Below is a detailed write-up based on my personal experience of months of driveshaft vibration troubleshooting. I'm a little wiser now, and though the board could benefit from my experience. I caution you that I am not an expert, but that I've learned a fair amount along the way and ultimately solved my vibration.
I'm also attaching a MS Word copy if people would like to email or print it. Perhaps it can be updated as others chime in on this thread.
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A. Choosing the driveshaft
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Important! 
Investigate the manufacturer thoroughly:
1) How long have they been in the driveshaft business?
2) Do they make, repair, and sell driveshafts for vehicles other than Mustangs?
3) What kind of facilities do they have? Do they have in-house high speed balancing equipment and runout gauges?
4) What is their guarantee / return policy?
- Pick from one of the two main types of shafts:
1) A Ford Ranger aluminum shaft that has been shortened. The aftermarket driveshaft shop sources the shaft from Ford, cuts the tube and rewelds the end on.
2) A custom made shaft. A couple of shops offer shafts made from scratch. Typically they are using new Alcoa aluminum tubes to make the shaft.
- A note on reworked Ranger shafts:
1) These shafts are
manufactured by Ford and
reworked by the shop. A shop that exclusively reworks Ranger shafts likely doesn’t have the full range of equipment that a full service shop does.
2) Consider that these shafts were engineered for a small pickup truck, not a high performance Mustang. However, consensus is that they adequately strong – question is whether that are refined enough (see next item).
3) More than one shop has stated that many of these shafts come from Ford with issues. Some exhibit runout (a hop up and down) and/or tubes that are not perfectly round.
4) If you buy a reworked Ranger shaft ask the shop if they are checking both their shortened end (typically the pinion flange end) AND the
tranny end for runout. Do they reweld or do their shortening from the
tranny end if the factory shaft shows runout on that end (more work, but a good shop will do this if the factory shaft shows runout).
- Decide on pinion flange replacement or adapter. Most offerings in the market allow you to choose. The pinion flange is what the shaft attaches to on the rear end. The stock shaft uses an atypical flange that requires an adapter with aftermarket shafts. The alternative is to remove the pinion flange and replace it with a Ford Ranger flange for a direct attachment.
1) Adapter advantages: easier install, no chance of messing up you pinion bearing preload (some argue that you can’t set the preload properly without taking the rear end apart). Adapter disadvantages: some believe it is not as strong, some question whether it can contribute to driveline vibrations as it is an extra part in the drive train.
2) Replacement flange advantages: considered a stronger / cleaner install, Ford makes one that fits the S197 rear end. Disadvantages: installation requires a pulley puller and impact gun, you will lose a small amount of gear fluid, and again the problem setting the pinion bearing preload by simply torquing the pinion nut after installing the flange. If you are doing gears at the same time, the replacement route makes perfect sense, if not you need to decide whether the potential preload issues are something you want to live with ( I have heard of only one failure on an S197, and other failures in older Mustangs).
- Do your homework. There is a fair amount of controversy over the different driveshaft offerings in the marketplace and this is not a mod you should take lightly – a bad driveshaft (e.g. excessive runout, poor welds, etc. puts stress on your drive train and can be dangerous). A failed driveshaft can cause extreme damage to your car, or worse you!
1) Search AFM and multiple other forums on the offerings.
2) Be critical of what you read. Don’t take one post as evidence of a good or bad shop. Look for facts, not opinions (
many people with positive experiences with their $600+ mod will shout from the hill tops how great their drive shaft shop is). Also, note that certain forums are sponsored by shops and this may influence what posts remain on the boards.
- The choice is yours. I’ll tell you that there is not one best offering.
B. The install - do you have a vibration?
- Two problems that could occur are harmonic noise, or worse drive train vibration. My focus is on vibrations. Something I’ve dealt with in my car extensively and what is most reported in posts.
- A few things before we get to testing for vibrations.
1) It is a good idea to test drive your car for vibrations BEFORE you put the shaft in. This means testing up to a speed you feel comfortable with to get a baseline.
2) Note that many people believe that the stock 2 piece shaft was put in by Ford to mask inherent design issues in the S197’s that cause vibrations. Take away – no vibration BEFORE doesn’t mean you don’t have pre-existing issues (perhaps pinion angle in lowered cars or tire balance / runout).
3) You should consider putting a driveshaft safety loop on when installing any aftermarket shaft. It the smart thing to do given the potential for damage from a failed shaft. Be mindful that Ford likely tests their components much more than any aftermarket shop AND they have deep pockets if something happens.
- Many cars show no problems up to a certain speed, then exhibit issues at higher speeds. Test as fast as you feel safely comfortable
(I am not suggesting you do anything illegal or dangerous, do so at your own risk). I have had a shaft that was fine up to 85mph or so, but then started vibrating beyond that – going up to 125mph produced a downright scary vibration. Take away – just because you don’t feel a vibration at modestly fast speed does not mean you are problem free.
- A nationally know Mustang shop (non driveshaft shop that installed my super charger) told me that by the time you feel a driveshaft vibration it is really bad and downright dangerous as the vibration is masked at lower RPMs. They gave me this speech when the dynoed my car up to 140mph and they encountered a shaft vibration that had them very concerned.
- If you have no problems, great. Based on the hundreds of threads on multiple boards I’ve read, I’d say you are in the majority. However, the remaining unlucky drive shaft installs are not insignificant. I can only guess, but I would say something more than 1% and less than 15%. Note that in the high end I’m considering that there are some people who never drive their car beyond 85mph and don’t know they have a problem.
