Bad driveline vibration...Please advise...

[pstocker]

In my recently purchased 85 SVO, when I hit about 65mph, I get a very harsh vibration which does not stop, not matter how much faster you go. It can be felt very strongly through the entire driveline, especially in the shifter. When I push in the clutch, you can even feel it vibrate through the clutch until disengaged, or then re-engaged. At first I though it might be the tires, but they look ok, and don't exhibit and kind of out-of-round symptoms while the vehicle is rolling slowly. I have done some searching on the threads and found a posting on a similar problem that ended up being a bad drive shaft.

A couple of questions. One, if it ends up being a driveshaft, I don't really want an aluminum one because I don't have that kind of $$ to shell out to get one fabricated to work. Will a driveshaft from a 4cylinder Mustang, say 87-93 work?

I am going to get under it and check the tailshaft bushing and flange bolts/ujoints this weekend. Anything else I should check while I am there?

Thanks and TGIF
Phil

[Jcamper]

Check the bolts that attach the driveshaft to the rear yoke. Mine used to like to loosen up. Ended up using loctite on them. Jeff

[Laredo]

check the bolts that attach the driveshaft to the rear yoke.

x 2 ^^^

[svono50]

Couple of other things to check are the u-joints and the front u-joint dampener for any looseness/wobble. Good luck.

[pstocker]

Thanks for all the tips! I will be checking them out this coming weekend and will report back!

[Unclesams_SVO]

A FRPP aluminum driveshaft will bolt right in, so you will not have to have one made. I would imagine just about any drive shaft from a 79-04 mustang will it.

[Special Fred]

The only driveshaft that will fit is one that is 45.5" from U-joint to U-joint, which disqualifies all of the A4LD equipped Mustangs since that transmission is longer. So, only the T5 & AOD equipped Mustangs will have one that is the right length.

You don't have to shell out big bucks for an aluminum driveshaft nor do you need to have one made. Just find an AWD Ford Aerostar minivan in the junkyard...they already have the correct length driveshaft if it's the aluminum version and it will bolt in, but I prefer to install new U-joints & a 1310 series T5 style yoke/flange whenever I use one of those.

[svono50]

The only driveshaft that will fit is one that is 45.5" from U-joint to U-joint, which disqualifies all of the A4LD equipped Mustangs since that transmission is longer. So, only the T5 & AOD equipped Mustangs will have one that is the right length.

You don't have to shell out big bucks for an aluminum driveshaft nor do you need to have one made. Just find an AWD Ford Aerostar minivan in the junkyard...they already have the correct length driveshaft if it's the aluminum version and it will bolt in, but I prefer to install new U-joints & a 1310 series T5 style yoke/flange whenever I use one of those.

Interesting, then you should be able to swap your factory DS yoke over to the Aerostar shaft, correct?? I hear you on the used u-joints, easy item to take care of BEFORE you swap it in. Also, any particular year Aero to look for?? Sorry for the hijack.

[Special Fred]

Interesting, then you should be able to swap your factory DS yoke over to the Aerostar shaft, correct?? I hear you on the used u-joints, easy item to take care of BEFORE you swap it in. Also, any particular year Aero to look for?? Sorry for the hijack.

Yes, you can absolutely swap your factory yoke & flange over to the Aerostar driveshaft. However I prefer to use a yoke which does not have the huge damper on it. Keep in mind that there are two types of U-joints: 1310 series and 1330 series. The 1310 series is narrower and is the type used on our cars. The 1330 series is wider and is typically used on the 5-liter Mustangs. You can also use a "bastard" 1310/1330 series combo U-joint for joining dissimilar parts but those are typically aftermarket and therefore are generally weaker due to the presence of a grease fitting that compromises the structural integrity of the entire U-joint. I prefer Motorcraft non-greaseable U-joints for their durability.

As for which year Aerostar that is a good question. AWD Aersotars were made between '92 and '97. Ford did not start putting aluminum shafts into the vans until '96...but there was a recall for out-of-balance shafts prior to that year, and the "fix" was the aluminum shaft. So the bottom line is that ANY AWD Aerostar could have the shaft; you just have to look underneath.

The Aerostar driveshafts are 3" in diameter (compared to the version that Ford Racing sells which is 3.5") and have welded ends (not pressed on). I have never heard of anyone breaking an Aerostar driveshaft yet, even with 6000+ RPM clutch dumps on slicks. Both my 1985 SVO and my 1989 GT have been fitted with converted Aerostar driveshafts.

[svono50]

Sweet, thanx for the info. Now I have another thing to add to my salvage yard list.

[Special Fred]

Not a problem. If you do end up using greasable U-joints, make sure that the grease fitting is on the "compression" side of the driveshaft rotation. Let me know if you need clarification on this.

[pstocker]

The only driveshaft that will fit is one that is 45.5" from U-joint to U-joint, which disqualifies all of the A4LD equipped Mustangs since that transmission is longer. So, only the T5 & AOD equipped Mustangs will have one that is the right length.

You don't have to shell out big bucks for an aluminum driveshaft nor do you need to have one made. Just find an AWD Ford Aerostar minivan in the junkyard...they already have the correct length driveshaft if it's the aluminum version and it will bolt in, but I prefer to install new U-joints & a 1310 series T5 style yoke/flange whenever I use one of those.

Fred, thanks for the tip from the Aerostar. I was in the u-pull-it yesterday and saw several Aerostars with the fully welded aluminum driveshaft. However, they were not AWD Aerostars. I didn't even know Ford made and AWD version of the Aerostar. Will this one I found work for my SVO?

[Special Fred]

Fred, thanks for the tip from the Aerostar. I was in the u-pull-it yesterday and saw several Aerostars with the fully welded aluminum driveshaft. However, they were not AWD Aerostars. I didn't even know Ford made and AWD version of the Aerostar. Will this one I found work for my SVO?

No it won't, sorry. The AWD section on the transmission is what makes the driveshaft the correct length. The shaft in non-AWD Aerostars is too long, aluminum or not.

Measure the distance between U-joints if you're not sure. It should be 45.5".

[pstocker]

No it won't, sorry. The AWD section on the transmission is what makes the driveshaft the correct length. The shaft in non-AWD Aerostars is too long, aluminum or not.

Measure the distance between U-joints if you're not sure. It should be 45.5".

Dang, that bites. Does the AWD aerostar have a solid axle front diff!

[Special Fred]

Does the AWD aerostar have a solid axle front diff!

No. It has a transfer case, two half shafts and four CV joints.