Seat fixing bolts

[Neil220]

I'm trying to find out the size of the 6 bolts that hold the seat frame in (1996 Supersport)

They are 7/32" with 24TPI but I don't know if they are UNC or BSW

Does anyone know please?

[Jonathan Kay]

For de Dion the 1996 Assembly Guide says M8 x 25mm.

Jonathan

[Neil220]

Thanks

I thought that age car would be imperial  fixings, but obviously not. 

Mine measure 5.72mm so pretty sure it's 7/32"!

[Jonathan Kay]

While you're down there... apart from wedging the heads in the runners with a tool do you know the other fixes for holding the bolts still while you tighten the nuts... welding them into the runners, rectangular heads and cutting a transverse slot on the free end?

Jonathan

[Neil220]

I'm referring to the Allen studs that hold the frame onto the runners rather than the ones that bolt through the floor.

I need to remove the seats to replace the seat belts.

Is it easier/ best to leave those and undo the nuts & bolts through the floor?

[Jonathan Kay]

"I'm referring to the Allen studs that hold the frame onto the runners rather than the ones that bolt through the floor.".

Doh! Sorry, that would explain it.

"Is it easier/ best to leave those and undo the nuts & bolts through the floor?"

I think that it's more common to disconnect the whole thing from the floor. And that's where the jamming tricks help.

Jonathan

[Neil220]

Thanks

Please tell me the "jamming tricks"!

[Jonathan Kay]

As above : - )

... apart from wedging the heads in the runners with a tool do you know the other fixes for holding the bolts still while you tighten the nuts... welding them into the runners, rectangular heads and cutting a transverse slot on the free end?

Jonathan

[Wrightpayne]

I've just undone one on my '98 car and they are M6 x 1.0! I checked with a thread gauge and metric 1.0 fitted perfectly but neither imperial 24 or 27tpi would fit. It also screwed into the M6 die nicely.

These 6 x M6 bolts screw into rivnuts in the seat runners which can work lose and spin. I've had this when rebuilding some seats for a fellow club member and had to re squeeze it with the rivnut gun.

While it is a PITA, I think undo the 4 bolts through the floor. My seats have M8 allen cap head bolts and with a long ball end allen key I can undo them on my own. Taking the runners out also releases trapped grit under the runners which can jam them.

Ian

[Neil220]

Many thanks.

Although mine measured 5.72mm with a vernier, 6mm is possible and I've just established that M6 has a pitch thread of 1mm giving a TPI of 25.4.

Currently looking for a 6mm nur to confirm!

[Wrightpayne]

Mine was 5.8 with the verniers. Measured a known m6 bolt and that was 5.8 too!

[7 wonders of the world]

Weld plain nuts into the runners and secure from underneath with hex head M8 machine screws with a dab of blue loctite - why they don't come like this from the factory I will never know.....

[Colin Heseltine]

As Ian (Wrightpayne) says having welded nuts or rivnuts in the runner and allen bolts from underneath is I think the best way.  This is how the seat runners for my Tillets on my new 420R are fitted.  The problem comes trying to line up the bolt holes to refit the bolts from below.  I tried just lining up by eye and failed miserably. This is obviously easier with standard seats where the squab can be removed.  I then found 4 off M6 or M8 (cannot remember what size the thread is) allen bolts (approx 35mm long) with partial plain shanks and then sawed the heads of them all.  These were then screwed into the seat runners.  The Tillet seat with runners was then easily located in the holes in the floor.  A stud was then removed, a bolt screwed in its place (easily) and the repeated for the next three bolts. I was then able to bolt the seats up without getting underneath the car.

Colin

[StevehS3]

I am looking to do the same as Colin above for my Tillets. I am surprised how heavy seat runners are!