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Steering wobble
dave107 - 5/11/18 at 06:02 PM

Hi guys

Havenít been on here for ages. Now want to spend the winter preparing my car for first MOT and using car more next year. Has anybody got any clues as to why when I decelerate for 70ish 😁 I get very bad front sideways wobble which is very unnerving, car is an MNR bike engine with inboard front shocks and suspension ride height is set 10 cm front and back.

Welcome any help.


AdamR20 - 5/11/18 at 06:09 PM

Ride heights are well out, air will be going under the nose and lifting it. If those heights are taken without you in the car it'll be even worse. Try raising the rear 30-40mm and dropping the front 10mm if you have room under the sump.


steve m - 5/11/18 at 11:06 PM

My car has 10cm clearance front and back, and doesn't have the wobble described, so I don't think that is the cause

steve


AdamR20 - 6/11/18 at 05:44 AM

Is it an MNR though?


Mr Whippy - 6/11/18 at 06:46 AM

Rust patches on the disk?

Worn lower balljoints?

Disks not running true?

Play in the steering?

Excessive lip on the disk edges?

[Edited on 6/11/18 by Mr Whippy]


dave107 - 6/11/18 at 07:45 AM

Thank you for suggestions. When I built the car I did set the Back higher than the front, car then went off to MNR so they could get it dinotuned and while they had the car get it IVA, when I got the car back ride height was changed to 10cm front and back.
I think when I set the ride height I had 12cm back and 9 cm front but hadnít road tested.


Mr Whippy

Front of car only wobbles on deceleration no braking involved. All brak parts are basically new as Iíve done very little mileage.


russbost - 6/11/18 at 08:07 AM

What's the tracking set at? Have you had a thorough check of everything that could move when you lift off the throttle, for instance you could have movement on an engine mount that's allowing the engine to rub against a steering shaft or something weird like that, but I would start with a thorough check of the front suspension in both loaded & unloaded conditions & see what moves


AdamR20 - 6/11/18 at 11:27 AM

So it's upon throttle lift at speed?

Is it instantaneous or happens throughout deceleration? Does it do it when you brake? And same question again?


nick205 - 6/11/18 at 11:59 AM

I'm with "russbost" on this to check all the steering joints (loaded and unloaded) first to see if there's any unwanted movement in any of them. Apart from brake judder I've usually found steering wobble is down to unwanted movement in a steering joint somewhere (ball joint or bush etc.).


Mr Whippy - 6/11/18 at 12:38 PM

little caster and little steering damping (worn rack) can cause alarming steering wobble just as Landy owners


dave107 - 19/11/18 at 01:36 PM

sorry for late reply's ive been away with work. Ok thanks all for ideas plenty to look at, this is something i shall get on with over the winter, and when i find the reason i shall let you know. one thought iv'e had is that my toyo R888 tyres are now 10 years old (but look like new) and although ive only done 200 miles in 10 years, i have been advised to get some new tyres as they have not been used enough and could fail at any time.

thought please.


Slater - 19/11/18 at 02:26 PM

I had a similar thing recently, the back end would shimmy/corkscrew when lifting off from 70 mph. I checked all the suspension, wheel hubs, nuts etc thinking something was loose. It turned out to be my damper settings (Gaz adjustable) on one damper was wrong. Once I corrected the setting it stopped doing the shimmy.

Not sure how the setting got changed in the first place though. Another thing to keep an eye on.


JAG - 19/11/18 at 03:35 PM

R888 tyres....

Old tyres will have less grip than brand new tyres but otherwise I would expect them to be OK.

Usual caveats apply; check them for flat spots, chunks of rubber missing, bulging in the sidewalls and other damage etc...

If you find none of the above and can live with a bit less ultimate grip then I'd carry on driving on them.