hogelectra Posted March 1, 2009 Share Posted March 1, 2009 History of the vehicle - don't know how many owner there have been or what they installed or partially de-installed. I'm surprised almost daily at what I have found I have stock springs upfront with a 1 3/4" spacer with swaybar disconnects What I did was replace my front axle with a newer DANA30 without a vacuum disconnect which made it simpler to install my Aussie locker and to match the gears on the back. After I did the install I noticed that the angle on the front axle looked awkward in that the drive shaft was almost binding at the transfer case. It seemed to me either the lower control arm was to long or the upper control arm not long enough. Is there some measurements or rule of thumb for pinion angle up front. Now the lower control arm is not stock and has been replaced by this very hefty looking aftermarket control arm. Link to comment Share on other sites More sharing options...
mvusse Posted March 1, 2009 Share Posted March 1, 2009 It is quite possible the vehicle has had a higher lift in the past, along with lower control arms. In any case, those control arms are probably longer than stock. If the upper control arms are stock, that will turn the pinion angle down. 2 solutions: 1- install stock lower control arms 2- install aftermarket adjustable lower and/or upper control arms The stock arms are very weak compared to any after market ones I have seen. I would go for option 2, and if you plan on lifting the truck beyond the 1 3/4" it has now I'd get upper AND lower arms. If the newer axle you installes is a low pinion, that would compound the problem. Link to comment Share on other sites More sharing options...
Eagle Posted March 1, 2009 Share Posted March 1, 2009 What vehicle did the "new" Dana 30 come out of? If it's from a ZJ (Grand Cherokee) or a TJ (round headlight Wrangler), it's a low pinion axle. The original for your MJ was a high pinion axle. It can make a lot of difference, but at less than a 2" lift it shouldn't be an issue. You may have to reduce the caster angle slightly, and that's where things get "iffy." If the caster angle is reduced below about 6 or 6-1/2 degrees, the possibility of death wobble is greatly increased. Link to comment Share on other sites More sharing options...
hogelectra Posted March 2, 2009 Author Share Posted March 2, 2009 ok you got my attention - the axle is from a Grand Cherokee and now I know the difference between a high and low pinion when they talk differentials. What are my options? Will changing my control arms to adjustable and forcing a better angle work or what else is reasonable - It took me a longtime to find a DANA 30 with the right gear ratio. And since I'm only $90 into this I can spend more if needed but would rather keep the axle. Link to comment Share on other sites More sharing options...
hogelectra Posted March 2, 2009 Author Share Posted March 2, 2009 Also what are my risk or potential damage to my transfer case running this way Link to comment Share on other sites More sharing options...
Eagle Posted March 2, 2009 Share Posted March 2, 2009 Can you post a photo? The double cardan joint in the front driveshaft should certainly be able to handle a 2" lift with a low pinion axle. Ummm ... I hope this is a foolish question, but ... your front driveshaft DOES have a double cardan joint, right? Link to comment Share on other sites More sharing options...
mvusse Posted March 2, 2009 Share Posted March 2, 2009 With adjustable upper control arms you can tilt the axle forward so get the pinion angle closer to where it needs to be. Or get adjustable lower control arms and adjust them to the stock length to do the same thing. a 2" lift is not enough to need longer control arms. If you are going to lift higher than 3" (1.25" more than you have) I would look for a high pinion axle. If/when you find one you can probably unload the low pinion axle for about what you have in it. Link to comment Share on other sites More sharing options...
BLHTAZ Posted March 2, 2009 Share Posted March 2, 2009 You want to keep the front pinion angle as close to stock position as possible or you will risk throwing the camber off and destroying your tires. When I did the SOA on our YJ, I raised the pinion angle by 2 degrees and it burned the outer half of $500 worth of 35" tires completely off in 3 months. :shake: Link to comment Share on other sites More sharing options...
hogelectra Posted March 5, 2009 Author Share Posted March 5, 2009 Ok here are the pictures of the front end Image Not Found Image Not Found Image Not Found I measure the after market lower control arm and it is only a 1/4" longer then stock Link to comment Share on other sites More sharing options...
jbhill Posted March 5, 2009 Share Posted March 5, 2009 you don't have enough pinion angle it looks like. Link to comment Share on other sites More sharing options...
BLHTAZ Posted March 5, 2009 Share Posted March 5, 2009 It's kind of hard to tell in those pics, but in this one it appears to be about right. It should be nearly parallel to the ground as it came stock. You do NOT want to rotate it up unless you plan on repositioning the knuckles to maintain your camber. Image Not Found Link to comment Share on other sites More sharing options...
Pete M Posted March 6, 2009 Share Posted March 6, 2009 caster Link to comment Share on other sites More sharing options...
