IS F (2008-2014) Discussion topics related to the IS F model

Top mount orientation

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Old 07-31-17, 02:02 PM
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UKF
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Default Top mount orientation

Hi guys,

Recently changed out my BCs for some Bilstein B6 dampers on OE springs. Now I have done some more miles with the car I have noticed a drift to the left which was not there when I had the BCs on. Wheel alignment has been done however not got any Caster readings however I have a feeling that maybe the top mounts have not been installed correctly. I am reading that most top mounts have arrows to indicate which way they should be fitted. Anyone shed any light on which way the arrows should be pointing on the ISF top mounts?

Thanks
Old 08-01-17, 04:21 AM
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UKF
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Hi, found this on the onine Haynes manual regarding the correct top mount orientation.

http://workshop-manuals.com/lexus/is...ber/page_6425/

can anyone take a pic of their OE top mounts so I can comprehensive with mine? The only indication marks I can see on mine are a yellow and blue dab of paint. They are not facing outwards to each respective side as above. Just want to check with another early ISF.
Old 08-03-17, 09:00 AM
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UCrazyKid
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I've been following your installation of these. Sorry to hear you are having issues. I don't know the answer to your question but I would be suspect of this as well. I will take a look at mine when I get a chance and let you know if I can see the paint you describe and note the orientation they are in on my car ('08).
Cheers,
AA
Old 08-04-17, 06:05 AM
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They did an alignment but didn't get a caster reading? It's part of the process to do a caster sweep with any Hunter alignment rack...
Old 08-04-17, 06:17 AM
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UKF
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Yes tell me about it. Going back in on Monday to get the strut mounts positioned correctly but the car is not right at the moment. Cars pulls to the left considerably and very unsteady at motor way speeds. Also when doing a left turn the steering wheel does not return to center, stops at about 22:00. Car was fine before the suspension change. So the work done has caused the issue. Can the top mounts not being in their correct orientation cause the problems above or could it be something damaged during the strut change over?
Old 08-05-17, 11:54 PM
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Changing the shock mounts will change nothing at all. This isn't a strut suspension.

There are many things that could have been done incorrectly to cause your issues, but the orientation of the shocks isn't one of them.
Old 08-06-17, 02:28 AM
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If the top shock mounts were put in wrong maybe they are putting pressure on some of the bushes causing it to pull, I have not pulled apart the ISF suspension but I have had a good look at it, the shock spring setup is independent to the suspension arms I hope this makes sense to you, I hope you put the right shocks in, let us know what you find cheer.
Old 08-06-17, 02:52 AM
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Originally Posted by lobuxracer
Changing the shock mounts will change nothing at all. This isn't a strut suspension.

There are many things that could have been done incorrectly to cause your issues, but the orientation of the shocks isn't one of them.
Thanks for the reply Lobux, I suspect you maybe correct, but why would Lexus specify the indicators on the shock mounts need to point in a specific direction as in the instruction link above ?

I'm going to swap the front wheels side to side first to see if its a tire problem but Im leaning towards maybe a castor/alignment problem. When I was running on the BCs the car was lower and running more
aggressive camber at the front then now. I'm not hearing any untoward noises from the suspension so everything seems tight but something is pulling the steering wheel from center to the left.
Old 08-06-17, 02:58 AM
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UKF
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Originally Posted by isfvss
If the top shock mounts were put in wrong maybe they are putting pressure on some of the bushes causing it to pull, I have not pulled apart the ISF suspension but I have had a good look at it, the shock spring setup is independent to the suspension arms I hope this makes sense to you, I hope you put the right shocks in, let us know what you find cheer.
Yes the OE springs and mounts were put on the B6 shocks, I have checked the shock part number which are correct. But as you say there is a possibility something was not put back together correctly when mounting the springs and top mounts, However the shocks and mounts are silent, there is no noise or knocking.

I've also read that after suspension work and alignment its advised to do a zero point calibration on the steering which resets the steering angle and yaw sensors however I suspect that is not the issue as I have no lights on the dash to suggest so.
Old 08-06-17, 05:26 PM
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Originally Posted by UKF
...I've also read that after suspension work and alignment its advised to do a zero point calibration on the steering which resets the steering angle and yaw sensors however I suspect that is not the issue as I have no lights on the dash to suggest so.
This is correct, and you will never see a CEL or MIL or DTC related to this unless the yaw sensor is completely dead. The FSM says to reset yaw zero point after any and every alignment.

Honestly, I'd be a lot more concerned about the bushings being set to a neutral position on any suspension install with OEM bushings. They act like springs when they are loaded, and can have significant negative impacts on handling if they are not at a neutral position at normal ride height.

Last edited by lobuxracer; 08-06-17 at 06:25 PM.
Old 08-07-17, 06:04 AM
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Originally Posted by lobuxracer
Honestly, I'd be a lot more concerned about the bushings being set to a neutral position on any suspension install with OEM bushings. They act like springs when they are loaded, and can have significant negative impacts on handling if they are not at a neutral position at normal ride height.
It's scary how many people don't know this, and/or even damn techs tighten suspension components with the car on a rack and not preloaded. I always used a screw jack to set the control arms to neutral prior to torquing hardware.
Old 08-07-17, 02:53 PM
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Hi, update.

So top mounts were re positioned as outlined in the workshop manuals, bushes were pre-loaded. Car is now driving spot on, all the issues I was having have been resolved, will go for a final alignment check after a few weeks to fine tune. Here is a pic showing the ride height on the B6 Bilsteins on standard springs, i think the shocks have settled in now as the car looks a little lower than when the shocks were brad new. I think its at standard ride height now, needs a wash !


Old 08-07-17, 04:41 PM
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Great news, what tyres and size are you using, the ride height look the same as mine, and how do you like the Bilstiens. And what year model , don't bother with a alignment if its driving spot on there is only toe adjustment Have you got RR,s USRS bush's, I'm about to order a set been waiting for the OZ dollar to rise but I'm sick of waiting, sorry for all the questions there's a fine line between obsession and enthusiast
Old 08-07-17, 04:48 PM
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Originally Posted by isfvss
Great news, what tyres and size are you using, the ride height look the same as mine, and how do you like the Bilstiens. And what year model , don't bother with a alignment if its driving spot on there is only toe adjustment Have you got RR,s USRS bush's, I'm about to order a set been waiting for the OZ dollar to rise but I'm sick of waiting, sorry for all the questions there's a fine line between obsession and enthusiast
Hi. Car is running standard tyre sizes for a 08 car. 225 fronts and 255 rears. Yes I have the USRS bushes. The Billys feel nice, adds the composure the car was missing on OE shocks. They ride a lot better on the roads I travel than my BCs and they are totally silent.
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