Monaro handling issues
Discussion
I have recently finished an 18 month overhaul of the underneath and running gear of my Monaro.
Pre the overhaul handling was predictable and for a big car it went round corner really well.
During the overhaul I replaced the rear inner and outer trailing arm bushes as the car has done 93K.
The inner has a new OEM bush and the outer has a new Pedder’s 5803 camber correction bush fitted. I also replaced the rear ARB bushes and drop links with polyurethane bushings. The rest of the rear suspension is as it was before the overhaul. (Custom springs, make unknown, and AVO adjustable shocks)
The handling has changed and not for the better, I feels like you have 200 litres of water slopping around in the boot.
The front turns in as I remember, positive and precise however the back feels like it is on a 1 second delay.
The only thoughts I have is the inner void bushes have the voids in the wrong position causing lots of movement?
Anyone on here with any experience of this combination of bushes on the rear?
Pre the overhaul handling was predictable and for a big car it went round corner really well.
During the overhaul I replaced the rear inner and outer trailing arm bushes as the car has done 93K.
The inner has a new OEM bush and the outer has a new Pedder’s 5803 camber correction bush fitted. I also replaced the rear ARB bushes and drop links with polyurethane bushings. The rest of the rear suspension is as it was before the overhaul. (Custom springs, make unknown, and AVO adjustable shocks)
The handling has changed and not for the better, I feels like you have 200 litres of water slopping around in the boot.
The front turns in as I remember, positive and precise however the back feels like it is on a 1 second delay.
The only thoughts I have is the inner void bushes have the voids in the wrong position causing lots of movement?
Anyone on here with any experience of this combination of bushes on the rear?
Full Hunter Geo done and all points are within tolerances. (set up to replicate my last Monkfish Geo results)
Front sub-frame aligned with the bent welding rod method and a tape measure, rear subframe has Polly bushes and again aligned as best I can with a tape measure. I don't know of anyone in the UK with the official alignment tools apart from what is now Pedders, and they do not provide any workshop type services anymore.
Ideally I would love to get the front and back alignment checked. However I don't think alignment is causing this particular issue. (but I could be wrong)
Front sub-frame aligned with the bent welding rod method and a tape measure, rear subframe has Polly bushes and again aligned as best I can with a tape measure. I don't know of anyone in the UK with the official alignment tools apart from what is now Pedders, and they do not provide any workshop type services anymore.
Ideally I would love to get the front and back alignment checked. However I don't think alignment is causing this particular issue. (but I could be wrong)
Because you have done so much work on your car this sound like you are going to have to check absolutely everything again....and again
When you fitted the control arm bushes and tightened every thing up, did you have the rear suspension at the correct ride height?
Failing that, as previously stated, do the simple stuff first, check tyre pressures, and may be swap the tyres around.
When you fitted the control arm bushes and tightened every thing up, did you have the rear suspension at the correct ride height?
Failing that, as previously stated, do the simple stuff first, check tyre pressures, and may be swap the tyres around.
Edited by mfp4073 on Sunday 24th June 09:01
Tyre pressure checked @ 36 psi
Tyres are the same as were on before the overhaul on the same corners (Front = Vredestein Ultrac Sessanta & back Vredestein Ultrac Vorti.)
The OEM inner bush does not appear to be adjustable, picture below. My though is the void in the bush has to go in a particular position in the arm and mine are in the wrong position.
Unfortunately like you say, I'm going to have to take it apart and compare the bush fitment with some known good arms or maybe change the bushes for poly.
I would have done that the first time but like all things Monaro even that is shrouded in mystery in you can fit all poly / you cant / you have to delete the toe link if you do.
Not the best picture but you get the idea. (you can see the void)
Tyres are the same as were on before the overhaul on the same corners (Front = Vredestein Ultrac Sessanta & back Vredestein Ultrac Vorti.)
The OEM inner bush does not appear to be adjustable, picture below. My though is the void in the bush has to go in a particular position in the arm and mine are in the wrong position.
Unfortunately like you say, I'm going to have to take it apart and compare the bush fitment with some known good arms or maybe change the bushes for poly.
I would have done that the first time but like all things Monaro even that is shrouded in mystery in you can fit all poly / you cant / you have to delete the toe link if you do.
Not the best picture but you get the idea. (you can see the void)
Edited by Global-i on Sunday 24th June 09:53
Global-i said:
Tyre pressure checked @ 36 psi
Tyres are the same as were on before the overhaul on the same corners (Front = Vredestein Ultrac Sessanta & back Vredestein Ultrac Vorti.)
The OEM inner bush does not appear to be adjustable, picture below. My though is the void in the bush has to go in a particular position in the arm and mine are in the wrong position.
Unfortunately like you say, I'm going to have to take it apart and compare the bush fitment with some known good arms or maybe change the bushes for poly.
I would have done that the first time but like all things Monaro even that is shrouded in mystery in you can fit all poly / you cant / you have to delete the toe link if you do.
Not the best picture but you get the idea. (you can see the void)
That void is definitely direction-specific.Tyres are the same as were on before the overhaul on the same corners (Front = Vredestein Ultrac Sessanta & back Vredestein Ultrac Vorti.)
The OEM inner bush does not appear to be adjustable, picture below. My though is the void in the bush has to go in a particular position in the arm and mine are in the wrong position.
Unfortunately like you say, I'm going to have to take it apart and compare the bush fitment with some known good arms or maybe change the bushes for poly.
I would have done that the first time but like all things Monaro even that is shrouded in mystery in you can fit all poly / you cant / you have to delete the toe link if you do.
