Non-toyota Tpms

[Fujisan]

I don't know about the Typhoon! I was think more of the Space Shuttle!

[Hoovie]

I thjink the answer is a Car PC - that could replace the TomTom on the right, the iPod on the Left, the Scanguage above the mirror, the radio/CD in the middle of course, as well as add DVD and TV capabilities.

The ultimate add-on like this I have seen has to be this Toyota MR2 -I hate to think how much time and money went into adapting the dash and adding interfaces - and now the guy is selling

It is on sale on eBay - MR2 Turbo Gen3

[anchorman]

I do believe he's had his dash flocked.

[Fujisan]

I do believe he's had his dash flocked.

Well and truely flocked! :o

[cabcurtains]

Anymore of this technology and we wont check anything, lets hope the onboard diagnostics dont fail :o

[Hoovie]

That MR2 is runing Windows XP so the car will probably take 10 minutes to boot up and crash every journey!

It looks cool but I think this kind of solution is best of kept on the 'entertainment' side

[Hoovie]

Back on Topic ......

Got the TPMS sensors fitted today when I got a set of General Grabbers fitted, and ended up having some interesting conversations with the tyre fitters and the TPMS company

The Tyre Company (ProTyre in Exeter) have a lot of experience dealing with wheels that are fitted with TPMS sensors and had two concerns about the kit I had.

1) The way the sensor is attached to the wheel, there is a significant risk that when the tyre is removed (for tyre replacement or puncture repair), the sensor could be broken as they see a weak point where the plastic sensor housing is connected to the valve at the same place that the tyre bead will drop down.

2) The sensor does not lie flush on the wheel well due to the inner profile of the alloy and a lip on the well - so there is a gap in the middle which is not supported by maybe 2-3 mm

called the TPMS Maker/Distributor to check about this and then passed phone over to fitters ... TPMS compamy said to fitters that any decent Tyre place can deal with #1 without an issue (you can imagine how that comment went down!). They were also not too concerned about the gap (I am not sure how significant that gap would be)

End of the day, Protyre were happy enough to fit it but would not say a tyre could be removed without potential damage to the sensor.

So they DID fit them and the display picked up each tyre as it got swiveled around on the various fitting machines, which was interesting to see the display build up with each tyre being added automatically.

now the tyres were inflated to 29PSI and the display showed 3 at 28PSI and 1 at 29PSI - Protyre were adamant that the sensors were slightly underreading as their stuff is calibrated frequently, but talking 1 PSI and no values under a whole number shown, so while it may have been just 0.5PSI out - well within required tolerances really. (within about 1/4 mile from leaving, the tyres all showed 29PSI, so it must have been borderline presure between 28 and 29 PSI and the little extra heat pushed it up)

Rubbish Pics, but took these with the phone after about 10 miles of driving, the last 5 at about 20-30mph on single track farm roads (!Removed! road works and sat nav mapping!)

interesting variation on the temperatures in different tyres

As an aside, ProTyre is a very competant tyre fitters that also have great prices. They bettered the Blackcircle fitted price without even knowing it and when I reminded them that I had a TPMS system which they said they would fit for free, they actually said "if you are providing a TPMS system, then fitting will be cheaper as you have the valves" and dropped £9 odd off the bill

They also have some very nice courtesy cars as well ......

I wish !! - but it does show the type of vehicles they work on, which is reassuring

[Fujisan]

Well done Protyre's

interesting variation on the temperatures in different tyres

I'd expect the front's to be hotter than the rears because the front disc's are doing must of the work during braking (so generating the most heat) but you'll have to help my poor old eyes

Does the top left say 29 or 39 degrees?

If it's 39 degrees, it look's to an untrained eye if one brake circuit (front left / rear right) is doing most of the work, (if the RAV's brake circuit's are set up in the usual cross-car X formation ) but I'm sure you would have felt that.

If it's 29 degrees, which I think it is, I would put it down to one of lifes interesting fact's.

Sure Anchorman could comment on this better than me!

