Rusty's Project

[Enright]

Good that is sorted, good luck with the brakes.

Maybe the moderators would like to move this to the Projects forum.

Done.

I've also renamed it to "Rusty's Project" because, well let's face it, "The First 300 Miles" are now a long time ago.

[Rusty Wishbone]

Maybe the moderators would like to move this to the Projects forum.

A very fair point.

[lotustonybassplayer]

maybe the first £3000

[Rusty Wishbone]

maybe the first £3000

I meant to record all costs incurred on my car in a spreadsheet, but I never got around to that. I'm sure that I am still below £2k in spend, so that makes it significantly cheaper to run than the big family Volvo.

[Ian T]

Rusty,

Thinking about your misfire on overrun causing popping in the exhaust - does this engine management system have an idle switch on the throttle body to detect the throttle position is at idle? Reason I ask is because on the Vauxhall 16v (20XE) engine, incorrect adjustment of the throttle cable can cause it never to register an idle input and therefore to continue to run the injectors supplying fuel during overrun, which causes the misfiring / popping. Sounds spookily familiar to me and might be a really quick fix.

Also noticed you are only a little way from me, if you find yourself short. Of something to do for an hour sometime, I wouldn't mind meeting up to have a look at your car and get se practical pointers of what you have learned to look for when buying one of these. I have read some of the excellent guides but there's no substitute for seeing something first hand.

Ian.

[Rusty Wishbone]

Some real progress on the task list this weekend. The new Brembo front brake discs arrived, so I fitted them on Friday evening. This immediately cured the vibrating/juddering brake pedal - a major result. On Saturday morning I had two new Toyo T1-Rs fitted on the front wheels to replace the 12 1/2 year-old Yokohamas. Today, I finished installing the new HT leads. So it will be interesting to see how the car feels over the next week, and how well the car starts. As I mentioned on Novacaine's thread, the old HT leads say "Sumitomo 1990" on them, so they are pretty old.

Thinking about your misfire on overrun causing popping in the exhaust - does this engine management system have an idle switch on the throttle body to detect the throttle position is at idle? Reason I ask is because on the Vauxhall 16v (20XE) engine, incorrect adjustment of the throttle cable can cause it never to register an idle input and therefore to continue to run the injectors supplying fuel during overrun, which causes the misfiring / popping. Sounds spookily familiar to me and might be a really quick fix.

Ian, thank you for your message. I don't think there is a switch - at least, I can't see one. This might be one reason why Elans tend to pop and bang. Good thinking, though.

Also noticed you are only a little way from me, if you find yourself short. Of something to do for an hour sometime, I wouldn't mind meeting up to have a look at your car and get se practical pointers of what you have learned to look for when buying one of these. I have read some of the excellent guides but there's no substitute for seeing something first hand.

It would be good to meet you too. I'll see what I have got on in the next few days and get in touch. It is a shame you missed last week's meeting at the Grasshopper. 7 Elans together.

[Brit-Car-Nut]

Thinking about your misfire on overrun causing popping in the exhaust - does this engine management system have an idle switch on the throttle body to detect the throttle position is at idle? Ian.

There is a TPS at the throttle body. Closed and full throttle adjustments can be made with ElanScan and an interface.

[Rusty Wishbone]

I thought that I would need to call the AA this morning, after the Elan ground to a halt. I think that the fuel pump stopped pumping - I couldn't hear the pump, at any rate. I went in search of an inertia cutout switch behind the passenger seat, but couldn't find one. Does the SE Turbo have one? In any event, after 10 minutes, the fuel pump was working again, so it couldn't have been an inertia switch.

Is this a typical precursor to fuel pump failure? If so, I had better order a replacement.

All I can say is, if you think the brakes are bad in normal use, you should try them when there is no servo pressure!

[cliff]

Inertia switch is here, not so easy to see with the plastic cover on.

Obviously not the problem but good to know where it is.

Are you sure it was the pump? The only time I hear mine is if the car has been sitting for a while.

[Rusty Wishbone]

Thanks. That is good to know. Not very accessible with the hardtop on.

I'm not certain about the fuel pump, but I do hear it for a moment whenever I turn on the ignition, and I didn't hear it today when I turned it on while stranded.

[chrisP]

Rusty, did you check the run out on the new brake discs when you put them on (with a dial gauge). I only ask as the judder could return if they are not within spec.

Chris

[Rusty Wishbone]

No I didn't check for run out. In fact, I didn't know what run out was to check for it. A good write up is here on the Ferodo website. What did we do before we had the Internet?

The vibration has gone, so I have concluded that one of the old discs had warped, although the new discs seem to have less bite than the old ones.

[dapinky]

Rusty,

To address your knowledge gaps (even though the job is now done, it never hurts to understand 'why' they are necessary.....

1) There is no such thing as 'brake disc warp' (in the sense that most people would understand as 'warp') - if you think about it, the discs are fairly chunky bits of steel, and to get enough heat into that volume of metal to warp it would mean driving through Hell itself (or I suppose, an errupting volcano may do it.....) - either way, by the time that happened, the car would likely be destroyed anyway by radiated heat!

