Mounting a transponder

[nate-dogg]

Another daft question from a racing newbie this year... where are you supposed to mount a transponder? The My Laps manual says in the wheel arch, but I’m concerned about it catching/rubbing... Am I being thick and there’s somewhere much better to mount it?

Would appreciate a nudge in the right direction!

[ginettajoe]

nate-dogg said:

Another daft question from a racing newbie this year... where are you supposed to mount a transponder? The My Laps manual says in the wheel arch, but I’m concerned about it catching/rubbing... Am I being thick and there’s somewhere much better to mount it?

Would appreciate a nudge in the right direction!

Mount it as near to the front of the car, inside the engine bay, with a clear space between the transponder and the tarmac, usually on the inner wing, or chassis member. Avoid placing it where it could suffer damage in a light or heavy impact. HTH

[Kraken]

Inside of one of the chassis legs just behind the front cross member is where I've always put mine with no issues.

[ChevronB19]

You can pretty much mount it anywhere so long as it’s reasonably close to the ground.

On my 105e Anglia it’s inside the car, tie wrapped to the front near side roll cage leg, same as most competitors in the series. Never had a problem with scrutineers or with sensors picking it up.

[Order66]

Check your series regs - some specify where it has to be, but generally if front wheel arch

[nate-dogg]

Thanks all. I’ve discovered a mysterious cable with nothing on the end of it leading to the wheel arch, which I now assume is for a transponder. I shall put it there I think!

[Robmarriott]

What car is it?

On my old Clio I mounted it on the panel behind the side of the front bumper, no chance of it catching there.

[nate-dogg]

Robmarriott said:

What car is it?

On my old Clio I mounted it on the panel behind the side of the front bumper, no chance of it catching there.

Mini Cooper S R53.

[sabid]

nate-dogg said:

Another daft question from a racing newbie this year... where are you supposed to mount a transponder? The My Laps manual says in the wheel arch, but I’m concerned about it catching/rubbing... Am I being thick and there’s somewhere much better to mount it?

Would appreciate a nudge in the right direction!

If you found the cable then I'm sure you've got this positioning sorted. In case you haven't then it is worth being aware that whilst many people will say it doesn't matter, it can be important.

For pure laptime it makes no difference where you put the transponder. In a race though it is different.

If you are in a drag to the line, it is who's transponder reaches the line first will determine the place - too far back could cost you a place(s)

Yes, if you are out front for the win then this is normally declared visually but it would be gutting to miss out on a win that way and either way, it is rubbish thing to go through whilst someone subjectively decides the positions ...

Depending on your race cars speed across the line, the position of the transponder can therefore be more important than many people think - the slower you cross the line the more this is important.

Equally, as has been said and as you suspect, putting the transponder out front in a vulnerable position is quite risky!

With a bit of maths you can work out how far back will start to make a difference. We had this same question come up on another forum recently so I put this short article together to help.

https://www.yourdatadriven.com/where-is-the-best-p...

Put simply, if you cross the line at 100 mph then the you can put the transponder anywhere in the first 20 cm behind front of the car without risk of loosing out in a drag race over the line.

At lower speeds this distance reduces so it might be worth knowing the exact trade off you are making, if that is getting too close to a vulnerable position.

You can quantify this exactly, per above, so thought I'd share as it is not often people really think this through.

Best of luck with the racing!

[ginettajoe]

sabid said:

nate-dogg said:

Another daft question from a racing newbie this year... where are you supposed to mount a transponder? The My Laps manual says in the wheel arch, but I’m concerned about it catching/rubbing... Am I being thick and there’s somewhere much better to mount it?

Would appreciate a nudge in the right direction!

If you found the cable then I'm sure you've got this positioning sorted. In case you haven't then it is worth being aware that whilst many people will say it doesn't matter, it can be important.

For pure laptime it makes no difference where you put the transponder. In a race though it is different.

If you are in a drag to the line, it is who's transponder reaches the line first will determine the place - too far back could cost you a place(s)

Yes, if you are out front for the win then this is normally declared visually but it would be gutting to miss out on a win that way and either way, it is rubbish thing to go through whilst someone subjectively decides the positions ...

Depending on your race cars speed across the line, the position of the transponder can therefore be more important than many people think - the slower you cross the line the more this is important.

Equally, as has been said and as you suspect, putting the transponder out front in a vulnerable position is quite risky!

With a bit of maths you can work out how far back will start to make a difference. We had this same question come up on another forum recently so I put this short article together to help.

https://www.yourdatadriven.com/where-is-the-best-p...

Put simply, if you cross the line at 100 mph then the you can put the transponder anywhere in the first 20 cm behind front of the car without risk of loosing out in a drag race over the line.

At lower speeds this distance reduces so it might be worth knowing the exact trade off you are making, if that is getting too close to a vulnerable position.

You can quantify this exactly, per above, so thought I'd share as it is not often people really think this through.

Best of luck with the racing!

..... yes, you are correct, and the reason I stated to fit it as close to the front of the car, but without explanation, which you kindly fulfilled!!

[sabid]

ginettajoe said:

..... yes, you are correct, and the reason I stated to fit it as close to the front of the car, but without explanation, which you kindly fulfilled!!

[MyVTECGoesBwaaah]

Don't forget to have it on the right plane/angle too

[BertBert]

sabid said:

ginettajoe said:

..... yes, you are correct, and the reason I stated to fit it as close to the front of the car, but without explanation, which you kindly fulfilled!!

Except that the website is sadly wrong
It's 44.704, not 44.4
Timing is done to 1/1000th second not 1/100 (well when TSL do it anyways)
1/1000 second is about 2cm at 100mph.
(the ever helpful) Bert

[BertBert]

On the subject, I am intrigued by how the transponder works with a detection loop. I don't even know whether it's electromagnetic,RF or IR (it's not the latter though). I can't really figure out using my schoolboy physics how it might work. It must encode the transponder number into an analogue signal and the receiver somehow has to decide when the transponder goes over the detection loop. It's not going to be a directional signal, so does it detect the point of maximum strength to be the point where the transponder is over the detector?

Not sure it's going to help me drive faster though!

Bert

[majordad]

Does the signal from the loop come from under the track? Or is it to the side, either left or right?

[BertBert]

The one picture I found with googling showed the 'loop' under the track. That makes the required working range of the transponder to be a few feet rather than a track width (or half a width).
Bert

[MyVTECGoesBwaaah]

The loop is under the track, you can often see where the track has been cut to lay it.

The transponder signal is picked up many times as you cross over the loop, the time comes from when you break the beam.

[BertBert]

MyVTECGoesBwaaah said:

The loop is under the track, you can often see where the track has been cut to lay it.

The transponder signal is picked up many times as you cross over the loop, the time comes from when you break the beam.

Which would make a complete nonsense of the whole - where to place your transponder question. However I am 99% certain that there is no 'beam'!
Bert

[MyVTECGoesBwaaah]

BertBert said:

MyVTECGoesBwaaah said:

The loop is under the track, you can often see where the track has been cut to lay it.

The transponder signal is picked up many times as you cross over the loop, the time comes from when you break the beam.

Which would make a complete nonsense of the whole - where to place your transponder question. However I am 99% certain that there is no 'beam'!
Bert

A beam is used, it may be a bit hidden at some circuits due to their setup but somewhere like Croft for example you can see on side on a tripod in the infield near the start/finish line.

There is no beam for the other loops like sectors or pits however.

[Kraken]

Beam timing systems and the AMB transponders are two different things.