Took the vert to the alignment shop today because I suspected a bad upper control arm bushing. The tech told me I should purchase a set of offset shafts and he would install them. Do I really need offset shafts? I want to keep the car as close to stock as I can. He said that to make the car ride better he would have to add a lot of caster and the offset shafts would allow him to do that. I'm a little suspicious.

 

Just how much caster does he want to add? My chassis shop has never had any troubles achieving great handling on any of the early '70s A-bodies I've brought them. Unless you have collision damage, you shouldn't need offset shafts. Ask your guy for more details.

 

I had to put an offset upper unit in my son's 71 Chebelle to get it to take a proper alignment, might have been some frame damage at some time. They are avalable thru Moog.

 

I say let him install them (use Moog parts).
The offset shafts will allow more caster for better handling, with fewer shims. The additional caster will not affect tire wear.
They will look much like stock as is. When covered with the splash shields, they will not be visible from the engine bay anyway.
I will go this route when i do Lady's suspension this fall / winter.

Also have him replace the upper A-arm bolts, too while it is apart.

It is bad when these break...
https://classicoldsmobile.com/forums...html#post74952

I got my bolts here, about a half mile from me:
http://www.firewheelclassics.com/sto...pID=&SKU=SUB21
They carry the correct style alignment shims, too. Most shops will use ones that are too large.
Other suppliers will carry these, but they are special and will need to be ordered regardless.

 

You will often find frame cracking or sag on these A-body frames. If he installs offset shafts they will help correct for sag or bow on the front crossmember.

If there are currently a lot of shims on the upper control arms to align the car, I'd say the offset shafts are a good move.

 

Thats exactly what the front end guy told me. He also said the crossmember starts to sag. I checked for number of shims and there's around 1/4 to 3/8ths of an inch worth. The ol girl is all original and I dont see any need to run offset shafts. The ride height is perfect so I think the frame sag is'nt an issue. I'm leaning toward just replacing the upper comtrol arm bushings and having her realigned. Thanks to everyone for your advice.

 

I just had a Sun alignment done and my guy said those offset shafts are a last resort when the cradle is so sagged you can't zero it in to the factory specs, never uses them. The bushings and ball joints would have to be replaced to even get an idea if you would even need them in any case. He also told me that worn steering boxes are the biggest problems on old A bodies and the extra degree or two of positive caster won't fix that. Every one I've had with the wandering steering always goes back to too much play in the box and it's like night and day when you replace it with an upgraded variable or quick ratio gear. My Vista handles like an overfed and bloated Porsche now with an AGR 16-1 x 13-1 variable ratio box with sport valving. The wheel stays firmly in the center with no play and you can actually feel the road, it's so nice.
I would just go with the stock set-up too, if it can't be aligned you go with the offset shafts.

 

Where did you get said box? Any other mods? Upgraded steering is on my to-do list in a couple years...

 

I ordered a pair of upper control arms some time back, and I just noticed this weekend that they are the offset kind. Does anyone know which way the resess surface of the offset go? Does it go inward toward the frame or outward away from it?

If it helps, I found this photo of the offset shaft online. Which way does the recess surface go?

 

the offset upper shafts won't help you add caster. It only helps if your frame is sagging.

Additional caster is created by adding more shims to the rear bolt position on the cross shafts. When you add shims to the front to add Camber, it lessens ammount of caster requiring MORE caster shims to make up for the extra Camber shims.

Since the offshet shafts add the same ammount to the front & back, you still wind up with the same big stack of shims in the rear position, without gaining any extra caster.

The most you can get with stock control arms is about +2 degrees with or without offset shafts.

This is why all the "improved geometry" tubular upper control arms are available. They are made with extra caster built in so you can have +5 degrees.

So basically, if you have a giant stack of shims in the front AND rear positions of your crossshafts already, then you are probably a good candidate for offset shafts.

If you don't have a big stack in the front position, then it will not help you any.

 

I just got a pair of these yesterday (Moog K5250), if you've got the same ones they've got "Wheel Side" stamped on the recessed part of the shaft. Putting that side outward toward the wheel will give more positive camber - the centerline of the threaded ends will be more outboard. If you want more negative camber you can install it the other way, but I think positive camber is usually the goal.

 

I have manual steering and run 0 caster. A few deg. of + caster is touted as good, but will be very hard to steer with manual steering. My '66 handles well at 116 mph, accelerating and braking, near the end of the quarter mile. Factory spec range for caster, 1972 A body, is -1.25 deg +/- 0.5 deg.

 

https://www.amkproducts.com/GM_Fastener_Kits.asp
...also has them. Kit part # G-4627 $14 - 4 correct bolts w/ lock nuts & comes w/ ~10 various shims.

AMK has a $30 min order though....so stock up on other fasteners while you're at it !

 

This opens up a whole new can of worms for me. Just how much can a front cross-member "sag" after 39 years of service? Could this explain why my fan is about 1/2" too low (and as a result someone cut out the fan shroud so the fan would clear it)? All this time I have been exploring motor mount issues.

Chumley

 

I put a set of those in my 65 when I rebuilt the front end, they look IMHO just like the stock ones and the front end shop got a real good alignment.

 

Chumley - just had the same problem with a '65 442 - was the motor mounts turning squishy!!
Replacement was instant fix!!