[Mk2] [Turbo] Speedo

Anything and everything to do with mechanical issues with your Mk2

Moderators: IMOC Moderators, IMOC Committee Members

Post Reply
Tomas_St
Posts: 329
Joined: Tue Aug 06, 2013 3:31 pm
Location: United Kingdom

[Mk2] [Turbo] Speedo

Post by Tomas_St »

my speedo is broken on rev2 so i bought another one but this one is from REv3 180MHR my old one is 160MHR. so what i need more for this its gonna work good for me. and will i get any other issues on it?
Tomas_St
Posts: 329
Joined: Tue Aug 06, 2013 3:31 pm
Location: United Kingdom

Re: [Mk2] [Turbo] Speedo

Post by Tomas_St »

somebody short answer ](*,)
Pauln
Posts: 850
Joined: Mon May 08, 2006 10:15 pm
Location: Cardiff, South Wales

Re: [Mk2] [Turbo] Speedo

Post by Pauln »

JDM turbos usually start life with a 180kph clock fitted.

These are then converted to read in mph on import. There are a number of ways to do this.

You can simply fit a new clock face overlay going up to the equivalent speed in mph, ie 110mph. The speedometer mechanism is therefore unchanged, which means the odometer will continue to show the km traveled not the miles.

Alternatively you can fit a converter to electronically modify the speedo so that what was 180kph now becomes 180 mph, and simply put a mph sticker over the kph sticker on the speedo face. In this case the odometer will now read in miles. Converters are usually fitted to the rear of the speedo cluster. Either bolted on, or attached by wires.

If your original 180mph speedo was reading your speed correctly, it almost certainly had a converter fitted.

The 160 mph speedo you have now purchased most likely came from a UK na, and therefore should read in mph without the need for a converter.

But...

What you've not made clear is whether you have purchased the entire cluster and want to know if you can just swap this for your broken cluster, or whether you just want to swap the speedo unit over.

The na and turbo clusters are not interchangeable, but the individual instruments are.

So you should be able to just swap the speedo unit over, but will need to remove any existing converter for it to read correctly in mph.

I've not done this myself as I've always fitted JDM 180kph with an overlay or converter, but that is my understanding of the situation

Paul
mrhappy62
Posts: 139
Joined: Wed May 20, 2015 7:21 pm
Location: rustington

Re: [Mk2] [Turbo] Speedo

Post by mrhappy62 »

I could be wrong but I think the rev2 is the same as rev1 with a cable driven speedo and the rev3 is electronic so wont work ! Sorry.
Pauln
Posts: 850
Joined: Mon May 08, 2006 10:15 pm
Location: Cardiff, South Wales

Re: [Mk2] [Turbo] Speedo

Post by Pauln »

mrhappy62 wrote:I could be wrong but I think the rev2 is the same as rev1 with a cable driven speedo and the rev3 is electronic so wont work ! Sorry.


I've owned both a JDM rev2 na and a JDM rev2 turbo, and both had electronic speedos. I think you'll find the mechanical speedo was only fitted to the rev1.

Paul
mrhappy62
Posts: 139
Joined: Wed May 20, 2015 7:21 pm
Location: rustington

Re: [Mk2] [Turbo] Speedo

Post by mrhappy62 »

I said i could be wrong !
Pauln
Posts: 850
Joined: Mon May 08, 2006 10:15 pm
Location: Cardiff, South Wales

Re: [Mk2] [Turbo] Speedo

Post by Pauln »

As can we all :D

Paul
Tomas_St
Posts: 329
Joined: Tue Aug 06, 2013 3:31 pm
Location: United Kingdom

Re: [Mk2] [Turbo] Speedo

Post by Tomas_St »

Pauln wrote:JDM turbos usually start life with a 180kph clock fitted.

These are then converted to read in mph on import. There are a number of ways to do this.

You can simply fit a new clock face overlay going up to the equivalent speed in mph, ie 110mph. The speedometer mechanism is therefore unchanged, which means the odometer will continue to show the km traveled not the miles.

