www.jec.org.uk

Hello

I am in the process of replacing the anti roll bar bushes on my 1964 Mk2. Having removed the 50 year old bolts I find that some of the thread from two of the captive nuts in the chassis rail have come away also. Apart from that the remainder of the nuts appear sound. Can anyone advise me whether the answer is to drill and fit a 'Heli Coil' type repair? Are the captive nuts strong enough to take this kind of repair?

Steve

Hi Steve,

I've not had this problem and can't remember if the 'captive nuts' were loose or not. The reason being that 'captive nuts' are usually square so have a lot more meat in them, sometimes they are a strip of steel held in place inside the chassis rail. Lyons was not known for throwing his money about so it will be the minimum of steel.

In your place I would drill and tap the holes oversize to a metric or imperial size just bigger than the original, or make and weld a plate onto the outside of the chassis rail (pre drilled and taped).

Someone told me to put spacers under the antiroll bar bushes to improve anti-dive under braking, so I have a 3/8 " plate beneath them, so there is no disadvantage in fitting an external plate, or none that I have found.

Remember to refit everything with copperslip.

Brian

Hello Steve,

I suspect that the 'captive' nut is no longer captive due to corrosion of the cage, so Helicoil or re-tapping is not an option (Personally I hate Metric fasteners in an Imperial car as it confuses subsequent maintenance.)

The answer, if my guess is right, is to make up new plates with nuts welded to them, cut out the original and weld in the repair plates.

Alec

Well Steve I hope you managed to sort something, imperial or Metric?

Brian

Hi

As Brian said, if the captive nut is still holding drill and tap EITHER metric or imperial, what ever you have (sorry Alec).
Your also correct Brian that the 3/8 inch plate will will improve the anti-roll. You can also fit the alloy spacer plates from the 340/240 to do the same, although these were there to give the alloy sump additional clearance.

regards

Thanks guys, definitely food for thought.
The captive nuts are still in situ, and still have some thread albeit not enough to tighten the bush brackets. For several reasons I would like to avoid any welding at this time if I can, so it looks like I may be going down the re-tapping route for starters. The captive nuts appear solid so that may address the problem.
There are already alloy spacers between the bush brackets and the chassis rail.

Steve.

Hello Steve,

in that case I would suggest a Recoil kit and keep the standard thread, not expensive and very useful to have.

Alec

Hi Steve

Just boring and tapping the next size up will remove the least amount of metal from the captive nut. While you can go the helical route to bring it back to standard size this process will remove more metal from the captive nut and if not done correctly and carefully could allow the helicoil to be driven through the captive nut.

my tuppence worth

Hello John,

it's Steve's choice but after using the Recoil kits for longer than I remember that's what I would do. There will be no strength compromise and they are easily inserted to the correct depth due to the design of the insert tool. I strongly favour keeping to the same fastener size as original. Not from a point of view of 'Originality' but making future maintenance easier.

Alec

Hi Alec

Sorry don't mean to get in a bun fight. I don't know Steve's skill level and if you don't bottom out the helicoil and break off the tang, when you screw the bolt into you can drive the helicoil out of the thread. Plus like you I've been using helicoils since I was a boy.

That's my last post on this subject.