C. You have a vibration, what now?
- Potential caused of a vibration that I know of, in order of things I would trouble shoot first. I leave the last item to people better versed (it wasn’t my problem).
1) Driveshaft - excessive runout or out of balance
2) Tires/wheels – excessive runout or out of balance (don’t forget the belief that the stock shaft masks some problems)
3) Pinion angle – outside of acceptable range (recall it isn’t clear what acceptable is)
4) Rear end – I’ve heard axles mentioned and even gears and pinion bearings (remember the pre-load discussion)
- Driveshaft trouble shooting. I thank another AFM member for coming up with this.
However, before you read this method, IT IS DANGEROUS – do this at your own risk. Better yet, have a professional shop do this.
1) Put the car up on jackstands on all 4 corners. I would suggest going under the axle tubes on the rear end to “load” it.
2) Start it and put it in gear, let it idle in gear
3) Observe the driveshaft in motion. (Again, be very careful of the spinning driveshaft and rear tires!!!). Look at both the front and end of the shaft.
4) My personal experience was that I did this with 2 after market shafts and visually saw very noticeable runout (shaft looked like it was hopping up and down). One in the front of the shaft, the other in the rear of the shaft.
5) If you see runout try to determine if the
tranny or pinion flange is out. There have been reports of bad replacement pinion flanges, but I believe they is rarely the problem.
6) If you notice this, stop here. Contact the place where you bought the shaft and either get it fixed or get another one. (Note that I can’t tell you what acceptable runout is. However, you will intuitively know what is unacceptable).
7) One other note – runout can be measured with gauges by hand spinning the drivetrain. A professional shop would likely use this method..
- Tire/wheel trouble shooting. Note that my father owned a tire business for 35 years so I have personally seen and resolved many such problems.
1) Of course tires and wheels should be balanced.
2) Traditionally this meant “computer high speed balancing” which only told the tech where and how much weight to put on the wheel.
3) Today, there is “roadforce balancing.” This technology not only deals with weights, but actually measures radial (up and down) and lateral (side-to-side) runout of the tire and wheel independently and as a unit.
4) If you are troubleshooting vibrations, get this done (it will cost $80-$100 for all four). Talk to the tech and watch if you can. Find out where your tire wheel units stand relative to tolerable levels. Get printouts of the machines readings or snap pics if there are problems.
- Pinion angle trouble shooting. The net angle of the driveshaft and the pinion flange is called pinion angle. Pinion angle is often blamed for vibration problems. Many posters believe pinion angle requires adjustment on lowered cars. Some people believe the whole pinion angle focus is overdone. Based on my personal experience I believe that pinion angle that is way off (2, 3 degrees or more) can cause a vibration, but if you are close this is not likely your problem.
1) I suggest leaving pinion angle alone to start. (If you have factory control arms or non-adjustable after market control arms do nothing, if you have adjustable control arms, set them at factory length).
2) To adjust pinion angle, you need either an adjustable upper control arm, or adjustable lower control arms. Most people seem to go with the former.
3) Instructions on setting the pinion angle abound on the forums, however, they are not always consistent. Some bring the
tranny flange into the calculations, others don’t. I’m not an expert so I’ll leave it at that.
4) What is the right pinion angle? I’ve read that the factory pinion angle on the V6 S197 which has a one piece shaft is -0.5 degrees. Many quote -2.0 degrees as ideal. I don’t know the right answer, but consensus is that it is slightly negative (-0.5 to -3.0).
5) You can buy an angle meter, research the posts and try to set the pinion angle. You can pay a shop to set the pinion angle. Don’t expect that this will solve your problem – it may, it may not.
6) I recommend adjusting your pinion angle by methodically adjusting your control arm(s). I have an adjustable upper and went to stock length and then did one turn of the adjuster at a time (note that Steeda and CHE have the same threads on their upper control arms and claim 1.65 turns = 1 degree). Write down your adjustments and test the car after each, note changes. I went as far as 5 turns longer and 5 turns shorter. In the end 1 turn longer than stock (about ¾ of a degree) on my 1.5” lowered car was best. Again, my belief that pinion angle over rated (stock length wasn’t much different if at all in my case).
D. Concluding remarks
- I covered a lot of ground in this write-up, but did not state some technical things in detail that can be had searching other posts (e.g. how to set pinion angle). It is long enough as is.
- I went through months of shaft changes and troubleshooting. I finally solved my problem when I did the visual runout check and found that the last 2 shafts I installed exhibited significant runout. I had the last shaft looked at by a different shop that has years of specialized experience with driveshafts. They found significant runout and balancing problems on their balancing machine. They machined off the weld at the front and rewelded it, and rebalanced it. I put it in, did a visual runout check which looked perfect. A test ride confirmed it – problem fixed, finally!!!
Visual before
Visual after
- I put a fair amount of effort into this write-up and I hope it helps those of you troubleshooting problems. Why? The same people who benefit from this post have helped me tremendously as I’ve modded my car beyond anything I planned. I have not mentioned which shafts had runout to avoid controversy. In the end you are better off doing the research yourself and making your own informed decision. GOOD LUCK!
Choosing a one piece driveshaft and troubleshooting vibrations 
).
This is the first time I've been wrong in say 3 or 4 years......
not.....
