21 replies to this topic

[oliver122]

hey guys , so im building my mini up and seem to have misplaced lots of bolts , now i was wondering if any of you guys could tell me what sizes i would need to buy and handy to have , cheers guys

[IainNeon91]

anything to do with the exhaust or inlet, 8mm

Edited by IainNeon91, 30 January 2013 - 04:24 PM.

[Cooperman]

The nuts and bolts on a Mini are virtually all either UNF (Unified Fine) or UNC (Unified Coarse). They are not metric.
Most popular sizes are 1/4", 5/16" and 3/8" UNF throughout the engine and the rest of the car, whilst most threaded holes in the aluminium gearbox casing are UNC.
An on-line company, Namrick Limited, are an excellent supplier of nuts, bolt & washers. They do a 450 piece pack of UNF nuts, bolts & washers for a rasonable price.
Make sure you always use Imperial size spanners, 7/16" AF, 1/2" AF and 9/16" AF, and are not tempted to try to use metric sizes.

[Vipernoir]

Metric and Imperial DO NOT MATCH - end of argument.

While some bolts on later Minis are metric, the vast majority are imperial UNF/UNC and the spanners used should be imperial.
13mm is fairly close to ½", and 14mm is fairly close to 9/16" - but as soon as you come across a tight fastener you WILL end up with a rounded off hexagon.

A decent selection of 1/4", 5/16" and 3/8" UNF & UNC nuts and bolts up to 2" long would be a good start. If you get longer bolts you can always cut them down if needed - a good hacksaw and a file are essential.

[ibrooks]

13mm is a hell of a big bolt - and it won't fit anything on a Mini.

Mini's are mostly imperial so to fit the existing stuff that's what you need to have handy. 1/4", 5/16" and 3/8" UNF are common sizes. Where a bolt goes into a casting a coarser thread is generally used so the same sizes in UNC are a good bet. Use 8.8 grade as a matter of course unless it's brakes or steering related in which case use better - pay attention to this as you get lots of bulk packs of 4.8 grade bolts that have the tensile strength of cheese.

There are a couple of traders on ebay that do big-ish mixed packs which are a good start. You'll often find that you then run out of a particular size so find a local hardware supplier - you'll pay a couple of quid for a hundred bolts or nuts or washers so just top up the box as you run out.

Use the imperial sockets in your toolbox as the metric equivalents are usually a fraction bigger and once there's a little bit of corrosion on a nut or bolt head that just leads to the things being rounded off and then the proper imperial one often won't get a proper grip either.

Beware the people selling stainless fastener kits. The cheaper grades of stainless that they usually sell are not as strong as 8.8 nuts and bolts and are therefore not suitable in a lot of places. Stainless is also a bugger for galling - in our case the thread inside a nut "picks up" and mangles itself inside the nut so it feels tight but hasn't really clamped anything and won't come off again without snapping.

Iain

[IainNeon91]

13mm is a hell of a big bolt - and it won't fit anything on a Mini.

I agree with you there!

Edited by IainNeon91, 30 January 2013 - 04:25 PM.

[tiger99]

Wrong, and wrong! It is an 8mm nut, same as the bolt, which fits a 13mm spanner, not a 13mm nut, which is a non-standard size anyway. And, metric spanners DO NOT fit imperial nuts, or vice versa. Just because a worn out or cheap Chinese 1/2" spanner seems to go on a 13mm nut, does not mean that it fits, and it it does, it certainly will not fit its supposedly correct 1/2" nut. ibrooks has already explained clearfly and correctly what will happen.

Frankly I am sick of this pathetic argument, which crops up from time to time.

[IainNeon91]

Wrong, and wrong! It is an 8mm nut, same as the bolt, which fits a 13mm spanner, not a 13mm nut, which is a non-standard size anyway. And, metric spanners DO NOT fit imperial nuts, or vice versa. Just because a worn out or cheap Chinese 1/2" spanner seems to go on a 13mm nut, does not mean that it fits, and it it does, it certainly will not fit its supposedly correct 1/2" nut. ibrooks has already explained clearfly and correctly what will happen.

Frankly I am sick of this pathetic argument, which crops up from time to time.

Top notch explanation

Edited by IainNeon91, 30 January 2013 - 04:25 PM.

[antcole]

Heres a list of what i recently ordered from Namrick, i figured since i was restoring two minis and possibly a third later on, it made sense to renew as many of the bolts as possible.
What isnt the right length can be cut to size and it will all look lovely and bright with new nuts and bolts on as much as i can find.

The previous comments on using metric spanners is right but for a reasonable ID of the bolt size, if you dont have imperial spanners to hand, 1/4 is 11mm AF, 5/16 is 13mm AF, 3/8 is 14mm AF, 7/16 is 16mm AF, 1/2 is 19mm AF.
As recommended though, use imperial spanners because they just fit better and its correct.

