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Hot!Bump Steer - what I never fully appreciated.

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TwoDogs
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2017/05/19 12:09:33 (permalink)
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Bump Steer - what I never fully appreciated.

My car has had bump steer for some time and I have read / ignored advice saying it can be dangerous. I would like to put an extra argument that the wear and tear on the steering linkages is significant, mandatory and will mean $$$ in the mid to long term.  Of course, if left long enough, a steering component could break and create some genuine adrenalin moments, but who would ignore the bad steering for that long?
Normally the steering linkages / rods work together one side pulling, the other side pushing due to the steering wheel being turned. When the wheels go up and down, horizontal forces going into the steering linkages are reasonably small. The only loads/ resistance coming from the tyres wanting to go straight ahead.
When there is bump steer, because the ride height has changed, there are undesirable, horizontal vectors (impacts) going into the steering rods and the connections between them. Much worse is when both front wheels hit a bump and forces enter L&R tie rods in opposing directions. Whack! The steering wheel doesn’t turn, but something has absorbed those significant forces. 
My steering linkages are worn, sometimes causing pulling to the side when braking and general vagueness in steering instead of “being on rails”. The more I’ve thought about it, I now realise it is caused by worn steering linkages which were caused by years of driving a lowered car.  Also I think I have been critical in my assessment of the Eibach springs as being too hard for Sydney roads, but now I think the steering linkages have been acting like bumpstops and restricting the wheels’ travel also, especially when both wheels hit at the same time. So I take back my assessment of the Eibachs for now. So I am going to fit some correction to the bump steer and replace worn components in the steering, then I'm convinced the car will be on rails and the Eibachs perhaps not as savage as I thought.
Those of you who know all this have obviously dealt with it by buying or building some bump steer compensation bits and pieces. I will do some research to see how easy that is to do. Any suggestions would be most welcome ?
 These really are sensational cars to drive.
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46 Replies Related Threads

    Phiz
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    Re: Bump Steer - what I never fully appreciated. 2017/05/19 12:32:16 (permalink)
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    TwoDogs
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    Re: Bump Steer - what I never fully appreciated. 2017/05/19 12:57:05 (permalink)
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    Thanks Phiz - looks like a good $$ solution for the front. When I get time I will look for similar for the rear also.
     I am planning on going to the next Syd meet at Rhodes, I think you said also, so hope to catch up then.
    cheers
    #3

    rikkir
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    Re: Bump Steer - what I never fully appreciated. 2017/05/19 13:36:45 (permalink)
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    Phiz
    https://technotoytuning.com/toyota/sw20/front-roll-center-adjusters-sw20-mr2
     
    :)


    I'll be interested on your opinion on these if you get them....

        Silver 1997 SW20 Bathurst with      

    #4
    TwoDogs
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    Re: Bump Steer - what I never fully appreciated. 2017/05/19 13:54:56 (permalink)
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     For sure, whatever I do, I'll update this thread.
     @Phiz -  these seem to be extension to lower where the control arm ball joint attach to the hub ...
     Is there something for the tie rod end as well ?
    #5
    Phiz
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    Re: Bump Steer - what I never fully appreciated. 2017/05/19 14:01:17 (permalink)
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    TwoDogs
     @Phiz -  these seem to be extension to lower where the control arm ball joint attach to the hub ...
     Is there something for the tie rod end as well ?



    No. Don't think its necessary either. But if you want a whole kit..
     
    http://wilhelmraceworks.c./suspension-geometry-kit
    #6
    TonyMR2
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    Re: Bump Steer - what I never fully appreciated. 2017/05/19 16:58:58 (permalink)
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    Street racers :) buy all the cool tuner parts :)

    Roll centre" has many opinions (suppliers and parts) and supporting studies. Different designs in the roll centre links bolt patterns, thickness - all with assumptions of how much you have lowered your car and other assumptions. Personally I liked the sonic boom however don't believe they are made anymore. It's not a blanket this is the fix for every mr2, some mr2 drivers have said over the years have not liked the handeling when installed (unsure if driver, set up, or what was the factor), nor is roll centre kit the only part required when the car is lowered.