SuperWade2 Posted March 6, 2009 Share Posted March 6, 2009 I just enjoy posting pics... Link to comment Share on other sites More sharing options...
BLHTAZ Posted March 6, 2009 Share Posted March 6, 2009 I know what caster is, but when you rotate the entire axle to move the pinion up...the change in caster also throws the camber off...I did it and have the worn out tires to prove it. When you rotate the pinion up, the top of the tire will move out causing the outer half of the tire to wear VERY quickly. Link to comment Share on other sites More sharing options...
mvusse Posted March 6, 2009 Share Posted March 6, 2009 I don't see any angles severe enough to cause binding. Maybe a seized U-joint in the drive shaft? Link to comment Share on other sites More sharing options...
Pete M Posted March 6, 2009 Share Posted March 6, 2009 Yes, that is true. But it's the caster that you're setting by adjusting the control arm length. The camber isn't adjustable by itself (without special ball joints). It just sorta follows along with the caster. Set one and you should be good with the other. hogelectra, I wouldn't worry too much about the pinion angle, as it's close enough with such a mild lift. Just make sure your caster is correct (and your toe setting too). An alignment should tell you that. Link to comment Share on other sites More sharing options...
Eagle Posted March 6, 2009 Share Posted March 6, 2009 I know what caster is, but when you rotate the entire axle to move the pinion up...the change in caster also throws the camber off...I did it and have the worn out tires to prove it. When you rotate the pinion up, the top of the tire will move out causing the outer half of the tire to wear VERY quickly. That shouldn't happen if the alignment is correct. The camber should be zero, and the toe-in should be nearly zero. A sliught change in caster shouldn't translate toe-in to camber by enough to even be noticeable. However, your experience does reinforce the wisdom of checking alignment after making any changes. In my case, I was reminded of this when I removed the 4" lift from the '88 and then drove it off to a NAXJA trail ride in another state. Steering was perceptibly odd on that drive. When I arrived at the camp site, one of the guys had a tape measure and some free time, so we checked the toe-in and found that it had become a significant toe-OUT. Naturally the adjusting sleeve was virtually welded in place (I guess the former owner had never had an alignment done), but I was eventually able to correct it enough to drive home again, where I soaked it down with PB Blaster and aligned it properly. Link to comment Share on other sites More sharing options...
BLHTAZ Posted March 6, 2009 Share Posted March 6, 2009 2 degrees killed me... :fs1: You want to keep the front pinion angle as close to stock position as possible or you will risk throwing the camber off and destroying your tires. When I did the SOA on our YJ, I raised the pinion angle by 2 degrees and it burned the outer half of $500 worth of 35" tires completely off in 3 months. :shake: It did this to both of my front tires in 3 months... I moved it back down the 2 degrees, repalced the tires and there is no problem now 3 years later. Link to comment Share on other sites More sharing options...
hogelectra Posted March 6, 2009 Author Share Posted March 6, 2009 Going to drive it to the store and back for the first time - been on blocks for weeks while I did all this changing in the front and rear. Then I'll do some alignment measurements tomrrow thanks for the advice Link to comment Share on other sites More sharing options...
hogelectra Posted March 7, 2009 Author Share Posted March 7, 2009 took a trip off-road for the first time - everything seemed to work and nothing fell off - but tomorrow I will check all the bolts to make sure nothing came lose. I have a question though - how can I configure the old vacuum lines so that my 4x4 light will come on when I shift the transfer case? Link to comment Share on other sites More sharing options...
BLHTAZ Posted March 7, 2009 Share Posted March 7, 2009 Most folks that I know try to figure out how to stop the light from coming on. There is no reason for that light as it doesn't actually mean that you are in 4WD...it just shows that you "should" be ;) . You should be able to tell whether you are in 4WD or not without the light. :thumbsup: Link to comment Share on other sites More sharing options...
mvusse Posted March 8, 2009 Share Posted March 8, 2009 On trucks with the CAD (all 4x4 MJs?), the light tells you when the front axle is engaged. Link to comment Share on other sites More sharing options...
Eagle Posted March 8, 2009 Share Posted March 8, 2009 On trucks with the CAD (all 4x4 MJs?), the light tells you when the front axle is engaged. No it doesn't. A few years ago the axle end fittings on my '88 XJ were so soaked with oil that they got too soft to seal. I was astonished one day leaving my GF's house in a snow storm that I couldn't get up the hill on my normal route home. The light was on, but the axle wasn't engaged. I think there's a switch for the light on the firewall. It really doesn't tell you much of anything except that you have enough vacuum to turn on the switch. Link to comment Share on other sites More sharing options...
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