Vibrations After Front Savvy Control Arm Install

Jamison C

Jamison C

Heil Savvy 🙋‍♂️
Supporting Member
Ride of the Month Winner
Joined
Sep 1, 2018
Messages
3,416
Location
Sedona, AZ
I just got finished rebuilding my front DS. I didn't think this would actually cure my vibs, but it needed done and I figured it wouldn't hurt. Anyways...

2005 Rubicon, auto, 32s, 5.13s. Last year I had my Jeep regeared to 5.13s and after the break in I was able to drive that thing around at freeway speeds smooth as silk. A few months later, I redid the rear and added Savvy arms with a Currie track bar. Still no issues. It's when I added the Savvy arms to the front of the Jeep that the vibs appeared. It was smooth up to 55 and that's when I could start to feel the resonance coming on and get gradually worse. I have played with pinion angles, DS orientation etc. When the front shaft is removed, the vibs go away. Axle is centered and squared.

I did my Savvy UA in September and have left the front DS out most of the time. I put it back in tonight and took it for a spin and sure enough, the exact same characteristics as before were present. Jeep is smooth up to 55MPH and from there the vibs get gradually worse. I don't think the tuck had any effect what the actual issue is.

I am at a loss on how to diagnose this, and hope there are answers. My only thought was maybe (I SAID MAYBE) the eight bushings in the original control arms were enough to act as a damper between the axle and the frame. Typically the issues come after a regear or tuck. In this case, I don't know.
 
  • Sad
Reactions: RINC
Ok…it’s hard to tell from your description (or I’m tired) but were you able to drive it after your tummy tuck without vibs and with the front shaft?
 
Mike_H said:
Ok…it’s hard to tell from your description (or I’m tired) but were you able to drive it after your tummy tuck without vibs and with the front shaft?
Click to expand...

No, tonight was the first time I drove it with the front shaft after doing the tummy tuck and I still had vibs. Same characteristics as before the tuck.
 
:cough: front hub kit :cough:

If I understand the timeline correctly…

Step one was a regear, SYE, and adj rear arms? -> no vibes

Step two was adj front arms -> vibes

Step 3 was tummy tuck -> no vibes, but no front shaft either

Step 4 rebuilt front shaft -> vibes
 
Last edited:
  • Like
Reactions: Andy-WhiteTJ
I had the same vibe on mine. Pulsating started at about 55 mph.

When I installed my rubicrawler the savvy crossmember hit the yoke. Instead of trimming the crossmember I added a spacer plate on top of the transmission mount, raising my tcase. Either 3/8 or 1/2, can’t recall and my Jeep isn’t here to check.

Pulsating was now completely gone. I had always thought it was a harmonic issue.

I’d try rotating the front pinion down to get the same effect. Maybe the key was effectively rotating both diffs down a bit or the slight change in powertrain angle.
 
  • Like
Reactions: Jamison C, Mike_H and freedom_in_4low
Apparition said:
I had the same vibe on mine. Pulsating started at about 55 mph.

When I installed my rubicrawler the savvy crossmember hit the yoke. Instead of trimming the crossmember I added a spacer plate on top of the transmission mount, raising my tcase. Either 3/8 or 1/2, can’t recall and my Jeep isn’t here to check.

Pulsating was now completely gone. I had always thought it was a harmonic issue.

I’d try rotating the front pinion down to get the same effect. Maybe the key was effectively rotating both diffs down a bit or the slight change in powertrain angle.
Click to expand...

Do you know what your angles were before or after you added the plate?
 
freedom_in_4low said:
Do you know what your angles were before or after you added the plate?
Click to expand...

Unfortunately I don’t remember them. When I set them up I aimed for the forum recommendation.

I never messed with angles after raising the tcase and it corrected everything.
 
Last edited:
Mike_H said:
:cough: front hub kit :cough:

If I understand the timeline correctly…

Step one was a regear, SYE, and adj rear arms? -> no vibes

Step two was adj front arms -> vibes

Step 3 was tummy tuck -> no vibes, but no front shaft either

Step 4 rebuilt front shaft -> vibes
Click to expand...

Yes that is correct, except no SYE since it's a Rubi.

Apparition said:
I had the same vibe on mine. Pulsating started at about 55 mph.

When I installed my rubicrawler the savvy crossmember hit the yoke. Instead of trimming the crossmember I added a spacer plate on top of the transmission mount, raising my tcase. Either 3/8 or 1/2, can’t recall and my Jeep isn’t here to check.

