Removing bushes using a threaded bar and cups - What thread?

[montyjohn]

Hi, I'm going to have a go at using a bush removal kit made for BMW rear control arms on a front Lexus control arms. They look a similar size, so think it it will work.

Last time I used it I stripped the thread. It's M12 normal pitch so I think 1.75mm.

When buying a new threaded bar, is there any benefit in using a fine pitch?
I know it will make the nuts easier to tighten, but are they less likely to strip.
I'm thinking there will be more threads, but they are skinnier. Which is least likely to strip.
I know course thread is more likely to shear as the threads cut deeper, but that doesn't seem to be the issue for me.

Looking on eBay the highest tensile bar I can see is 8.8.
Would A4 stainless be tougher?

I'm not anticipating these bushes to come out early.

Anybody in Purley CR8 have a press I can use

[paintman]

Take the rubber & centre tube out using drill bits to cut the rubber up.

Use a hacksaw to cut through the outer metal tube in one place - try & avoid cutting into the arm.

Use a punch/cold chisel to bend the cut part of the outer tube inwards - done a few on various cars before I bought a press & they usually come out quite easily.

Edited by paintman on Friday 7th January 20:08

[Easternlight]

I would say use a fine pitch with as lager a diameter as possible, maybe half inch UNF as the fine pitch gives you more mechanical advantage.
Use Steel high tensile not the stainless as it is more likely to pickup (gall)
Grease the threads and put a couple of greased washers under the nut to act as a thrust bearing.

In an ideal world you would use a ACME shaped thread form as they are better in shear because of the shallow flank angle.

[GreenV8S]

Consider using a hex coupling nut rather than an ordinary nut. These have many times more thread engagement so will be less likely to strip the thread. Or buy a proper puller - they aren't terribly expensive in the scheme of things,

[TRIUMPHBULLET]

GreenV8S said:

Consider using a hex coupling nut rather than an ordinary nut. These have many times more thread engagement so will be less likely to strip the thread. Or buy a proper puller - they aren't terribly expensive in the scheme of things,

As above but also use 10.9 grade all thread from somewhere like boltworld.co.uk.

[Error_404_Username_not_found]

As above on fine thread, coupler nut, the longer the better. Definitely not Stainless. High grade (10.9 for Metric, grade 8 for SAE (UNF). Grease and washers. All good stuff.
But first soak it with as much PlusGas as you have the time and patience for. Not WD40, it won't penetrate. PlusGas is getting harder to find but it's worth it.

[E-bmw]

As above, absolutely not stainless, the threads will gall guaranteed.

[montyjohn]

Thanks for all the feedback, I know what to look for now

[Trickey67]

I’ve got a fiesta 09 plate need rear suspension bushes replaced . What’s an average cost - been told £250- but friends say £150

[paintman]

Trickey67 said:

I’ve got a fiesta 09 plate need rear suspension bushes replaced . What’s an average cost - been told £250- but friends say £150

You'll be best ringing local garages & getting actual quotes as prices vary across the country & online guesstimating may not be helpful.

Much the same as your mates guesstimating unless they are mechanics & are offering to do the job for you or have had the same job carried out & that's what the garage charged.

Edited by paintman on Thursday 10th February 22:49

[stevieturbo]

Trickey67 said:

I’ve got a fiesta 09 plate need rear suspension bushes replaced . What’s an average cost - been told £250- but friends say £150

get your friends to do it then and save £100.