Bennyandthejets

Hey all,

I just installed the Foose Handling pack in my 2005 GT. This kit includes struts, dampeners, front and rear coils and rear sway bar. The drop is not too aggressive. All work was done personally. I am not experienced but can find my way around a garage.

Anywho, I had the front end aligned and recambered after installation. No problems here.

I have noticed that at around 80 miles per hour a vibration comes from the rear end. It is tricky to explain. It is not drastic but was definately not there before.

My first though is that it is something wheel/tire related back there. I will probably run over and get the tires balanced again and see if that helps.

At normal speeds the car drives great.

Any thoughts?

Thanks,


Ben

05YellowGT

Like you say , tire balance would be the first suspect ...

CO_VaporGT_09

But unless you did something to the wheels/tires with the install, it would be odd to notice it after and not before the suspension upgrades. None of the bushings involved in what you replaced should transmit so much more vibration that you'd notice it.

You might check your pinion angle on the driveshaft and make sure it's still in spec. If you were at the limit of Ford factory tolerances before, lowering might have put you just outside spec.

Also, there's an axle damper on some of the earlier S197s that help to quell vibration. IF your's doesn't have it, it might need it now, though I think it interferes with certain rear suspension piece upgrades.

Bennyandthejets

Thanks for the thoughts guys.

I have decided to knock to birds out with one stone and install an adjustable pan-hard bar ( I discovered rear end is a bit out of whack) and get the tires rotated and balanced.

This should fix the problem, tires running down the road sideways and all...

If that doesn't fix it, then I will have a look at the pinion angle. I'm not doing this first because so many others have installed this kit with no driveshaft problems.

In any case, this would be a great excuse to buy myself a new light weight drive shaft.

slidejob

You may want to contact Foose & ask them how much change this kit & your tire size did to your front & rear roll centers? The stock panhard bar has a slight left to right angle. Left side lower then right. This determines how weight is transferred to the rear wheels. In this case it is an upward force. I would suggest to start setting the bar level with the desired roll center height & tune it to your liking.

CO_VaporGT_09

A new shaft wouldn't fix this if that's the problem, you have to get adjustable upper (preferred) or lower control arms to change the pinion angle. In fact a 1 piece DS might make it worse. Good idea to get the balance/rotate first, and if you're off center in the rear and adjustable panhard is needed regardless.

Bennyandthejets

Good news. Edelbrock adjustable panhard bar did the trick. Great quality part as well. Vibration solved. Thanks all for the input.

I cannot believe the difference in driving with the Foose pack. Should have done this suspension stuff years ago. Now all that remains is to get rid of that **** vibration in my TCI ratchet shifter (caused by exhaust clamp supposedly).


Ben

CandyRedGT

possibly pinion angle??? I'd recheck tirfe balance first though.

crescent_wrench

So the panhard bar fixed the problem?

Bennyandthejets

Well I thought it was gone but it turns out it just moved to a bit higher speed. You can still feel a little shimmer at 90-95. Not that I'm going that speed all the time.

On top of that I hit a freaking deer that was already down on the road. It was broad daylight but the truck I was about to pass drove right over it so I never had a chance. Damage doesn't seem too severe but I have yet to lift it and further check.

TTS197

Sorry to hear about your car.


Might want to have your pinion angle checked as Candyred suggested.
http://www.youtube.com/watch?v=i8FNg...layer_embedded

Bennyandthejets

Right after I get the tires balanced again I will probably check this. I just have a hard time believing that the pinion angle would have been drastically affected with such a mild drop that so many before me have performed with no issue. It seems an easy enough job to perform if I need to though. Hope the parts don't cost too much. Thanks a bunch for the video. Next to TacoBill that's about as clear as it gets. Think I might even have an angle finder laying around somewhere. Not sure about two.

On the plus side, car looks ok underneath. The deer snagged the bracket on my exhaust pretty good so I'll have to tighten that up/bend it back into place. That said, that irritating rattle that was coming from that clamp after I installed my TCI ratchet shifter is now gone.

Bennyandthejets

In unrelated news I installed an Edelbrock strut tower brace yesterday. Took the car in to check alignment once again and to figure out this vibration. (No I have still not checked the pinion angle.)

This time the shop tells me that I need caster bolts to get the car back into spec. I think they are right but it is just a bit odd that they didn't tell me this the first time.

Anyway, the car drives like a million dollars now. The vibration is still present but honestly I can't tell if it's real or psychosomatic half the time. It is only noticeable at all at 85+ mph.

I would like to compare to a stock GT. Do you guys get any more vibration at 85+ with the stock suspension. I seem to remember it wasn't all that smooth at that speed in the first place.

Thanks to all who have helped. If anyone is interested, I chose the Edelbrock brace due to its third firewall connection. Safe to say those towers aren't going anywhere.

Overall the car handles like a BMW or better (which is what I was targeting). Steering is extremely precise and the car is not darty in the least. I probably won't make any further handling modifications from here. I would very much recommend this setup (FordRacing) to anyone who wants a great compromise between comfort and performance. Also, Edelbrock parts were extremely high quality as expected.


