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Signs of a failing LSD? Car Unstable at Speed..

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Old Apr 5, 2019 | 07:39 AM
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Icon4 Signs of a failing LSD? Car Unstable at Speed..

Hi guys. I have an MB6 which is a uk only civic. Its running a b18c4 with an S9B gearbox. Its roughly 600hp.

Now when at WOT in 3rd onwards the car is super unstable and wonders all over the road. Its basically unusable.
I have changed almost everything, all bushes and balljoints, tyres and alignment etc.

Im starting to think its the diff...Has anyone got any experience of a failing LSD causing a high powered FWD car to exhibit these issues?
It feels like its shuffling the power from one wheel to the other.

Thanks in advance.
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Old Apr 5, 2019 | 08:17 AM
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Default Re: Signs of a failing LSD? Car Unstable at Speed..

Do you have a traction bar?
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Old Apr 5, 2019 | 08:32 AM
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Default Re: Signs of a failing LSD? Car Unstable at Speed..

Originally Posted by Balor_Gr
Do you have a traction bar?
No i don't.
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Old Apr 5, 2019 | 08:40 AM
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Default Re: Signs of a failing LSD? Car Unstable at Speed..

The "changing lanes" prolem MANY times can be solved with a traction bar.
Not sure about LSD malfuntion tho dont want to bet it doesnt do it when it goes bad.
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Old Apr 5, 2019 | 08:45 AM
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Default Re: Signs of a failing LSD? Car Unstable at Speed..

A damaged LSD like toren Honda LSD won't show those symptoms of failure. This sounds more like a sway bar , or tie rod issue
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Old Apr 5, 2019 | 08:49 AM
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Default Re: Signs of a failing LSD? Car Unstable at Speed..

Originally Posted by TheShodan
A damaged LSD like toren Honda LSD won't show those symptoms of failure. This sounds more like a sway bar , or tie rod issue
hmm
Cant see the ARB affecting it as i just want to go straight. That only comes into play when turning, right? Tie rods are perfect. Brand new polybushes all over also.
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Old Apr 5, 2019 | 11:11 AM
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Default Re: Signs of a failing LSD? Car Unstable at Speed..

Can you measure if the front left with the back left and front right with the back right wheel are at the same distance?
I had some simila issues with wide tyres and too a littel bit too much camber on the front tyres. The car would rest either on the left tyre or on the right tyre if this makes any sence
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Old Apr 5, 2019 | 12:10 PM
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Default Re: Signs of a failing LSD? Car Unstable at Speed..

With the helical LSD that the S9B uses (same as the ITR LSD); power transfer from side to side and eventually it will go nowhere as if the car is in neutral.
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Old Apr 5, 2019 | 02:09 PM
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Default Re: Signs of a failing LSD? Car Unstable at Speed..

Originally Posted by Aquafina
With the helical LSD that the S9B uses (same as the ITR LSD); power transfer from side to side and eventually it will go nowhere as if the car is in neutral.
could you please expand? Are you saying that the problem i am having could be the LSD or not?
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Old Apr 5, 2019 | 02:14 PM
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Default Re: Signs of a failing LSD? Car Unstable at Speed..

Originally Posted by vtisturbo
could you please expand? Are you saying that the problem i am having could be the LSD or not?
In other words, no, it's not your LSD. What the post says is your LSD transfers power from side to side as needed. if it were a bad LSD, you wouldn't go anywhere as it would behave like the car was in neutral.

**Unless I read it wrong?**
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Old Apr 5, 2019 | 02:17 PM
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Default Re: Signs of a failing LSD? Car Unstable at Speed..

Originally Posted by Txdragon
In other words, no, it's not your LSD. What the post says is your LSD transfers power from side to side as needed. if it were a bad LSD, you wouldn't go anywhere as it would behave like the car was in neutral.

**Unless I read it wrong?**
Thats how an open diff works not an LSD...the point of a helical LSD is that it transfers power equally to both wheels..
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Old Apr 5, 2019 | 03:27 PM
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Default Re: Signs of a failing LSD? Car Unstable at Speed..

Originally Posted by TheShodan
Is this an OEM LSD?
Yes OEM.
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Old Apr 5, 2019 | 04:25 PM
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Default Re: Signs of a failing LSD? Car Unstable at Speed..

Originally Posted by vtisturbo
could you please expand? Are you saying that the problem i am having could be the LSD or not?
Sorry, that was a poorly written response.

Under normal driving in a straight line the LSD will not be transferring power side to side, your issue there is not with the LSD. When a helical LSD wears out the car will not move under its own power.
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Old Apr 6, 2019 | 12:09 AM
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Default Re: Signs of a failing LSD? Car Unstable at Speed..

Originally Posted by Aquafina
Sorry, that was a poorly written response.

