| Author |
Message |
    
Randall Smith
| | Posted on Thursday, January 02, 2003 - 06:58 pm: | 
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I am engineering some corrections to my u-joint angles as the ultimate solution to drive line vibration problems. However I would like to consider the castor angle before I make any changes to my suspension.
Does anybody know how much the castor angle changes per inch of lift??
Also... Do you have a good method for measuring the castor angle?? And... What is the castor angle of a stock RRC/Discovery??
Randall |
Keith Kreutzer (Revor)
| | Posted on Friday, January 03, 2003 - 12:04 am: |
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Caster angle is set for about 3 degrees from the factory... A three inch lift will net pretty much zero castor... At least thats what Autocad says.. If you have a fixed factory angle and you know the length of the control arm and you know the appromimate lift amount you can make a pretty good guess of it using those trig tables we learned so much about in school.. Or you just draw it on some cad program like i did and cheat! |
Randall Smith
| | Posted on Friday, January 03, 2003 - 12:53 pm: |
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Keith: thanks for responding
I pay people to do my "autocading" now, so I was hoping someone would just tell me how the lift effects castor angle. So maybe 3 degrees stock and about 1 degree per inch of lift?
Would be nice to be told a method for measuring castor angle also(this isn't covered in the shop manual). I have an inclinometer, if that helps, which has shown me that that my front diff is pointed up about 4 degrees. Using the DC drive shaft, this angle should be 3 degrees maximum.
Also wanted to thank Rob(Pokeman) and Muskyman for confirming that when you decellerate the truck, the front pinion points even further upwards. This torquing upwards combined with the 4 degree upwards angle results in a nasty vibration when I take my foot off the gas at speed.
So my goal is to include u-joint angles in my front arm design, but I don't want to screw up the castor angles too.
Randall |
Greg Davis (Gregdavis)
| | Posted on Friday, January 03, 2003 - 01:09 pm: |
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Keith, were those numbers for a DI? A Di has a shorter radius arm than a DII, so I was just being curious? Mind calculating the castor loss per inch of lift on a DII with a radius arm length of 33"(I think)? |
Milan (Milan)
| | Posted on Friday, January 03, 2003 - 01:23 pm: |
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"So my goal is to include u-joint angles in my front arm design, but I don't want to screw up the castor angles too. "
Every time you change pinion angle, you will change caster. |
Randall Smith
| | Posted on Friday, January 03, 2003 - 02:00 pm: |
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Milan
That's why I ask...what was it originally, and how do you check it in your own shop.
My guess is that the castor angle is less critical that u-joint angle. But bad castor could be unnerving too as you drive down the interstate at 80mph.
Bad u-joint angles ruin seals, bearings, u-joints, etc. Driveshaft vibrations just ruin the experience of driving a RR.
Randall |
Greg Davis (Gregdavis)
| | Posted on Friday, January 03, 2003 - 02:21 pm: |
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"Every time you change pinion angle, you will change caster."
This is true if you're only using corrected arms. However, you can correct your castor and keep your pinion angles in tolerence by rotating your knuckles, like RoverTym does. Can't do that on a DII though. |
Peter Bullock (Downunderdisco)
| | Posted on Friday, January 03, 2003 - 05:04 pm: |
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Im sorry Milan but I think what you should have said there is "castor" not caster as everyone knows that caster is in fact, a type of sugar.
Glad I could contribute usefully...I plan to trawl the whole site, iron out indescrepencies and eradicate or educate the ignorant. |
Keith Kreutzer (Revor)
| | Posted on Saturday, January 04, 2003 - 04:13 pm: |
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The Castor (sorry Peter) angle i spoke of was for a D1..
I don't remember all that i did on ACAD but i would have measured the radius arms and stuck them in a drawing of the whole thing... I do know i have a 3" lift and figured the castor was now zero. Of note i found that when i rotated the axle housing with the lift the pinion pointed straight at the t case yoke... providing the perfect setup for a DC driveshaft.
I anyone has a D2 and want's me to CAD their caster send me the dimensions... |
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