They also have some very nice courtesy cars as well ......

[Hoovie]

Well done Protyre's

interesting variation on the temperatures in different tyres

I'd expect the front's to be hotter than the rears because the front disc's are doing must of the work during braking (so generating the most heat) but you'll have to help my poor old eyes

Does the top left say 29 or 39 degrees?

If it's 39 degrees, it look's to an untrained eye if one brake circuit (front left / rear right) is doing most of the work, (if the RAV's brake circuit's are set up in the usual cross-car X formation ) but I'm sure you would have felt that.

If it's 29 degrees, which I think it is, I would put it down to one of lifes interesting fact's.

Sure Anchorman could comment on this better than me!

That is 29 - your eyes are in fine fettle :D (PS - the reflection is not there from the driving postion ;) )

So Temps read:

FL=29; FR=31

RL=25; RR=29

So temps front/back vary by about 4 C, which does makes sense to me, but also vary right to left, which doesn't so much (unless something to do with weight distribution? only me in car, so weight slight biased towards right?)

be interesting to know why this is the case

[anchorman]

I would expect the fronts to be hotter than the rears for the same reason as Fuj but quite honestly I wouldn't be at all concerned by that temperature spread with that kind of temperature measuring device.

When measureing brake temperature for development or testing, rubbing thermocouples are used. These have a temperature sensitive head that look a bit like a blob of solder and is held in physical contact with the disc by a lightly loaded length of spring steel. Even these are not perfect as they can get caught op in different amounts of air flow and turbulance around the wheels.

If your TPMS devices are measuring air temperature inside the tyre then there could be similar reasons for that kind of variance and I would say that if it is within +/- 5degC at ambient or +/-15degC at 100degC then don't worry.

Incidentally, the system is split into 4 seperate channels on a vehicle with ABS to allow it to modulate each brake in the event of it locking up prematurely.

Cheers

[Fujisan]

Incidentally, the system is split into 4 seperate channels on a vehicle with ABS to allow it to modulate each brake in the event of it locking up prematurely.

Thanks AM

Showing my age when refering to X circuit brakes!

[quinnmar]

A quick question or two if I may?

I've read this thread with great interest and would be keen on fitting a TPMS. I've only driven 2600 miles in my new 4.3 and was wondering if it's new tyres and inner tubes I need, just new tyres, just new inner tubes or could a TPMS be installed on factory-fitted tyres et al?

If I need to buy anything, would someone please be so kind to point me in the general direction of reputable online dealers?

TIA

quinnmar

[Hoovie]

No innertubes on these cars nowadays :)

TPMS systems are almost always based on a replacement valve with a sensor fitted onto the valve inside the tyre, so no new tyres needed

Chris (Three5) can probably advise best on his experience as he had on fitted on his RAV4.3 with just 3,000 miles driven

[three5]

I would expect the fronts to be hotter than the rears for the same reason as Fuj but quite honestly I wouldn't be at all concerned by that temperature spread with that kind of temperature measuring device.

When measureing brake temperature for development or testing, rubbing thermocouples are used. These have a temperature sensitive head that look a bit like a blob of solder and is held in physical contact with the disc by a lightly loaded length of spring steel. Even these are not perfect as they can get caught op in different amounts of air flow and turbulance around the wheels.

If your TPMS devices are measuring air temperature inside the tyre then there could be similar reasons for that kind of variance and I would say that if it is within +/- 5degC at ambient or +/-15degC at 100degC then don't worry.

Incidentally, the system is split into 4 seperate channels on a vehicle with ABS to allow it to modulate each brake in the event of it locking up prematurely.

Cheers

There is another possible explanation for at least some the difference between the front and rear temperatures: The drive is through the front tyres so there should be more sidewall flexing as the power is transmitted. This "working" of the sidewall would produce heat in the same way as continually bending a piece of metal in the same place. Well - it's a theory anyway!

