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MG MGF Technical - Steering Geometry

Hi, just a quick one for the experts amongst us.
Elise Parts are selling both steering racks, and (longer?) steering arms that optimise front geometry and negate bump steer.
Firstly, what does that mean?
Secondly, would different (to standard length) steering arms improve the MGF/TF steering feel?
Thanks again
John Reed

Hi all,
Yet another quick one.
I'm thinking of having a spare pair of rear tie bar's fitted with spherical bearings at the bar to subframe joint instead of bushes.
This should limit the front and back movement of the rear wheels to the slack/compliance of the tie bar/bottom bracket bush.
Will the remaining bush be sufficent to limit NVH transfer to an acceptable level?
Or will it just shake the subframe apart?
your thoughts and comments would be welcome!
Happy weekend
John Reed

I presume that the eliseparts steering rack is for the Elise? The Elise rack is different to the MGF item.

Bump steer describes how toe angle changes over the arc of suspension movement, as the steering arm acts as a part of the suspension assembly. Too short arms will pull the wheel in at extreme ends of suspension movement - giving excess toe-in if the rack is mount forward of the front wheel axle, or toe-out if mounted behind.

There's more on this here:

Hope this helps
Rob Bell

Thanks again Rob,
I guessed the elise rack was different to ours, simply because we'd all have fitted them.
I was startled to find that the boy's at Hethel had left room for improvement in this area, and elise parts offer optimised rack and steering arms to compensate for this.
I had read your site on tracking and understand the reasons why the relationship between rack and the position of its joints in relation to the wish bone pivet points, effect wheel position.
I had the idea that 10mm longer steering arms would alter/reduce the steering effort needed to turn the wheels one way or the other, but then, 10mm shorter steering arms may improve the steering responces, have limited effects on toe in and camber, and might just be the answer to this elusive last bit of improved steering feel and responce after a TF rack, bushes and mounts are changed.
It is only an idea (loosly based on fact), but im thinking of having a pair of 10mm smaller one's made up in aluminimum (less unsprung weight) and find a driver who knows his onions (ie, any one brave enough) to try them out,
let me know what you think
John Reed

Why not sound out the very nice chaps at VHS? They're the guys who designed the suspension on our cars in the first place, so should be ideally placed to answer this. Their contact details can be had through their website:
Rob Bell

Yeah, i had that same thought just as i posted the last reply (they really are the guru's in this field)
If it were that simple, they would have done it years ago, I think this one might just be an over active imagination on my part, but i'll ring them(if only to get laugthed at!), i need to order their lowered seat base, my lowering springs are bouncing me out of the seat at higher speeds or larger pot holes.
John Reed

I need their lowering seat kit too! LOL Must get around to that sometime soon... :o)
Rob Bell

Hi Rob,
I emailed VHS instead of calling (well no one likes getting laughed at!)I was sure a heard a stifled snigger even in Newbury.
I'll let you know what they say, but the more i mull it over the dafter it sounds!
Shorter steering arms and spherical jointed suspention members (or solid aluminium tie bar bushes, hmm?), what am i like eh?
I dont think even hard core racers have this set up out side of F3!
Not my best what if, and i really dont want to upset the chaps at VHS either, they are respected specialists.
John Reed

No harm in asking John! :o)

VHS have a sprint car on which they've heavily modified the geometry on (it has wider tracks too - and I do wonder how close it mimicks the TF2 prototype that MG Rover were developing before the company folded? More on that project here:
Rob Bell

please stop doing this!
I'm inches away from taking out a loan to commision some square 6 spoke wheels in 17" as it is,
How i want a bolt on subframe conversion with uneven length wishbones, a 2.4 rack and wider track, and I'm asking paint magic in reading to quote for a bonnet radiator vent conversion,
and you so me a picture of a Coupe!
My wife already thinks im having an affair, mind you, emailing chinese companies about "one off" services didnt help! and i promised i wouldnt log on tonight, to prove i'm not addicted to the forum!
help me!
john ;-)
John Reed

If we get a few TF's,
We'll approach S+D to make the TF2 body kits,
Alter the radiator vent to the bonnet,
Have VHS make 25mm longer wish bones and finally get a 2.4 rack fitted,
mount the front suspention (or subfame)further forward (50-100mm?),
Stiffen the whole lot with a front to rear subframe crusifix,
fit the k2000 engine, ( 3 tune stages 120ish 180ish and 220ish)
fit the quafe 6 speed pg1 box (LSD optional,sequential shift optional,)
develope a coupe,
call it the Mine Get off Hi performance(MGH) and the Mine Get off Hi performance Coupe (MGHC),
and sell it for 10kish less than the mid range (30k ish) boxster and cayman.
easy eh!
Let NAI sell the regurgitated TF,
and we'll have a real alternative to the Elise (great, but too hardcore)and Boxster( Great but, too, well, sterile?).
and i promise to use the profits to develop a real midget model!
John Reed

John, it's too late! You're addicted! LOL ;oD

I've already approached S&D regarding GRP panels. They're certainly interested in the standard panels, but not in a vented bonnet unfortunately. But if an individual were to stand the cost of the moulds, they'd be delighted to do what ever was asked! Unfortunately, a loft conversion means that my funds are thoroughly tied up, but I am sure that there would be a market in "200HPD" panels, such as the bonnet and side scoops.