    The rev3 had revisions to improve the handeling, look at the rear cross member and other suspension changes.

    Change the vehicles bushings is a given. On a 25+ year old car, many (all) suspension associated parts need to be replaced.

    Do a weekend driver training that helps your driving technique of a mid-mounted mr2.

    Keep the car on the road :)
    #7
    TwoDogs
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    Re: Bump Steer - what I never fully appreciated. 2017/05/19 17:24:03 (permalink)
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    Tony, did you read my initial post ?  I am not talking about street racing, I am talking about worn out steering components caused by bumpy, Sydney roads if the car is lowered, which mine was when I bought it.
    I always felt something was not right, in fact several things were not right and 1 by 1 the car is getting more excellenterer.  I wrote this, suspecting there may be others who endure the odd steering wheel twitch who may not realise that there is 'damage' occurring as well. 
       
     
    #8
    TonyMR2
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    Re: Bump Steer - what I never fully appreciated. 2017/05/19 17:42:56 (permalink)
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    U missed the humour - street racers

    25 year old car, previously flogged by young drivers who have often missed service items summarises a lot of mr2s... Agree with you, owners should be looking at the vehicle components for their condition.
    #9
    TwoDogs
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    Re: Bump Steer - what I never fully appreciated. 2017/05/19 19:31:27 (permalink)
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    Sorry Tony, yes I missed your humour. Yes indeed, I bought it from a young guy, and I think that he or someone before him had chopped the stock springs to lower the car on a stock damper unit. It was stuffed..so I got Koni inserts, which I like, with Eibachs, which have so far been too firm, but now I realise the bangs are probably not due to spring rate alone.
    #10
    Eric
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    Re: Bump Steer - what I never fully appreciated. 2017/05/19 20:55:15 (permalink)
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    Hey TwoDogs,
     
    Have you replaced the front tie rod ends to start with? I found mine had a fair bit of play which gave quite a vague feeling and it increased the bump steer feeling. 

    My car is lowered on very stiff coilovers and I only notice bump steer when I go too long without a wheel alignment.

    Good rule of thumb when looking at the suspension arms is that they should be at a 90 Degree angle from Vertical. 
    if you go any lower the angle will decrease and this is when it becomes quite noticeable. 

    Hope this helps

    -Eric
     

    1990 SW20 Hardtop - Supercharged 2GR-FZE
    #11
    5SGTE
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    Re: Bump Steer - what I never fully appreciated. 2017/05/19 21:01:40 (permalink)
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    Interesting topic. Mines always had a slight vibration at 95ish. I've never actively tried to solve it, as it's not too bad.

    However the car has had the rack rebuilt, new tie rod ends, ball joints, coilovers, bushes and many tyres over the years. I've on occasion considered I may be increasing wear.

    I really should look into it more.
    #12
    TwoDogs
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    Re: Bump Steer - what I never fully appreciated. 2017/05/19 21:17:45 (permalink)
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    Hi Eric,
     
     yes I had a tie rod replaced a year or so ago. I am having all components checked this week. I would not be surprised if the report comes back that ball joints, bushes and/or other tie rods should be replaced. You seem to be saying that the tire rods contribute to the bump steer. I am suggesting it is the other way round. Bump steer, if left, will create wear in the whole steering system..
     5sgte - I also had vibrations in my steering wheel, now solved. I needed hub centric rings plus discs machined. 2 separate vibrations.
    #13
    5SGTE
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    Re: Bump Steer - what I never fully appreciated. 2017/05/20 12:06:47 (permalink)
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    My rotors have done less than 2000km. I however don't have hub centric rings installed. I do have an assortment on the shelf so I should experiment. Thanks, would be nice if it was smooth.
    #14
    TwoDogs
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    Re: Bump Steer - what I never fully appreciated. 2017/05/20 18:11:01 (permalink)
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    @5sgte - you don't need to experiment. The internal diameter is 62mm and the OD is... whatever you measure the big hole in your wheels.
    #15
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