Lightweight Chassis Improvements

[Guest zoomzoom]

Hi all

Just want to sound off a few of my first thoughts on how to improve the lightweight chassis to pass sva.

(please be kind!!)

I hope some of you will have been able to see a l/w at donnie (couldn't go working) and might have a few ideas to help.

 

1. Close the box sections at the chassis top rail which run from the front suspension mountings to the seat panel at the rear.

 

2. Add a lower box section which connects the floor and the side panel in the same fashion as in 1 above.

 

3. Add box to the prop tunnel at top and bottom and connect this to the outer box section as in 1 and 2 above.

 

4. Extra strengthing plates to the seat back where this box section meets it and joins up with the rear suspension/diff box.

 

5. Strengthing plates to all seat belt mountings to spread the load.

 

6. An extra plate under the roll over hoops to connect it to the rear suspension.

 

Let me know what you think

 

Marcus

[peter_m7uk]

Hi Marcus,

 

Don't know if I'll go for all those mods, but I am currently:

 

1) Changing the screws in the rear box sections for high tensile bolts (probably the same for the rivets at the front)

 

2) Bolting and bonding in further angled strengtheners to attach the rear box sections to the diff box

(Have already put extra strengtheners in the front)

 

I will then

 

3) Bolt steel plates on the underside of the roll over bar and the two arms which extend from it so

that there is ali sandwiched by steel, preventing the roll over bar from pulling out.

 

4) Beef up the chassis in the area of the seat belt mounting with multiple sheets of ali, or again

steel plate.

 

That is how I intend to take the car for SVA in Nottingham, after being told last week that they would

pass any Lightweight that is built to a good standard with seat belt mount strengthening.

 

In the event that Nottingham takes a Southampton line and still fails me on the chassis, then I will go

back and close the box sections at the chassis top rail which run from the front suspension mountings to the seat panel at the rear, as suggested below. I was also thinking of removing the rivets from the cockpit

floor strengtheners and using the holes to bolt steel box to the underside.

 

If that still doesn't pass, then I'll *really* go to town! Whatever it takes, the LW will pass

 

Pete

[Guest timswait]

I reckon the box sections proposed by Marcus are a good idea. How much weight will it add? I'd have thought 10-20kg at most. Use an engine which isn't a pinto or use lighter seats, fittings etc and you'd easily save that back again. A closed section is something like 50% stiffer in bending, 2 or three times stiffer in torsion and 2 or 3 times stronger in crushing than an open section of the same dimensions. By making the area around the cockpit the stiffest area of the car you ensure that in an accident the rest of the car crumples before the bit you're sitting in. It also adds stiffness which should improve handling. I don't really know that much about the design to comment much on the other aspects, but it sounds like between you you're turning the lightweight into the car it should have been when it was released.

What do your furry workforce think of the extra work, you're not going to have any strikes are you Marcus?! I used to have Robin Bear as a mascot, a teddy dressed as Robin Hood, until some B******d nicked him!

If you need extra metal for doing the work there's a very helpful guy in Sheffield who runs BDS Trading. I've used him to get materials, most companies won't deal with small orders, so he's pretty useful.

[Guest gdc]

I reckon the box sections proposed by Marcus are a good idea. How much weight will it add? I'd have thought 10-20kg at most. Use an engine which isn't a pinto or use lighter seats, fittings etc and you'd easily save that back again. A closed section is something like 50% stiffer in bending, 2 or three times stiffer in torsion and 2 or 3 times stronger in crushing than an open section of the same dimensions. By making the area around the cockpit the stiffest area of the car you ensure that in an accident the rest of the car crumples before the bit you're sitting in. It also adds stiffness which should improve handling. I don't really know that much about the design to comment much on the other aspects, but it sounds like between you you're turning the lightweight into the car it should have been when it was released.

What do your furry workforce think of the extra work, you're not going to have any strikes are you Marcus?! I used to have Robin Bear as a mascot, a teddy dressed as Robin Hood, until some B******d nicked him!

If you need extra metal for doing the work there's a very helpful guy in Sheffield who runs BDS Trading. I've used him to get materials, most companies won't deal with small orders, so he's pretty useful.

[Guest gdc]

excelent ideas to sort out the probs ,im going to have to start mine again ,my wiring and fuel lines run down the two outer top channels. the car was all but finished, small ammount of trim left. to say im pi sed of is an understatment, weight increase should not be a prob as i am running a 140 bhp burton xflow.

 

there is already a lightweight shell for sale on ebay!!!

 

did rhsc know of the scale of the prob prior to their financial prob .

 

how many lightweights have been sold.

 

 

 

 

has the lightweight prob had a bearing on the rhsc insolvancy.

 

why did rhsc take back a lightweight and give the guy a new 2b kit only a couple of weeks ago

[Guest timswait]

As I understand it (mostly from reading this board):

did rhsc know of the scale of the prob prior to their financial prob

I'm guessing they had an inkling, and if they didn't they should have.

how many lightweights have been sold.

Good question, no idea.

has the lightweight prob had a bearing on the rhsc insolvancy.

I don't think it caused it, that was the insolvency of the parent company. On the other hand it can't of helped, and it won't help them find a backer to buy out the business as a going concern.

why did rhsc take back a lightweight and give the guy a new 2b kit only a couple of weeks ago

RH claim it was because Trev hadn't built the car to a sufficiently high standard to pass SVA. However this smells of BS, because by all accounts the car was built to a high standard, and all the SVA faults (well all the serious ones) were DESIGN faults not construction.