Under normal driving in a straight line the LSD will not be transferring power side to side, your issue there is not with the LSD. When a helical LSD wears out the car will not move under its own power.
Thanks,
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Old Apr 6, 2019 | 12:36 AM
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Default Re: Signs of a failing LSD? Car Unstable at Speed..

Originally Posted by Balor_Gr
The "changing lanes" prolem MANY times can be solved with a traction bar.
Not sure about LSD malfuntion tho dont want to bet it doesnt do it when it goes bad.
Do these help with high speed stuff though?
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Old Apr 6, 2019 | 04:45 AM
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Default Re: Signs of a failing LSD? Car Unstable at Speed..

Originally Posted by vtisturbo
Do these help with high speed stuff though?
when installed and adjusted properly, yes, they help a LOT. The more power the car makes, the more a traction bar becomes necessary
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Old Apr 6, 2019 | 04:47 AM
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Default Re: Signs of a failing LSD? Car Unstable at Speed..

Originally Posted by motoxxxman
when installed and adjusted properly, yes, they help a LOT. The more power the car makes, the more a traction bar becomes necessary
but from everything I’ve read it’s more for drag cars. Helps with launch and traction etc. .
my issues come after 80mph..
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Old Apr 6, 2019 | 10:13 PM
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Default Re: Signs of a failing LSD? Car Unstable at Speed..

Originally Posted by vtisturbo
but from everything I’ve read it’s more for drag cars. Helps with launch and traction etc. .
my issues come after 80mph..
Traction bars reduce/eliminate front/rear LCA flex. Civics that don't have a traction bar are relying on just the bushings to reduce flex. And even poly bushings still flex, they just flex less than stock style rubber bushings. When the LCA (lower control arm) flexes front/rear, you are essentially altering the caster. camber in itself causes steering pull to one side or the other. But when caster changes, it also affects camber and toe due to the geometry of everything, both of which also cause steering pull. The faster you go, the more of a pull you will feel. Also, if you run boost by gear, or you have a large turbo, you typically aren't putting down peak torque until you're in 4th gear (~80mph applies here).

I don't think I saw a hp figure anywhere in this thread. If you're over 300hp though, you definitely should get a traction bar.

Last edited by motoxxxman; Nov 9, 2019 at 08:30 PM.
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Old Apr 7, 2019 | 01:21 AM
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Default Re: Signs of a failing LSD? Car Unstable at Speed..

Originally Posted by motoxxxman
Traction bars reduce/eliminate front/rear LCA flex. Civics that don't have a traction bar are relying on just the bushings to reduce flex. And even poly bushings still flex, they just flex less than stock style rubber bushings. When the LCA (lower control arm) flexes front/rear, you are essentially altering the camber. camber in itself causes steering pull to one side or the other. But when caster changes, it also affects camber and toe due to the geometry of everything, both of which also cause steering pull. The faster you go, the more of a pull you will feel. Also, if you run boost by gear, or you have a large turbo, you typically aren't putting down peak torque until you're in 4th gear (~80mph applies here).

I don't think I saw a hp figure anywhere in this thread. If you're over 300hp though, you definitely should get a traction bar.
yeah I said In the OP. Im 600hp.
Thanks for the info.
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Old Apr 7, 2019 | 06:32 AM
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Default Re: Signs of a failing LSD? Car Unstable at Speed..

Originally Posted by vtisturbo
Thats how an open diff works not an LSD...the point of a helical LSD is that it transfers power equally to both wheels..
I was NOT differentiating between the types, merely making that post clearer for you..
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Old Apr 15, 2019 | 11:40 AM
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Default Re: Signs of a failing LSD? Car Unstable at Speed..

Originally Posted by vtisturbo
Hi guys. I have an MB6 which is a uk only civic. Its running a b18c4 with an S9B gearbox. Its roughly 600hp.

Now when at WOT in 3rd onwards the car is super unstable and wonders all over the road. Its basically unusable.
I have changed almost everything, all bushes and balljoints, tyres and alignment etc.

Im starting to think its the diff...Has anyone got any experience of a failing LSD causing a high powered FWD car to exhibit these issues?
It feels like its shuffling the power from one wheel to the other.

Thanks in advance.
Have you checked the welded nuts in the subframe that hold the lower control arm?
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Old Apr 24, 2019 | 02:54 PM
  #22  
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Default Re: Signs of a failing LSD? Car Unstable at Speed..

Originally Posted by TimeAttackR
Have you checked the welded nuts in the subframe that hold the lower control arm?
No, but im sure they are ok as it would show up come alignment time right?
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Old Apr 24, 2019 | 05:14 PM
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Default Re: Signs of a failing LSD? Car Unstable at Speed..

It won't appear until you put load on the powertrain.
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