SteveB_RET

I installed a Shaftmaster direct bolt on DS and a Steeda UCA on my 2007 Mustang GT. My car is not lowered so I did not go with an adjustable UCA. The Install went smooth. No issues. Took it out for a test drive. As long as I keep the car under 75 mph, it feels and sounds good. As I get up to 78 I begin to get noise from the Rear axle area. It goes away when you let off the gas, but come right back when you excelerate. Yesterday, I jacked up the car and loosened the 6 rear pinion bolts and torqued them back down again per the install instructions and took it for a test drive. Still has the same issue. So now I'm thinking that when I installed the UCA, I did not get a good enough load on the rear suspension and so tonight I am going to loosen the 2 bolts on the UCA, Load the suspension with my floor jack and tighten them back down.

Anyone have any other ideas or things to try. I am almost at the point of putting the 2 piece DS back on.

chopper_man

Did you clean the flanges really well? There could be crap under one of them causing an imbalance.

Blair

Is it just noise or is it vibration and noise?

Driveshafts transmit more driveline and exhaust sound, it might just be more noise. To test if it is vibrating, do this: Drive your car up to 78 mph where it makes the noise. Throw the transmission into neutral and get off the gas. If the noise continues it is your driveline. If it stops, you're just hearing the exhaust or engine vibrations magnified by the driveshaft. If it keeps making the noise in neutral with no gas, then it is the driveshaft. Mark the position of the driveshaft and unbolt the driveshaft at the axle end and rotate it 180 degrees and bolt it down. If that helps, then keep moving the axle end around until you find a spot where the noise is minimized the most.

Also, did you get the blue non adjustable Steeda UCA? That UCA is shorter than stock and is designed to restore pinion angle on lowered cars. If your not lowered, your pinion angle with the stock UCA should be fine for the driveshaft. I would consider going back to the stock UCA before ditching the driveshaft.

Marc S

Blair is correct, the one piece driveshafts will transmit more noise than the factory two piece will.

I just installed my Shaftmasters direct fit last weekend and road raced the car on Sunday. Before I lowered the car and with the stock driveshaft, the pinion angle was -1.75. After I installed the H&R race springs, the car sat 1.4" lower and the pinion angle with the stock driveshaft was -1.3. After the driveshaft was installed, the pinion angle was -1.0 with the H&R's. While the car was on the hoist and with the rear tires off the ground, I ran the car up to 125 MPH. I did not notice any vibration. I ran the car up to 130 MPH on a road race course over the weekend. Again, smooth as silk. The car is much more responsive to throttle imputs and my brake points on the race track have decreased as well. I did noticed that under excelleration, more drivetrain noise (not vibration) was greater than before.

I installed a Coast driveshaft in a customers car last year. I noticed the same noise under excelleration.

brunobluto

I agree with the above posts, along with your new 1-piece ds, the new UCA will transmit alot more driveline noise right up into the cabin. There very well might not be anything wrong with the installation of these parts, you're just now hearing normal driveline noise that has always been there . Its very common to get more noise after installing stiffer, aftermarket control arms.

baddog671

acceleration.....ACCELeration

BAKnBLK2010

When I installed the UMI LCA's with the poly bushings I experienced the same noise that you describe. I think it's the poly bushings verses the rubber factory bushings. The poly bushings just transmit more noise. I suspect I always had the rear end whine but couldn't here it before installing the new LCA's.

Marc S

What was I thinking! Possibly to many pain meds from my back injury yesterday. Thanks for the correction baddog, it won't happen again.

East87

SteveB what rear end gears do you have? Something you may want to try first is to completely unbolt the driveshaft and rotate it 180 degrees. Rotate neither of the two flanges though.

I'm experiencing the same exact issue. The noise and vibration I feel seems like a big subwoofer is sitting in my back seat and just buzzing. It gets worse as I decelerate from above 85 mph. There's a thread about it here (https://mustangforums.com/forum/2005...xperience.html) that you can refer to. The weird thing is, the driveshaft seemed to be "wearing" to the driveline. Basically, as I kept putting miles on the car, the vibrations at higher speeds seemed to diminish.

Shaftmasters is helping me out big time, and I should be able to post the results of the fix soon enough. Contact them, I'm sure they can give you some really helpful advice. I would expect to see them jump into this thread soon enough. They're really awesome when it comes to customer service.

SteveB_RET

Thanks for all of the input... After reading all of the comments, here is what I discovered. Steeda makes 2 fixed UCA's. one for lowered applications and one for stock appications. CJPonyParts lists the Steeda UCA for stock applications but it is actually the one for the Lowered vehicles. I called CJPonyParts and pointed out their mistake and they agreed to the mistake. So now I just need to find time to go back to the Auto Craft shop and swap back to the stock UCA.

I will let you all know how it goes.