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General Question: Fasteners


ajh
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Other than the obvious ones (head bolts, etc) is there any reason to stick with the flange-head bolts as provided by Land Rover when rebuilding an engine? (300TDI) I was hoping to fit the more available (and cheaper) 10.9 hex bolts that I can purchase in bulk locally and just have them milspec (QQ-P-416-F) plated and chromate passivated by the box.

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In my opinion the bolts that are used in the engines are rather rubbish, (undersized AF M8's) in the most part. The heads very easily round off.

I've replaced some with standard 13mm AF 8.8 bolts and they're fine, I can't see any reason why there would be any problems, just be uber careful where threads go into aluminium and observe strict torque loads or you'll end up stripping the threads, but you can say that about most bolts.

The only possible downside is that 10.9 being a little less ductile, you might find if any age and you end up snapping them, they will be a royal pain to have to drill out.

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Generally, there are two reasons for using flange bolts.

1. Cost. They do not require a washer, so reduce assembly time

2. Anti-rotation. Where teeth are cut into the underside of the flange, it saves the need for other anti-rotation solutions - so is related to 1,

If the flange bolt has a smooth underside, yes, you can replace it with a bolt + washer. If not, the bolts will require another anti-rotation mechanism.

Replace bolts with the same grade. Although on the surface, 10.9 appears to be 'stronger' and a better option, they are more brittle. An 8.8 bolt if over stressed, will stretch and loosen (giving you warning of the over stress). 10.9 is likely just to snap - potentially leading to a catastrophic failure. 8.8 Bolts due to their higher elasticity and ductility are better at averaging out impulse loads, even when these exceed their ultimate strength. Often a higher grade will just snap.

Higher grade bolts are good when you know the load profile and loading is mostly static. However, use with caution!

Si

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I think the OEM bolts are that way mainly for automated/semi-automated assembly with magnetic sockets , the washer face registers the bolt in the socket and holds it true to the drive axis , I've replaced as needed with 8.8 std. hex head's with no problems .

cheers

Steveb

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Think 10.9 require higher fastening torque... may be a consideration with aluminium. (One of the problems with 12.9 bolts is the higher required locking torque(unless the threaded hole is designed for tgem that is)).

Aluminium and corrosion... consider galvanic series (Google search)... thread inserts won't stop corrosion as the thread insert is still steel... but they are likley to offer a lower force per area against the aluminium as the threadsert is of a larger diameter into the aluminium than the bolt is (was).

I believe galvanic series does require an electrolyte though to speed up the process (ionised salt ... water...), without the electrolyte the process is slower relatively than with the electrolyte.

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I was under the impression the reason for under sized heads was for torque settings. ie 10mm head is this torque where as a 13mm head is that torque regardless of thread size. This system makes it impossible for a half Witt to over torque them as a 10mm socket driver is only set to one torque.

Mike

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  • 2 months later...
On 8/23/2016 at 1:53 PM, Maverik said:

In my opinion the bolts that are used in the engines are rather rubbish, (undersized AF M8's) in the most part. The heads very easily round off.

I've replaced some with standard 13mm AF 8.8 bolts and they're fine, I can't see any reason why there would be any problems, just be uber careful where threads go into aluminium and observe strict torque loads or you'll end up stripping the threads, but you can say that about most bolts.

The only possible downside is that 10.9 being a little less ductile, you might find if any age and you end up snapping them, they will be a royal pain to have to drill out.

Hi ajh,

I'm going through the same process just now and spotted your post.  What did you decide to do in the end?

Did you find anywhere that has a definitive list of all the fastenings needed on a 300tdi engine?  Its a pain in the wotsit to go through every component and work out what fasteners are required.

Cheers

Tim

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If you go to standard fasteners, then seriously consider using Nordlock Washers to provide the anti-back-off function. Much, much better than Loctite, Nylock or Split Washers. I've seen the comparison on the Junker Rig and we use them all of the time at work.

If you want to evaluate their effectiveness, make up a wing nut "barely hand tight", with a Nordlock under it, then try and back it off.... Their online training is also worth doing, even if you do not intend to use their product. There was some stuff that I was not aware of, but then thought "d'oh, thats common sense..." when i read it.

You get different varieties depending on special applications (materials, bridging slots, large versions etc)

I'm sure most decent Fastener Supplier will have them in stock. (Grampian Fasteners in Aberdeen definitely do).

I'm not linked to Nordlock, or anyone who works for them btw, I just really like a clever, simple product that works.

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21 hours ago, Bowie69 said:

On the Nordlock washers, is there additional chance of mashing the metal under the washer? More so than say a split locking washer.

Sorry, not sure of their method of working...

There are some really good explanations on their website.

The short answer is "no". The system consists of a pair of similar washers which have serrations on one side, and a slope/step on the other. The serrated sides go to the workpiece and fastener, and the two slopes/steps mate together. The two pieces are lightly glued together when you get them to make assembly easy.

As you tighten the fastener, the serrated sides grip onto the nut and workpiece, they do not move relative to their hosts.

The sloping bits ride up over each other until the desired torque is acquired. The step portion then prevents the washers backing off relative to each other until you exert a significant force to break them over. 

The washers leave marks on their hosts, which are light indents, certainly not as bad as flanged nuts which have to chew the host material. I've put them on the V8 exhaust manifolds with excellent results. 

If you are using a nut & bolt, the washers need to go under the head of the nut and the head of the bolt to prevent either component from backing off.. (Thats one of the "oh, that makes sense..." bits that you get from the training).

They are reusable... PM me your address and I'll send you a couple to play with :)

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10 hours ago, studmuffin said:

I really like the look of those Nordlock washers.

Are they made from stainless steel or ferritic steel or something else entirely?

Screen%20Shot%202016-11-15%20at%2006.53.

Honestly, they walk all over Nylocks, Loctite, Split Washers etc.

The funny thing is, when you try and back off a fastener with Nordlocks on it, the initial effort to overcome the "step" is very significant and gives you that awful sinking feeling that you are about to shear the stud / bolt....:wacko: Then you remember that the effort is required to break the hold between the face of the nut and the workpiece, it is not being exerted on the threads at all - happy days. :D

Enough of my ramblings on the pro's for Nordlock, I am beginning to sound like I'm related... In reality, I've seen their demo's a few times, I've asked them for advice and they are quick and thorough, and I've done their free online training and learnt quite a bit, thus I am nothing more than a very happy customer.

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