Best regards

Chris

[Hoovie]

Hi Chris - do you get a similar variation on your display?

re the difference, I am suspecting it is not so much the drive (especially as the RAV4.2 is permenent 4WD), but due to more flexing on the fronts for steering reasons, plus the front brakes doing a lot more work then rears.

Something I am not really worried about at all, but it is just interesting to see more information about how a car is reacting and working (bit like the Scangauge, but for the tyres instead of the engine :) )

[anchorman]

Ask shcm but there must be some sort of potentiometer or strain gauge device built in. I suspect the accuracy (unless you pay considerably more than you did for these) is not better than +/- 1 degC and that will only be "somewhere" in a temperature range.

I think you are looking too hard and there is no problem with them.

IMHO

[Hoovie]

I don't think anyone is worrying (I'm not anyway :) ) - it is just curiosity when presented with data that has not been visible before.

[anchorman]

I don't think anyone is worrying (I'm not anyway :) ) - it is just curiosity when presented with data that has not been visible before.

[shcm]

Ask shcm but there must be some sort of potentiometer or strain gauge device built in.

Well sort of for the pressure sensing, but probably not for the temperature sensing.

At a basic overview level, the pressure sensing is going to be probably either piezo-resistive (resistance change with mechanical deformation) or capacitive (physics recap - capacitance is inversely proportional to the distance between the capacitor plates, so if you "push" one of the plates slightly, the capacitance changes, which you can measure).

Various way to measure temperature, but if a piece of silicon is involved, it will rely on the basic fact that the forward biased "on" voltage of a diode changes with temperature. For a silicon diode, about 0.8V @ -40C and about 0.5V @ +125C. Most 'lecky engineers use a figure of about 0.7V at room temp. (Off Topic - don't assume it is the same for LEDs, because it isn't. LEDs use different materials, because standard silicon diodes are inefficient at emitting visible light).

http://en.wikipedia.org/wiki/Silicon_bandg...perature_sensor

That wikipedia page claims it's OK up to about 200C to 250C, but in my experience it's more like 150C.

I suspect the accuracy (unless you pay considerably more than you did for these) is not better than +/- 1 degC and that will only be "somewhere" in a temperature range.

You can do better. Devices exist that do say +/- 0.3C, but they will be typically 3 to 5 times more expensive than something doing typically +/- 1.5C. That tolerance will also get worse at extremes of temperature. The additional expense of the more accurate devices may well be due to extra testing and selection or trimming at the end of the silicon device production line.

Yep, I agree with AM (and I know you're not bothered Hoovie ) those temperature differences don't look too concerning to me. You could perhaps expect that the transmitters might be fitted with silicon devices from the same silicon wafer or batch and would therefore "track" in their behaviour to some extent (which does happen), but there's no guarantee.

Just curious, did the box/instructions they came with quote any tolerance/accuracy figures?

Cheers

[Hoovie]

"Just curious, did the box/instructions they came with quote any tolerance/accuracy figures?" Not that I have come across.

Interestingly (in that I expected something different), the PSI of the tyres only vary by about 4 PSI between cold in the morning and a 30 odd mile run on the motorway at 70MPH - I would have thought the difference would be greater.

I am impressed at the accuracy of the pressure data being effectively the same as the tyre fitters calibrated gear.

I just checked the temperature of the valve stems compared to the Display reading and there is about a 2 Deg C difference between them (offside valve stems both read 18.6 C (and were in the sun for a few hours today) and Display says 21C, nearside valve stems both read 15.1 C and Display says 17C front and 16C rear), so the temp is probably pretty accurate as well as I would expect the air in the tyre to cool slower then the external metal once sun had gone it.

[bothwell_buyer]

I thjink the answer is a Car PC - that could replace the TomTom on the right, the iPod on the Left, the Scanguage above the mirror, the radio/CD in the middle of course, as well as add DVD and TV capabilities.

