Cawthray's Roadster Build

[flyerncle]

The daft thing is,so long as your seat belt mounts comply with the regs there is nothing mandatory for a roll bar so its probably out of the remit of the tester to say yes or no to how it is fitted.

[davidimurray]

Originally Posted by flyerncle

The daft thing is,so long as your seat belt mounts comply with the regs there is nothing mandatory for a roll bar so its probably out of the remit of the tester to say yes or no to how it is fitted.

But if your seatbelts are mounted onto any part of the roll bar, then the roll bar structure becomes a structural part of the safety system. hence you may need to show that it is adequate to take the load of the seatbelts in an accident + that any fixings are adequate + that any fixings are secured against vibration - e.g. lock nuts / spring washers.

In particular taken from the manual :-

In a severe accident, the seated occupant can exert huge loads upon their seatbelts (in the region of 1.5 tonnes for a 75kg person). Seatbelt anchorages together must withstand these large loads from the seatbelts. These loads in turn must be dissipated by the vehicle structure.
In assessing the strength of the anchorages, it is essential to consider

the vehicle structure in the immediate vicinity of the anchorage, and

the parts of the vehicle structure into which the loads from the anchorages will be dissipated.
These large loads will act in several directions as shown in Figure 1.
All Vehicles
What to look for:

Evidence that anchorages in a vehicle of the same or a very similar type have been subjected to a seatbelt anchorage strength test to “European Standards” by a recognised authority. This may be acceptable where there is clear evidence that the structure is identical to the vehicle originally tested.

Welding should appear neat and of good quality; whilst it is impossible to judge the quality of a weld just by looking at it, messy welding is rarely strong welding.

Bolts used in structural areas should be of grade 8.8 or better. Such bolts will be marked 8.8 or 12.9 on the hexagonal head, however, cap-head bolts or 7/16" ( 11mm ) UNF seat belt anchorage bolts (with an anodised finish) not marked in this way may normally be considered to be of equivalent strength. Bolts should be M8 or larger.

Threaded bushes should be welded (at both ends) through the tube, and not end mounted on the surface. (A threaded bush may be attached by its side surface to a structural component).
Cause for Concern:

Welds of poor appearance, gaps or visible lack of penetration.

Anchorages in thin and/or flat panels with little stiffness or reinforcing structure or in thin walled tube.

Low grade bolts (less than grade 8.8).

Insufficient bolt capacity, e.g. number of bolts and/or diameter of bolts


and


Steel Chassis with Anchorages on Roll Cage (See Figure 3)
What to look for:

Triangulation and bracing which will provide strength and spread the loads effectively into the chassis.

The joint where the roll cage joins the chassis and the chassis itself must be sufficiently strong to withstand the loads from the anchorages.

Upper anchorage must be adequately braced from near the anchorage to strong areas of the chassis.

Threaded seatbelt anchorage fastening should be welded into tubes or onto plates of sufficient thickness.

Bolted joints joining the cage to the chassis and parts of the cage to each other should be of sufficient strength.

[flyerncle]

Agreed David,if you look at the angle the book roll bar rear supports act's in, the flimsy rear stay fitted to the original metal work for the ally rear panel it could pull forward in an extreme accident (god forbid),it should go to the diff cage or lower chassis to give it strength.

The seat belt plates should also be folded in to make a stronger base to weld to the chassis.

It's been said a hundred times before on here its how the manual is interpreted and not how its written.

[TomC]

Wow cheers for all the info fellas. I think what we might do is grind this bit back and just weld it round. Only thing is if we do that the stays will be welded to the chassis obviously and the main bit is bolted in. I know its difficult to say for sure but does anyone think that will matter for Mr IVA?

[voucht]

Originally Posted by TomC

Wow cheers for all the info fellas. I think what we might do is grind this bit back and just weld it round. Only thing is if we do that the stays will be welded to the chassis obviously and the main bit is bolted in. I know its difficult to say for sure but does anyone think that will matter for Mr IVA?

