2b Front Suspension Dimensions

[Mat-Moo]

Can someone help me out with this I'm trying to work out if I can use the double wishbones from the 2b on my onld Exmo... if I can get the measurements below I should be able to work it out. BTW is I have anything worng, let me know as I can't see any documents showing the suspension, just a few pictures.

[Guest TerryBarry]

Hi Mat,

As requested the dimensions are ( in cm) :

A = 24.8

B = 55.8

C = 14.0 to centreline of rack 9.5 to edge of mounting plate

D = 67.2

E = 14.1

F = 29.0 external & 19.5 internal

G = ~9.5

B & D are the width of the metal plate not distance between mounting holes

 

If you want a look I'm in central Camberley (please e-mail me)

 

Terry

[Mat-Moo]

Thanks - b is smaller than I had hoped Are you on the road? any chance you could pop over some time (I'm only down the road in Cove/Farnborough)

[Guest TerryBarry]

Hi Mat,

On the Road ?? At the moment it's a chassis with two rear wheels.

With luck and a good wind may be a rolling chassis in a few weeks.

I know that Cove is reasonably close but it's a long way to push it.

Regards,

Terry

[Mat-Moo]

HE HE - If your willing I'll accept otherwise perhaps I should visit you instead then!

[Guest TerryBarry]

If you'd made that suggestion last week I could have put a bucket on the chassis, a wig on my head and collected money for Comic Relief on the way.

Terry

[Mat-Moo]

Is it possible for anyone with this (2b+) suspension kit to measure up the mishbone details for me? I need some accurate dimensions (well pretty close anyway!) and also the sizing of tube used etc.

[Guest Richard Banks]

Mat,

If the standard RH 2B wisbones are of no use, may I suggest you speak to bob@RSjigtec.co.uk who fabricates the conversion kits for the 2B. If you can supply all of the info on the mkIII, he may be prepared to make a few "one-offs" for you. Tel 01384 636636

Regards, RB

[Guest piddy]

Hi Matt.

Ive just converted my sliding pilar 2b over to wishbones. I like you first thought to use the Robin hood 2b wishbones but there were two problems with this.

1.The only way Richard would sell them to me was for £700. :angry:

2. The front track should be equal or greater than the back this doesn't happen using it on the 2b. ( might on the Exmo).

You could get the dimensions and make them your self, but if your going to do that you may as well make your own to the correct dimension for your car.

I have the dimensions of the 2b wishbone's somewhere if you give me a couple of days to sort them.

Hope this is of some use.

Piddy.

[Mat-Moo]

Greater or equal? seems wrong - anyway I (probably wrongly now!) assumed that the 2b front suspension was the same width as the sierra setup? becasue of geomotry etc.

[Guest piddy]

May help.

 

Track Width and Wheelbase

The definition of track width is the distance between the right and left wheel centerlines. This dimension is important for cornering since it resists the overturning moment due to the inertia force at the center of gravity (CG) and the lateral force at the tires [2]. For the designer, track width is important since it is one component that affects the amount of lateral weight transfer [3]. Also, the designers must know the track width before kinematic analysis of the suspension geometry can begin.

 

Track Width

When selecting the track width, the front and rear track widths do not necessarily have to be the same. For example, track width is typically wider in the front for a rear wheel drive race car. This design concept is used to increase rear traction during corner exit by reducing the amount of body roll resisted by the rear tires relative to the front tires [4]. Based on the corner speeds and horsepower to weight ratio of FSAE cars, this concept should be considered by the designer.

The wheelbase also needs to be determined. Wheelbase is defined as the distance between the front and rear axle centerlines, and also influences weight transfer, but in the longitudinal direction. Except for anti-dive and anti-squat characteristics, the wheelbase relative to the CG location does not have a large effect on the kinematics of the suspension system. However, the wheelbase should be determined early in the design process since the wheelbase has a large influence on the packaging of components.

For track width and wheelbase starting points, the designers should research the opposition's dimensions to serve as a baseline for their own calculations. FSAE car specifications for the competing teams, including track width and wheelbase, are available in the event program published by SAE.

The 1996 design team selected a 1727 mm wheelbase, 1270 mm front track width, and a 1219 mm rear track width, which were based on previous UM-Rolla cars. Although this wheelbase was adequate for the FSAE competition size courses, the UM-Rolla design team has decided to increase the wheelbase for the next car to 1854.2 mm. This increase in wheelbase is an attempt to improve stability for high speed corner entry at the competition.

 

Piddy.

[Guest Julian B]

Wow

 

Now that’s what i call a definitive answer.

Just a couple of questions Piddy , Is the track width measured to the centerline of the tyre or the outside edge. I was following a Porche and looking from the rear the rear axle looks wider than the front! as it does with a GT 40 and even a comer J4 van and a 2B. With the first 2 i think that the rear tyres are wider and just give the impression of a wider track

 

I have no idea what i am on about here but your answer is fascinating as it suggests that the 2b could do with longer wishbones ... or does it...? And whilst we are on the subject, why no anti roll bars, front or rear, surely a sports car needs them! Well I’m confused now.

 

Cheers Julian

[ibrooks]

The track is measured to the centre line of the wheels so competition cars can have a wider overall width at the rear because the wheels are wider or have a different offset (the Porsche, Smart cars and various others). Wider at the front is generally better with the extreme being the early three-wheelers (Morgans etc) some kits use this style too (Grinnal etc). Narrower at the front is a bad thing for cornering (Reliant Robin - nuff said). Generally road cars have the same track front and rear because they don't want to carry two different spares. The sliding pillar 2B has a narrower track at the front than the rear - probably a function of the steering rack that RHE used rather than any calculations. I beleive the wishbone motors had the same track front and rear as they use the Sierra rack. Some of the NW guys have converted to wishbones using parts of the Sierra rack on the original RHE supplied one to increase it's width.

 

Anti-roll bars are a good thing when they are correctly tuned but WILL cause more trouble than not being there if they are not. The Sierra bar is unsuitable for a car as much lighter as the Robin Hood and so it is better left on the shell than messing around trying to fit it. Westfield's rear anti roll bar should be a doddle to fit to a 2B if you can adjust the lengths of the drop links enough.

 

Have Fun

 

Iain

[Guest Ant]

RHE wishbone 2B (as opposed to a pilock system converted to wishbones) has a narrower overall width at the front than at the rear. I think it's the converted boys who end up with the same width.

[Guest piddy]

Yes Ant your correct.

The 2b in sliding pilar form and wishbone form both have a narrower front track than back.

The Wishy 2b has a front track of 1350mm ish were the rear track is 1490mm ish.

Piddy.