Castor Angles for an 80

[Discyota]

Since my truck is an 80 when it comes to steering and axles, I figure this is a good question to post here rather than a rover board. My truck was set up with 5* pos castor after the axle swap. My old rover axle was at about 4* castor after correction arms with the same lift. I had no vibes. Since the 80 axle is different when comparing castor to pinion angle than the rover is, im thinking of killing some castor in favor of a happy driveline.

I know stock for an 80 is 3*, and the old rover axle was about that in stock form too. My truck with the rover axle was at abour -4* before my castor correction arms. It drove bad, had some wander, and was floppy, i didnt like it, but i put up with it. Im considering making a plate on the back side of my axle to rotate it. I want to bring the pinion angle up 6*. This will get rid of my driveline vibes, but it will put my castor to about -1*

I searched alot before posting, but would still appreciate some input. How does an 80 steer/ride with 0 to -3* of castor. I know every truck is different, but for those of you within or even over (more neg) than that range, how does your truck act? The rover axle disliked negative castor, how does the 80 respond to it. Thanks for help, im almost trail ready

 

[alkaline747trio]

You could over correct and keep the driveline happy (Slee Arms for 6" springs on 4" springs idea). I think if you match the t-case flange angle with a non CV shaft you wont have vibes, which is what Slee arms do on 4" springs.

 

[landtank]

what are you running for a drive shaft right now? And what are you drive angles at the u-joints. Knowing the caster number is only half the equation.

 

[Discyota]

Right now ive got a CV shaft, and it vibes pretty bad. My pinion is only upwards at 10*, but my t-case output is up at 5* Which gives me a total of 15* That accompanied with my almost 6" lift leaves me with a pinion not pointed at my t-case. I know that bringing it up about 5-6* would solve my driveline issues. I cant run a standard shaft, because on a Discovery the front shaft is just too short.

 

[alkaline747trio]

sounds like you're gonna lose caster to get your pinion where it needs to be, a cut and turn may be in order.

 

[Discyota]

sounds like you're gonna lose caster to get your pinion where it needs to be, a cut and turn may be in order.

Exactly, I know that. Id rather have less than perfect steering than s***ty vibes. Hense the origional post, I know thats the situation, i was just wondering what people think of their trucks handling when between 0 to -3* castor.

 

[alkaline747trio]

Handling would probably suck, I vote leave your caster where it is and get a cut and turn done, in the end you will be much happier.

 

[landtank]

Exactly, I know that. Id rather have less than perfect steering than s***ty vibes. Hense the origional post, I know thats the situation, i was just wondering what people think of their trucks handling when between 0 to -3* castor.

The handling will be absolutely terrible.

When setting up my drive shaft I worked with the angles at the joints so what you're describing isn't making any sense to me, sorry.


Since you have a DC shaft in there you would need to add more caster to zero that front joint, correct.

Have you tried a stock shaft?

 

[Discyota]

Since you have a DC shaft in there you would need to add more caster to zero that front joint, correct.

Have you tried a stock shaft?

Stock shaft on a disco is a DC/CV shaft.

More positive castor? as in rotating the axle clockwise, that would further flatten out my pinion angle. I need to raise the pinion angle, which would worsen my castor, as in rotating it counter clockwise and adding more neg castor.

After looking at a image posted by christo in and thread, my castor if adjusted to fix the pinion angle, would be about -1* or right between where a truck with 2 and 4" slee springs and stock arms is in terms of castor.

 

[landtank]

Here is what I'm having trouble with, the 15* and 5* angles. They don't really tell me what the angles at the U-joints are. On our trucks the stock shaft is NOT a DC shaft. So when we lift our trucks the angles change to where we need a DC shaft. That happens at around 4" of lift.

In your case you might be in a broken back situation which means a DC shaft is the last thing you want in there.

If the pinion on the axle seems to point to behind the transfer case then a simple 2 joint drive shaft might be what you need.

A few pics might go a long way with helping us to see what you're doing.

 

[Waggoner5]

The minimum castor that I like on a lifted 80 is 3* to get the truck to drive right down the road and keep vibs at a minimum. At this setting a CV style shaft isn't always needed but I use them anyway. It sounds like the only way you are going to get rid of the vibs is to do the C&T as Alkaline said earlier. Since you obviously have the skills to do the axle conversion, I would point the pinion at the tcase, and cut and turn the knuckle to give at least 3* castor. This should fix all of your issues.

 

[Discyota]

Thanks guys. I cant do a C&T till december when I get home again and have access to my shop. The pinion is pointed behind the T-case, but my problem is i only have ~23" of driveshaft to work with up front. which is worse than the 80 so a standard shaft would be out of the question. Im out of town right now and dont have the measurements infront of me, but the angle between the pinion and driveshaft at operation is more than a 3* difference. I used to drive the disco around with no castor correction arms, and it was liveable. I think for now im going to make "reverse castor plates" and raise the pinion to leave me with about 0* castor. Sure it will drive less than par for a while, but I wont tear everything apart from vibes. Ill have it C&T'd around december.