Alternatively you can fit a converter to electronically modify the speedo so that what was 180kph now becomes 180 mph, and simply put a mph sticker over the kph sticker on the speedo face. In this case the odometer will now read in miles. Converters are usually fitted to the rear of the speedo cluster. Either bolted on, or attached by wires.

If your original 180mph speedo was reading your speed correctly, it almost certainly had a converter fitted.

The 160 mph speedo you have now purchased most likely came from a UK na, and therefore should read in mph without the need for a converter.

But...

What you've not made clear is whether you have purchased the entire cluster and want to know if you can just swap this for your broken cluster, or whether you just want to swap the speedo unit over.

The na and turbo clusters are not interchangeable, but the individual instruments are.

So you should be able to just swap the speedo unit over, but will need to remove any existing converter for it to read correctly in mph.

I've not done this myself as I've always fitted JDM 180kph with an overlay or converter, but that is my understanding of the situation

Paul

my is import . and yes is converted in Mph got paper work left
Tomas_St
Posts: 329
Joined: Tue Aug 06, 2013 3:31 pm
Location: United Kingdom

Re: [Mk2] [Turbo] Speedo

Post by Tomas_St »

mrhappy62 wrote:I could be wrong but I think the rev2 is the same as rev1 with a cable driven speedo and the rev3 is electronic so wont work ! Sorry.

its electronic not cable same like rev3
Tomas_St
Posts: 329
Joined: Tue Aug 06, 2013 3:31 pm
Location: United Kingdom

Re: [Mk2] [Turbo] Speedo

Post by Tomas_St »

Pauln wrote:JDM turbos usually start life with a 180kph clock fitted.

These are then converted to read in mph on import. There are a number of ways to do this.

You can simply fit a new clock face overlay going up to the equivalent speed in mph, ie 110mph. The speedometer mechanism is therefore unchanged, which means the odometer will continue to show the km traveled not the miles.

Alternatively you can fit a converter to electronically modify the speedo so that what was 180kph now becomes 180 mph, and simply put a mph sticker over the kph sticker on the speedo face. In this case the odometer will now read in miles. Converters are usually fitted to the rear of the speedo cluster. Either bolted on, or attached by wires.

If your original 180mph speedo was reading your speed correctly, it almost certainly had a converter fitted.

The 160 mph speedo you have now purchased most likely came from a UK na, and therefore should read in mph without the need for a converter.

But...

What you've not made clear is whether you have purchased the entire cluster and want to know if you can just swap this for your broken cluster, or whether you just want to swap the speedo unit over.

The na and turbo clusters are not interchangeable, but the individual instruments are.

So you should be able to just swap the speedo unit over, but will need to remove any existing converter for it to read correctly in mph.

I've not done this myself as I've always fitted JDM 180kph with an overlay or converter, but that is my understanding of the situation

Paul

Thank you for help
now i know what i have to do
Madabout
Posts: 323
Joined: Sun Jun 12, 2011 1:08 pm

Re: [Mk2] [Turbo] Speedo

Post by Madabout »

I've been looking into this as thinking of changes to my rev3 turbo. This is what I have found out:

1. Rev2 onwards as mentioned electronic - above info on overlays, etc. fit with what I've done on other Japanese imports.
2. I'm thinking of a genuine UK speedo (as mentioned would need to change speedo clock in cluster as I'm told some of the converters upset the power steering - urban legend?)
3. Turbo and NA use a different electronic speedo sender in the gearbox.
4. Speedo sender plug is 3 core into wiring loom - trying to find out if the same on turbo or NA.

Based on part 2 I'm thinking of a UK speedo but think this means I still need to de-limit the speedo which can be done iirc.
Pauln
Posts: 850
Joined: Mon May 08, 2006 10:15 pm
Location: Cardiff, South Wales

Re: [Mk2] [Turbo] Speedo

Post by Pauln »

Madabout wrote:I've been looking into this as thinking of changes to my rev3 turbo. This is what I have found out:

1. Rev2 onwards as mentioned electronic - above info on overlays, etc. fit with what I've done on other Japanese imports.
2. I'm thinking of a genuine UK speedo (as mentioned would need to change speedo clock in cluster as I'm told some of the converters upset the power steering - urban legend?)