The ultimate add-on like this I have seen has to be this Toyota MR2 -I hate to think how much time and money went into adapting the dash and adding interfaces - and now the guy is selling

It is on sale on eBay - MR2 Turbo Gen3

There's some sense in adding in extras when its running a decent engine - the 3SGTE deserves looking after. However I have to smile at monitoring a 1998 VVTi lump :P With the added weight of the 5 doors; electronics; alternator drag; and sundry sensors; all you need is a robotic arm to fill the thing with petrol..... B)

Next will it be the brushes below to pick up current from the road??

Scalextric is a career!

[chatman]

Hoovie,

Did you catch the Gadget show on 5 last night. They had a TPMS system similar to yours on there.... Came out tops in the user survey.... :D

Also had a rather good Sat Nav and rear wireless camera linked into reversing light... select reveres and Sat Nav then picks up camera mounted on rear... and in colour...

[Hoovie]

Didn't see that. I'll have to try and catch a rerun or on line

EDIT: Looks like it is repeated on "Fiver" at 8pm tonight

I was gonna post a little update actually on the TPMS.

it has reported low pressure on two tyres now as the cold snap we had recently meant the pressures were 5 PSI lower and just on the warning threshold.

So something I never really picked up on, thought it is obvious, is the need to adjust the pressures for different seasons

It has a very clear warning display - numbers go from being shown in Green to being shown in Red and a LOUD warning beep goes on and STAYS ON until the problem is fixed.

[stompe]

Been discussions on TPMS (Tyre Pressure Monitoring Systems) here and I mentioned that I think the principle is a great idea and I have been looking at aftermarket solutions.

Just thought I would post some info on the one that has particularly caught my eye with a view to retro-fit to my RAV4 ....

System Features

The system can be configured to display pressures in psi, bar, or kg/cm3. The user can specify the high and low pressure warning thresholds as well as high temperature warning threshold. If the pressures or temperature change from the specified limits the system will alarm to warn the driver. The system will also detect a rapid deflation that might still be within the set limits. This feature is vital in warning the driver as early as possible to a tyre problem.

• Supplied with internal sensors. No unsightly external sensors that you find in cheaper systems elsewhere.
  
• External sensors can be stolen with ease. The internal sensors we supply means no one will even know that you have a TPMS fitted to your car.
  
• Receiver has internal battery, so no need to have wires all over your dashboard. Supplied with car charger for your convenience.
  
• Backlight screen with sensor. Comes on automatically when it gets dark.
  
• Intelligent warning system that alerts you quickly if tyre deflates suddenly.
  
• Sensors have a 5 year battery life.
  

This is the kit

Shame you don't get a 5th sensor for the spare wheel - IIRC, another extra sensor can be bought for £25

Display shows info for all 4 wheels

Sensors are pre-configured for specific wheels

But can be reconfigured via a menu to move them around.

Sensors are rated to last 5 years before battery fails, and battery is not replacable, which effectively means this system has a 5-year life cycle.

Quite a neat display

Guy on eBay selling for £97 inc Postage

TPMS Here

Spoke to the tyre fitting company I got a quote from for a new set of tyres and asked them if they charged for fitting TPMS systems and they said that if it was fitted at same time as new tyres and the the system was a Valve based one (as opposed to a band-one) they would fit for free.

I would strongly recommend not buying this unit as I have fitted this to my Toyota Prius and have had nothing but trouble i.e. only three sensors working out of four. I suspect Battery life could be a problem, they reckon 5 years Battery life but I have not even had a year yet. Dealt with this company (http://www.automotivestyling.co.uk/tpms.html), they sent me a replacement sensor and unit which I had fitted at my own cost and have not received a refund yet from them. I would suggest you go for the "tyre sure" as they guarantee a 7 year Battery life.

Stompe

[Bodgit-fixit-run]

OK dumb or even obvious question time.

I've heard of the sensors before and it's really interesting to read about how they might work. here come the questions.

I've always understood that when tyres are changed the valve should be changed.

Are these fitted instead of conventional valves?

If so what happens when you replace a tyre if valves should be traditionally be replaced at the same time? I was always told this was a safety feature in terms of valves.