floor to chassis bolts

[rocket]

I have a bolt that runs through floor which have worked loose both sides,they would appear to bolt from underneath and should come up somewhere in the area of where your feet are.Anyone know if this is so and is it simply lift carpet and under felt to find the nut?

[gerrym]

Rocket, you should find that the setscrews that fasten the chassis to body (central chassis section) are screwed in threaded bobbins in the body. I.e no nuts. There should be shakeproof washers in place. You might want to check the bobbin threads. And/or the threadlocking method. Have a look a Nordlock washers for example.
Regards
Gerry

[rocket]

Thanks Gerry.In tnat case then it seems either the bobbin threads are stripping or the bobbins are turning as i tighten bolt.How are the bobbins fixed into the body?

[mikealdren]

Rocket,
They're fibreglassed in, the workshop manual gives good details but I don't have it to hand at the moment.

The bobbin is held flush with the outer surface of the fibreglass and layers of glass are laid up around/over it to hold it in place.

Most bobbin sizes are available from the likes of Paul Matty. I've replaced several of mine because they were completely worn out. Unfortunately, I don't think the small (1/4 UNC) bobbins are available (unless anyone knows a supplier please?)

Mike

[john.p.clegg]

Helicoil anyone?

John

[mikealdren]

John,
I tried a helicoil on the bonnet bobbins but they were too far gone and the hole was too large on the inner side. I also found that helicoils are quite short and you need better thread engagement to support the bonnet so I grasped the nettle and cut the old bobbins out - I haven't fitted the replacements yet because I'm refurbising the bonnet metalwork first. It's not a job I'm looking forward to!

Mike

[oldokie]

Have you considered using Rivnuts?

[CBUEB1771]

I also found that helicoils are quite short and you need better thread engagement to support the bonnet

HeliCoil inserts are readily available up to 5/8" long for 1/4-20 fasteners. The bonnet bobbins are 5/8" thick so you can get full engagment. Keyinserts are another option. It does sound as though you had several reasons for deciding to replace the bobbins.

[mikealdren]

Gene,
For me it's too late, I've got bobbin sized holes now!
I've not tried Rivnuts but i'm not sure they would hold too well in fibreglass; steel and aluminium sheet are much better at holding rivets. I think the advantage of bonding bobbins is that it anchors the bobbin well in the fibreglass and spreads the loads.
Mike

[garyeanderson]

If the bobbin is still well attached to the fiberglass (most likely) then you can drill the chassis to the next size. The current bobbins should be 3/8 UNC so the next size would be 7/16 UNC. Get a 7/16 drill bit and a collor stop to prevent the drill from going into the softer bobbin. drill the bobbin with a U size bit and tap to 7/16-14 and install a new 7/16 UNC bolt. There is plenty of meat in the bobbin for this. If this seems all to complicated get a longer 3/8 bolt and put a nyloc on it. Riv-nuts, heli-coils ain't going to work in this application...

two more cents
Gary

drill and tap sizes here
http://www.victornet.com/cgi-bin/victor ... Drill.html



top row left to right
new replacement 7/16 UNC, 7/16 clear, 7/16 clear
3/8 UNC, 3/8 clear 3/8 clear
5/16 UNC, 5/16 slotted bumper bolt
1/4 UNC

[rocket]

Probly a dim ?..to fit new bobbins do you need to remove body then?

[kstrutt11]

I've used thread inserts to repair the rover V8 block on my other toy, they are much stronger than helicoils and available in stainless steel, being larger outer diameter they are usefull where substantual damage has occured.

Kevin +2S130

[mikealdren]

Rocket,
The bobbins sit on the rough side of the fibreglass so that's generally inside the cabin and you can probably replace them without removing the chassis. You will have to remove carpets, trim etc. to get at them and you will also have to find a way of controlling the resin on the good side of the fibreglass adjacent to the chassis but that shouldn't be too hard.

The bobbins under the bonnet are fitted from the wheelarch so it would be very hard to replace them with the chassis in place.

Mike

[661]

Is there a UK source for 1/4" UNC bobbins?

[Barney]

Is there a UK source for 1/4" UNC bobbins?

SJ Sportscars list them