[Guest gdc]

last post makes sense ,trevors build quality looked very good .i have tried to find out the actual design faults so as to be able to sort out a solution. can anyone list the probs!!!!in full or are we just to keep taking them for sva ,

[E.Hunt]

 

this is a look from behind the car showing the bottom suspension mountings.

 

Could I attatch a angle iron along the part dropping down and pick up the square suspension tubes and forward for seat belt attachment or would I have to use box tube ?

[Guest timswait]

last post makes sense ,trevors build quality looked very good .i have tried to find out the actual design faults so as to be able to sort out a solution. can anyone list the probs!!!!in full or are we just to keep taking them for sva ,

Quoted from the thread in SVA section:

FAILURE SECTION 5

A seat belt anchorage or the surrounding vehicle structure is of inadequate strength and likely to fail. (No box section in areas of seat belt mountings or associated component attachments, no triangulation or bracing of thin panels, pop rivets used near seat belt anchorage strengths.)

 

FAILURE SECTION 15.1

When driven, the safe control of the vehicle is or is likely to be impaired due to design or construction feature or characteristic (Monocoque has absence of structural box section in construction)

 

FAILURE SECTION 15.1

The vehicle structure is of inadequate strength and likely to fail prematurely. (vehicle construction not considered to withstand forces and vibration to which it is likely to be subjected to.)

 

FAILURE SECTION 15.1

A suspension unit anchor, shackle or attachment bracket of inadequate strength and likely to fail prematurely. (All suspension components in box sections bonded and fixed with pop rivets and self tapping screws to main panels.)

[Guest warwick7735]

Hi all

 

 

How can RHSC say that Trev didnt build it to a high enough standard, the DVDs they supply show u how to build the main tub, and thats what most of the failure points are. You cant exactly build it wrong (can u Trev ) In the DVD they dont even mention bonding the alloy panels together.

 

If Trev had gone to Nottingham his car would of more than likely passed

 

Warwick

[Guest zoomzoom]

Hi

E.Hunt a good idea to strengthen the inner seat belt points, do you intend to run the angle section from the rear box all the way to the midpoint crossmember and also on which side of the centre lid on the underside of the chassis (or both sides??).

The build dvds shows the lower inner seat belts mounted to the upright part of the prop tunnel, do you intend the seat belts to be mounted to the floor or will do you add a right angle section to pick up the under floor bracing?

Also what will you use? steel or alloy. (sorry for all the questions)

 

As for my car well my first thoughts are to do the following

 

Replace all rivets (or every other rivet??) that connect the box sections to the panels with bolts (8.8 h/t) and washers to spread the load. Not all the way throught the box, as without support this will crush it but through one side using a extended spanner to reach the nut.

 

Fit a plate (4 mm steel) to the underside of the roll over bar across the whole width of the car and bolt this with 8.8 h/t bolts. Also a plate to the underside of the rear hoop supports.

 

A frame of some sorts to help take the load of seat belts and seats in the cockpit area (or as above) and replace all rivets (or every other??) along the side and floor a with bolts

 

 

Let me know what you all think

 

Marcus

[Guest captn Pugwash]

Hi

E.Hunt a good idea to strengthen the inner seat belt points, do you intend to run the angle section from the

 

Fit a plate (4 mm steel) to the underside of the roll over bar across the whole width of the car and bolt this with 8.8 h/t bolts. Also a plate to the underside of the rear hoop supports.

 

 

Marcus

 

I may be mistaken, but is ther not a chemical reacton between two differant types of metal when fastened together, electrolitic action, or some corrosion, also of two differant metals, one softer than the other, will there still not be wear on the softer metal from movement and vibration?

 

Just a thought.

 

Captn P

[Guest Stevebn2]

I may be mistaken, but is ther not a chemical reacton between two differant types of metal when fastened together, electrolitic action, or some corrosion, also of two differant metals, one softer than the other, will there still not be wear on the softer metal from movement and vibration?

 

Just a thought.

 

Captn P

 

The reaction is Galvanic, see link

 

I believe it needs the presence of an electrolyte.

 

Also stainless steel 18.8 is quite restistant (see above link)

 

Also if the two are bonded this provides insulation, prevents movement and suppresses vibration.

[peter_m7uk]

I've already begun the replacement of screws in the rear box sections with M6 high tensile bolts.

I got them from Namrick in Hove and they're zinc plated. Zinc and aluminium are right next

to each other in the galvanic voltage range, so corrosion will be next to nothing. So take note,

use zinc fasteners on your ali chassis!

 

Anyone else who is doing this, another good tip is to get a telescopic magnetic pick-up tool.

I used this to place the nuts and washers inside the box sections and line them up with the holes

left by the removed screws. To tighten up the nuts, I forced a 10mm spanner into the end of

a piece of tube and pushed the tube along the box sections until I get could the ring over the

nut. If you do all this, a tricky sounding job becomes surprisingly easy

 

Pete

[Guest ady]

You will get galvanic corrosion where aluminium touches any other metal, including zink. the thing to do is provide insulation between the aluminium and the other metal. Bonding the steel plate would work providing you ensure there is no contact. On bolts use nylon washers under the head or steel washer, for thicker sections you can get top hat washers that go into the hole aswell, stopping the bolt from toucging the sides.