mx5cartalk.com

So basically, i had to put a new battery in the other week. But in doing so i managed to strip the thread of the bolt that hold the brace thing that holds the battery down. Now i cant get in tight or out.... so the battery is just loosely sitting there (i can feel it jump when i go over speed bumps. Anyone know how to fix this....

You probably cross threaded the nut and damaged the thread. If its like a bolt with a thread you would run a die over the thread.Look up taps/ and dies and you will see what that means. If the thread is really cactus then you could buy/ source another of the damaged hold down. If you have the nut then that will give "you" the size of the damaged thread and you buy a die for that size. Or probably a a mechanic or the battery supplier may be able to fix it very quickly.

Hey RElapse,
I think these are pretty much a generic item.

You should be able to pick one up from a wreckers, just measure yours to make sure you get one to fit.

To get your dud one off, an angle grinder should take care of that.

PS measure before you cut. :-)

AS above.

the hold down (I assume you mean the threaded rod with the hook on one end?) is a generic item.


You can either borrow/buy a tap/die set and cut a new thread.
or buy a replacement battery hold down

The replacement hold down will usually be cheaper than a tap and die set.
Although tap sets are very useful to have if you intend on working on the car yourself more often

NA6089 wrote:Hey RElapse,

To get your dud one off, an angle grinder should take care of that.

PS measure before you cut. :-)

the bolt is stuck inside the nut though. and the nut is internally within the car if that makes sense. If i angle grind the net off, then half of it will still be stuck inside the nut.... thus getting a new nut would be useless as i have nothing to screw it into.

It's been a long time since I removed a battery in an NA so I could be misremembering but the bolt you're referring to, is it actually a black rod with a hook at the bottom and threaded for about an inch or two at the top? If so, depending on how far down you got the nut you may be able to manoeuvre it around enough to unhook the bottom then bring it out. Would be easier to work on out of the car.

If you can't then you're option is to try and get some upwards leverage on the nut. A large flat blade screwdriver or an open end spanner. Apply upwards pressure while undoing it and you may be able to get it off. You can then use a tap and die set to clean up both pieces. Otherwise cut and replace both the both the nut and threaded rod.

Perhaps a pic of your problem area would help suggestions. I keep thinking of this

If the nut is jammed onto the rod and cant be removed you have a few options:


1: Use a nut splitter, it will basically cut a slot in the nut letting it fall off. Then buy a new nut after having re-tapped the threads on the rod.

2: cut the rod in half and buy a new one.




I'd just do #2
it's the easiest, and also cheapest.
You can buy a new battery hold down from Autobarn/SCA/Repco etc for under $20 (and that will usually come with two of them, and a strap for the top of the battery.

Otherwise, just go to the wrecker and grab one, they'll probably charge you $5, if they even charge you at all for it.




If for whatever reason you cant find a hold down, then even bunnings etc will have long bolts for sale.
Buy one long enough, cut off the bolt head, and then bash the non-threaded end into an L shape like the proper hold down.

That hook thing that holds the battery down connects to a plate on the boot floor on an NA. That plate is bolted to the floor with 2 bolts (at least on my car) that go through onto captive nuts below the floor. It's common for those nuts to start turning, so you can't tighten or loosen the 2 bolts. Unfortunately there's no way of reaching the nuts from underneath. It's a total PITA and I've yet to see anyone come up with a simple easy solution.

If that's what's happened to yours then I'd probably take it to someone with cutting and welding expertise, like a panelbeater, to get the captive nuts re-captured or else find some way of getting them out and replacing them. I personally wouldn't go cutting and welding there myself because it's in an area which can easily accumulate mud and moisture to become a rust hotspot. I'd leave it to an expert and stress the need to keep it rust-proof.

manga_blue wrote:That hook thing that holds the battery down connects to a plate on the boot floor on an NA. That plate is bolted to the floor with 2 bolts (at least on my car) that go through onto captive nuts below the floor.

Agree Phil, believe OP is actually referring to the floor bracket as opposed to the upright rod & top holder. Haven't heard of a fix for that, but may be miata.net has something.

When I looked at my pic above I noticed some acid residue so I pulled it apart to clean it up. I noticed the bottom bracket that seems to be causing the op grief.

If it were me I'd have the bracket tack welded to the floor. If that's not acceptable to the op, he can try to extract the bolt by trying to get a wedge under the bolt head and unscrewing until you get past the stripped section.
Good luck.

NA6089 wrote:When I looked at my pic above I noticed some acid residue so I pulled it apart to clean it up. I noticed the bottom bracket that seems to be causing the op grief.

If it were me I'd have the bracket tack welded to the floor. If that's not acceptable to the op, he can try to extract the bolt by trying to get a wedge under the bolt head and unscrewing until you get past the stripped section.
Good luck.

Personally i'd just drill out the hole and re-tap it

If it's really stuffed, drill it out by the next size up and tap that to suit a larger bolt.

If the captive nut underneath has broken free then just thread a Nyloc nut on the bolt that you've pushed through from above.

those hooked threaded poles can be brought in various lengths. just put the old one and buy new.

manga_blue wrote:That hook thing that holds the battery down connects to a plate on the boot floor on an NA. That plate is bolted to the floor with 2 bolts (at least on my car) that go through onto captive nuts below the floor. It's common for those nuts to start turning, so you can't tighten or loosen the 2 bolts. Unfortunately there's no way of reaching the nuts from underneath. It's a total PITA and I've yet to see anyone come up with a simple easy solution.

If that's what's happened to yours then I'd probably take it to someone with cutting and welding expertise, like a panelbeater, to get the captive nuts re-captured or else find some way of getting them out and replacing them. I personally wouldn't go cutting and welding there myself because it's in an area which can easily accumulate mud and moisture to become a rust hotspot. I'd leave it to an expert and stress the need to keep it rust-proof.

Yeah, you are spot on. This is what has occurred. Sucks there is no easy fix for it, dont really have the money to get it done properly. Guess ill just leave it as is and hope i never have to change the battery again.

It's not a good idea to have a loose battery. As previously mentioned tack weld the bracket to floor, or maybe a few decent rivets is possible?

It sounds like there are no stripped threads, so another option could be to pack between the top of the battery & the clamp across the battery. Then use the nuts on the rods to tension the complete assembly of rods & floor brackets.