Front suspension

[apc01]

Just completed a 3000 mile trip and I noticed that the car was not handling as well as usual. Specifically it lacked road feel/feedback particularly on the front nearside which also seems to have more movement over bumps, braking etc. Also the car feels looser like it is over-steering turning right or sharp right bends.

Also just checked the suspension while parked and is easier to push down on the front nearside than offside and more bouncy.

I then measured the height between tyre and wheel arch and the nearside is 1.5 CM lower than the offside.

Are there any adjustments that can be made or does it need new parts? Could it be related to the AHC system/sensors?

Thanks.

 

[desertrogue]

Hi Apc

I do not know what the UK spec cruisers have
Do you know if it has AHC suspension?

If not then it sounds like your torsion bar just needs tightening up - assuming there is no damage to the coupling, tensioner bolt, bushing.

And I assume no leaking shock absorber? - again assuming no AHC

I do not know much about the AHC system, however I would hazard a guess that it could be a sensor telling it to lower, or the suspension unit has a leak.

Good luck

 

[apc01]

Thanks for your reply desertrogue.

My car does in fact have AHC. It was actually one of the first seven official dealer 100 series in Britain when I bought it, so I guess AHC has been fitted to the model from then.

I dont see any leaks but I have noticed that my car handles and feels significantly different almost day to day, sometimes feeling solid with good road feedback and other times feeling loose and jittery with poor or no feel to it, particularly front nearside, so I guess it could be a sensor issue.

 

[frank rabbets]

I would check all the suspension joints and wheel bearings then change the suspension fluid using only Toyota genuine. If it varies from day to day you might have air in the system.

 

[BobMurphy]

The Struts (one at each corner) are just hydraulic rams. The height they sit at is controlled by an ECU (naturally!) that takes its readings from the three height sensors and the "Suspension Height" switch.

Each Ram is fed fluid by the "Height Control Valve Assembly" which is mid-way along the N/S chassis rail.

Damping is controlled by an "Accumulator Assembly" (one per strut) which has an electric valve that is set by the 'Sport/Comfort' switch on the centre console. If one side is more bouncy than the other it may be something to do with its dedicated Accumulator - or its electrical connections.


The $64,000 question is . . What happens when you try to raise or lower the suspension height ??

If its low on fluid, or the sensors are mal-adjusted it may not maintain the 'high' setting.

The result will give us a better clue as to where to look .

Bob.

 

[apc01]

The Struts (one at each corner) are just hydraulic rams. The height they sit at is controlled by an ECU (naturally!) that takes its readings from the three height sensors and the "Suspension Height" switch.

Each Ram is fed fluid by the "Height Control Valve Assembly" which is mid-way along the N/S chassis rail.

Damping is controlled by an "Accumulator Assembly" (one per strut) which has an electric valve that is set by the 'Sport/Comfort' switch on the centre console. If one side is more bouncy than the other it may be something to do with its dedicated Accumulator - or its electrical connections.


The $64,000 question is . . What happens when you try to raise or lower the suspension height ??

If its low on fluid, or the sensors are mal-adjusted it may not maintain the 'high' setting.

The result will give us a better clue as to where to look .

Bob.

Thanks very much for this Bob. Very informative.


As for your questions regarding the ride height - when I switch to "low" the light flashes on "low" and then stops flashing, but the ride height did not seem to change. When I switched it to "normal" the "normal" light flashes and then stops flashing, but again I could not detect any change in height. When I switch it to "high" the light flashes and it definitely raises the height somewhat and stays there until I switch it back to normal.

The various driving modes, "comfort", "sport" etc do seem to work as expected.

Any further help would be much appreciated.

I do have a question - does the system you describe only work when the car is switched on or does it work all the time? I ask because I measured and tested the suspension height and bounce with the car switched off.

 

[desertrogue]

By switched off do you mean that the key was in the ACC position? or totally off? I would assume totally off , or ACC may not work - would have thought enough power would be needed for the hydraulic pump / actuators

 

[t1pper]

A few quick checks for the AHC,

A. Check both hieght sensor linkages on the front upper wishbones both left/right side (one of my linkage arms broke and gave problems)
both these linkages can be adjusted longer or shorter this will compensate for the 1.5 cm difference you discribe.

B.The rear axle only has one senson with a similar linkage this sits ontop of the rear axle and again check it to make sure it is intact (agian this one broke on my 1999 car).

C. When the car is in the middle (normal) ride hieght setting I would expect all the ride hieght sensors to be about mid distance in their travel (the lever coming from the sensor to be somewhere near horizontal).

Lastly aside from making some obivious checks on bushings etc I would suggest that you check the steering rack mounting bushes if they are still the original ones I suspect thet they wil be very loose, this can affect the feel ot the steering in the way that you discribe.

The rack is slightly hidden under the sump guard but if you get some to rock the steering while looking at the rack you may (probably will) see it moving, mine had towards 10mm movement when the steering was rocked from left to right, I upgraded to poly bushes and this really sharpened up the steering feel.

 

[uHu]

Just completed a 3000 mile trip and I noticed that the car was not handling as well as usual. Specifically it lacked road feel/feedback particularly on the front nearside which also seems to have more movement over bumps, braking etc. Also the car feels looser like it is over-steering turning right or sharp right bends.

Also just checked the suspension while parked and is easier to push down on the front nearside than offside and more bouncy.

I then measured the height between tyre and wheel arch and the nearside is 1.5 CM lower than the offside.

Are there any adjustments that can be made or does it need new parts? Could it be related to the AHC system/sensors?

Thanks.

There are quite a few threads on these issues, both on this forum and on mud. Read a bit, get an understanding of how the ahc/tems system works. Some of the advice given above here is inaccurate.

You really need the FSM and either TechStream or Toyota Tester to read the values of the ahc system in order to find out exactly what is wrong. And, after getting heights and Neutral Pressure right, you have to do a spheres-test by checking fluid level change from Lo to Hi by counting graduations on the reservoir.

Left/right lean is corrected by adjusting the torsion bars (the front steel springs), but you have to know the reading of the steering angle signal of the ahc ecu first, to ensure that the gate valve is open.

Without an electronic tester you can check that the link arms of the height sensors are ok. They sometimes get stuck in the joints, or fall apart; or the arm on the sensor becomes loose, making the sensor "see" only a part of the suspension movement. This latter issue can be because the sensor itself is stuck internally.
Common faults are:
Flat spheres (out of gas - lost pressure)
Faulty sensors (corrotion or worn carbon trace)
Loose, bent or broken sensor links
Cable broken (esp to height sensors)
Neutral Pressure out of range (either wrong height or weak steel springs)
Wrong fluid, leading to disintegrated rubber parts.

 

[apc01]

Thanks very much everyone for all your excellent comments and advice. A lot to absorb and check but I will get on with it.

One fact is certain - AHC leaves a lot to go wrong over time and miles. I definitely see the attraction of the suspension conversion kits such as Pedders. Anyone any comments or experience with those?

 

[BobMurphy]

I do have a question - does the system you describe only work when the car is switched on or does it work all the time? I ask because I measured and tested the suspension height and bounce with the car switched off.

The ignition has to be on - and the doors have to be shut !!

'uHu' is the expert and you should follow his advice, a Toyota Tester is invaluable (I have one and must set my AHC up properly as the Height Sensor readings are all over the place).

Its a lot more involved than conventional springs and shock absorbers .

Bob.