Removal of a smallish screw with a rusty head

[Ross365]

I have given you realistic measurements to work to. All you have to do is to measure the gap without a shim and work out how thick the shim needs to be for minimum clearance. It's that easy! It just needs to as close as possible without fouling when hot.

If it seems to you that I'm dithering, it's just that I've never worked on an ABS sensor before and I'm getting some conflicting info. One person has told me that he's dealt with a number of Gen7 Celica ABS and never seen shims and the Toyota manual does not show them, but I've got them and think I should return the car to "as was working" configuration ! I'll try get the no-shim gap.

 

[ajlelectronics]

If it seems to you that I'm dithering, it's just that I've never worked on an ABS sensor before and I'm getting some conflicting info. One person has told me that he's dealt with a number of Gen7 Celica ABS and never seen shims and the Toyota manual does not show them, but I've got them and think I should return the car to "as was working" configuration ! I'll try get the no-shim gap.

Ideally stop seeing a car in front of you and think electronics. The shim is 'selected' on test to achieve the minimum clearance, which is why it will be different across the range of quoted vehicles. Measure the gap without a shim and then work out the thickness required. If the gap is too small, it will foul, if too large the sensor won't. The vehicle is irrelevant which is why I posted the LT discussion.

 

[not done it yet]

That told me, I will book in with my GP for a sense of humour bypass immediately now ive been made aware its not to be tolerated!
Owning a land Rover product with aluminium panels I can confirm they have indeed not dissolved but they do have quite a few layers of anti corrosion treatment

It’s not me - just don’t post anything that can be used as an excuse for a moderator to close down a thread.

 

[ajlelectronics]

It’s not me - just don’t post anything that can be used as an excuse for a moderator to close down a thread.

This isn't the https://www.vintage-radio.net forum! Moderators here are nice people who are not power crazed N a z i s ;-)

 

[bricol]

I'd be surprised if a production line built vehicle had shims installed based on careful measurement of actual fit at all corners. The sensor will have a working range, and if Toyota can't make components so tolerance stack up doesn't take it out of that range, I'd be extremely surprised!

What does a new sensor come with? Is it not just a corroded part of the standard sensor - a seating face/stiffener?

 

[Ross365]

Inserting the sensor as far as it will go in to the hub (presumably the point at which the sensor is touching the ring) then there is a gap of ~1.5mm between the underside of the sensor shoulder and the hub. So to give a clearance to the ring of say 0.5mm, the 'shim' would need to be ~2mm thick.

The sensor is all plastic. The video in post 45, and ajlectronics' data clearly show some vehicles have shims. I'm not expressing any sort of opinion on how ABS sensors are/should be used, simply seeking advice on the seemingly odd situation I'm dealing with.

 

[not done it yet]

two shims cut out of a corn flake packet that should be about right

Agreed. Greased to prevent moisture entering If necessary.

I would not countenance drilling sheet unless with a step drill through a fair sized piece of sheet. The favourite is a tank cutter for anything larger than about 16mm.

 

[MetalMonkey]

If you need to make it out of something that isn't metal, you could try plastic - I've made various plastic repair bits for cars out of old square downpipe - easy to cut flat strips, UV stable and pretty robust.
Unless you live in the Sahara, I'd give cardboard, greased or otherwise until the first winter puddle... A wheel well is a harsh environment

 

[ajlelectronics]

If you need to make it out of something that isn't metal, you could try plastic - I've made various plastic repair bits for cars out of old square downpipe - easy to cut flat strips, UV stable and pretty robust.
Unless you live in the Sahara, I'd give cardboard, greased or otherwise until the first winter puddle... A wheel well is a harsh environment

Many of us have the facility to print just such a beast, on request.

 

[MetalMonkey]

Many of us have the facility to print just such a beast, on request.

That's a good point, and something I'd like to get into someday - I needed some trim clips the other day which were horrendously expensive from the dealer, but I noticed there was a 3d print file floating about for them.
I have been quite tempted to bite the bullet on a couple of occasions, but I really need to finish some of the other projects before getting distracted and it seems like the technology is getting cheaper and better the longer I wait.

 

[roofman]

Is this shimie shamied yet?? just give it an air gap of 2 to 4mm and all will be shimie shammed just right. Too close and it will pick up corrosion off the tips.

 

[ukracer]

Many of us have the facility to print just such a beast, on request.

But less of us have the ability to produce the file to print it from.

 

[ajlelectronics]

But fewer of us have the ability to produce the file to print it from.

A 2d shim is simple though. It doesn't even need to be the right shape because it can be trimmed down in situ. Besides you only have to shout if you need a design knocking up.

 

[ukracer]

A 2d shim is simple though. It doesn't even need to be the right shape because it can be trimmed down in situ. Besides you only have to shout if you need a design knocking up.

It was a genetic reply . Plus I do regularly.

 

[Ross365]

Firstly, thanks for the offer of help with the shim(s). What I've done is made up an ali shim which (painted) is ~2.1mm which is about what I think it needs to be, but if that is not right, I've armed myself with some cardboard pieces of 1.35 and 0.6mm, so I can mix and match to get it right.

Someone has suggested to me that there are no shims on Celicas and that it's a thick layer of rust that has become detached from the hub. What came off with the sensor was very hard, brittle and slightly magnetic with no silvery metal present and it's hard to believe that Toyota would have used a shim material that would have changed to 100% rust, but it's weird which ever way you look at it.

 

[Ross365]

All problems solved... I think. The outcome is a surprise, but makes everything understandable, which is good.
The issue lies with the precise shape of the sensor; it has a shoulder on the section that goes in to the hub and I had not noticed that the shoulder has a slight taper and so it sits in the hub a bit like a cork in a bottle. The "shim" was 21 years of rust and muck. I've tried to do a reasonable drawing as attached. Put it back with no shim (it's a long story getting to that point) and all is good and the ABS rumbling at low speed appears to be gone. Changed the oil and filter while I had it on stands.

Many thanks for you contributions - always good to be able to bounce ideas off people when you're struggling