Pulsating was now completely gone. I had always thought it was a harmonic issue.

I’d try rotating the front pinion down to get the same effect. Maybe the key was effectively rotating both diffs down a bit or the slight change in powertrain angle.
Click to expand...

I'll give this a try. Maybe like what, 1-2 degrees?
 
  • Like
Reactions: RINC
I had vibes after rebuilding my front drive shaft. I took it out and had it rebalanced at a drive shaft shop. It reduced the vibes but not that much. Eventually I got disgusted and ordered a new drive shaft from Tom Woods. Vibes completely went away.
 
  • Like
Reactions: 06TJ35's
TurboTJ said:
I had vibes after rebuilding my front drive shaft. I took it out and had it rebalanced at a drive shaft shop. It reduced the vibes but not that much. Eventually I got disgusted and ordered a new drive shaft from Tom Woods. Vibes completely went away.
Click to expand...

And it could be as simple as this. I’m just wondering what changed between the OEM front control arms and the Savvy arms. Before swapping the arms out, there were no vibs. Suspension stayed the same.
 
  • Like
Reactions: RINC and freedom_in_4low
Jamison C said:
And it could be as simple as this. I’m just wondering what changed between the OEM front control arms and the Savvy arms. Before swapping the arms out, there were no vibs. Suspension stayed the same.
Click to expand...

I have Tom woods driveshafts front and rear with and without the pulsating.
 
Jamison C said:
And it could be as simple as this. I’m just wondering what changed between the OEM front control arms and the Savvy arms. Before swapping the arms out, there were no vibs. Suspension stayed the same.
Click to expand...

How did you set the arm length? Did you match the OE arms or did you adjust them to set caster/pinion?
 
Jamison C said:
And it could be as simple as this. I’m just wondering what changed between the OEM front control arms and the Savvy arms. Before swapping the arms out, there were no vibs. Suspension stayed the same.
Click to expand...

Be careful with this assumption…you’ve changed it since you last ran (on account of the tummy tuck). I really think you should spend some time playing with pinion angle.

Also, check the slip splines for rotational play. I had some vibs and found play there. A new driveshaft fixed that problem
 
  • Like
Reactions: freedom_in_4low and JMT
freedom_in_4low said:
How did you set the arm length? Did you match the OE arms or did you adjust them to set caster/pinion?
Click to expand...

Good point. I did set them for the proper pinion angle and not what the OE arms were originally at.

Mike_H said:
Be careful with this assumption…you’ve changed it since you last ran (on account of the tummy tuck). I really think you should spend some time playing with pinion angle.

Also, check the slip splines for rotational play. I had some vibs and found play there. A new driveshaft fixed that problem
Click to expand...

Yep you’re right. I didn’t even consider the splines. I’m guessing if the splines are bad that means new DS time?

What do you think is excessive in terms of angles? 3° or more +/-? Or just kind of like gears do you set a wide range and work your way tighter?
 
@Jamison C

Arms could be different lengths which changed the driveline spline engagement. The angles don’t matter near as much since the front driveshaft is so long compared to a TJ rear. You’re probably running a stock front shaft.

I had the same problem. Tried every reasonable pinion angle and it didn’t change at all. I rebuilt the front driveshaft and it didn’t change at all. I bought a new Tom Wood’s shaft and it was better. My vibes went from coming on at 65mph to coming on at 76mph. Sometimes the rotational velocity is just so much and balance really matters. I concluded the Wood’s shaft is balanced better than my stock shaft. Spline engagement could be involved too.
 
  • Like
Reactions: RINC
Jamison C said:
Good point. I did set them for the proper pinion angle and not what the OE arms were originally at.



Yep you’re right. I didn’t even consider the splines. I’m guessing if the splines are bad that means new DS time?

What do you think is excessive in terms of angles? 3° or more +/-? Or just kind of like gears do you set a wide range and work your way tighter?
Click to expand...

The splines should be really tight, rotationally. Like no movement…it should only slide in and out.

Yeah, if the splines are bad, it’s time for a new D/S. To be honest though, I doubt that is it. Blaine has told me that he’s either never replaced one for that reason or it’s very rare. I live in the land of salt, silt, and mud, so things wear out differently here than they do in the desert SW.
 
  • Like
Reactions: John Cooper
Top Bottom
Back