The whole lot came to about 120 quid which is pretty good value considering theyre all high tensile and as good as the original manufacturers fixings.





311004 1/4" UNF x 3/4" HT Hex Head Set Screw

314005 7/16" UNF x 1" HT Hex Head Set Screw 12

313005 3/8" UNF x 1" HT Hex Head Set Screw 16

315004 1/2" UNF x 1-1/2" HT Hex Head Set Screw 6

313003 3/8" UNF x 3/4" HT Hex Head Set Screw 20

312003 5/16" UNF x 3/4" HT Hex Head Set Screw 10

311008 1/4" UNF x 1-1/2" HT Hex Head Set Screw 20

314007 7/16" UNF x 1-1/2" HT Hex Head Set Screw 12

312001 5/16" UNF x 1/2" HT Hex Head Set Screw 10

313007 3/8" UNF x 1-1/2" HT Hex Head Set Screw 8

313001 3/8" UNF x 1/2" HT Hex Head Set Screw 10

311002 1/4" UNF x 1/2" HT Hex Head Set Screw 10

312007 5/16" UNF x 1-1/2" HT Hex Head Set Screw 20

3169705 5/16" UNF Full Nut - Pack of 10 2

3169674 1/4" UNF Nyloc Nut - Pack of 10

3169707 5/16" UNF Nyloc Nut - Pack of 10

3169672 1/4" UNF Full Nut - Pack of 10

3169837 1/2" UNF Full Nut - Pack of 10

3169771 7/16" UNF Full Nut - Pack of 10

3169738 3/8" UNF Full Nut - Pack of 10

3169740 3/8" UNF Nyloc Nut - Pack of 10

3169839 1/2" UNF Nyloc Nut - Pack of 10

3169773 7/16" UNF Nyloc Nut - Pack of 10

23169488 1/2" Spring Washers BZP - Pack of 10

23169479 5/16" Spring Washers BZP - Pack of 10

23169485 7/16" Spring Washers BZP - Pack of 10

3169482 3/8" Spring Washers BZP - Pack of 10

3169476 1/4" Spring Washers BZP - Pack of 10 2

3169473 3/16" Spring Washers BZP - Pack of 10 2

3168505 Mixed B.A Plain Washers (6,4,2BA) 2

3168503 Mixed Imperial Plain Washers (1/4" to 1/2") 2

3168504 Mixed Metric Plain Washers (6mm to 12mm) 2

3168646 Mixed Pack Assorted Penny Washers 1

[tiger99]

That is all very well, but beware of replacing bolts with set screws. Often it matters. Perversely, the rear subframe mounts on all of my Minis had set screws, where it would have been reasonable to have bolts, and definitely none of the subframes had ever been removed. And watch out for the clutch cover (wok) etc, which screw into softish alloy and so are UNC threads.

In case anyone wonders, a set screw is threaded for its full length, while a bolt has a length of plain shank. Some bolts are "fitted" bolts, where the plain shank is made to exact dimensions so it will fit closely in a hole, usually if the bolt will be stressed in shear.

Oh, and special nuts, bolts etc made to specific dimensions are required on suspension parts (e,g. tie rod to lower arm), steering column pinch bolt, etc, and obviously engine internals. Use ONLY the proper parts form a Mini specialist for those.

[A-Cell]

Amen to that. I got a Mini where the majority of fixings used to rebuild it were 4.2 grade stainless set screws, including the tie bar to bottom arm fixings! Bloody dangerous. Very pretty, even passed an MoT. Not funny.

[Marlin]

What is different about the specialty bolts? As long as you are using the same size and style as well as equivilent grade or better I can't see an issue substituting.

[tiger99]

In many cases thay are machined to fit exactly, especially the tie rod bolts, and they are not necessarily all grade 8.8, some may be higher. A standard off the shelf bolt may not have the same thread length or tolerance on its diameter as the official part. The problem is largely that we don't know the minimum requirements for some of the bolts, but it is not safe to blindly fit substitutes, without knowing what is actually required.

[rally515]

I need to tap all my threads in both subframes can anybody help with imperial sizes ?
Its pre 76 so has twin tower bolts on the front also
Sorry bit off topic .

Cliff

Edited by rally515, 01 February 2013 - 02:05 PM.

[Cooperman]

In many cases thay are machined to fit exactly, especially the tie rod bolts, and they are not necessarily all grade 8.8, some may be higher. A standard off the shelf bolt may not have the same thread length or tolerance on its diameter as the official part. The problem is largely that we don't know the minimum requirements for some of the bolts, but it is not safe to blindly fit substitutes, without knowing what is actually required.

With the tie-bar to lower arm bolts you can ream out the arm and tie rod to 8mm and use a fitted high quality M8 Fine bolt, like a 10.9 grade. Then you know it's been done properly and will be strong enough. That is stronger than the original BMC design.