Judd K2000 engines are just a little too expensive. But 1.9 litre blocks are readily available. Dave Livingstone I think has the first 1.9 litre VVC! Before the capacity increase, it already had around 180bhp with a DVA ported head... no idea what it has now!

I've got a Mini Cooper S 6-speed Getrag gearbox in the garage (100 quid off fleabay) that's awaiting some measuring up - hopefully it'll fit with minimal modifications to mounts etc; Rover used Getrag 'boxes with K-series engines in the ZT/ R75 ranges :o)

LSDs are readily available for the PG1 gearboxes - you need one from a Rover 220 or 620 turbo - they're the nice Torsen torque biasing units :o)

TF2 spec suspension? I am sure that VHS could help us out if we wanted to go down that route...

It's all worryingly "do-able" isn't it? ;o)
Rob Bell

I really am raking over old coals, arnt I!
I was so proud of that little rant,
only to find youve already been there!
But on a serious note.
Picking up a rear tf ARB+links to develop a droplink which allows fitting to the F. (Then meeting a fabricator.)
and a secondhand head light to strip down to get some dimentions to a company in china.
It'll take a bit of time but we'll get their with this, i promise!
Any more bright ideas stanley?
John ;-)
John Reed

Not really raking over old coals John - just good ideas! :o)

Do you know any fabrication companies?
Rob Bell

Hi Rob,
Been away fitting showers and fixing leaks at my mothers, why cant parents use the yellow pages?
My uncle is a foreman at a fabrication place, but looks like he'll be made redundent next week.
Im trying to get him into the idea of me setting him up and fabricating our ideas for parts, but hes not keen, and just wants me to send blue prints off to fabrication works in china.
At this time we have,

Tie Rod Bars with spherical bearings/rose joints and stainless fittings/ washer and nut.

Stainless Steal exhaust bush/heat sheild bracket and the curved heat sheild strengthening bracket(the one which rivets onto the heat sheild) Due to curves, these might be made in alloy instead, but pick up stainless proto types tomorrow.

F to TF rear anti rollbar Droplinks, (Should pick up a pair tomorrow.)

And anti roll bar bush clamps in stainless steal or alloy, i wanted stainless, but again the curve may rapidly wear out the moulds/template.

And, the headlight company are getting back to me tomorrow. but no matter what the outcome, i'll be using there parts to make up a kit to replace both bulbs with a large and a small projector, with and without the misteron halo, (does anyone know the cost of resilvering and laquring the reflectors with p+p charges? )

John Reed

Dual metalising do the MGF standard reflectors for 70 quid plus P&P (which I don't think is an excessive amount).

Good work - will be very interested to hear how this pans out :o)
Rob Bell

Hi All,
Interesting to see the 'new' TF 85 has anti bump steer spaces! (and bonkers wheel sizes! they do look good though!)
not longer or shorter steering arms!
Typical eh, bringing a football to a cricket match! (more like knife to a gun fight, bum:-(.)
close, but no cigar!
Anyone tried spacers yet?
If I make up some spacers, does anyone feel (brave)like trying them out?
Thanks in advance
John Reed

I'd try them on the Shed John :o)

Where do the spacers fit - and do you have any more information on them?
Rob Bell

Hi Rob and All,
I love the fact that you think its optional Mr bell, you are my Stig!
Is project Shed on F subframes?
If so, coming your way is spherical (Rose) jointed Tie bars(less rear wheel front back motion under hard braking and acceleration, slightly more NVH transfered to cabin) with Flat Washers to mate properly with the flat face of poly bushes, and shanked bolts to act as an axis pin, instead of standard bolt threads to inner bush gap/ erosion.
(Im in the process of having 3mm thicker than standard washers made up in stainless steel for those with standard bushes and / or replace compliance washers at the same time, ie only one washer and its shiny! im such a kid!)
The steering arm shims are a mix of science and a bit of art.
as you corner, the outer front side dips with weight transference, coursing the front steering geometery to develop its intended/ designed (and build quality intolerences add to this) safe state of Toe Out,
so the inner wheel is pointing as normal around the corner, and the outer wheel is pointing straight on(ish).
This gives the car its turnin once, then add abit more lock mid corner characteristics.
The next time you have your tracking done by laser, ask the lads/lass to leave it set up and whatch the values change as you pull down on the front anti roll bar!
Last night mine changed by 1.2 degrees, and that was only a gentle pull, ie not my whole body weight.
This value will differ car to car, left to right and ride height to ride height.
However, this arc of toe in/out movement can be "tuned" by rasing or lowering the steering arm joints position relative to the steering racks joints position.
So armed with a "pack" of different thickness shims to raise the steering arm up from the hub carrier. you can eliminate the mid turn in vagueness/ turn in, then turn in some more.
Any questions?
This bloody car will get me divorced!
off to water garden.

John Reed

Given that the Shed is intended for the track more than the road, a bit more noise and vibration here and there are no problems John :o)

Drop me an email :o) Would rather go rose-jointed than polybush, which is/was on the agenda for the car anyway...

Cheers :o)
Rob Bell

This thread was discussed between 10/06/2009 and 05/07/2009

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