Differential UCA bushing

Pentalab

forum member
Joined
Mar 5, 2013
Posts
5,211
Reaction score
1,093
How many of you folks have replaced the oem ford uca bushing, that's at the differential end ?

I have a feeling that mine is trashed... and if that's the case, replacing it with the steeda uca differential spherical. My uca is the adjustable bmr..with poly at front end...+ mating bmr uca mount. BMR does makes a poly for differential end. But poly to poly is bad news. Poly at differential end + spherical at forward end would work, but I think the nvh would increase some what. Spherical to spherical would be the ultimate.... but I fear nvh would be unacceptable.

I think that with my current oem rubber bushing at differential + poly at forward end, that the poly is causing the oem rear rubber bushing to wear even faster, since the rubber is the only thing that can articulate. With the oem setup, there is rubber at both ends...and both ends can articulate.

I will find out this week when car is on the lift, if it is semi trashed. I don't need another repeat down the road with another oem rubber bushing.

The steeda differential spherical looks beefy to me.... do they last?
 
Last edited:

Voltwings

Junior Member
Joined
Aug 25, 2014
Posts
30
Reaction score
0
I installed the Steeda Poly bushing in the differential of my wife's car. The steeda bushing(s) is actually 4 separate pieces if i remember, an inner and outer section that press in from each side.

The outer section obviously presses into the pumpkin, and the inner section is then free to "articulate" within the outer section if that makes sense. It seemed to make enough sense to me, and because of NVH i wasnt quite prepared to make the jump to spherical like you mentioned. There was an increase in NVH, but we also have a barton 2 post bracket and a steeda transmission bushing insert, so our driveline is relatively solid anyways.
 

Pentalab

forum member
Joined
Mar 5, 2013
Posts
5,211
Reaction score
1,093
I installed the Steeda Poly bushing in the differential of my wife's car. The steeda bushing(s) is actually 4 separate pieces if i remember, an inner and outer section that press in from each side.

The outer section obviously presses into the pumpkin, and the inner section is then free to "articulate" within the outer section if that makes sense. It seemed to make enough sense to me, and because of NVH I wasn't quite prepared to make the jump to spherical like you mentioned. There was an increase in NVH, but we also have a barton 2 post bracket and a steeda transmission bushing insert, so our driveline is relatively solid anyways.

I looked at the steeda poly bushing..and it appears to be virtually identical to the BMR poly version, same price, and both are 4 x section types. The BMR version uses multiple durometer poly, so it articulates a bit.

I think either poly version...or the steeda spherical version would be better than the oem version. I just saw a pix of a friends oem rubber bushing..and it was beyond trashed. I highly suspect that there is a lot of trashed oem rubber bushings out there, that folks don't realize. It would explain a lot of issues.
 

modernbeat

Jason McDaniel @ Vorshlag
Official Vendor
Joined
Jan 30, 2012
Posts
412
Reaction score
15
Location
Dallas, TX
We've seen a number of them in bad shape. We either replace them with a stock rubber bushing or a spherical bearing from Steeda. I don't like using poly in that location.
 

Scott

Senior Member
S197 Team Member
Joined
Nov 17, 2009
Posts
2,337
Reaction score
37
Location
King City, Ontario, Canada
I went with the BMR in my diff build. Was not aware of the Steeda spherical bushing.

b6ztQpX.jpg
 

Pentalab

forum member
Joined
Mar 5, 2013
Posts
5,211
Reaction score
1,093
We've seen a number of them in bad shape. We either replace them with a stock rubber bushing or a spherical bearing from Steeda. I don't like using poly in that location.

With a steeda spherical at the differential end.... and a poly at the other end, how much nvh can be expected ? I would have thought that any nvh from the spherical would not make its way past the poly... at the opposite end.

On a similar note, on bmr's install sheet, the method used to get the oem rubber bushing removed consisted of using a 1.5" hole saw, (long one).... followed by a 1.5" wire brush.
 

Voltwings

Junior Member
Joined
Aug 25, 2014
Posts
30
Reaction score
0
With a steeda spherical at the differential end.... and a poly at the other end, how much nvh can be expected ? I would have thought that any nvh from the spherical would not make its way past the poly... at the opposite end.

