Handling & Geometry

[mikey]

I recently posted regarding handling on my Dax. Having borrowed a Camber gauge I have found my settings to be different by approx 1/2 degree between the sides. The point is I had paid over £300 over two set ups that were supposedly carried out by professionals who knew what they were doing. The equipment was right i.e. lazer optiflex, but I think the problem is that nowadays some operatives just dont know how to use them, or if they do they have little understanding of what caster and camber is and the relationship with all the other settings such as Ackerman etc.

Taking Wilfs advice I spoke to cheng at Thunder cars and he tends to agree. I will be taking my car down to Cheng for set up as he has confidently stated that he can get it to handle perfectly. If any of you have the very old Dax chassis ( mine is not this type) Cheng has stated that he can get this and any other to handle as well as any other, even on the track. Slight modification may be needed depending on the type e.g. I suppose G.D.s will need slightly less work than JCB,s for example.

It was great to talk to somebody who obviously knows their stuff and I have reniewed confidence in that I can have the handling put right so thanks for the tip Wilf.

The morale of this posting is tose who are building, when it comes the time, either do your own or make sure you use somebody who understands. Money and glitsy machinery do not necessarily provide the results, and in this case you can get better than a quick fit fritter.
mike the slide shortly to become mike a grippa

[robert]

Mikey

Unfortuantely, you are working with people who when confronted with a replica, cannot find it in their little book of settings, even if you do tell them their settings. Now if you went in with a Mondeo, it would be a whole different kettle of fish as they would be listed in the magical book of camber and castor settings.

It is much the same as trying to get a set of brake pads for example from Halfords, the first thing they ask is what is your make of car and registration number, No hope!!

I did read with interest your comment on getting any other replica to handle as well as any other, on the road or on the track, and would like to understand how Cheng would be able to acheive this, unless he is going to completely strip out the chassis and install a backbone chassis.

Robert
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[dave]

Hi Mikey.
I don't know if Cheng will check this, but try to get him to check it anyway.
On your car you might have 1/2 a degree of toe in on the rear...Or hopefully it has, but get him to check if it is toeing in 1/2 a degree on one side and zero on the other or something like that,to remedy this Dax recomend that you fit shims between the chassis and the rear wishbone where it pivots near the diff.
To do this you must first disconnect the radius rods, then loosen the 4 diff mounting bolts slightly,and then loosen the wishbone to chassis pin drop a shim in and re tighten, then re check the rear axle for "crab" characteristics.Keep fiddling about with the shims until the toe in is the same both sides.
It is best to do this after the front suspension is set as you can then use the front wheel bearing grease caps as a datum point,unless Cheng has one of these 4 wheel lazer thingys.
It's good to see you feeling optimistic about your car at last.
Good luck.

P.S. Take no notice of Robert....A bit of flex in the chassis department never did Nadia Kommonech or Olga Korbut any harm, but the stiff bloke down the pub died of a heart attack.}>

[robert]

>A bit of flex in the chassis
>department never did Nadia Kommonech or Olga Korbut any harm, but the
>stiff bloke down the pub died of a heart attack.}>

But they were designed to flex in all the right places, and what lovely flexing it was.

Robert
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[wilf]

Mikey - once Cheng has worked his magic, some feedback on this forum on how you feel the car "works" then would be great.

Wilf

[mikey]

No problem I would be happy to feed back. With regards your question Robert, I think what Cheng was probably saying was in relative terms to vehicles with chassis and components of the same generic family. Even with his ability and enthusiasm I doubt if he could get a Cobra to handle like an Audi Le Mans Car extrapolating the argument. Ditto for the backbone chassis argument. I was simply trying to bring enthusiasm back to those who have handling problems which certainly the earliest Dax did and is admitted by D.J.Sportcars that Cheng can play with his wand and sort the problem out or so he says. The way he gets a Cobra to handle tempts me to believe in him.
Cheers.
Mike.

[robert]

Yeah, I always know what I mean to say, but sometimes it doesn't come out right.

To clarify the point made of Cheng getting any Cobra to handle the same.

Handling - is what the car is like to drive, its feel. How well the car is
set up for say balance, understeer/oversteer and turn in. So you can have a
well set-up Austin 7 special that does all things beautifully and is a joy
to drive.

Road Holding - Now that's a different story, presuming the car is set-up to
its best, road holding is the cars dynamic ability to create grip in the
corners, this is when chassis and suspension come into play. A poor car
set-up well can out perform a good car set-up badly with the driver having
to do all the work to compensate, but don't expect an Austin 7 to keep up
with a Lotus 7 when they are both set up right because then they are chalk
and cheese.


Robert
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[mikey]

I think we cold be opening up a can of worms here if I'm getting the drift right. I could go on to say dont expect any cobra to keep up with a well set up Lotus 7 but I wont, I,ll leave the banter up to others. Interestingly enough I used to own an old Ford Anglia that I prepared and set up. Cost quite a bit but it would outhandle I would think any Cobra and outsprint most.

From Humble beginnings........

Mike.:P :P

[robert]

Ummm, you did say that you spent a lot of dosh getting the Anglia right, but if I read it right, we are talking about a pretty much standard car, without expensive modifications.

To continue this, as I am having a slow day at work, would you expect your Dax, when set-up correctly to handle as well as say a Magnum or Ram, which has been set-up correctly.

Actually, I am not having a slow day, I just don't want to do some documentation. }> }>

Robert
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[robert]

Ride height will make a difference as this will affect the vehicles centre of gravity.

The higher the ride height, the more yaw will be experienced under braking and cornering, however as Cobras normally run a couple of inches only, it isn't a major issue.

Regarding adjustments front to back, if you think of a brick, then you are basicaly looking at the aerodynamics of a Cobra Shape, some are worse than others. By lowering the front, and raising the rear, you are doing two things. You are intoducing more downforce at the front of the car to aid in initial turn-in, but there is a possibility of creating lift at the back, which can be fun. The Cobra body has very poor aerodynamics, and the back of the car is a real pain, as the nicely rounded rear which looks very good when stationary, really doesn't work when in the move.

Unfortuantely, a simple change can have a major knock-on effect, which is why this sort of work is best left to the experts like Cheng and Andy, who race their cars and have the ability and experience to "play" with settings to find out what actually does work.

Please don't forget that this is my opinion only, and opinions are like bottoms, everyone has one.

Robert
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