Front Dana 60 pinion/caster Angle
05-23-2024, 04:36 PM
#1
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Year: 1996
Model: Cherokee (XJ)
Engine: 4.0
Front Dana 60 pinion/caster Angle
What's up everyone, I'm sure this topic has been beaten half to death but I have a question regarding pinion angle on my one-ton swapped XJ.
1996 4.0, AW4, NP231, 4 door, 3 linked up front with 4 link rear coil springs all around and planning to have double cardan driveshafts front and back, 05+ SD axles and 40" tires.
I'm getting to the point now to where I'm ready to start fabing my links up for the front axle and need to know the procedure to find my pinion/caster angle. I know the two are different angles all together and I do know that its generally not possibly to have both exact without cutting and spinning the C's. Right now I'm running Artec's TJ front Dana 60 truss for coil spring applications with Metal Cloak 6" springs with plans to run 40" tires. I've read in a few places to try and find the caster angle via either the top or bottom C, or to find my pinion angle on a flat part of the axle....I've also seen that the ideal angle is like 7ish degrees but I dont know if they mean 7 pinion or 7 caster haha. Am I over thinking this? Thanks in advance and if anyone has any good starting link lengths (just the tube length) they'd like to share I'd love to hear what you guys got and how much stretch it put you at!
1996 4.0, AW4, NP231, 4 door, 3 linked up front with 4 link rear coil springs all around and planning to have double cardan driveshafts front and back, 05+ SD axles and 40" tires.
I'm getting to the point now to where I'm ready to start fabing my links up for the front axle and need to know the procedure to find my pinion/caster angle. I know the two are different angles all together and I do know that its generally not possibly to have both exact without cutting and spinning the C's. Right now I'm running Artec's TJ front Dana 60 truss for coil spring applications with Metal Cloak 6" springs with plans to run 40" tires. I've read in a few places to try and find the caster angle via either the top or bottom C, or to find my pinion angle on a flat part of the axle....I've also seen that the ideal angle is like 7ish degrees but I dont know if they mean 7 pinion or 7 caster haha. Am I over thinking this? Thanks in advance and if anyone has any good starting link lengths (just the tube length) they'd like to share I'd love to hear what you guys got and how much stretch it put you at!
05-24-2024, 06:47 AM
#2
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Year: 1999
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You're not overthinking it. Getting those two angles correct is very important to a successful swap. You should be putting some effort into getting them correct. Sounds like you already have a decent idea of how they're related.
With double cardan driveshafts, you want the u-joint at the pinion to have an operating angle of zero degrees under load at ride height. The best way you'll be able to achieve this is to bolt up your driveshaft and compare the angle of your pinion to your driveshaft. They should be zero degrees at ride height. In a perfect world you would favor the pinion pointing slightly high because in theory the pinion will rotate down under load to achieve a better pinion angle. When balancing pinion and castor, you'll likely end up having the pinion point lower than the driveshaft. That angle should be no more than 3 degrees, but optimally 0.5 - 0 degrees.
Now, enter castor angle. With your pinion set exactly where you need it, you have no control over your castor. You get what you get which is determined by the position of the C's. They can be cut/turned, but many people don't. I'm not familiar with the pinion/castor separation on those axles.
After you set your pinion angle, measure the castor angle. I've done this off the upper ball joint, which probably isn't perfect, but its easy and close enough. Note that this angle needs to be with respect to level ground with the vehicle sitting level at ride height. This angle should ideally be 5-7 degrees. Probably no more than 8 and no less than 4. Less castor will give sketchy road manners and poor return to center. More castor will strain the steering, but is generally okay if you have hydro-assist. I've read a bit of theory of larger tires requiring less castor because there is greater trailing distance, but I'd still say 4 degrees of castor is on the verge of unacceptable.
So, you have to balance the two angles. There is a pretty small margin of error here. You're talking a few degrees either way. Once you get your pinion set and you measure your castor, you'll have to decide if they are close enough that you can work with them, or if you need to cut and turn. You might end up with your pinion being 3 degrees out with 4 degrees of castor. That will probably be okay, but is certainly not great.
With double cardan driveshafts, you want the u-joint at the pinion to have an operating angle of zero degrees under load at ride height. The best way you'll be able to achieve this is to bolt up your driveshaft and compare the angle of your pinion to your driveshaft. They should be zero degrees at ride height. In a perfect world you would favor the pinion pointing slightly high because in theory the pinion will rotate down under load to achieve a better pinion angle. When balancing pinion and castor, you'll likely end up having the pinion point lower than the driveshaft. That angle should be no more than 3 degrees, but optimally 0.5 - 0 degrees.
Now, enter castor angle. With your pinion set exactly where you need it, you have no control over your castor. You get what you get which is determined by the position of the C's. They can be cut/turned, but many people don't. I'm not familiar with the pinion/castor separation on those axles.
After you set your pinion angle, measure the castor angle. I've done this off the upper ball joint, which probably isn't perfect, but its easy and close enough. Note that this angle needs to be with respect to level ground with the vehicle sitting level at ride height. This angle should ideally be 5-7 degrees. Probably no more than 8 and no less than 4. Less castor will give sketchy road manners and poor return to center. More castor will strain the steering, but is generally okay if you have hydro-assist. I've read a bit of theory of larger tires requiring less castor because there is greater trailing distance, but I'd still say 4 degrees of castor is on the verge of unacceptable.
So, you have to balance the two angles. There is a pretty small margin of error here. You're talking a few degrees either way. Once you get your pinion set and you measure your castor, you'll have to decide if they are close enough that you can work with them, or if you need to cut and turn. You might end up with your pinion being 3 degrees out with 4 degrees of castor. That will probably be okay, but is certainly not great.