That's not to say that the discs aren't affected by the heat from brake applications.....

..... the material structure of the mating surface between disc/pad change with heat application.

The easiest way to understand it is to consider playing with sand on the beach - I'm sure we've all (at some stage) built a sandcastle, and the first step to any sandcastle is to make a perfectly flat base.... usually achieved by scraping a spade (or an arm) across a patch of sand until its smooth and flat - this is your brake disc.

Then, if you again wipe your arm across the dry sand, but press down very slightly, you will 'plough' a small quantity of sand particles in front of your arm - but when you stop, most of the accumulated pile of dry sand will spread out across the imediate area, but a small quantity will remain proud of the 'flat bit', as a ridge..... (your arm is the brake pad!!).

Back to the car..... As you apply the brakes, motion energy is converted to heat energy in accordance with the laws of Physics, as the brak discs heat up, the metal particles change density within the structure, and some will move arround the disc as it rotates (pile of sand), when you stop braking, the heat dissipates, and the metal stabilises (but the density still varies due to the movement of particles).

The only way to prevent it (with 'modern' brake pads anyway!) is to ensure that you only brake for as long as it takes for an EXACT rotation of the disc (or multiples therof), and get the same temperature into the entire disc, and when you stop braking, imediately cool the disc down to ambient temperature evenly, oh, and change the pads after each braking incident.....

...so it can't be done....

obviosly, we are talking atomic levels of distortion, and it takes a while to happen, so goes mainly unnoticed until it gets too bad.

If you then get your disc skimmed, it will return to 'flat' but the material density is still disturbed, so wear will never be even, and the same thing will start all over again, but each time it's skimmed, the rate of wear will increase.

This is why i change my discs every time i change my pads (but I suffer OCD on braking issues!).

If you think what would happen if the disc was made of plasticine, it would be simple to visualise, and the wear (and material distortion) would be immediately obvious .

2) "Run out" refers to the disc running in the same plain as the hub - it needs to have flat mating surfaces, free of loose rust, particles and paint. If the 2 items don't mate correctly, then the disc will not run 'straight', causing one area to touch the pads before the opposite side - it can be accurately measured with a dial guage, but is usually obvious when you refit the wheel and rotate it - you may hear one bit touching before another bit as the wheel turns.

3) New pads/discs need a while to 'bed in' - ie, the pads and discs will wear against each other until it gets to the stage where the entire pad area is in contact with the rotating disc...

...this is compounded with the brake pad material construction - it's a bit like the material construction of the disc, but far more 'granular'. Heat affects the density of the granules.....

....as such, all manufacturers will publish 'bedding in' details for each brake compound they supply - for example, on Ferrodo DS2500, you need to drive at 40mph, apply the brakes firmly (in a straight line), until you get to 5mph - repeat 3 times - do it again at 70mph - all done! this allows the material to settle down - the solvents used in the manufacture will heat up and dissipate, and braking will be okay.

With new pads,this effect is compounded by possible oil contamination on your fingers, or protective grease on the new disc...

.... people tend to worry about grease/oil on the brakes more that you should - obviously there will be a negative effect on braking performance, but it would have to be an awfull lot of very slippery grease before it makes a huge difference.

[chrisP]

In my experience, the wobble under braking will go away for a while once new disc are fitted. But if the hub is out of true or the mating face corroded then the problem will most likely return - something I found out on my daily car.

Chris

[Rusty Wishbone]

Wow! It is at times like this that I am put in awe by the contribution of others here.

[Simon_P]

Hmmm, not sure about your sand analogy Dave.

I understood it that local hot spotting changed the crystal structure making a local hard spot.

[dapinky]

Simon,

I accept what you are saying - the actual metallurgy/material science is difficult to explain in 'simple' terms, and the sand analogy was the best I could come up with

Either way, it is a change in the structure at molecular level, not a 'warp' of the metal!

[Simon_P]

Actually I should correct my earlier comment - The sand analogy is quite good for the spreading of brake material over the disk - see below

I'm no expert! I found this:
http://www.stoptech.com/technical-suppo ... ther-myths

if you read long enough it says that you can correct it if you catch it early enough.

[Rusty Wishbone]

A serious gear change problem has arisen this morning. I thought that I had cocked up a change from 1st to 2nd. I now realise that the stick won't move below the cross gate, so I can only use 1st, 3rd & 5th. It is as if the longitudinal gear cable has slipped on the gear stick so that there is no longer any space for the stick to move back.

I have new cables and short shift on order that I was going to install at my leisure. If it arrives in time, this coming weekend is likely to be dedicated to car care.

Hopefully, the person parked in the space in front of me in the station car park will leave before me this evening so that I can drive out forwards, because reverse is a missing gear, of course.

As always, I'm in two minds about the work involved in keeping the car on the road as a daily driver. One part is rubbing its hands together with relish at an opportunity to get stuck in to a fairly major task, and the other part tells me to go and buy an Evora.

[daveiow]

My "parts" are always telling me to buy an Evora
daveiow