Tote

As the title suggests I am interested in why when a front end upgrade is suggested people recommend that you change from the early stlye bronze bushed upper control arms to the later rubber ones. As far as I am aware there is no difference in the length of the arm and hence no effect on geometry.
By going to the rubber mounts you are introducing compliance in the pivots that is not there with a bronze bush.
I can see why ford changed them, softer ride, less noise and no greasing necessary but these are not traits that are necessarily desirable in a performance application.
Or is it a simple case of newer must be better?

Regards,
Tote

xbgs351

You are correct. "softer ride, less noise and no greasing necessary". They are inferior for handling.

RPO-083

Personally, I fit the upper XC onwards arms for two reasons.

1. The steel bushes and "pins" are getting expensive and hard to find.
2. They ride a bit better (not as bone jarring with stiff springs).
3. They have a stiffener plate that isn't on the earlier ones.

Now, I don't use rubber bushes, as I feel these are TOO compliant. I use aftermarket urephane (spelling!!) bushes.

Also, if I happen to fit the lot (upper, lower and stub), I NEVER fit the later calipers. I know lots of people are in love with alloy calipers, but they are rubbish. The caliper of choice is a KH.

Oh yeah, last point, the later caster rods (strut rods, radius rods, etc, etc) don't fit. You need to use your originals as XD onwards are shorter in the nose.

ZC-Cruiser

I would suggest that for all practical purposes (i.e. all except full race applications) the "inferiority" would be unnoticable.

On the other hand, if you are into creative wheel alignment, the ability to adjust the top arms so that the inner end sits further back could give the bronze bush arms an advantage - once again, a fairly "racey" thing that 99% of us would never bother with.

I haven't checked, but I would imagine that getting new bushes pressed into late model arms to be cheaper than doing up the early ones...

__________________
"It's good to honk in a Henry"
FTW Racing - Fabricated To Win

1970 ZC Fairlane - Pictures HERE
1971 XY Falcon Ute - Pictures HERE

brenx

I don't like the squeaks the pre XC ones offer. It sounds like you don't maintain your car. I've greased mine to no end. First chance I get they are gone. I had XF ones in my old XB chassis. Not an issue, picked them up from the wreckers. Looked like they hadn't been in there long either. Pitty I forgot about them when I sent the chassis off to "Sims Metal". I'd only put roughly 30,000k's on them.

__________________
XB Fairmont (street car) 11.07@123.02mph.

ZC-Cruiser

What is "rubbish" enough about the alloy calipers to eschew the massive saving in unsprung weight??

__________________
"It's good to honk in a Henry"
FTW Racing - Fabricated To Win

1970 ZC Fairlane - Pictures HERE
1971 XY Falcon Ute - Pictures HERE

ZC-Cruiser

I agree - 15 years of pumping grease into the old top arms is now over - thank goodness...

__________________
"It's good to honk in a Henry"
FTW Racing - Fabricated To Win

1970 ZC Fairlane - Pictures HERE
1971 XY Falcon Ute - Pictures HERE

RPO-083

What does "eschew" mean? No offence, but I can't figure it out.

As for alloy calipers, I personally don't like the way that they perform. The pedal isn't as firm, and the smaller pad size means that brake fade is an all too frequent problem. They may be fine for Mr and Mrs average, but if you drive the car 'enthusiastically', then they just don't cut it.

On the subject of unsprung weight, do you really think that the weight difference between cast iron and alloy calipers makes that much difference when expressed as a percentage difference of the sprung weight?, bearing in mind that the sprung weight over the front wheels incorporates most of the weight of the engine, which in most 70's vehicles is a cleveland V8???

I take unsprung/sprung weights into account with my cars, which is why most of my street cars and daily drivers have never had 9" diffs fitted. They make a huge difference to the sprung/unsprung ratio and affect the car's handling more than what a few kilos on the front will.

ZC-Cruiser

eschew
v : avoid and stay away from deliberately; stay clear of

The actual amount of unsprung weight is MUCH more important than the ratio of sprung to unsprung weight.
The amount of unsprung weight affects directly the ability of the suspension system to keep the tyre in contact with the road, the amount of work that must be done by the spring damper in doing so and the wear and tear on all associated suspension components - regardless of the overall mass of the vehicle.

Yep, 9" diffs are WAY over-engineered for the vast majority of applications and so their use should be carefully considered...

The effect of a few of kilos of unsprung weight in the front suspension should not be underestimated - we don't use steel wheels if we are serious about handling performance do we??

__________________
"It's good to honk in a Henry"
FTW Racing - Fabricated To Win

1970 ZC Fairlane - Pictures HERE
1971 XY Falcon Ute - Pictures HERE

RPO-083

Thanks, I'd never heard it before.....

As for the rest of the topic, I will let this one go. I've just offered an apology and backed down on another thread, one a day is enough...!