23 replies to this topic

[mugginz]

So Rare Spares bolts to mount a gearbox to a 6 cylinder engine have a shank and their bolts for a V8 to gearbox dont.

 

 

Does anyone know if the factory bolts for the V8 to trans bolts have a shank or not?

[rodomo]

It's because the 6's deliver way more torque and the shanks act as auxiliary dowls.

[mugginz]

It's because the 6's deliver way more torque

😯

[dattoman]

To be truly trans they would have no shank or nuts

6's are weird

[S pack]

I always thought the manual transmission to bellhousing bolts were all the same for 6 & 8 cyl with Aussie M15, M20, M21 & M22.

From memory the original transmission mounting bolts in my LJ don't have a blank shank on them.

[UCSLE]

what gearbox do you have ? some later stuff has longer bolts

[mugginz]

what gearbox do you have ? some later stuff has longer bolts

Just a good old m20

[mugginz]

I always thought the manual transmission to bellhousing bolts were all the same for 6 & 8 cyl with Aussie M15, M20, M21 & M22.
From memory the original transmission mounting bolts in my LJ don't have a blank shank on them.

The Torana Parts manual I have had the page missing that lists the part number for the V8 bolts but it does list a part number for the 6 but when I checked the part number on one website it came up as a different size to 3/8 UNC so that must of been wrong. When I get home I'll post the number up here

[mugginz]

6's are weird

Yeh, they can be

Edited by mugginz, 27 January 2019 - 04:04 PM.

[Balfizar]

GMH don't change much so for what its worth mine were set screws.  (*83 V8  VH)

 

OK - with a "shank"  (unthreaded section) is a bolt.

fully threaded on the entire length is a set screw.

Bolts are for a specific length application.

Set screws are for a variable length application or  generally used to secure an object within or against another object, normally not using a nut .

 

bolts are generally cheaper than set screws 

 

in some applications you also have to consider:-

Tensile strength is along the axis of the bolt (the hold together strength) shear strength is resistance to two surfaces twisting in opposite directions and "shearing" the bolt that holds them together. 

Bolts of the same grade as set screws are generally of a higher shear strength. (Bigger shaft diameter at the shear point - no threads to weaken the shear point)

​In a doweled assembly application shear stress is not applicable, the dowel takes care of those forces.

I have replaced my T5 bellhousing bolts with allen header set screws (H8) just for ease of disassemble.   torqued twice and checked - 8 track days OK.

Edited by Balfizar, 27 January 2019 - 05:51 PM.

[Balfizar]

looks like

4 and 6 cyl were 7/16" - 14 tpi  x 2" Bolts

8 Cyl were 3/8"  - 16 tpi x 1.5 " set screws

which aligns with the photo

[grumpy xu1]

GMH don't change much so for what its worth mine were set screws.  (*83 V8  VH)
 
OK - with a "shank"  (unthreaded section) is a bolt.
fully threaded on the entire length is a set screw.
Bolts are for a specific length application.
Set screws are for a variable length application or  generally used to secure an object within or against another object, normally not using a nut .[/size]
 
bolts are generally cheaper than set screws 
 
in some applications you also have to consider:-
Tensile strength is along the axis of the bolt (the hold together strength) shear strength is resistance to two surfaces twisting in opposite directions and "shearing" the bolt that holds them together. 
Bolts of the same grade as set screws are generally of a higher shear strength. (Bigger shaft diameter at the shear point - no threads to weaken the shear point)
​In a doweled assembly application shear stress is not applicable, the dowel takes care of those forces.
I have replaced my T5 bellhousing bolts with allen header set screws (H8) just for ease of disassemble.   torqued twice and checked - 8 track days OK.

That's a good explanation mate. Gary.

[S pack]

Just a good old m20

From the HX parts catalogue for 6cyl & V8 M15, M20, M21 & M22 4spd.

Bolt & Lock Washer - Transmission to Clutch Housing - All...................................SP2029 ....................QTY 4

 

The LC, LJ, LH (4,6 & 8 cyl) & LX (6 & 8 cyl) parts books all list the same part number SP2029.

[UCSLE]

is it gearbox to bell housing or bell-housing to motor the op wants ?

 

if its  gearbox to bell housing its whats dave has posted , there all the same

[mugginz]

is it gearbox to bell housing or bell-housing to motor the op wants ?

 

if its  gearbox to bell housing its whats dave has posted , there all the same

Bell housing to block is what I was chasing but the other info is handy.

 

The parts book I have list the Trimatic to 6Cyl engine as part number 179866 which MTS list as - "Bolt Hex HD 7/16" - 14 X 2" Grd 5" and V8's are 3/8UNC so that clears that up I guess.

 

The V8 bell housing mounting face includes two fairly decent dowels so I spose Holden decided that was sufficient and going by Balfizar's experience, actually is completely fine.

 

The Rare Spares part being a set screw sounds like it might be as per factory, but as I've had a few Rares parts not be quite right I wanted to confirm with the community.

 

Many thanks for all the info and will go with the Rares part.

[UCSLE]

as long as the bellhousing is from a torana, not from like vb-vk commodore or even maybe a UC / WB  (the bolts a are longer ) you should be right

[mugginz]

as long as the bellhousing is from a torana, not from like vb-vk commodore or even maybe a UC / WB  (the bolts a are longer ) you should be right

Good point.

 

Will check for a part number on the bell housing tomorrow.

[Bigfella237]

Late UC (Starfire) and Commodore bellhousings will have a 'pull-fork' clutch release system with a big lug/hole to hold the lower end of the cable...

 

 

Older 'push-fork' type systems just have two threaded bolt holes tapped into the side of the housing.

 

 ~ The V8 bell housing mounting face includes two fairly decent dowels so I spose Holden decided that was sufficient ~

 

Also a V8 has six bolts (bellhousing to block) and L6 only has four.

[mugginz]

Mine is a push fork arrangement so definitely not Commodore or Starfire then.

[mugginz]

Turns out the Rares bolts include a shank

 

 

They should do as a replacement for the following hopefully

 

 

Anyone know the dimensions, etc for the SP2029 trans to bell housing bolts?

[Bigfella237]

If anyone has a copy of the "Standard Parts Catalogue" Part No. M37600 it's probably listed in that?

[Kevrev]

The HJ parts manual still includes section 8.899 to 8.991 listing many of the standard parts

 

SP2029: 3/8"-16 x 1 3/8" with washer

Attached Files

•  SP2029.jpg   161.31K   10 downloads

[mugginz]

The HJ parts manual still includes section 8.899 to 8.991 listing many of the standard parts

 

SP2029: 3/8"-16 x 1 3/8" with washer

Many thanks for that.  I'll go to the bolt shop today.  I looked through the LC parts manual section 8.899 to 8.991 and I couldn't find it in there and the only link I've found so far for the HJ manual links instead to the HK manual.  Is a download for the HJ manual still around somewhere?

[Kevrev]

Yep, the link to the HJ manual was fixed. Its in the same folder as the HK one

https://www.dropbox....kFWNWL6hYa?dl=0