I don't think that's an urban legend as evertything seems to depend on whether you buy a basic converter, or a fully fledged converter/delimiter.

My understanding is that the speedo sensor on the gearbox sends a 12v pulse to the speedo head where it's converted to a 5v pulse for the speedo, and the pulse is then also sent to the ECU. On JDM models the pulse sent to the ECU is also used to apply the speed limit and determine the point at which PS should be turned off.

I think most of the "black boxes" with four flying leads are usually basic converters. As such they simply convert the kph pulses to mph pulses, so 180kph on the dial now becomes 180mph, the converted pulse is the sent to the ECU where it "fools" the ECU into raising the preset limit. Unfortunately this also effects the PAS. This should turn off at 80kph(50mph), but because the pulse has been converted to mph, will now turn off at 80mph causing the reported light steering at high speed.

If however you fit something like the Stef converter/delimiter that separates the signals that go the the speedo and the ECU all will be well.

Please ignore all the extra black wires on this photo. They were used to connect a temporary power supply for testing and repair a damaged track.

Image

The Stef unit converts the pulse to mph for the speedo, disconnects the output from the speedo to the ECU, and instead generates it's own output for the ECU. This uses a kph pulse that is "clamped" at a maximum speed slightly below the JDM ECU default preset limit (around112mph).

As a result, the speedo will now read in mph (180kph becomes 180mph), but the PAS will continue to switch off at 80kph(50mph). The default ECU limit is also lifted because the speed pulse sent to the ECU is clamped and never exceeds that limit - even though the actual speed of the car does.

The Stef unit also has a test mode which handy for checking the speedo calibration. When you switch on the ignition in test mode the needle will sweep around to 120 then 60 then zero.

But you need to switch the test mode off in normal use, or your odometer reading will go up by a small amount every time you turn the ignition on :)

Madabout wrote:

3. Turbo and NA use a different electronic speedo sender in the gearbox.
4. Speedo sender plug is 3 core into wiring loom - trying to find out if the same on turbo or NA.

Based on part 2 I'm thinking of a UK speedo but think this means I still need to de-limit the speedo which can be done iirc.


I'm afraid I've never fitted a UK speedo in a JDM cluster myself, but I don't remember reading anything about having to change the gearbox sender as well.

The na and turbo clusters aren't the same, perhaps that's why the senders are also different. I really don't know.

But there are only four connections to the speedo on the back of the JDM cluster. The feed from the speedo sender, +12v, ground and the feed from the speedo to the ecu. So as there's only one pulse wire, I've always assumed that turning the speed pulse into the correct signal to display kph or mph all took place in the speedo head itself. But I don't know for sure.

Paul
markstevieandmads
Posts: 2025
Joined: Mon Aug 05, 2013 8:18 pm
Location: Swindon, Wilts

Re: [Mk2] [Turbo] Speedo

Post by markstevieandmads »

I have done the uk swap.

Basically i disconnected the convertor at the cluster end , joined the cables that was spliced into my the convertor and removed the jap speedometer and instead put the uk speedometer in. I also adjusted the mileometer so it matched the original clocks.

This then gives me the correct speedo reading (after adjusting the needle when driving - on a private rd).

This has now supposedly left me with mph reading but the 112mph limit. I am then told to reinstall the convertor but at the ecu end so it does not affect the power steering.
I havent actually done this bit and left the converter off , however i found on a track day last year that i was actually hitting 140mph on the speedo so im guessing i havent actually got a limiter? Even though its been disconnected?

I know there could be a discrepancy on my speedo but surely not that much? Ive checked my speedo reading at slower speeds up to around 70mph and its accurate to gps up to this speed.

Anyway, hope that helps a bit.
Madabout
Posts: 323
Joined: Sun Jun 12, 2011 1:08 pm

Re: [Mk2] [Turbo] Speedo

Post by Madabout »

I have bought a UK speedo with pretty much the same mileage as my car today as a spare. Probably a useful spare to have I thought.
Post Reply

Return to “Mechanical”