Not the best picture but you get the idea. (you can see the void)
Edited by Global-i on Sunday 24th June 09:53
Maybe a Haynes manual or similar will show how it should be aligned.
Gary C said:
I would always dump void bushes for solid rubber if available and avoid poly.
Solid rubber gives similar compliance without the failure rate from tearing at the expense of NVH whereas poly can change the way the suspension responds,
I have a void bush engine mount in my not-monaro, and have secured short pieces of rubber hose in the voids, limiting travel while keeping some compliance. Polybushed engine mounts in that application can lead to tearing the firewall engine mount. Solid rubber gives similar compliance without the failure rate from tearing at the expense of NVH whereas poly can change the way the suspension responds,
Tyre are load rated at 93.
Just been out in her this afternoon for probably 75 miles and I am convinced its the trailing arm bushes.
Defo feels like the boot is full of water on turn in once it settles into the turn it feels planted again, it is just the transition that feels bad.
Also checked my Commodore Max Ellery's manual and there are no pictures of the bushes, the description on changing them has no mention of orientation, so more searching required.
Just been out in her this afternoon for probably 75 miles and I am convinced its the trailing arm bushes.
Defo feels like the boot is full of water on turn in once it settles into the turn it feels planted again, it is just the transition that feels bad.
Also checked my Commodore Max Ellery's manual and there are no pictures of the bushes, the description on changing them has no mention of orientation, so more searching required.
Edited by Global-i on Sunday 24th June 19:08
Global-i said:
Tyre are load rated at 93.
Just been out in her this afternoon for probably 75 miles and I am convinced its the trailing arm bushes.
Defo feels like the boot is full of water on turn in once it settles into the turn it feels planted again, it is just the transition that feels bad.
Also checked my Commodore Max Ellery's manual and there are no pictures of the bushes, the description on changing them has no mention of orientation, so more searching required.
Have a word with AASJust been out in her this afternoon for probably 75 miles and I am convinced its the trailing arm bushes.
Defo feels like the boot is full of water on turn in once it settles into the turn it feels planted again, it is just the transition that feels bad.
Also checked my Commodore Max Ellery's manual and there are no pictures of the bushes, the description on changing them has no mention of orientation, so more searching required.
Edited by Global-i on Sunday 24th June 19:08
Newcastle regarding which way the void bushes are to be fitted.
Ade
Edited by THUNDER STORM on Sunday 24th June 21:41
93 will give you a sloppy end , 95 is quite a bit better but still loose , i would tyre rotate and see if you get any change , i had a set of 93 rated kuhmos ku39 and it was shocking verging on dangerous , they are on the fronts now and things are much better , i have
95 vredstiens ? on the rear which is much improved
95 vredstiens ? on the rear which is much improved
I appreciate they're the same tyres in the same corners as before, but for what it's worth you are describing exactly the see-saw sensation I have experienced when putting different tyres on the rear.
First time was PSS on the front and a pair of Avon ZZ3s on the rear. Sold those on within 500 miles as it was horrible and felt dangerous. Sold them to Tempy on here who had ZZ3s all round and he was perfectly happy with them.
Currently I have PS4S on the rear, still with PSS on the front, and am getting a similar but much less drastic sensation, although it's still there.
Oddly a friend has the same mix on his M3 and it doesn't display the same traits at all, although his rears are the 265s and these have a higher load rating...
Anyway I've waffled on enough, just thought I'd chime in as it is the same sensation I've experienced and only ever had it because of a rear tyre swap, no other worn suspension components have caused the sensation.
First time was PSS on the front and a pair of Avon ZZ3s on the rear. Sold those on within 500 miles as it was horrible and felt dangerous. Sold them to Tempy on here who had ZZ3s all round and he was perfectly happy with them.
Currently I have PS4S on the rear, still with PSS on the front, and am getting a similar but much less drastic sensation, although it's still there.
Oddly a friend has the same mix on his M3 and it doesn't display the same traits at all, although his rears are the 265s and these have a higher load rating...
Anyway I've waffled on enough, just thought I'd chime in as it is the same sensation I've experienced and only ever had it because of a rear tyre swap, no other worn suspension components have caused the sensation.
Update, so today I checked the inner void bushes were installed correctly which they were.
Outer camber correction bushes also looked okay, & everything is tight.
In the interests of completeness I changed the wheels front to back, and blow me down problem resolved. So either I had forgotten or not noticed the issue before the overhaul, the offending tyres were almost new before I took it of the road. They may also have been on the front before, which I am sure they weren’t.
Anyway it is fixed. Good call all those that got it right.
Conclusion.
Vredestein Ultrac Sessanta 245-35-19 are good no issues front or back.
Vredestein Ultrac Vorti 245-35-19 do not handle well on the rear. (Good excuse for a drift day or something to get shot of em)
Strangely both sets of tyres have the same load rating of 93 although the Sessanta is described as 93 extra load.
Outer camber correction bushes also looked okay, & everything is tight.
In the interests of completeness I changed the wheels front to back, and blow me down problem resolved. So either I had forgotten or not noticed the issue before the overhaul, the offending tyres were almost new before I took it of the road. They may also have been on the front before, which I am sure they weren’t.
Anyway it is fixed. Good call all those that got it right.
Conclusion.
Vredestein Ultrac Sessanta 245-35-19 are good no issues front or back.
Vredestein Ultrac Vorti 245-35-19 do not handle well on the rear. (Good excuse for a drift day or something to get shot of em)
Strangely both sets of tyres have the same load rating of 93 although the Sessanta is described as 93 extra load.
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