On a similar note, on bmr's install sheet, the method used to get the oem rubber bushing removed consisted of using a 1.5" hole saw, (long one).... followed by a 1.5" wire brush.

That's what i did. I went to home depot and built a PVC press like you'll see most people do, but our bushing was so mangled that it just pushed the center section out, the entire outer part of the bushing was still attached to the housing. I just happened to notice the hole saw fit and said "F- it," then cleaned it up with a wire wheel on the dremel. Worked like a charm.
 

Norm Peterson

corner barstool sitter
Joined
Feb 5, 2011
Posts
3,615
Reaction score
316
Location
RIP - You will be missed
All that stiffness that's good for reducing wheel hop on a hard launch gets in the way of suspension movement when you take a corner and the car rolls slightly. It's not good for suspension function/tuning and it beats up the poly more because it's not as good about returning to its original shape as the OE rubber.

In a little more detail, your car might roll 3° at 1g cornering. The axle will 'tilt' slightly because the extra load on the outside tires will compress them (the loss of load on the inside tire will let those tires gain a little height), but this effect is generally less than 1° per g, so the poly is still having to accommodate at least 2°/g. That's for roll as a direct effect.

Indirectly, roll will move the chassis end of the UCA laterally relative to the axle end. Only a little of this is due to the PHB's arc; it's mostly because the UCA lies above the PHB that any rotation about the PHB height will result in lateral movement of any part of the rear of the body that is at a different height (I'm intentionally simplifying things here a bit)

The first effect tries to twists the UCA and the second effect tries to bend it. But either OE rubber or aftermarket poly bushings accommodate nearly all of these distortions instead because they're not as rigid as the steel or aluminum bars themselves. Poly puts up more of a fight because it's much stiffer, and this is what gets in the way of suspension function in the corners (it acts a little like an invisible rear stabilizer bar).

Those effects scale down directly to however hard you actually take corners but don't go away completely. How you might notice them (or whether you notice at all) is a whole 'nother discussion.


Norm
 
Last edited:

slackinoff

Senior Member
S197 Team Member
Joined
Feb 14, 2016
Posts
843
Reaction score
9
Location
East Texas
Those effects scale down directly to however hard you actually take corners but don't go away completely. How you might notice them (or whether you notice at all) is a whole 'nother discussion.


Norm

Awesome explanation. I would be the one to not notice. But in the future, who knows. I plan on keeping the car forever, road racing might be there one day.

Thanks,
 

Pentalab

forum member
Joined
Mar 5, 2013
Posts
5,211
Reaction score
1,093
I have poly to poly.....what's so bad?

Poly to Poly won't twist, they bind. Just got a note back from BMR..and they did not recommend a poly to poly configuration, same reason...at least if you want to fly around corners..even at moderate loadings.

I suspect that even with poly at one end..(either end)... and oem rubber at the opposite end, the rubber end will get trashed even sooner. At least one end needs to be able to rotate a bit... if poly used on the opposite end. The spherical generates the nvh. To generate the least amount of nvh into the rear cabin, the quietest combo would be a spherical at differential end... and a poly at front end. With the poly at differential end... and a spherical at front end, the nvh from the front mounted spherical goes straight into the rear cabin, between the back seats.

Spherical to spherical would be the ultimate for handling, but the resulting nvh for dd use would drive me nuts...esp the wife.
 

Mustang dog

forum member
Joined
Apr 24, 2016
Posts
172
Reaction score
19
Im replacing the poly/ poly this coming week to a Poly/Spherical (diff end) after reading this thread.
It makes total sense. I couldn't care less about NVH, with my LTH and o/r H combined with the pleasant whine of my 3;90's. I doubt I'll notice.
 

tj@steeda

Member
Official Vendor
Joined
Oct 18, 2011
Posts
310
Reaction score
7
Happy to help anyone interested in the Steeda units ... happy to extend a forum discount good for 10% off!

Shoot me a note to [email protected].

Best Regards,

TJ
 

Latest posts

Support us!

Support Us - Become A Supporting Member Today!

Click Here For Details

Sponsor Links

Banner image
Back
Top