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Old 29-10-2008
alexander  alexander is offline
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Default SJ suspension lift

i have been putting in suspension lift hardware in my 81 cherokee.
the front part of it consisted of shackles 3" longer than standard. that is ok, but had two consequences: the front was only lifted about 1.5", as the rear of the spring was, of course, still mounted at the original height. as i put 3" blocks on the rear axle, it left the car pointing down a bit at the front. secondly, it alters the castor angle of the steering. while no doubt easier on the universal joint on the front shaft, it seemed desirable and prudent to raise the front a bit more.

so, my solution was to cut the mounting brackets off the rear of the front spring, and make new ones with holes at original height, 1.5" and 3". i used 10mm plate, cut with an angle grinder. one major issue with to ensure that the axle went back in properly aligned, i first cut a piece of flat steel so it went over the spring eye bolt, with the original bracket in place, and screwed its other end to the chassis. i then measured from the backside of the top ball joint nut, to the middle of the head of the bolt on the front shackle mount. with one side fixed in place by the flat bar, i then shifted the other side back and forth to the same measurement.
the 3" lift at the rear increased the angle on the rear uni, so i would expect that to shorten its life. i have, however, just put new unis in the tailshaft so they will likely outlast my ownership of this car. i notice that one can buy slightly angled wedges, which fit between the rear liftblocks and the axle, to tile the front of the rear diff up a little. i would reckon that to be a really good idea, but of course they are in the US and i had already done the rear axle bit by then.

i also put in new spring eye bushes, having previously put in polyurethane shackle bushes. the PU bushes are a good idea, i think, but it is important that they are lubricated between the sleeve and the PU. someone had put PU spring eye bushes at the rear of the front spring, but they were evidently not greased at all. further, the bolt had fused with the inside of the sleeve so strongly, that i ultimately couldn't dislodge it with a 20t press! as can be seen, i opted for the cheaper metalastik bushes. note: my understanding of these is that the bolt needs to be torqued up sufficiently such the inner tube cannot rotate on the bolt, or with respect to the mounting bracket. all movement is therefor taken up by flex in the rubber in the bush. surprisingly hard to find a definitive statement to that effect!

i am now working on some panel repair so have not yet driven the car. in theory, the front has a bit less castor, so perhaps will have a little less self correction, but that remains to be seen. i can set the rear of the front spring a bit 'higher' anyhow, to restore original castor. i have been advised that 3" lift does not require a drop pitman arm, but the proof of that will be in the driving as well. see how we go!

alexander.



plates cut out, with angle grinder, from 10mm plate. gosh, dont drill bits get expensive once they go beyond 1/2"!!
a 1/2" bit may be bought for $20, but the 9/16 bit was almost $60. to preserve the life of this precious item, i worked up to 9/16 with two smaller bits, and plenty of cutting fluid.

in retrospect, 1/4" plate was an overkill, and i think 3/16" would be more than enough. once the brackets were welded up, it took significant force to expand the two sides by even 1mm or so, to slide the spring eye in between. that was achieved by some threaded rod through the lower holes, and nuts on the inside of the side plates, but even then, i had to apply real torque to the spanners to do it!




plates assembled ready to weld



bracket welded together



new bracket held in correct spot with locating jig, and spring jacked up to just contact chassis



bracket finally welded into place. i will add that i was not impressed with the existing brackets anyway. as many of you will know, they are held on to the chassis with 3 rivets. when i bought the car some years back, i noticed that they flexed from side to side when the wheel was turned. at the time, i welded around the edge of the bracket, which was the main reason why the old ones were so hard to get off! the newly made brackets, aside from being a likely overkill at 10mm thick, are welded right around the edge, with strengthening tabs, and two rose welds on the underside. despite the extra distance from the chassis to spring eye, i am confident there will be absolutely no flex at all.


Last edited by alexander; 08-09-2009 at 05:22 PM.
  #2  
Old 10-11-2008
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Lucafer  Lucafer is offline
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Simple & brutal! Whats not to like?
I'd like to see more tho. There appears to be a discrepancy in the numbers of
people who are modding the older stuff comparerd to the newer gear. *sigh*
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Old 14-11-2008
alexander  alexander is offline
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Quote:
Originally Posted by Lucafer View Post
There appears to be a discrepancy in the numbers of
people who are modding the older stuff comparerd to the newer gear. *sigh*
quite so!, but the reality is that if you have excess cash to spend on modding a car, you are likely to have a new(ish) car in the first place. older vehicles do of course have one great advantage: they are not worth much and are usually a bit rough, so it really doesnt matter what you do with them. even rather average modification to an old car can still look a bit cool, and will always be excused, but badly done modifications to a new car just dont cut it!

regards
alexander.
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Old 08-09-2009
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one less than desirable consequence of the 2" lift, was that the steering developed an unsettling wiggle over bumps. that was most noticeable where you dont want it: at highway speed on country roads. i must say it felt quite dangerous, as it seriously upset the directional stability of the car; much more than i would have expected from such a mild lift. i believe that was due to the angle which had appeared between the rod connecting the pitman are to the tie rod, and the tie rod.

i purchased a drop pitman arm for a 4" lift, from bj's jeep parts in the US. that has moved the two rods back in to almost perfect parallel. i have yet to drive out of town with this change, but initial impression is that it has removed the wiggle over bumps.

aside: one more for the 'why i prefer to repair my own car' book... the nut holding the pitman arm is supposed to be torqued to 185 ft/lbs. i have the steering box recod a couple of years back. when i went to remove the pitman arm, i found that the nut had worked partially loose, and was barely compressing the spring washer! obviously, yet again, a paid professional failed to tighten it up properly.

alexander.
  #5  
Old 08-09-2009
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turbomart  turbomart is offline
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Yeah, good to see someone modding stuff themselves not just buying bolt on bits.
I reckon 10mm was overkill but at least you know its strong.
Sounds like you where getting bump steer ,occurs when drag link is not parrallel with axle & gets worse as angle gets steeper, drop pitman arm should remedy.
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  #6  
Old 10-09-2009
alexander  alexander is offline
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Quote:
Originally Posted by turbomart View Post
Sounds like you where getting bump steer ,occurs when drag link is not parrallel with axle & gets worse as angle gets steeper, drop pitman arm should remedy.
yes, i think that is so. you can feel the difference even driving around the burbs, so i am hoping it will have returned it's surefootedness on country roads as well.

for posterity, i used a 33m socket on the pitman arm nut. it wasnt a really snug fit, but the closest i could find, as a 1 1/4" was too small, and a 1 5/16" is actually a slightly bigger than a 33mm (33.3mm).
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