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seat belt bolt head sizes

Started by _devilsadvocate_ , Jan 15 2007 02:08 AM

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14 replies to this topic

#1 _devilsadvocate_

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Posted 15 January 2007 - 02:08 AM

Just been shifting some belts around in the UC and found to my displeasure that half the bolts have 25/32in heads and the other half 13/16, fit the sockets perfectly, same thread. A 25/32 head wont actually slip inside a 13/16 socket, so perhaps people havent noticed, I had on previous occasions always just used the 13/16 spark plug socket and noticed that sometimes it would slip if not pressed onto the bolt firmly enough, which I put down to the the grooves in the socket not extending right to the end and the head of the bolt being quite slim.
It wasnt until today that I couldnt locate the 13/16 socket and picked out another one out of a more ancient socket set and found the 25/32 to be a perfect fit for the bolt I tried......wasnt til I moved onto another bolt and found that it wouldnt go over it that I discovered the prob.
Metric size would be 25/32 = 19.8mm and 13/16 = 20.6mm, so its possible that the 25/32 sized one could be a 20mm metric sized head? But the actual heads of the bolts measure 19.69mm and 20.45mm respectively(micrometer), the 25/32 is going to be a tighter fit than the 20mm. Obviously a 1/2 spanner and a 1/2 in bolt head cant be exactly the same size or they would need to be pushed together quite hard?, which is made slightly larger or smaller? Given what Ive measured on these two bolt heads perhaps it is the head that is made slightly smaller than the respective spanner size?
Has anyone else found this? The other uc is entirely 25/32, and has little black pieces of plastic that go over all the bolt heads, they wont fit on the 13/16 bolts.
Do I possibly have bolts in there from an LX or LH that someone fitted with some belts pulled out of one of those. It does seem strange 25/32 is not a very common size.

Edited by devilsadvocate, 15 January 2007 - 02:11 AM.

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#2 Struggler

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Posted 15 January 2007 - 09:21 AM

Well they couldn't be metric in a UC could they ? Not after the last thread when you argued that you had never seen a metric fastener in a UC before.....................................

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#3 _devilsadvocate_

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Posted 15 January 2007 - 11:03 AM

I thought you wont going to post in threads where I had posted Struggler. Still no one has been able to point out where a metric bolt is on a UC, maybe I have done the hard work for you............maybe not, do you have an answer to the dilemma to the seat bolt head sizes or have found a metric UC bolt........... :<_<:

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#4 _Yella SLuR_

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Posted 15 January 2007 - 11:15 AM

With such a large bolt, slight difference in the socket size isn't going to make a huge difference. I used a 20mm socket on an imperial LH. The bolts also don't have to be done up shit tight due to all the washers/spacers/seatbelt holder hooks, etc. Just quarter turn to nip up.

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#5 dattoman

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Posted 15 January 2007 - 11:19 AM

I know the brake pipe fittings on master cylinder and caliper are metric on UC after 7/79
Maybe they started throwing some metric/commodore parts into the UC's hoping no-one would notice

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#6 _devilsadvocate_

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Posted 15 January 2007 - 11:43 AM

With such a large bolt, slight difference in the socket size isn't going to make a huge difference. I used a 20mm socket on an imperial LH. The bolts also don't have to be done up shit tight due to all the washers/spacers/seatbelt holder hooks, etc. Just quarter turn to nip up.

You have provided some good info Yella, the LH has the smaller of the two bolts given you can fit a 20mm socket on it. Dont know about your advice about what torque to tighten them to(any of the ones Ive had to undo have been tightened by a gorilla)....... yes there are spacers there that allow the metal/belt retainer to swivel in any direction to prevent wear on the belt.........they will still function no matter how tight the bolt is, there are also spring washers that should obviously be torqued flat as well.

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#7 Bazza

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Posted 15 January 2007 - 12:02 PM

Hi all

A little off-topic - but the Max Ellery Torana book says that seat belt attaching bolts should be torqued to 39-52 lb. ft.

Bazza

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#8 _devilsadvocate_

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Posted 15 January 2007 - 01:48 PM

Good info Bazza, not off topic at all, the specs suggest a significant torque......having the right sized socket may prevent some skinned knuckles or damaged nuts(take that what ever way you want to!)....okay they are bolts!

Edited by devilsadvocate, 15 January 2007 - 01:56 PM.

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#9 _devilsadvocate_

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Posted 15 January 2007 - 02:00 PM

I know the brake pipe fittings on master cylinder and caliper are metric on UC after 7/79
Maybe they started throwing some metric/commodore parts into the UC's hoping no-one would notice

Well that sheds some light on it, I completely removed the calipers/master cylinder and booster from my UC sunbudgie last week, AF tools fit perfectly.....its a 78 model as are my other 3 UC's.

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#10 rodomo

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Posted 15 January 2007 - 02:53 PM

I know the brake pipe fittings on master cylinder and caliper are metric on UC after 7/79
Maybe they started throwing some metric/commodore parts into the UC's hoping no-one would notice

I should have got the build date of Leith's hatch when i fixed it.

Top Bosch alternator bolt, M8 X 1.25 thread, 13mm hex. Goes back further than UC. A bit of trivia. :spoton:

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#11 arrimar

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Posted 15 January 2007 - 03:34 PM

the bolt is supplied with a new alternator. hence the metric.

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#12 rodomo

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Posted 16 January 2007 - 12:22 AM

the bolt is supplied with a new alternator. hence the metric.

You may be correct, but I remember when I had my EH (a thousand years ago before metric bolts were readily available) that I had to look hard in the "box of bolts" to find the one that would fit. You are probably aware of a lot of "top bolt" holes being drilled and a nut and bolt used probably for this reason.

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#13 _Flamenco_

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Posted 16 January 2007 - 06:38 PM

You may be correct, but I remember when I had my EH (a thousand years ago before metric bolts were readily available)

And I thought EH's were made in the sixties!

I found the problem with spanners not fitting the brake lines on a UC before too. Maybe they could have been replaced with metric at some point-not sure...

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#14 _Yella SLuR_

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Posted 18 January 2007 - 01:06 PM

39-52 ft/lb aint that much. Try doing a FWD stub axle bolt ---> 175 ft/lb. Usually need a lever to achieve this, or a slipped disk in your back, your choice.

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#15 _devilsadvocate_

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Posted 18 January 2007 - 05:34 PM

Yella, yes those fwd stub axle bolts torques are very large, however, as a comparison 55-59 lbft is recommended for wheel nuts in the torrie owners manual which is relatively close to the seat belt recommendation. You may be right though, as long as taking all the slack out of the spring washers all should be okay, but as for getting them undone....

Anyway, has anyone found any that are 13/16in in their torrie......its just a curiosity for the moment(how did they get there, how many had this size in them) ie have sockets for both 13/16 and 25/32.
How do you know if you dont have a 25/32 socket? as a 13/16 may fit the smaller one okay(if you can get a good piece of the socket on the skinny head), a 20mm will fit(go on) the smaller one but not the larger.