Birty Dastards Jeep Club
Tech Forum => Workshop => Topic started by: just-boot-it! on May 23, 2013, 01:48:44 PM
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Having finally got a lift done to my Jeep today we noticed both rear hubs have slight in/out play as in towards the centre of the diff. I dont remember this before. When installing the new leafs we did one side at a time, could this have affected the way the shafts locate as we had the diff at all sorts of angles, it dosent feel like wheel bearings as the wheel dosen't move in another direction. Abit dissapointed to say the least :banghead:
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That's normal
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:iagree: Dana 35's do move like that. "it's a feature"... :icon_winkle:
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Like I said I never noticed it before but we were looking for faults so.... Also the new leafs i fitted came with shims but there is a little vibration due to the new prop angle I think, is that ok to live with as its only like tyre noise? Before and after pics included.
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It's sitting a little high at the back at the moment. Give it a while and it will settle a little that will help the prop angle..
If its the props that are vibrating it will probably only do it at certain speeds (a bit like an unbalanced wheel). If it keeps doing it after a few weeks you could fit a T case drop kit (if you've not done it already. That should sort it out.
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If you dont want to hang about waiting for the vehicle to settle, load her up with a few bags of cement or what ever, just so the back end has drooped from where it is now and take it for a spin.
If it's the propshaft angle causing problems the speed at which the vibration comes and goes will have changed.
It might also be that the old U joints are on their last legs and cant cope with the extra deflection.
If it were me, I would lift the front end to restore driveshaft angle equilibrium before too long and then start looking for gremlins, if any persist.
BUT who knows, I might be wrong! Wont be the last time I dont suppose.
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The shims should be used to make the pinion at the rear diff parallel to the output from the transfer case. Other driveshaft styles need the pinion to aim upwards towards the transfer case so it might be worth checking they are installed right.
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The wedge of the shim is pointing to the front. We also removed the flat bottom leaf because the u bolts werent long enough and I could see it collecting crap as you drive along. New and old leaf comparison pic :
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try turning the shim around :icon_winkle:
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Just been down a lane near me a few times to help it settle and every time i measure it the left side seems to be a little higher than the right, and the vibration gets worse under acceleration / speed increase as oppose to any set speed :017:
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Lifted xj's always lean to the right. Don't know why, they just do. It will definitely be propshft vibration. Try it without the shims in.
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I added an extra spring isolator to my drivers side front spring when i did my lift. It fixed the lean and runs true and straight
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Got a laning trip monday with 2 passengers so ill see how it goes with some weight in it, on a positive note how much better do XJs look with a lift :icon_super:
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Lifted xj's always lean to the right. Don't know why, they just do.
Not after snapping and welding a spring!! :lol_hitting:
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Try without shim and then with shim facing other way. The way you have it at the moment is definitely not right.
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:imwitstupid: I was running the same springs as those when I bought this xj and it had vibes until I removed the shims.
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Im in the process of getting a transfer box drop kit for next to nowt made up so im gonna fit that and try it first as its alot simpler than getting those shims out on a drive with limited tools etc until my mechanic mate comes back from his hols.
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I was puzzled at the shims when I removed the springs.... They seem to have been fitted to make the nose of the diff point further towards the ground which I'm sure is wrong....I think that the wedges should be fitted the other way round.... The axel on my Jeep always made funny noises which I assumed was a worn axel
The car looks much better raised a little... I doubt that you'll need that bottom leaf but if you look at worn springs, they seem to deform around where the Ubolts clamp... My guess is that the lower leaf is to reduce this deformaton over time
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Pointing the nose of the diff (pinion) down towards the ground is what you want to do but no shims at all might be the way to go. A transfer case drop might not fix the prob as it affects the angles dfifferently. Adjusting the shims on the drive isn't too bad cos the springs can stay in place and it'll be easier if it's only recently fitted
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James, I don't understand why the nose should point to the ground...I would have thought that the nose would have been better pointing up to redce the angle between the axel and the output on the transfer case....Or am I just being dumb?
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If running a standard prop then the output on the transfer should be at the same angle as the diff flange so the ujs are in time with each other. Ujs being out of time with each other is what causes the vibration. Usually the diff is set slightly low to allow for the pinion climbing the crown wheel on acceleration. If you run a prop with a double cardon in it you then need to point the diff at the transfer output.
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Right, so if I understand, if the output flange on the transfer case is vertical then even if you raise the car (within reasonable limits) then as long as the flange on the pinion is vertical then it should be fine.... So really you should only need the wedges if you have droped the rear end of the transfer case by the same number of degrees.....Have I got that bit right?
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Kind of. You certainly don't want the nose if the diff to be pointing up'ards
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At the risk of asking a really dumb question then, what is the purpose of the wedges? The only other use that I can think for them would be if the axle is either forward or rearward of the apex of the spring and the nose of the axel is either pointing up or down and needs correcting to make it level again...
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They are to correct the pinion angles. I had to fit some when I put extended shackles on and the effect was tipping the pinion up towards the transfer case. The shims were put in fat end forward to compensate for it
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Ok, yep I understand that now... so on a moderate 3 inch lift with no extended shackles then wedges are not needed..
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Normally the best way to start is no shims. Then if there are problems you can use shims to help. Springs are made differently, some might put the angles perfect others might not. Unfortunately it's never just fit it and be done, there always seems to be a bit of tweaking steering, brakelines, prop angles, trimming body work and bump stop adjustments
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You may also need them if a transfer case drop kit was installed 'cos that would point the output on the T'case downwards.
In that situation you'd install them the other way round with the thick end towards the back so the nose of the diff is lifted.
The idea is that the output on the T'case and diff are kept parallel.
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Cheers guys.... What I thought I knew about this stuff was all wrong
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Thanks for all the responses, after reading that lot my brain is overheating :icon_biggrin: Been out today for an awesome day out laning down lincs/leics border, had a passenger in the back and the noise was a little quieter. Ill post some pics on laning trips later. An old problem has arisen again, driving through a ford to wash the crap off the jeep starts being hesitant after a few hundred yards, will keep you all posted.
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Look under your inlet manifold for a wee beastie bolted through the gearbox bellhousing and spray it with WD40.
If the hesitation/misfire goes away then the problem is the crank position sensor, it's wiring or the connector.
My water tells me your problem lies there!
I might be wrong but I doubt it!
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Having driven it since it went through the water it drives fine now, does the cps get wet and play up maybe? Ill take a look at it tomorrow after work.
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Did you tighten the leaf spring bolts before you fitted the wheels or after?
The bolts should have been tightened after the wheels have been fitted so stopping the rubber bushes being in a torsion mode which will result in premature failure
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Yeah we lowered the car onto the ground then rocked it side to side afew times then tightened up the leaf spring bolts. Been out laning today and on the way home we got up to 70 mph on the bypass and the vibration is almost non existant :icon_biggrin:
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Ah! The solution is simple then.....Drive everywhere at 70..
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:hysterical: I mean before it vibrated bad from 30-50 mph and now I can get upto 70 :lol_hitting:
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take off the front prop and see if it still vibrates.
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Just an update for you all, now been a month since I did my lift and the vibrations I had have almost gone. I have got to the stage of no weight in the boot and no fuel in the tank ( shock! ) so to make the propshaft sit at its maximum normal angle and its almost fine. I have had to buy a 15mm spacer for the drivers side coil as the front was on the piss :017: