vibration

[joe dick]

did a rear end change to go from stock gears to 373's and have noticed a vibration from the rear only when reaching speeds of 120 kph. google search seems to say this is common with gear change. Don't think its tires or rims as I changed to a different set of rims and tires and no change, universal joint has no play and driveshaft bolts are tightened and loctited. So i think I narrowed it down to drive shaft, do I switch to aluminum or if anyone else that has experienced this how did you solve it? It's a 1988 with 8.8.

[Ponyryd]

Pull the weight off that sits at the bottom of the front of the diff, aluminum driveshaft often makes the vibration worse, unless of course your shaft is outta balance.
Are you sure the gears are set up properly? No yoke play?

[ZR]

Super super super common after you do a gear change (increased shaft speed) and retain the stock steel shaft. Go alum and put that little to no vibration smile back on your face.

[55 HD]

Joe Dick, vibration, rear end.......I stopped reading after that, thinking I wouldn't have your answer. lol

[joe dick]

thanks for replies, and you see my confusion one response says aluminum shaft will make it worse the other says it will fix it, its the same thing when you search google and look at other forums, i guess i'll be searching for aluminum driveshaft and start there.

[ZR]

Yet to see a quality alum shaft ever make it worse, greatly improves or totally eliminates.

[NickD]

Yet to see a quality alum shaft ever make it worse, greatly improves or totally eliminates.So when are we putting mine in? Still in the box waiting for you lol

Sent from my Pixel 2 XL using Tapatalk

[ZR]

^ Soon as your schedule opens up.

[Ponyryd]

thanks for replies, and you see my confusion one response says aluminum shaft will make it worse the other says it will fix it, its the same thing when you search google and look at other forums, i guess i'll be searching for aluminum driveshaft and start there.

Personally I’ve never seen it, only heard about it from others, which is why I said it. Any cars I’ve had with aluminum shafts were very smooth. I’d tend to go with ZRs advice on this one, I know he’s played with more shafts than I have ;)

[ZR]

^ HEY.........too much information. LOL

[hammerhead]

u-joints are about $25 good place to start...

[1BAD92LX]

aluminum drive shaft fixed mine. Even balanced the stock steel one, no difference

[hsousa88]

Weren’t aluminum driveshafts stupid cheap 10 years ago? I want one since my car does the same after 110km/hr but who’s paying 6 bills for one? Goddamn..

[ZR]

In the scheme of things, FMS shaft is still within reality price wise.

[Ponyryd]

Weren’t aluminum driveshafts stupid cheap 10 years ago? I want one since my car does the same after 110km/hr but who’s paying 6 bills for one? Goddamn..

Last time I checked I think they were $249 us, but that was probably ten years ago.

[joe dick]

i was thinking about the aerostar driveshafts but again internet is a wonderful place for info, some say they fit without mods, others say you need special offset u joint, or just the same u joint thats on your mustang. I'm old and slow, not that often i get a chance to get over 120km\h, so i'll wait until something that comes up for sale thats at a price i can afford.

[Old Fart]

^^^I did this on my former 89 and used the offset u-joint...worked very well.

[hammerhead]

i was thinking about the aerostar driveshafts but again internet is a wonderful place for info, some say they fit without mods, others say you need special offset u joint, or just the same u joint thats on your mustang. I'm old and slow, not that often i get a chance to get over 120km\h, so i'll wait until somethin g that comes up for sale thats at a price i can afford.

sometimes it's hard to detect play in a u joint - if the vibration occurs at or beyond 120 there may be very little play in the u joint - if you buy a new drive shaft you will also get a new u joint - you will never know if it was the drive shaft or the u joint that was the real fix - u joints are cheap and easy to replace, if it doesn't help then you will know to look elsewhere - in my experience it has always been wise to begin the process with the cheapest part...if the vibration begins to happen sooner and gets more aggressive as time goes on, you will likely feel the play in the u joint - best of luck!

[Ponyryd]

Solid advice, do the cheap easy stuff first. Even if it’s not the u joint, you won’t suffer because of new ones

I agree with doing cheap easy stuff first, but this is a new problem after gears, I highly doubt it’s a u-joint.

[machinedoc]

Friend a gear change done by " Mustang " performance shop in Brantford- GTA area. Same vibration 110- 130.
Found that the preload on the pinion bearing was wrong.

[Hutch]

I had the same thing happen to me before on my 91. I rebuilt the rear end and swapped gears. Car drove very smooth before. My gear pattern was good and pinion bearing preload was adjusted within spec. The car had a vibration at 110 -130. The ujoints checked out fine but I went and replaced them anyways. I even tore the rear end apart again and did it over. Nothing worked. I was going crazy!! I put in an aluminum ford racing driveshaft, the car was smooth as a foxbody could be.

[ZR]

Back in the day, club member after member blew their brains out changing U joints and having the stock shaft rebalanced only to see a marginal at best improvement vs biting the bullet and buying an alum shaft.

[joe dick]

contacted this guy to see if he would ship to canada, no response yet, why can't we have prices like this here?


https://grandrapids.craigslist.org/pts/d/mustang-50-foxbody-alum/6634228852.html

[hsousa88]

^ because Canada

[ZR]

Crazy cheap.

[joe dick]

how did you even find that item?


i get bored, search internet, craigslist in U.S is similar to kijiji.

[joe dick]

bought driveshaft, measures 45 1/2" u joint to u joint, won't fit, bottoms out on yoke before clearing pinion nut, going to have fun figuring this one out.

[Minaccia]

Your U-Joints are bad.

[joe dick]

Your U-Joints are bad.

u joints are bad meaning worn out or wrong ones? they are on an low mile aluminum driveshaft and look brand new, what is the difference between u joints for an aod and those for t5? checking parts online says there is a specific u joint for aod and one for t5 manual. Anyways gonna get u joints for manual and switch yoke from old driveshaft onto new one and see what happens.

[Minaccia]

Bad as in worn, I had the same issue with my first Fox many years ago. They looked and felt good but once removed you could see missing pins.


u joints are bad meaning worn out or wrong ones? they are on an low mile aluminum driveshaft and look brand new, what is the difference between u joints for an aod and those for t5? checking parts online says there is a specific u joint for aod and one for t5 manual. Anyways gonna get u joints for manual and switch yoke from old driveshaft onto new one and see what happens.

[joe dick]

all done, new u joints and used yoke off old driveshaft. Take it for a drive tomorrow see if vibration is gone.