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MG MGB Technical - Bolts and nuts

Hi All.
Thanks for recent help with restoration queries. I have now stripped roadster body shell ready for repairs and respray and have been trying to sort wants. In particular I wondered if anyone has ideas regarding nuts and bolts,etc. Is it a good idea to buy custom packages of all fixings or buy loose nuts and bolts. Has any member quantified the number of fixings for B's. Not sure whether to get stainless steel rather than zinc plated. Any thoughts
Thanks
Brian
Brian Paddon

Look at a sample of 'kits' from the likes of Moss and B&G against the individual items and you will get an idea as regards fasteners for specific jobs. As for bulk packs I have no idea. You could do the same thing, but are bound to end up with loads of some things left over and not enough of another. 'Cheap' fasteners can be as poor as their cost indicates, such as threads stripping and 'spring' washers that flatten when first tightened.

As for stainless vs standard that's personal taste between bling and originality, and cost of stainless.
paulh4

If you're going down the stainless route be a bit careful what grade of ss fittings you buy. A2 is not that strong, but fine for applications not needing high tensile strength. A4 is better - about the equivalent of 8.8 (many applications in a car). However, I'm guessing that suspension fittings etc are going to be 10.9, which I don't think is available in stainless.

Maybe a metallurgist will be along in a minute to comment!

Interesting conversation, though. Even with zinc plated fittings anything underneath the car will be rusty in five minutes flat if driven on salty roads. It's always a shame after you've fitted a new component to the chassis to find in a few weeks that it's corroded. Cadmium plated would be good, but not sure if you can get this now.
Peter Allen

There are many sources of nuts & bolts, whether it be the likes of Moss & B & G kits as Paul says. Personally, other than load / stress / safety areas,over the last 5 years i have gone down the stainless steel route when replacing/restoring fittings on my car which i have had from new. On earlier exercises i simply replaced the original nuts,washers & bolts with zinc plated & was disappointed how quickly they rusted & spoilt the overall finish. The stainless steel replacements look as good now as the day(s) they were put in. (This was not aiming for the bling look as i have not gone down that route for component covers / shrouds other than the coil cover).
I spent a lot of time using the bolt references etc. of Moss as a guide when sourcing stainless steel alternatives. I bought several packs of regular sizes at shows such as Stoneleigh as well as on line from Westfield Fasteners & Spalding Fasteners. (The on line suppliers have comprehensive lists which enable you to take the time to order / understand exactly what you need - makes sense to make up a reasonable size order as you need to factor in postage / delivery charges). Since going down that route i became more aware of how many bespoke stainless sets are marketed on ebay & indeed have used that route for items such as the cable /fuel / brake line retainer brackets etc. under the car.
Sure it comes down to cost, but i think it is worth it.
Attached photo to show the slam plate / rad / bumper grill/ heater box with SS bolts,nuts etc. taken this spring some some 4 - 5 years after they replaced Zinc plated as an example.
(Given the cost of body shell renovation & painting to me its a non-brainer)!
Cheers,
Charles


Charles9

I'm with Peter on this. On todays cars most fixings will be medium strength 8.8 (yield 640, ultimate 800 N/mm2) but specialist and safety critical will be 10.9 (yield 900, ultimate 1000 N/mm2) exceptionally they may be heat treated alloy steel 12.9 (yield 1080, ultimate 1200 N/mm2)
On the MGB the fasteners would have been specified using the 'English' designation :-
R Ultimate 45 tonf/in2 695 N/mm2
S 50 772
T 55 850
U 60 927
V 65 1004
W 70 1081

You should be able to see the letter stamped on the head of the fastener. I'd suggest you need to go for V grade to be on the safe side.
Paul Hollingworth

Paul-
We yanks over here on the other side of the pond have only a vague understanding of the British classification system. Is there a URL for the chart that you posted where we can find the information?
Stephen Strange

Brian-
Do not be tempted to employ stainless-steel bolts for any machinery purpose on your car. In terms of strength and hardness, a good-quality SAE 304 stainless-steel bolt is approximately equivalent to an SAE Grade 1 carbon steel bolt. Those are the ones that have no markings on the head, and can be purchased in little plastic packets at home-improvement-type stores. Stainless-steel fasteners produce their own protective oxide film that prevents corrosion, but are especially prone to galling. This is due to the protective oxide film breaking down under installation pressures, and the resultant metal-to-metal friction produces heat that fuses the oxide film to adjacent metal, resulting in the fastener seizing. This is one of the best reasons to use a copper-based anti-seize compound on the threads of any fastener that is used wherever thermal cycling will be encountered.

The strength and type of steel that is employed in a machine-grade bolt is indicated by a raised mark on the head of the machine-grade bolt. The type of mark depends upon the standard to which the machine-grade bolt was manufactured. Most often, machine-grade bolts that are employed for use in machinery are manufactured according to SAE standard J429, while machine-grade bolts that are employed in structures are produced according to various ASTM standards. Machine-grade bolts that are fabricated to SAE standard J429 Grade 5 will have small linear markings that radiate outwards on their heads at the twelve o’clock, four o’clock, and eight o’clock positions, and have a tensile strength of 105,000 PSI (7,382.23 kg/cm2) to 120,000 PSI (8,436.83 kg/cm2). These are fabricated out of medium-carbon steel that has been both quenched and tempered. These are the type of machine-grade bolts that are employed as Original Equipment for most machinery purposes in the MGB. Higher-grade machine-grade bolts require more torque in order to achieve the necessary amount of 'stretch' that makes them secure. Therefore, they should not be utilized for machinery purposes in any mechanical component of the MGB, otherwise thread damage is likely to result.
Stephen Strange

I know this seems like hard work, but I have recently gone through this process. Time consuming but like any aspect of an MG restoration, it is very satisfying, not to mention saving on excess boxed or bulk over purchasing. I went online and by using both Rimmer Bros and Moss Europe, I checked through each component as if I was physically re-assembling the car. Started with the bumper irons at the rear and worked my way to the front, included rear springs, axle, tailshaft, gearbox, lower engine, front suspension. Wrote out a comprehensive list as I went along and noted every bolt nut and washer. Only then, did I order zinc coated product from a company in Adelaide Australia - Classic Fasteners, and ordered everything I needed plus a few spares. Cost a lot less than boxed sets and it is so nice to have the correct hardware to match the original.

Maurie
R M Prior

This thread was discussed between 04/05/2022 and 24/05/2022

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