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Post by Roger on Oct 26, 2008 20:50:59 GMT 11
Hi all.
When I engage 4H in the MU and get some speed, up to 80km/h, I get a vibration that feels like I'm driving over corregations.
I have a late 95 MU manual with shift on the fly and auto hubs. Shifting between 2H to 4H while moving it is noticeable in 4H, so it's not the road making the vibrations when in 4H.
Any ideas?
Cheers.
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fly3r
Isuzu Senior
Shmoou
Posts: 197
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Post by fly3r on Oct 26, 2008 22:15:13 GMT 11
Just a thought, It migh be a universal joint in the front drive shaft?
I had one a while back in the rear, i found the tail shaft vibrated above 80-90km/hr, it looked all right but one of the ball bearing pack in the uv joint was gone.
good luck with it...
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Post by geeves on Oct 27, 2008 17:51:35 GMT 11
That or the spline are the most likely culprits. A couple of questions though. Are you trying this on gravel or tar seal. If on a hard surface then different wear on your front and back tyres can cause vibrations or worse. It is highly recommended that 4wd is not engaged on tar seal. The isuzu is far stronger that other part time 4wds but the strains can be huge.
If while driving at that speed does the vibration stop if you go back to 2wd. The hubs will remain locked in this situation so this could point to the transfer case.
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Post by Roger on Oct 28, 2008 20:41:21 GMT 11
If while driving at that speed does the vibration stop if you go back to 2wd. The hubs will remain locked in this situation so this could point to the transfer case. I'm sure the 4wd light on the dash tells me if the hubs are locked. It will stay on, even in 2H, until the hubs come unstuck. It happens with either 4L/4H - 2H. I think there might be switch in the hub for that light. Regardless, that's another job that needs doing! |
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Post by geeves on Oct 29, 2008 6:22:40 GMT 11
sorry missed the shift on the fly part.
Crawl underneath the car and grab eack of the front axles and see if there is any side movement A tiny amount is ok
Grab the front drive shaft and check for movement both sideways and rotationaly in the u joints
Not sure if this can be done in your set up but best chance of success will be engage 4h and neutral with engine running then switch off. Jack up the front and turn the front wheels feeling for tight spots.
Do all your tyres have the same brand and tread depth?
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Post by Roger on Nov 7, 2008 16:30:20 GMT 11
Front and rear wheels have different tread depths. Front wheels have a little bit more than the rears. I have ordered 4 new tyres and have been waiting for a good month for them. I think I'll be getting them soon.
I never thought of slightly different diameters (a few mm) possibly giving trouble.
Can that give you grief even on loose dirt?
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Post by geeves on Nov 7, 2008 19:42:23 GMT 11
Shouldnt cause probs in low traction conditions. When you get the new tyres remember to rotate them evey 10000km and get a wheel alignment done every now and then (tyre dealers say every year but that would depend on usage. The only time mines been done was after 8 years and its anouther 3 now). Some tyre dealers can skim your old tyres to get the tread the same.
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Post by mudgrip4 on Nov 13, 2008 9:16:30 GMT 11
Just solving a similar case in Chch with 90 bighorn running 32" muds. Fine in 2wd but vibrated and steered badly in 4wd, and esp bad when tested on tarmac. Tested various options, and finally measured diff ratios front and rear after owner mentioned rear diff had been changed a year before.
OOOOHH!! - 4.31 original diff size in front, and 4.56 diff in the rear!! Over 5% difference in drive ratio!! And somehow the isuzu drivetrain handled this through a year of offroading! Must be tough.
Owner took truck back to diff supplier/fitter who put in another 2nd hand diff without charge. Tested new diff for him last nite and runs very well - quiet, no backlash, and definitely 4.3 this time. Then while doing sharp u-turn during roadtest noticed a bit of chirrip noise from rear tyres. Aha!! So straight home, jacked up rear, and found he now has nice tight LSD - worth $450-$550 retail from wreckers here! Has to be bonus after such a bad mistake...