I can't say for IVA, but I think the main problem will be to fit the fuel tank, or actually to remove it if you need to, after the roll bar stay are welded. Perhaps a books specs fuel tank will be small enough to be removed, and it is not sure at all, but if you intend to fit a bigger fuel tank as a lot of us did, that will be a problem (actually, the problem is not passing between the stays, but actually handling and manipulating it in the rear tube to get it in the right position to pass between the stays will be a problem in my opinion).

Also (and I don't say this because I sell brake lines, don't misunderstand me, it is just my opinion I want to give you about that) but I think the bend of the flexi lines on the calliper side is definitely too tight and not natural. The stainless braid will force and pull on the ferrule (and actually even more when the car will be on wheels), which in time, can lead to a failure of the line. The straight fittings you have are good for drum set-up, as the wheel cylinder's port is almost perpendicular to the longitudinal axis, but with these callipers, with the port on top, a 45° or even a 90° fitting would have been much preferable.

Sorry about all these comments Tom, it sounds like we are just pointing problems and give you critics. That is not the case: your build looks very nice, and the job you did with your father is just great I think. I thought I would just give you my opinion about these two points, but let me tell you that I think that the rest of your build is stunning

Hope this will help

[davidimurray]

Before you do anything I would give your IVA inspector a call and have a chat with him. Some have passed with just the single point, I put two in to be sure. It is useful to be able to remove your hoop.

[TomC]

Originally Posted by voucht

I can't say for IVA, but I think the main problem will be to fit the fuel tank, or actually to remove it if you need to, after the roll bar stay are welded. Perhaps a books specs fuel tank will be small enough to be removed, and it is not sure at all, but if you intend to fit a bigger fuel tank as a lot of us did, that will be a problem (actually, the problem is not passing between the stays, but actually handling and manipulating it in the rear tube to get it in the right position to pass between the stays will be a problem in my opinion).

Also (and I don't say this because I sell brake lines, don't misunderstand me, it is just my opinion I want to give you about that) but I think the bend of the flexi lines on the calliper side is definitely too tight and not natural. The stainless braid will force and pull on the ferrule (and actually even more when the car will be on wheels), which in time, can lead to a failure of the line. The straight fittings you have are good for drum set-up, as the wheel cylinder's port is almost perpendicular to the longitudinal axis, but with these callipers, with the port on top, a 45° or even a 90° fitting would have been much preferable.

Sorry about all these comments Tom, it sounds like we are just pointing problems and give you critics. That is not the case: your build looks very nice, and the job you did with your father is just great I think. I thought I would just give you my opinion about these two points, but let me tell you that I think that the rest of your build is stunning

Hope this will help

Don't worry I appreciate the advise and I'd rather solve the problems now than have everything fail later on. We need to have a good look at the brake lines and everything when we get it on the ground again.

Didnt really think to ring the IVA inspector good idea

[rpjg1975]

I did exactly that regarding my harnesses. Very helpful and gave me a few suggestions too

[jps]

Originally Posted by TomC

Wow cheers for all the info fellas. I think what we might do is grind this bit back and just weld it round. Only thing is if we do that the stays will be welded to the chassis obviously and the main bit is bolted in. I know its difficult to say for sure but does anyone think that will matter for Mr IVA?

I've been looking at this with interest - as i'm not 100% happy with the rear stays i've got. Mine are similar to those pic - although wider plates where the stay joins the chassis - and I had intended to drill and bolt on either side of the stay much the same as David did.

The plates are flush with the top rail though - which means I need to butcher my Equinox back end to get it to fit round - the grp moulding 'wraps' over the top very neatly .... Not sure whether to rethink the whole lot now...

[TomC]

How do chaps, not much to report really at the mo and not got any further with the potential roll cage stay issue either BUT, we have just ordered a microsquirt ecu so should hopefully have her running soon pics and vids coming at the weekend if all goes to plan.