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Official 3.73 DS Vibration Thread - Post your experiences!

2K views 14 replies 10 participants last post by  David Young 
#1 ·
I think we end up hearing a lot more from people with issues than those who have no issues after a gear swap to 3.73s.

So I'm calling on all who have done the swap - Do/did you get any vibration with the stock DS? If you do at what speed? Any issues besides vibration? What top speed have you been to with no problems? etc...

Also please include other things that would affect it such as suspension or transmission mods.

I think many people on here want the new gears but don't care for speeding anywhere above 110mph, where it seems most people are having issues with 3.73s.



I will keep track of the responses and keep this top post up to date with feedback. :bigthumbsup
 
#2 ·
140mph on 3.55 gears stock drive shaft. bad vibration on decel.

now with the shaft masters drive shafts its silky smooth.
 
#5 ·
This is consistent with what I've read elsewhere - lots of strain on the driveshaft when taking foot off the gas at a high RPM / speed. I think this is how a couple of aftermarket shafts broke actually while on a dyno.

EDIT: Hmmm seems I can't edit the original post, but I'll compile all of the data into a single post after enough feedback, since there will probably be a lot of discussion on top of just the feedback posts (this seems to be a hot topic).
 
G
#3 ·
I switched to 3.73s at the end of December. I've only gone as fast as 85, and have driven fairly hard but haven't noticed anything different than before the swap. I've put about 7000 miles on my car since then. I do plan to buy a DS mainly for peace of mind.
 
#4 ·
what pinion angle should be best to set it at?
what is normal with the stock setup
i wonder if 1/4 to 1/2 +/- degree will smooth it out
 
#8 ·
I have 3.73 gears and a shaftmasters revised aluminum driveshaft. I have a Procharged V6 Auto trans. I've been up to 140 mph. I've experienced some gear whine at high speeds during deacceleration, but no vibration at any speed. My driveshaft pinion angle was set at zero degrees at the flange face per Shaftmaster's installation guide. I had more problems with the BMR front safety loop that either the rear end or the driveshaft. I'm replacing the 4 transmission mounting bolts with higher grade bolts than those that come with the BMR loop. According to shaftmasters, a lot of the noise folks are experiencing after installing the aluminum driveshaft and safety loop is coming from the safety loop. I felt one of the BMR bolts yield below 76 ft-lbs as I was torquing it, and decided to pull the safety loop back out and order higher strength bolts (12 x 1.75 x 65 mm) from the bolt depot. If you shear off one of these transmission girdle bolts, I would imagine it would be very difficult to remove the broken portion of the fastener from the transmission mounting nuts in the frame, as they are set up to move for alignment purposes. I just did this install 10 days ago, and my bolts should arrive today. This is not a case where home depot bolts should be used. I sent an email to BMR asking them why they didn't just reuse the OEM bolts instead of providing longer bolts, but never got a response. I decided to upgrade the bolts on my own. I'll probably bring in the BMR bolts to work and have them penetrant inspected to check for cracks.

I plan on pulling my rear end cover and checking the gear pattern just as a safety precaution.
 
#12 ·
Who did you email?

As for the loop causing a noise issue, this is news to me. I am the Ford Tech that deals with ALL of the tech here at BMR, and the only case of this I have heard of was when the DSL017 was not modified/redesigned to fit the V-6 Automatic cars. There was a part of the brace that hit the transmission mount, causing a vibration.

That has long since been fixed. If you are having a noise come from that area, and the loop is not hitting the shaft, I can assure you 100% that it is not our loop.

Regarding your bolts, please send me an email and we can discuss. kelly@bmrsuspension.com

Thanks
 
#14 ·
3.73 vibration

October 4, 2016 changed to 3.73 gears from 2.73. Car is 2014 v6 mustang. Purchased gear install kit from AM and had Capital Ford in Charlotte NC to do work. Noticed vibration between 60 and 85. Ford service manager is a fellow Mustang owner. He heads a local race team. Took it back when I noticed vibration. He is not happy with it. Went back into rear end re-checked everything. He wants me to call AM and give them the specifics of various tests that they did. He believes it is faulty pinion bearing. Believes it was flawed from the factory. He tells me that AM is very user friendly and that it should be no problem in them sending me a new one. They will send old one back to them.
This is my experience.
I am Randy Ardis,
Charlotte NC
 
#15 ·
My 2011 has never had a driveshaft vibration. Now, I have Steeda sport springs and an Axle Exchange driveshaft with a Steeda Safety loop with 3.73 gears. I still don't have any vibration :)
 
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