 3550 rpm at 70; with 4.10s it's at 3950 rpm or so--this is 29% faster than with the 3.27s, and roughly that same as going 90 mph with the stock gears.

Like anything else in the world, as you make it spin faster any imbalances stand out more--a lighter weight (I.e aluminum) drive shaft can help...

smythge

Mine did it with the 3.27s, 3.73s and 4.10s also did it with 26" tall tire and now 28" tall tire all at 70mph or above. I just had new u-joints installed and the driveshaft rebalanced, before I spend another $300 on this problem I need to find someone with an aluminum driveshaft to borrow and see if it helps.

I really noticed the problem when changed my control arms and had subframe connectors welded in. I put the stock control arms back to see if that would help, but it was the same. I don't think the subframe connectors could cause the problem, perhaps they are transmitting a vibration?

cliffyk

There are a lot of things manufacturers do to address NVH that have an adverse affect on performance , and as we undo those things the trade-off is often increased NVH...

cisurfer

well if you wanna know the secret to cure this problem i have it..i had the exact same problem when i put in my 410s couldnt figure it out, thought it was the spider gears so i went and bought a cobra diff and moser 31 spline axles, so no cure, went and bought a alumnium ds, still there, talked rick at downs ford, knows a ton about mustangs and he helped me, told me to check the bronze transmission bushing, its in the tailshaft where the yoke for the drive shaft goes in, sure enough it was that and i installed a new one, costs about 16 bucks for the bushing and 10 for the new seal, easy to do, if anyone needs to know where to buy this from and how to do it let me know ill be glad to help but this is the cure to everyones vibration problem i promise

smythge

I replaced my entire tailshaft last week, still have the problem.

nagata

Well, given that it has helped a couple people who seem to have had the same problem, I'm gonna at least try replacing the transmission tailshaft bushing. Hopefully it helps. fisher, might be something to try, especially with as 'low cost' as it's supposed to be.

smythge - I don't know what to tell you man, it sounds like you've replaced damn near everything. I'm sure you've probably already done this, but have you gotten input from a quality, reputable shop that deals primarily with suspension/drivetrain?

One thing I just remembered: the vibration in my 96 seems to ocsillate, even when going a steady speed; that is to say, I'll be cruising at 75 and I will feel the vibration significantly, and then, without changing speed or having a road surface change, the vibration will decrease for a few minutes, and then it will slowly start vibrating again. My g/f has noticed this also, and we can tell primarily because we feel it slightly less and the dash/door panels will pretty much stop rattling, where as they rattle and kind of buzz when the vibration is present. Anyone else have this?

cisurfer

ok you replaced the tail shaft housing, which i assume has a new bushing, how about the drive shaft? if its the same one, it would be the yoke that needs to be replaced, since that bushing was probably shot the yoke gets grooved out causing problems

smythge

I think my problem is in the transmission, I have an automatic and am having other issues with it, as for yoke the original tail shaft bushings was fine so I don't think it's the yoke.