Rear suspension, rubber pinion bushings or spherical

[b1lk1]

OK, after a sh#t ton of reading I managed to get a "budget" suspension in my car. Only thing left to change are the rear end pinion bushings. For a car like mine, that will see limited street use, it seems more logical to go with spherical since I went with the taboo urethane upper bushing. As long as I keep the urethane bushing greased, i feel it shouldn't bind any more than rubber. Now I know I will not be using urethane for the bushing in the differential, but it seems to me it makes more sense to just step up to the spherical. While I don't have quads in now, I will be putting them in.

If you managed to weed through all that, can anyone give me a good explanation why I should use rubber bushings that will, by design, bind, or use spherical, which by design do not.

Just to be clear, we're talking about the mickey mouse ear bushings in the upper rear control arms on the differential.

[Ponyryd]

Urethane have very little give, which causes the suspension to bind, it's not because of the bushing, it's the 4-link design, but the urethane makes it worse. Rubber does the same but has a lot of flex built into it so it allows more movement than urethane. Spherical is the best since it really can't bind unless it's rusted and seized up, which won't happen unless it sees tons of snow and salt.

[tulowd]

Spherical bushings like the Edelbrock / QA1 s still use the rubber in the ears of the axle like the OEMs.

According to MM, if you run a PHB, you have to use rubber on both ends of the uppers, otherwise the bind forces will be pushed thru only half as much rubber as intended.

If you stick with the 4 link stock architecture, the best bet is rubber in the axle housing, (Ford still makes the bushings) and Motorsport or '99 and up GT arms with the rubber in the other end. This way the upper arms will allow the axle to move in wider planes than spherical bearings can. Then use real lower control arms with ideally 2 sets of spherical bearings or at least the 3 pc urethane so the arms can articulate properly and be controlled in terms of length.

The upper arms fight with the lower arms when the axle articulates - they are angled inwards significantly whereas the lowers are pretty much straight in line with the wheelbase. Think of the stock rubber bushings actually adding spring stiffness when the rubber compresses.

Street driving is actually harder on the torque boxes and floor with urethane because turning corners and driveways etc is what makes the suspension articulate/bind in different planes than straight line acceleration/ squatting.

read this: http://www.maximummotorsports.com/tech_rear_susp_rlca.aspx

[b1lk1]

These are what I am talking about:

http://www.latemodelrestoration.com/item/UPR-2003-88/79-04-Mustang-Rear-Upper-Spherical-Axle-Bushings-88-7075-Billet

What I was curious of is if they would allow better articulation than rubber. I realize that my cheaper parts will never work like the good stuff, but I can't afford the good stuff, at least not for awhile (we're talking years). Otherwise, I have been heavily leaning towards new rubber, the ones currently installed are cracked/worn out and need to go.

http://www.latemodelrestoration.com/item/M4050B/Mustang-88-Rear-Axle-Installation-Kit

I should also add I already planned on welding in some reinforcement plating on the torque boxes.

[tulowd]

These are what I am talking about:

http://www.latemodelrestoration.com/item/UPR-2003-88/79-04-Mustang-Rear-Upper-Spherical-Axle-Bushings-88-7075-Billet

What I was curious of is if they would allow better articulation than rubber. I realize that my cheaper parts will never work like the good stuff, but I can't afford the good stuff, at least not for awhile (we're talking years). Otherwise, I have been heavily leaning towards new rubber, the ones currently installed are cracked/worn out and need to go.

http://www.latemodelrestoration.com/item/M4050B/Mustang-88-Rear-Axle-Installation-Kit

I should also add I already planned on welding in some reinforcement plating on the torque boxes.

The difference between rubber (which also allows the effective length of the upper arms to shrink and grow as needed) and spherical bearings is the bind that will still be induced. That bind is what tears up the floor.

Don't waste your dough on the fancy looking crap, buy decent shocks and make sure the suspension can articulate properly. Tires in contact with the ground is what gives you traction, handling and a nicer ride all at once. Welding in supports for the upper and lower torque boxes is a great idea on any Fox.

[b1lk1]

OK, that is the answer I needed. I'll get the Ford rubber ones. Thanks!

[Frankie]

I've now had it both ways in my car - rubber in the ears and poly in the ears, still using the stock control arms.
I have seen no issues and the rear of the car definitely feels more solid with the poly everywhere.
Seems people really have issues when with tearing up the mounts when they swap everything to aftermarket (stiff) arms and bushings.
To my way of thinking, the stock arms still move and twist enough to compensate for the stiffer bushings - the main reason I didn't box then either.

[b1lk1]

My car feels really solid now as well, only issue I have is some wheel hop which I expect new quads to take away (currently none on). I have urethane pretty much everywhere you can now too. I am in the middle of tearing out the interior to fix 2 small holes, that's when I'll weld in the reinforcements for the torque boxes.

[ZR]

Reason it feels more solid, suspension is bound up. With full poly hit in the back, just a matter of time before it does damage to the upper mounts. Damage ranges from bent to torn completely off the floor pan.

[ZR]

Stock style FMS upper arms combined with a quality lower arm = no wheel hop + no quad shocks required.

[Ponyryd]

^Agreed, both posts are right on.

[b1lk1]

Don't argue, just working with what I have now. Member selling upper torque box kit for $25, the kit for the rubber differential bushings is about $60 to my door and that is about all the budget I have for the suspension for now. Another member is donating a set of quads to me when he's got the time, plus one of my original quads still works. I did leave the old rubber bushings in the pinion ears. I didn't mean to imply my car was overly stiff, if anything it articulates better than ever. I have WAY more traction, that is what I feel the hop is from. Before there was so much slop in the rear suspension it just never hooked.

I can't build an all out racing car. Even using budget parts I spent $800 or so. At least I replaced a worn out dangerous suspension. Next up is interior as mine is useless. All I can salvage is the plastic and headliner.