True or just a Story ?

[Dilkris]

You are more than welcome to borrow this proper job for nowt


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Wow !! That's serious stuff - I cannot thankyou enough for the offer but I fear it is a bit advanced for me.. !!!
Out of intertest - is the data sheet in there for a 1973, Lotus Twin Cam Europa Special?
Also - where is Nescient in the vale?

 

[voipio]

Larger diameter fluorescent tubes (about 30mm dia?) are a lot stiffer than the thinner ones. All tubes will flex a bit, when sideways pressure is applied, but not so much under their own weight. Rolling them on a flat surface will help weed out the wonky ones.

Plasterers feather edges can be very good, viewed along the edge, though the flat sides will tend to sag. I use one for checking wheel tracking, but buying 4-off starts to get expensive.

 

[zzr1200]

I hear you -
Sure, we can all go out and "buy stuff" - but this forum excels at identifying techniques of ingenuity which costs nowt....

"Back in the old days, when money was tight"....... it was done like this:-

You appear to have a fairly flat floor under the chassis, clear out the lifting frame (?) and use a plumb bob to drop the centre line of the chassis and all other points to the floor and then measure the layout/dimensions.

If you need to check the alignment of the wheels clamp a straightedge to each face of the disc's/drums this will extend any runout/misalignment and make it easier to find/measure/see.

The expensive method is as follows:-

If worse comes to worse, level the chassis then frame out the floor underneath the chassis and fill with self-levelling floor compound, once dry this will give you a good flat surface to drop the measurement points down too........QED....

I will be going through a similar process, later on when I start on my Scimitar chassis rebuild.

 

[Screwdriver]

I appreciate some extreme care will be required.
But (if) they are straight - they are also extremely light - and I have plenty of them.

...and that's fine but how do you transfer that straightness to a workpiece? You're not going to strike a line with anything better than +/- the diameter of the fragile glass cylinder as you run your pencil in a vaguely straight line along it.

I hear you -
Sure, we can all go out and "buy stuff" - but this forum excels at identifying techniques of ingenuity which costs nowt....

Fine. Take a bit of wood, anything will do like a 4x2 or a broomhandle. Drive a nail or screw in so you can run a length of (ideally stainless) wire between the two. Tension it to the yield point of the wire if you like. If the wire is a bit bumpy, kinked or whatever put one end in a vice and the other end in a drill chuck. Pull it with some tension while spinning and the wire will become laser straight. Stainless is great because it will also work harden.

You can make as many as you like with the advantage being you can easily fix the straight edge in place, cross them over at right angles etc.

 

[8ob]

Wow !! That's serious stuff - I cannot thankyou enough for the offer but I fear it is a bit advanced for me.. !!!
Out of intertest - is the data sheet in there for a 1973, Lotus Twin Cam Europa Special?
Also - where is Nescient in the vale?

Its pretty basic really, what's nice about it is its incredibly rigid and all of the moving fixtures have calibration tapes on them as well as the main spine. No dangling tapes about and can be guaranteed to be both symmetrical and square, only issue is it can highlight inaccuracies in chassis/suspension pickup points you may not want to know about. Eg, start to dial in caster angles and may notice the wheelbase is suddenly different on one side of the vehicle to the other, its all a compromise unless you want to spend a lot of time rectifying manufacturers tolerances.

Bob

 

[Dilkris]

"Back in the old days, when money was tight"....... it was done like this:-

You appear to have a fairly flat floor under the chassis, clear out the lifting frame (?) and use a plumb bob to drop the centre line of the chassis and all other points to the floor and then measure the layout/dimensions.

If you need to check the alignment of the wheels clamp a straightedge to each face of the disc's/drums this will extend any runout/misalignment and make it easier to find/measure/see.

You have described exactly what I am planning to do and clearly understand where I am - equally you will know why I am looking for the 4 straight edges. Caster angles are easy with a digital level - but I am focusing on toe angles on front and rear wheels. I need straight edges to effectively extend the faces of the drums and discs.

 

[Dilkris]

No chance, you can flex a fluorescent tube a little way before it breaks, they're not stiff enough to be "perfectly straight".

I was drawn to this comment and my first reaction was "boll*cks"- but.... I hang my head in total surprise.

See below pictures......
The tube (5' long) was 0.050" out of round at mid point, and with great ease, I could generate 0.025" of deflection

So "Maker" you were 100% correct!!!

 

[Dilkris]

...and that's fine but how do you transfer that straightness to a workpiece? You're not going to strike a line with anything better than +/- the diameter of the fragile glass cylinder as you run your pencil in a vaguely straight line along it.

Fine. Take a bit of wood, anything will do like a 4x2 or a broomhandle. Drive a nail or screw in so you can run a length of (ideally stainless) wire between the two. Tension it to the yield point of the wire if you like. If the wire is a bit bumpy, kinked or whatever put one end in a vice and the other end in a drill chuck. Pull it with some tension while spinning and the wire will become laser straight. Stainless is great because it will also work harden.

You can make as many as you like with the advantage being you can easily fix the straight edge in place, cross them over at right angles etc.

I don't want to "strike a line" I want to attach straight edges to the discs and drums and from their ends drop string lines (typically cotton with small plumb bobs attached) down to the floor and then measure across to the reference centre line of the chassis.
Are you with me - or have I explained poorly?
Maybe I should do a sketch and attach a photo.

 

[Screwdriver]

I don't want to "strike a line" I want to attach straight edges to the discs and drums and from their ends drop string lines (typically cotton with small plumb bobs attached) down to the floor and then measure across to the reference centre line of the chassis.
Are you with me - or have I explained poorly?
Maybe I should do a sketch and attach a photo.

Forgive me for not being so interested in what you're doing with the straight line, plenty of people on here with a lot more experience with setting up vehicles. I'm just chipping in to suggest having a delicate glass tube hanging around in a workshop is an accident waiting to happen. A very nasty accident due to the nature of those tubes.

 

[8ob]

 

[Gareth J]

A 6' spirit level will suffice for this. If you only clamp where it's supported, it'll be straight enough. While the deflection of striplights may not be an issue in for your requirements, clamping them in place to make them usable sounds impossible, though I guess you could carefully hold them up every time. It all seems a bit unnecessarily MacGuyver though.

 

[Memmeddu]

Many years ago a very well established panel beater I knew well told me that if you wanted a perfectly straight, light and convenient straight edge, you could use 6 foot (or 3, 4, or 5 foot) fluorescent light tubes as they were perfectly straight. (He used them for identifying areas of distortion/twist in car chassis - note: I'm not referring to monocoque but the ladder type ).
So - true or a Story?
I'm wanting 4 off straight edges about 5'/6' long for some alignment work in my workshop.

I know it's used in body shops to identify dents in car panels as the light reflection will show exactly imperfections, don't know about how straight they are and if enough accurate to be used on machinery

 

[CompoSimmonite]

I am at this stage with my rebuild and I want to get the alignment approximately dialed in - (For those that understand these cars, there is some geometry regarding the rear radius arms that I am concerned about ). "Yes" I can use string and yes I can use lazers, (have some from old go-karting days). So ... I am wanting to effectively extending the length of the faces of the rear drums and those of the front discs, ( yes - I know I will have to remove the calipers...).
There is a method to my madness - once I have established a center line through the chassis from front to back.

View attachment 453533

Renault powered Europa ?

 

[Dilkris]

Forgive me for not being so interested in what you're doing with the straight line, plenty of people on here with a lot more experience with setting up vehicles. I'm just chipping in to suggest having a delicate glass tube hanging around in a workshop is an accident waiting to happen. A very nasty accident due to the nature of those tubes.

I hear you but believe me - there are more accidents waiting to happen in your average well equipped home workshop. Being old, aware and super careful helps.

 

[Dilkris]

Renault powered Europa ?

No - transaxle is Renault 6 but the engine is Ford block, Lotus head. Refer back in early messages from me in this thread - there is a photograph.

 

[zzr1200]

You have described exactly what I am planning to do and clearly understand where I am - equally you will know why I am looking for the 4 straight edges. Caster angles are easy with a digital level - but I am focusing on toe angles on front and rear wheels. I need straight edges to effectively extend the faces of the drums and discs.

I'd just strip the tyres off of the rims and fit them, toe-in angle is measured at/on the wheel rims, having a 3 or 6 foot long bar or straight edge will throw things out, provided the rims are serviceable (and not bent) use what the normal toe-in measuring system uses as data points.... I take it you have a set of wheels?

 

[8ob]

All of this needs to be done with the vehicle sat at ride height, normally means swapping out the coil overs for spacer bars to mimic ride height. Also quite hard to measure toe at hub centre height,might be better to make some drop plates so you can pass a tape under the car or buy a cheap set of steering gauges.

Bob

 

[octo0072000]

No - but the engine is Ford block, Lotus head. Refer back in early messages from me in this thread - there is a photograph.

do you mean transaxle is Renault 16 not 6 is same as reno 4 but bigger body

 

[cheb]

Its pretty basic really, what's nice about it is its incredibly rigid and all of the moving fixtures have calibration tapes on them as well as the main spine. No dangling tapes about and can be guaranteed to be both symmetrical and square, only issue is it can highlight inaccuracies in chassis/suspension pickup points you may not want to know about. Eg, start to dial in caster angles and may notice the wheelbase is suddenly different on one side of the vehicle to the other, its all a compromise unless you want to spend a lot of time rectifying manufacturers tolerances.

Bob

My Renault 4 was so badly made there was about 100mm difference between the left and right hand wheelbases.

 

[Kram]

These were much cheaper for 1.5m versions.. thjnk they were £6 each.... Milled face so should be relatevely good

https://www.zoro.co.uk/shop/tools-and-machining/spirit-levels/1200mm-48inch-box-profile-spirit-level/p/ZT1008716X