Hellish Bump Steer (MegaBlade)

[Numptie]

Paul Hurdsfield / neilb,

When you say Paul, do you mean Mr Helsby ?

Cheers,

N

[Paul Hurdsfield - Joint Manchester AO]

Yep he's the one  

He sold it because it didnt fit in with his new job  

He's taken up Hairdressing  

.

.

.

.

.

.

.

.

.

.

.

.

.

.

so he bought an Elise

[Mike-SEiW]

That isn't bump steer.

Not strictly speaking, but that's how it manifests itself in it's most obvious may to most average drivers (myself included). The answers are the same though........

I guess this is purely academic (and mostly to get the "archives" right), but I don't agree.

I'm not sure I would feel the effect of small bumpsteer problems over the effects of large scrub radius and (probably) a bit of toe-out, which are much "stronger" than a small amount of bumpsteer.

One of the few cars out there with zero scrub is the 14" wheeled MX-5 (think it was 90-95 models), if you've ever driven one of those you'll know what zero scrub means when you go over potholes and curbs. You feel it, but it doesn't rip your hands off the wheel the same way. When you put wheels with less offset on (original is 45mm), you start to feel the effect of more scrub. This I know from experience, I went as far as 30mm offset just to try it on my car.

YMMV of course and we're all different...

[Numptie]

so he bought an Elise

Yeah, I heard that. It must be a b******* when the cans of hairspray roll under the brake pedal

I've never actually met the chap. I bought it from the fella he sold it to.

Yup, no doubt it's a good 'un - it's a cracker !

Some pics here.

Cheers,

N

[Paul Hurdsfield - Joint Manchester AO]

Dont really need the pics......I helped him build it  

[Nick.Petty]

How weird's that, that is exactly the same steering wheel I have just ordered for mine ... be nice if Demon Twonks could actually get their arses in gear and deliver it. Apparently there is a problem in the supply from Italy.

Of all the steering wheels in all the world ....  

Now from your pics I can see what it will look like though, and I reckon I picked the right one.

Nicko.

[Mike-SEiW]

Apparently there is a problem in the supply from Italy.

well...I've been waiting for my Mychron 3 dash from Italy too. We're now into the third calendar month. I've been promised delivery on Friday....Italian style.

[Bazzer]

OK, this is the way I understand it.

Matt - I think your response is on the track of what I intended at the start.

I've only had the car a few weeks and the weather's not been conducive to spending time out with the car and trying different suspension settings.

The car was purchased from someone who'd had the car in a garage, used it on the odd fine day and never used it on track. He said he'd never touched the suspension.

So, in a nutshell, I don't know what I'm dealing with here. That's not very helpful to you guys since you don't know where you're starting from.

So, let's assume that the geometry is way off. My question is whether getting it set-up is likely to improve matters or whether this is something I've just got to live with. BTW, yes, I know that getting the geometry right is a must regardless of its influence on bump steer behaviour.

The dampers are currently set hard, as soon as an opportunity arises, I'll soften them up and give it a go. That sounds like an excellent start - thanks.

Cheers,

N

p.s. - please pay heed to my signature below.

Hmm

How stiff is the car setup ? Over stiff dampers can send the car hoping all over the place. My car was like this initialy and I though I was going to end up in a hedge.

The other thing that can happen is the car is soft enough but runs out of travel and hits the bump stop or tops out on the damper. This will obviously increase the damping momentarly to huge levels.

Bazzer

[neilb]

Dont really need the pics......I helped him build it

No need to upset the guy.......he seems quite happy with the car

[hilux]

One cause is the steering rack arm not being geometry not being correct

Bump steer is PRIMARILY caused by steering rack arms not being perpendicular to the actuating plane ie: at an angle that isnt horizontal to the rack.

If it is (and westfields arent bad believe me) then I`m sure its a tyre pressure/damper thang and is a jittery car rather than `bump steer`

Explain symptoms please, particularly damper settings, spring rates and tyre pressures.

[higgsti]

not having seen the car but met paul i would definatly say the car would have been set up correctly when he had it .i also have a megablade and after fitting new "13 wheels("15 originaly) i had similiar probs the tyre pressures were changed (thanks mr beeland)to 14psi i then wound the spax adjustables to the softest setting on all 4 corners i have since wound rears up 3 clicks and fronts up 4 what a difference this has made try this before you start spending any money on geometry setup etc. told you it was more entertaining than the scoob a far more entertainig drive .i once thought that if they brought out a faster car than the sti i would have it well they have the wr1 but i told the dealer when he was giving me first refusal on one of 5 alocated to them that i would rather spend my £9000 to change on the westy which they also service for me

[Megablade Paul]

Yep, looks like the car I built, did 3000 miles in and sold to guy from Wolverhampton. I don't think the issue is bump steer for a number of reasons - IMHO bump steer tends to be caused by poor initial design (not normally associated with Westfield products), secondly I was about to get a full geo set up by Playskool when I decided to sell so the car is set up by eye and using the settings Westfield specify in the build manual, a professional set up will make a big difference especially on track, thirdly it had AO32's on when I sold it which were on the legal limit so have they been replaced? I found that with the 205's on the front the tyres caused tramlining on poor surfaces (not pleasant when it try's to throw you into a hedge! Also tyre pressures are critical with such a light car I found it was happiest running about 16psi all round.

As some of the guys have kindly said, it was built sparing no expense or time and should only require a good geo set up before you start trying anything else.

The ARB's all round do tend to make it very stiff for the road so you may want to disconnect them and only use them on track and by the way the dampers are not Spax but Gaz.

Not sure who could do the geo up in Scotland but someone on here should be able to recommend someone. The advantage of going to a specialist who understands Westfields is that they will do it to your preference ie track driving and base the settings on the tyres fitted whereas if you go to the usually kwik fit type place they will set it up to what camber and toe and damper settings in you ask them to do (if you're lucky) Playskool are in Yorkshire but could be worth the trip if there are no specialists locally.

Regards

Paul

[Megablade Paul]

so he bought an Elise

Yeah, I heard that. It must be a b******* when the cans of hairspray roll under the brake pedal

I've never actually met the chap. I bought it from the fella he sold it to.

Yup, no doubt it's a good 'un - it's a cracker !

Some pics here.

Cheers,

N

There's a little net behind the seats for the hair spray so no danger of them rolling under the pedals

[Paul Hurdsfield - Joint Manchester AO]

You not workin' today Paul  

or are you just dossin' in the office  

[Megablade Paul]

Certainly not dossing in the office, no phones, email or access to the server in the office.

How's the house sale going Paul, any joy?