Winter Upgrades 72 Challenger

witorque · Post by **witorque** » Mon Jan 26, 15 6:20 pm

The Challenger is in bits

-Engine is out upping the compression from 9.6 to 10.5 : 1
Achieved by changing the Diamond pistons dish from 10 cc to 2.3 cc.

-Bee hive valve springs being set up on the Magnum style heads

-Increasing brake discs from 10 3/4 to 11 3/4", local precision engineers making bells and adapters to suit. Already has Wilwood calipers and hubs.

-Torsion bars - increasing from .908" to .920"

-Green Bearings going into the 8 3/4 - trying to solve LHR brakes dragging when hot....
- Tempted by Strange axle shafts, any good for a small block car, or overkill?
- Change bent Strut Rods
- K frame getting a scrub , blast and fresh paint
-Jake's cleaning the engine bay
- New black door panels at last

Pete · Post by **Pete** » Mon Jan 26, 15 6:46 pm

I would not bother with Strange shafts if there is no damage to the stock ones (i.e. broaching starting to spiral).

I know where there are a good stock set anyway, they did not twist on an 11 second Big Block.

Hammer the strut rods straight and re-use unless you are going for Hiem type......

Adrian Worman · Post by **Adrian Worman** » Mon Jan 26, 15 6:47 pm

Good work Chris

I wouldn't bother with aftermarket shafts unless yours are twisted or bent. If it's the orig axle I'd doubt it.

How did you bend the strut rods?

MilesnMiles · Post by **MilesnMiles** » Mon Jan 26, 15 6:49 pm

Some subtle mods here, be interested in how the torsion bar changes the car as that's on my list too.
What's the story with the dragging brake? I have the same issue and I have no green bearings. Wondering what the relationship is?

witorque · Post by **witorque** » Tue Jan 27, 15 10:03 am

Dragging LH rear brake has been an issue for some time
The LH shoes are maybe 80 % worn out, the RH maybe 10%
-Wheel cylinder is free. Any hydraulic anomalies should compensate out.
-LH brake cable is new, old was tight. The inner was 1/2" shorter on the new cable and I had to back off the adjustment to fit. Any anomalies should compensate out.
-All the springs, shoes etc seem correctly assembled.
Drum brakes and shoes self servo, so slight drag can self perpetuate.
- Wheel bearings have slight play, which gets looser when hot after a long drive
- I suspect the problem got worse when I rebuilt the axle with a new Suregrip. There may be some bizarre internal problem that is causing the LH shaft to get thrust out causing more play when driven, or bearing worn into the axle shaft, or outer bearing track loose in the axle casing.
I need to strip out the shaft and examine.
Green bearings don't rely on one shaft pushing against the other to take out bearing play, so they could be a solution if there is no other obvious cause.

MrNorm · Post by **MrNorm** » Tue Jan 27, 15 12:11 pm

I'm making an assumption (which could be wrong!) from the fact you are upgrading torsion bars and discs, plus your avatar, that you are interested in going round corners as well as the drags? If so...personally I'd stay away from the Green bearings and also consider larger torsion bars than 0.920. Everyone has their own opinion on the Green bearings, but anyway it is a fact that they are not taper rollers so their ability to take sideways forces is way inferior to the originals. Will that cause a problem? Probably not. Has it for some? Yes.

witorque · Post by **witorque** » Tue Jan 27, 15 12:44 pm

I heard early versions of green bearings were troublesome, and current ones are better.
A lot of modern cars no longer use taper roller bearings in hubs

MilesnMiles · Post by **MilesnMiles** » Tue Jan 27, 15 2:12 pm

Small or big block car? I'm going for 1" bars for my 340 B body to keep it in line better.

witorque · Post by **witorque** » Tue Jan 27, 15 3:55 pm

Small block 340
It bump steers a bit, weaves under hard braking and handling is a bit lurchy
with the old bars

Mossy68 · Post by **Mossy68** » Tue Jan 27, 15 4:17 pm

witorque wrote:I heard early versions of green bearings were troublesome, and current ones are better.
A lot of modern cars no longer use taper roller bearings in hubs

Without starting the green bearing debate.
A fella I know has a 67 Coronet wagon in regular use. Fitted green bearings and they lasted a couple of years. He went back to stock on Saturday

Dave-R · Post by **Dave-R** » Tue Jan 27, 15 4:18 pm

witorque wrote:Small block 340
It bump steers a bit, weaves under hard braking and handling is a bit lurchy
with the old bars

That sounds more like alignment and weak steering/suspension bushings to me.

Dave-R · Post by **Dave-R** » Tue Jan 27, 15 4:19 pm

Nothing wrong with the original axle bearings. As long as they are not worn, shafts straight, and adjusted for correct end play.

witorque · Post by **witorque** » Tue Jan 27, 15 4:25 pm

Adrian Worman wrote:Good work Chris

I wouldn't bother with aftermarket shafts unless yours are twisted or bent. If it's the orig axle I'd doubt it.

How did you bend the strut rods?

I think the strut rods got bent in the States, the underside of the car looked like it got beached in a boulder field at some time. Before the respray, I had to panel beat out many small indentations from the floor pan, the exhausts had big abrasions, there was even a dent in the prop /drive shaft.
Maybe someone went on an off road rallying. There was a fatigue crack on the inner fender, which JC sorted

Pete · Post by **Pete** » Tue Jan 27, 15 4:57 pm

It sounds to me like the LCA bushes may need some attention - unless you tell me you have done them already...........

witorque · Post by **witorque** » Tue Jan 27, 15 5:04 pm

The bushes tore apart when I withdrew the pins.
The control arms are going off for blasting, zinc electroplating and maybe black EPC.