offset upper control arm bushings for radials

I read this in a previous thread and have never heard about offset bushings,so I have questions.It was said that Moog part #K-7103 bushings were used to increase positive caster in order to run radial tires.Why is positive caster required?My car is a '69 Plymouth B Body,the car in the previous thread was a '71 B Body.I'm assuming that since they used the same UCA that the same offset bushing would be used.Is this correct?I will be rebuilding my front suspension very soon and will be running radials.This is a rotissourie restoration and am curious if I install the offset bushings,can I still run bias ply tires,should I need, for factory correctness.One other question is,do I use the same alignment bolts?

The bushings help provide negative camber and/or positive caster. The alignment adjustment system on these cars trades off one for the other... you can adjust for max neg camber or max positive caster but not both at the same time. The bushings improve the "trade off" so you can get more of both.

The positive caster increases steering feel and improves the tendancy of the wheel to self center. The negative camber helps the outside tire - which takes most of the cornering load - "bite" on corners.

Increased positive caster shouldn't have adverse impact with bias ply tires. The negative camber will increase tire wear on the inside of the front tires if you run lots of miles without heavy cornering. This effect is a bit worse with bias ply tires vs radials.

These cars were designed with lots of understeer built in. In other words the front will plow in a heavy corner. This was considered safe and forgiving.

The alignment mods will increase bite on the front and reduce understeer. Handling will improve and it may be less forgiving. If you make the changes to bushings and alignment settings, suggest you find a safe place to really push it on a corner to get the feel for it.

If you do change the bushings and run bias ply tires, you can back off a little on the negative camber and see how you like it. -.25 degrees might be a safe place to start.

Just dont install them as per the instructions.Mopars they get installed backwards.Rocky

The Moog bushings in question were not designed for radials or anything other than to "fix" a sagging front end that prevented you from getting correct camber.

What people use them for is another thing.

First time I ever heard the radial claim you mentioned, I've never run the Moog bushings and I have run radials for 30+ years on my old Mopars with no issues.

The design of a radial is more tolerant of a wider range of settings before it shows abnormal wear when compared to a bias ply. So, you can get more agressive with the alignment without the tires wearing out unevenly.

Remember the mid 70s Pontiacs with the "Radial Tuned Suspension"? They used no different hard parts than the proceeding years, but since they came from the factory with radials, they changed the alignment specs.

You can get a Mopar frt to sit as high or low as you want with the Tbars.They were designed for bias tires and after 40 years the specs dont cut it with radials.Most will have neg caster and positive camber.Not great with radials.I do my own alingments and have been doing they for 30 years.Ive had very few Mopars that I could get the caster to positive without the bushings or asjustable upper arms.Rocky

You only install the front uca bushing backwards.