Cambered rear axles

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   I seem to recall an article describing the method used to establish a certain amount of camber in the rear axle of trans am cars, by cutting the axle tubes from the diff housing and angling them slightly upwards and rewelding them. That said, I haven't seen any reference to it here....

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Raccoonman Members Profile Send Private Message Find Members Posts Add to Buddy List AMC Nut Joined: Dec/11/2016 Location: North Charlesto Status: Offline Points: 447	Post Options Post Reply Quote Raccoonman Report Post Thanks(0) Quote Reply Topic: Cambered rear axles Posted: Jan/04/2017 at 4:39pm
	I seem to recall an article describing the method used to establish a certain amount of camber in the rear axle of trans am cars, by cutting the axle tubes from the diff housing and angling them slightly upwards and rewelding them. That said, I haven't seen any reference to it here....

scott Members Profile Send Private Message Find Members Posts Add to Buddy List AMC Addicted Joined: Jul/10/2007 Location: Wildwood Pa. Status: Online Points: 3502	Post Options Post Reply Quote scott Report Post Thanks(0) Quote Reply Posted: Jan/04/2017 at 4:50pm
	In Mark Donohue's book Unfair Advantage he describes modifying the rear axle in a Trans Am Javelin as you mention. He found that there was no advantage on the track, & that the rear axle made lots of bad noises. I believe he referred to that axle as "gronked".

304-dude Members Profile Send Private Message Find Members Posts Add to Buddy List AMC Addicted Joined: Sep/29/2008 Location: Central Illinoi Status: Offline Points: 9082	Post Options Post Reply Quote 304-dude Report Post Thanks(0) Quote Reply Posted: Jan/04/2017 at 4:51pm
	Not sure if any stuck with doing the gronked rear end. Back in the late 60s and mid 70s tires were basic compared to today's tech. You probably will do better obtaining a full floater axle for long term use. A good rear suspension setup with a proper wheel and tire set makes more of an impact. It is when your cornering performance needs just a wee more to get over the brick wall.
	71 Javelin SST body 390 69 crank, 70 block & heads NASCAR SB2 rods & pistons 78 Jeep TH400 w/ 2.76 Low 50/50 Ford-AMC Suspension 79 F150 rear & 8.8 axles Ford Racing 3.25 gears & 9" /w Detroit locker

Raccoonman Members Profile Send Private Message Find Members Posts Add to Buddy List AMC Nut Joined: Dec/11/2016 Location: North Charlesto Status: Offline Points: 447	Post Options Post Reply Quote Raccoonman Report Post Thanks(0) Quote Reply Posted: Jan/04/2017 at 5:34pm
	I do remember "gronked" now, I probably read about it in high school. I personally have no reason to try it, just wondered if it was still a "thing".

Red Devil Members Profile Send Private Message Find Members Posts Add to Buddy List AMC Addicted Joined: Jul/10/2007 Location: Canada Status: Offline Points: 1743	Post Options Post Reply Quote Red Devil Report Post Thanks(0) Quote Reply Posted: Jan/04/2017 at 5:51pm
	Cambered snouts are common for circle track axles. The outer splines of the full-floating axle shafts are typically crowned to allow it to accommodate the camber in the snout and not cause excessive wear of the drive plate ... but not something you'd want to try with a stock-type flanged axle. e.g. Coleman offers various cambered snouts: http://www.colemanracing.com/Search.aspx?k=cambered Here's a couple pictures from the '71TA Javelin AMC20 that was modified to be a full-floater. Hope this helps,RD.

tyrodtom Members Profile Send Private Message Find Members Posts Add to Buddy List AMC Addicted Joined: Sep/14/2007 Location: Virginia Status: Offline Points: 6214	Post Options Post Reply Quote tyrodtom Report Post Thanks(0) Quote Reply Posted: Jan/04/2017 at 7:35pm
	That is something circle track racers did, until the inspectors started checking for it, and would DQ you if you were detected with any camber. I don't know what the limit is with the crowned splines. They were doing it mostly to counter for the camber being forced into the rear end by the high downforce of banked turns. On circle track cars that turn in only one direction, left, you have the right wheel leaning in at the top, and the left leaning out. It's allowed in the class I race in. You can't be competitive in the turns without it. You have to find the happy balance where it helps you just enough in the turns, but doesn't slow you down on the too much on the straights. Because you do have to countersteer for it on the straights. We have a heavy metal table that we use to straighten rear ends, 1/4 inch steel top, must weigh 500 lbs. We chain the rearend down to the table with heavy truck load binders, put a bottle jack under the axle tube where we wanted to straighten, or bend it, and apply heat . I think cambering a rear end on a street car, especially if you don't have the crowned axle splines, to be something to stay away from.
	66 American SW, 66 American 2dr, 82 J10, 70 Hornet, Pound, Va.

amc67rogue Members Profile Send Private Message Find Members Posts Add to Buddy List AMC Addicted Joined: Nov/05/2008 Location: Phx. AZ. Status: Offline Points: 1578	Post Options Post Reply Quote amc67rogue Report Post Thanks(0) Quote Reply Posted: Jan/04/2017 at 9:36pm
	Food for thought , would crowned splines be barrel shaped.
	Keith Coggins 67Rogue X code

Raccoonman Members Profile Send Private Message Find Members Posts Add to Buddy List AMC Nut Joined: Dec/11/2016 Location: North Charlesto Status: Offline Points: 447	Post Options Post Reply Quote Raccoonman Report Post Thanks(0) Quote Reply Posted: Jan/04/2017 at 9:53pm
	I am reminded of the de dion Mercedes axles

tyrodtom Members Profile Send Private Message Find Members Posts Add to Buddy List AMC Addicted Joined: Sep/14/2007 Location: Virginia Status: Offline Points: 6214	Post Options Post Reply Quote tyrodtom Report Post Thanks(0) Quote Reply Posted: Jan/05/2017 at 7:49am
	Yes, crowned axle splines are kind of barrel shaped. So you do have less total spline contact area, but all the ones i've seen were only on premium axles, better much more durable steel. I just don't see any positive benefit for a street driven car. It will cause uneven tire wear when driven on mostly straight roads. On a side note, if you check your stock rear ends alignment, you might be surprised. It's not uncommon to run into one that isn't perfectly straight. They're easier to bend than you'd think, or they were never right from the factory.
	66 American SW, 66 American 2dr, 82 J10, 70 Hornet, Pound, Va.