I have a vibration at about 60kph, a little slower downhill, a little faster uphill. The vibration is at the same speed no matter what gear the car is in. I have a few things I wanted to check, one of which was the HICAS. I am driving a 1989 TT Auto Jap import Z Fairlady. I have tried the HICAS Diagnosis (turn steering left & right 20 degrees 5 times, push brake 5 times, etc., etc.) with no outcome. The HICAS light is not coming on or flashing. If the self diagnosis will work on my Z, can somebody please give me proper instructions on how to do this? I have not got a Conzult yet but have heard that this will give any fault readings, is this true? If the vibration is not caused from the HICAS, what other issues should be checked? What has been done and advise I have received.- I had a wheel alignment, fronts are not aligned true as the strut bar is gone. Does have a slight pull to the left. Need to get custom castors. I got a wheel balance and a tyre changed after I picked up a bone on the Hiway. I have been told if they rotated the tyres that it will cause eggs. Is there a way of testing this without getting another balance? I was told by a mechanic (not a good one) that one of my mags is warped. I find this hard to believe as I have not hit anything and it was not picked up on the balance. He also couldn't tell me which one. Tyres currently have craploads of tread, so I have no plans to replace tyres or mags in the near future. I would like to eliminate any other issues in the meantime.
Re: HICAS Vibration issues can be difficult to locate, it's a process of elimination. Going on your description of the answers you have been given so far, it's possible the people working on, or diagnosing your issues, don't know what they're doing. Which unfortunately means the wheel balance you had done, could be suspect. The reasons not to rotate your wheels/tyres would be, if the tyres are directional, or the wheels are staggered.
Have you had the tail shaft looked at? It is possible the universal joints are worn enough to cause the vibration. You said the speed at which the vibration occurs changes with load (uphill/downhill) which makes universal joints a suspect. If the vibration was caused by the rims or tyres then it would be less likely to change speed under load. Maybe you can borrow a set of rears tyres to rule them out then move onto checking the tail shaft.
I had shaft inspected for balance issues, all was good. Don't recall any mention of uni joint problems but it has been slowly getting worse. Might be worth checking again.
I can only assume this has not been done. I've owned the car for 2 years now. It was imported in 2005 and has been kept pristine looking condition although I don't think any general maintenance had been done between 2005 and when I purchased it. I have been slowly going through the 100k service and replacing anything that is in fair to poor condition.
This is all interesting. I assumed most of this was crap but added it in for second opinions. The mechanics etc. that had spoken of most of these issues, I no longer deal with for obvious reasons. I thought, seems I was wrong, that the Z32's had a strut bar fitted from factory. This is extremely helpful knowledge as it now proves the tyre centre I went to, has no f'n idea what they are doing. Thanks for your input. Very helpful.
If you pay attention to the frequency of the vibration, you should be able to tell whether it is on the input side of the diff (tailshaft), or the output side (wheels, tyres etc). The input side will register a faster frequency than the output side, which doesn't rotate as quickly, because of the diff ratio. Remove whatever you can from the vehicle that may be loose, like spare wheel, jack, tools etc. even take out the boot & floor mats. Take your car for a test drive on a flat section of smooth road, the quieter the better. Be a good idea to have a passenger with you to take note, so you can concentrate on driving. Don't have it in overdrive & take note of the RPM the vibration occurs. Does the vibration increase the faster you go?
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