Ben

tdbrown75

Benny,

I'm running that same kit (only with Steeda Ultralites) and also have a high speed vibration. Mine's only present on cruise or deceleration, if I give it gas it goes away. It was diagnosed as a pinion angle issue due to lowering. In my case it starts out around 72MPH and gets worse the faster you go. I have 4.10s so that would probably be right in the ballpark of 90MPH with 3.31's as far as drive shaft rotation goes.

After ruling out the basics (wheel bearings, tire balance, etc etc) analysis was done with a vibration analyzer and dyno by my local dealership who is mod friendly awesome to work with. They checked the gears (which they installed), indexed the driveshaft, tried the driveshaft balancing procedure and went through the car with a fine tooth comb. After several days of troubleshooting they contacted Ford Engineering who diagnosed the issue as being drive line vibrations due to an incorrect pinion angle as a result of performance suspension modifications.

I expect the vibration has been there for quite some time (I had a leaky pinion seal before the gear swap) however before the 4.10s I probably never had the drive train rotating fast enough on a regular basis to notice. The dealership they told me to pickup an Adjustable Upper Control Arm from the local speed shop to correct the pinion angle.

I stopped by the speed shop today and spoke with the owner who confirmed the pinion angle in the S197 is very sensitive and claims to have seen this issue before even with mild suspension drops. I have an appointment to install the Adjustable UCA and have the angle adjusted mid-next week, I'll come back and post the results.

Tim

tdbrown75

Here are a couple of really good articles from Randy's Ring and Pinion that describe how pinion angle can contribute to driveline vibrations:

http://www.ringpinion.com/ContentFrame.aspx?FilePath=Content%2fHowTo%2fGener alInfo%2f%2fDiagnosing_Noise_(Part_2).inc

"Driveline vibrations can be caused by several problems. Worn universal joints or a driveline that is out of balance are often the problem, but driveline angle can cause a balanced driveline with good U-joints to vibrate. If the U-joints are bad, they can cause several different noises from squeaking, to clunking, to grinding, to vibrations. If the driveline is out of balance, it will vibrate with a steady pitch that increases as the vehicle speed increases. If the pinion shaft is out of alignment and not parallel to the transmission yoke, the difference in the angles between the front and back U-joints can cause the driveline to vibrate. If the vibration is due to improper angles, it will create a cyclic sound that increases and decreases in intensity. An out-of-alignment problem can also be identified by the change in the noise when accelerating or decelerating. As the pinion yoke torques up from acceleration or down from deceleration, the rear U-joint angle changes and causes the vibration to change."

http://www.ringpinion.com/ContentFrame.aspx?FilePath=Content%2fHowTo%2fGener alInfo%2f%2fDirveline_Angles_%26_Vibration.inc

"I have had more than a few customers come back to our service shop after a gear ratio change to complain that we caused a new vibration in their vehicle. In actuality, we inadvertently caused the vibration by increasing the driveline speed.

When changing to a lower gear ratio (numerically higher) the driveline speed increases proportionally to the change in the ratio. For example, when changing the ratio from 3.08 to 4.56 there is a 48% change in the ratio and a 48% increase in driveline speed. This means that a vibration that would have been noticeable at about 90 mph is now noticeable at 60 mph. This higher driveline speed makes the vibration more noticeable because while it previously existed at 90 mph, it may have gone unnoticed due to the amount of vehicle vibrations it had to overcome in order to be noticed. If the customer installed taller tires and raised the vehicle before changing the gear ratio, the vibration is probably caused by the lift. This vibration caused by the lift and wrong driveline angles would not be noticeable until the new ratio was installed, since the tall tires and stock ratio kept the driveline speeds too slow for the vibrations to be felt. Vibrations due to wrong angles are usually easy to identify because they are harmonic or cyclic. This means that the vibration varies in pitch or intensity even when traveling at a steady speed. The results is a "whir ... whir ... whir" type of noise.

The solution to wrong angles is easy in theory, but not always easy in practice. There have been many good technical papers written on this subject, so I won't go into detail now. I will however cover a few of the basics. In order for a two U-joint driveline to be free of vibration it must be in balance, and the angle of the front U-joint must be the same as, or very close to, the angle of the rear U-joint. If there is a noticeable difference in the angles, there will be a vibration."

Bennyandthejets

Very interesting. That will be very cool if the control arms fix the issue.

tdbrown75

She goes in Friday! *fingers crossed*

Tim

tdbrown75

I got the UCA installed and no dice... vibration is still there. At this stage I believe it may be gear related (last thing I changed) but there's really no way to tell and I'm not about to drop $700-$800 to find out, or worse end up with a noisier setup then I have now.

Truth be told the car has had a noisy rear end since I got it, and overall it's the quietest it's been since the car was new. I did not buy the Mustang for a comfort cruiser, everything is in spec/tolerance and there's probably no long term damage being caused. I have a feeling I could dump a ton of cash and time into this and may never figure it out.

If it's really a problem it will worsen and eventually make itself known, otherwise it's a mild annoyance at best. At this stage I'm chalking it up to "character" and calling it a day.

Tim

70MACH1OWNER

Hey Tim,
Did you ever get your 4:10 auto trans tune from AM? Never saw where you received it and what your opinion was.
Scott

tdbrown75

I did... however I was getting rich codes and after several revisions gave up on it. The shift schedule was fun, but for some reason we just were not able to get it dialed in.

Tim