Is there any reason why I shouldn't replace bolts

[owas]

I don't want a single rusty part being bolted back on the car, including all the bolts, washers and nuts.

Pricing them up at jaguar prices becomes very expensive,
Majority are just part threaded M12 bolts, the ones I drilled out seemed to be very soft, only a few come with the factory thread lock, and a few special bits I will clean up.

any reason why I shouldn't just replace them with standard 8.8 zinc bolts?

i've already measured every single nut and bolts and ordered everything plus a load of spares for around £40, compared to some bolts costing £8+ on their own ..

 

[Craig-SM]

Unless you intend on the showing the car then I would replace bolts so long as they’re correct spec

 

[Spark plug]

Normal 8.8’s will be fine for just about everything, might have to be a bit more careful when it comes to suspension etc.

 

[slim_boy_fat]

I don't want a single rusty part being bolted back on the car, including all the bolts, washers and nuts.

Bench grinder with wire wheel, followed by polishing, unless time is of the essence.

 

[stuvy]

Bench grinder with wire wheel, followed by polishing, unless time is of the essence.

We do this and our cars are just a bit rare, 1924 is the oldest

 

[Pigeon_Droppings2]

On Jap cars you'd be lucky to get m4/m6 bolts off to clean them in exposed areas....generally they snap off and have to be drilled.

I replace with stainless flange heads....not everyones cup of tea but I don't really care (drives Mr C totally nuts!)

Do whatever you want I think....provided they are correctly specced for the application.

 

[Craig-SM]

Bench grinder with wire wheel, followed by polishing, unless time is of the essence.

A torch and magnet on a stick so you can search for it when it gets flung at the speed of light from your grip into the darkest recesses of your garage.

 

[grim_d]

For general purpose bits and bobs go nuts. Pun intended.

For fasteners in critical locations I would either get new from OEM or clean and have replated the originals.

In most cases you simply cannot know the material spec for a specific application, manufacturers head markings do not necessarily relate to industry standard markings.

You often see people saying...just replace everything with 12.9! It's the strongest. Well yes...in tension. But what about shear? Many critical fasteners are in shear. More strong doesn't always mean more better.

A torch and magnet on a stick so you can search for it when it gets flung at the speed of light from your grip into the darkest recesses of your garage.

You need a hand vice.

 

[eLuSiVeMiTe]

A torch and magnet on a stick so you can search for it when it gets flung at the speed of light from your grip into the darkest recesses of your garage.

I clamp the bolt in my Ali jawed vice and take. Wire brush to it in the angle drill.
Much safer.

 

[owas]

Perhaps I should've just cleaned the bolt heads before making this thread, they all say 8.8

 

[slim_boy_fat]

A torch and magnet on a stick so you can search for it when it gets flung at the speed of light from your grip into the darkest recesses of your garage.

You need a hand vice.

Nobody here is going to post that they get better results using manual means

 

[owas]

Rookie mistake, didn't measure the thread pitch site I ordered them off doesn't list the pitch so assuming 1.5, everything is 1.75 so I'll cancel that order,
Get a load of new nuts and washers, and the vinegar and wire wheel out for the bolts,

How to protect them after getting them back to bare metal? Never plated anything,don't particularly want to get into that.
Paint the bolt head and just copper grease the bolt?

 

[slim_boy_fat]

and just copper grease the bolt?

As long as it's torque critical.

 

[Turbo]

I used a hot citric acid bath to derust some bolts & it worked quite well.

 

[Pigeon_Droppings2]

I was trying to figure out the sorts of loads that these fasteners can handle.....I prefer to get a feel for the loads the fastener can handle then think about the likely loads involved in a particular application!

via google I found the proof load of a m12 8.8 bolt to be about 4,500Kg...I expect the shear to be quite a bit lower but still this figure seems a bit high to me! I could hang 2 Volvo V70s off one bolt if this were true!

 

[slim_boy_fat]

As long as it's not torque critical.

Edited: should have read

 

[Stueeee]

via google I found the proof load of a m12 8.8 bolt to be about 4,500Kg...I expect the shear to be quite a bit lower but still this figure seems a bit high to me! I could hang 2 Volvo V70s off one bolt if this were true!

Colin Chapman (of Lotus cars fame) was on record for saying that you could hang a London bus off a 1/4" bolt. But like your example with the 2 Volvos, that would be a static load. Static load figures will be useful for when your car is parked, shock loads are what a lot of the fasteners will see when the car is being driven.

The shock load figure would be a small fraction of that static load.

 

[owas]

It turned out the ones I ordered were 1.75mm pitch so I went ahead with it.

Theres 4 m10s in my bunch that are 12.9, and the propshaft bolts are 10.9, so I'll reuse them, everything else can be nice and shiny

 

[Screwdriver]

@grim_d is dead right, some bolts are a critical spec. They should be easy to spot though. I would be wary of treating fasteners to an acid etch. Any protective coating with the possible exception of chrome plating is going to be removed and leave bare steel exposed to the elements. They won't last five minutes and regular paint will be of little help. Even lightly corroded fasteners will likely still retain some surface protection, a light nickel passivate or even the hard skin of existing corrosion can continue to protect the surfaces. Bare etched metal rusts very very quickly, especially if you don't give them a good flush with a base to remove any trace of acid.

If at all possible, a good going over with a wire wheel to remove any existing corrosion then investigate the fixing for re-use. To just throw everything is a bucket of acid is fine for vices etc. but vehicles require a little more care because they often have weird sizes and threads and will require some form of protective coating.

 

[indy4x]

There was a thread on here a while back, think it was a Suzuki Vitara rebuild and the OP sent all the fasteners away to be replated. Can't remember if they were derusted by the OP or whether is was done at the platers

Personally I don't fret about things looking original, want it to last and come undone at some unspecified point in the future

I have struggled to find fasteners with good quality plating, lots of new stuff just doesn't seem to last