RE different tread depths causing probs - worn muds can lose 10-12+mm of tread = 20-25mm loss in diameter from new tyre width and that's alot. A typical 32" mud might be about 800mm in diameter, and if you've got new muds on one end and v worn ones on the other, you will have 20-25mm or around 3% difference in drive ratio in 4wd. This is bound to cause drive problems, wind-up, vibration, steering wander, and excessive wear through drivetrain in 4wd, esp if used on road.
Sound idea to keep tread depths even, and rotate tyres regularly to keep them this way.
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Post by geeves on Nov 13, 2008 10:14:00 GMT 11
ouch!
I would of been looking for a matching 4.5 for the front to get the lower ration although the bighorn still works well on 32s and 4.3. Getting a good lsd is still a good bonus.
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Post by mudgrip4 on Nov 13, 2008 12:48:46 GMT 11
Amazing the drivetrain survived that long with serious stresses everywhere from the different ratios - must be very strong components. He's happy with his new rear 4.3 lsd because its in and done. Also hell of a job removing front diff from the bighorn - about 5 hrs work in and out from memory - not easy.
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Post by geeves on Nov 13, 2008 13:44:31 GMT 11
Ive seen a mazda bounty blow its gearbox from useing 4wd on the road but isuzus seem to take it If anything was to go it would be the cv
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Post by bedford4x4 on Mar 29, 2009 18:58:20 GMT 11
My Mu was driven from Dunedin to Nelson in 4H - possibly even further by the last owner. When I bought the thing, I noticed that the strain had caused the Allen bolts holding the FWH on the left side to come completely loose. The front tyres now have triangular lugs so I'll have to get some more tyres. No other damage done to the drivetrain - just re-tighten the Allen bolts and look for some tyres.
I'm wondering whether I should stick with 31x10.5x15's or whether I should go for 33x12.5x15's for a bit more ground clearance. Does anyone run 33x12.5x15's on the standard 7" rim?
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Post by geeves on Mar 29, 2009 19:34:50 GMT 11
Really a bit narrow but it can be done but expect the wof man to have a fit. Hes then more likely to notice the other mods and send you to the certifyer if this has not already been done. Worst part of this experiance will be the 400 fee
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ken
Isuzu Junior
Posts: 87
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Post by ken on Mar 30, 2009 11:02:01 GMT 11
The instruction manual says drive the truck backwards for a meter or so to disengage the lock when taking it out 4WD. I think this is because the mechanism is a wedge arrangement and can get wedged in pretty tight.
Ken
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Post by geeves on Mar 30, 2009 13:17:13 GMT 11
That instruction is only for auto hubs. They are designed to disengage when direction of rotation changes and this can take a meter or so. They give a nice clunk when they release. This design is also why serious 4wder do not like them as the last thing you want at the apex of a failed hill climb is unlocked front hubs
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Post by bedford4x4 on Mar 30, 2009 18:30:01 GMT 11
Really a bit narrow but it can be done but expect the wof man to have a fit. Hes then more likely to notice the other mods and send you to the certifyer if this has not already been done. Worst part of this experiance will be the 400 fee I went for a WOF today and got the bad news. Body lift, suspension lift, sway-bar disconnects, fuel tank lift - told to pay out $325 for the L.V.V. cert. A bit rude of the last owners to have done the mods and not got the cert. Now I'm paying for it. Upside is that that is all that's needed for a WOF. Anyway, my plans to put a CD player/tuner in it and go to 33" tyres have now been postponed until I get the cert.  |
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Post by geeves on Mar 30, 2009 19:47:15 GMT 11
That will depend on what the certifier finds but if its all done right should be no drama. You might have a clain in the disputes tribunal against the previous owner and if it was issued a wof before with those mods against that wof issuer. Best action is to talk to the seller (if this is a dealer the lmvd should also be able to help) and play it from there. Even if you get the seller to pay half this fee your on a winner as everything else is good.
Also if you want 33s down the track see if you can borrow some for cert time. Once you have the cert with 33s you can fit any smaller tyres till you can afford them but if you do this later you could end up paying anouther 325+gst
When you see the certifier list all the mods you know about even if you dont think they matter. I missed the boost gage on mine but the certifier didnt and had anouther 3 pages of paperwork just for that (interier impact rules).
Im regreting not doing mine with 32s as I now have to put the 31s on for every wof.
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