Last edited by XJlimitedx99; 05-24-2024 at 06:56 AM.
05-24-2024, 07:53 AM
#3
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Year: 1996
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You're not overthinking it. Getting those two angles correct is very important to a successful swap. You should be putting some effort into getting them correct. Sounds like you already have a decent idea of how they're related.
With double cardan driveshafts, you want the u-joint at the pinion to have an operating angle of zero degrees under load at ride height. The best way you'll be able to achieve this is to bolt up your driveshaft and compare the angle of your pinion to your driveshaft. They should be zero degrees at ride height. In a perfect world you would favor the pinion pointing slightly high because in theory the pinion will rotate down under load to achieve a better pinion angle. When balancing pinion and castor, you'll likely end up having the pinion point lower than the driveshaft. That angle should be no more than 3 degrees, but optimally 0.5 - 0 degrees.
Now, enter castor angle. With your pinion set exactly where you need it, you have no control over your castor. You get what you get which is determined by the position of the C's. They can be cut/turned, but many people don't. I'm not familiar with the pinion/castor separation on those axles.
After you set your pinion angle, measure the castor angle. I've done this off the upper ball joint, which probably isn't perfect, but its easy and close enough. Note that this angle needs to be with respect to level ground with the vehicle sitting level at ride height. This angle should ideally be 5-7 degrees. Probably no more than 8 and no less than 4. Less castor will give sketchy road manners and poor return to center. More castor will strain the steering, but is generally okay if you have hydro-assist. I've read a bit of theory of larger tires requiring less castor because there is greater trailing distance, but I'd still say 4 degrees of castor is on the verge of unacceptable.
So, you have to balance the two angles. There is a pretty small margin of error here. You're talking a few degrees either way. Once you get your pinion set and you measure your castor, you'll have to decide if they are close enough that you can work with them, or if you need to cut and turn. You might end up with your pinion being 3 degrees out with 4 degrees of castor. That will probably be okay, but is certainly not great.
With double cardan driveshafts, you want the u-joint at the pinion to have an operating angle of zero degrees under load at ride height. The best way you'll be able to achieve this is to bolt up your driveshaft and compare the angle of your pinion to your driveshaft. They should be zero degrees at ride height. In a perfect world you would favor the pinion pointing slightly high because in theory the pinion will rotate down under load to achieve a better pinion angle. When balancing pinion and castor, you'll likely end up having the pinion point lower than the driveshaft. That angle should be no more than 3 degrees, but optimally 0.5 - 0 degrees.
Now, enter castor angle. With your pinion set exactly where you need it, you have no control over your castor. You get what you get which is determined by the position of the C's. They can be cut/turned, but many people don't. I'm not familiar with the pinion/castor separation on those axles.
After you set your pinion angle, measure the castor angle. I've done this off the upper ball joint, which probably isn't perfect, but its easy and close enough. Note that this angle needs to be with respect to level ground with the vehicle sitting level at ride height. This angle should ideally be 5-7 degrees. Probably no more than 8 and no less than 4. Less castor will give sketchy road manners and poor return to center. More castor will strain the steering, but is generally okay if you have hydro-assist. I've read a bit of theory of larger tires requiring less castor because there is greater trailing distance, but I'd still say 4 degrees of castor is on the verge of unacceptable.
So, you have to balance the two angles. There is a pretty small margin of error here. You're talking a few degrees either way. Once you get your pinion set and you measure your castor, you'll have to decide if they are close enough that you can work with them, or if you need to cut and turn. You might end up with your pinion being 3 degrees out with 4 degrees of castor. That will probably be okay, but is certainly not great.
Yea I am not cutting and rotating C's haha. That just sounds like a road to more issues and I feel like whatever I can get now will be good enough. This will not be a DD kinda project by any sorts but maybe a 'cruise to work every once and awhile and beat the crap outta it on the weekends' kinda deal.
At this point in time, the jeep is currently on jackstands. the way its sitting right now, the rear axle is probably sitting about 75% full droop, links already cut and roughed together for adequate adjustment at ride height.....so not quite completely hanging and where the front axle is right now is relatively the same, if not closer to 100% full droop. Do you think I should worry too much about setting these two angles at the moment or wait till i can get tires on the ground? (Keeping your comment about ride height on level ground). I just got the rest of my joints, missalignment spacers, and track bar mount so I'm eager to get that front axle in.
05-24-2024, 08:33 AM
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If your links are already cut and you're definitely not going to cut/turn, don't worry about it now. Get it close enough and then you can adjust link lengths when everything is together.
05-24-2024, 08:36 AM
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Sorry I shoulda been more specific, the rear links are already cut and roughed together. I havent dont anything on the front axle other than roughly place it where I want it under the jeep.
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05-24-2024, 12:51 PM
#8
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What I do is to first set the castor at 8 degrees and then check the the driveline angle at the pinion. You can use an angle finder across the pinion flange. Then you will say, the pinion is way off. So you can use a stick from the pinion to the tcase flange and get a good idea how many degrees, as close as you can that way. So the deal is that difference between the stick angle and pinion angle needs to be within 4 degrees. Then you adjust until you get that 4 degree angle. Any more and the driveline will vibrate
05-24-2024, 02:32 PM
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What I do is to first set the castor at 8 degrees and then check the the driveline angle at the pinion. You can use an angle finder across the pinion flange. Then you will say, the pinion is way off. So you can use a stick from the pinion to the tcase flange and get a good idea how many degrees, as close as you can that way. So the deal is that difference between the stick angle and pinion angle needs to be within 4 degrees. Then you adjust until you get that 4 degree angle. Any more and the driveline will vibrate
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