Tach Questions

[OrangeMax]

I'm having issues with the tach on my Caterham. It won't rev past 1000 RPM. I've contacted Caterham about this issue. According to them the tach I have is for a 2 Coil engine and mine is a 4 Coil engine (210 HP Duratec).

The Tach plug is square in shape with 8 Pins. The car also has the Cosworth ECU. Is there a way to get this tach to work with my engine? if not does anyone have a part number of the correct Tach for this setup? Thanks!

[Croc]

  OrangeMax said:

The car also has the Cosworth ECU.

 

Can I clarify please? Do you have a Cosworth ECU like a Motec? Or do you have the Caterham MBE ECU that was installed on the Caterham CSR260 Cosworth Duratec?

 

Depending on the answer then it may be as simple as just installing the correct Caterham tach or another brand of tach. The Caterham Tachs are made by Caerbont

[OrangeMax]

  Croc said:

Can I clarify please? Do you have a Cosworth ECU like a Motec? Or do you have the Caterham MBE ECU that was installed on the Caterham CSR260 Cosworth Duratec?

 

Depending on the answer then it may be as simple as just installing the correct Caterham tach or another brand of tach. The Caterham Tachs are made by Caerbont

 

Greeting Croc,

 

Here is a picture of the ECU:

From a conversation I had with the folks at Caterham this particular ECU was supplied to Caterham from Cosworth when they were getting Duratec engines from Cosworth.

Here is a photo of the back of my current Tach:

It works, but only at half speed. Caterhams says its because this particular tach is for a 2 coil engine and I need a tach for a 4 coil engine. Unfortunately because of running specification changes at

Caterham, they are having difficulty supplying me with the correct part number. So if someone on this forum can supply me with the correct part number for a 4 Coil Duratec engine using a Cosworth

EC, that would really help my search. Thanks!

[Croc]

You have an MBE 9A4 ECU. The YD prefix to YD8083 tells me it is Cosworth supplied to Caterham. You have coil on plug Duratec I assume? 2L or 2.3L? I have not got my Caterham anywhere close to me but I suspect it is the same ECU code as mine since mine was supplied by Cosworth along with the engine.

 

The options you have available to you seem to be (in no order of preference):

 

1) Ring Caterham parts and see if they can source a Caterham CSR260 tach here:

Tachometer - CSR - Black (caterhamparts.co.uk)

 

The CSR260 was a Cosworth 2.3L Duratec with a Cosworth supplied tune. Coil on plug so 4 coils. The tach for a CSR260 "should" work but you need to check that with Caterham parts - I have no way of verifying. I would also ask the follow up question to them - what other Caterham models used a 4 coil on 4 plug 2L(?) Duratec set up? I suspect an EU4 model tach may work but thats just gut feel based on those models being coil on plug.

 

If an EU4 does work then you will need to also buy the new style connector and update the engine loom connector as these changed from EU3 to EU4 as seen here on this part:

Tachometer - 2015 on - Caterham Parts

 

 

2) Ring Nisonger

http://www.nisonger.com

 

They are the US agents for Caerbont gauges. Explain that you have a Caerbont gauge out of a Caterham designed for a 2 coil set up but you have a coil on plug/4 coil set up and do they know how to source a replacement that would work. It may end up being a non-matching replacement. You may need to ring Caerbont directly in the UK if Nisonger cannot help. They should be able to help on new connectors if you need them.

 

 

3) Source an aftermarket tach here in the US. It was a standard size (80mm from recollection) so there should be something available. Look at Racetech brand - fairly close look.

 

 

Sorry not a precise answer but hopefully it gets you closer to an end solution.

[OrangeMax]

Thanks Croc for the information. Yes my engine has the COP (coil on plug). If you happen to be close to your Caterham I'd be interested in knowing the part number on the back of your tach. Thanks!

[Croc]

Right now it’s 2 hours drive away from me but I should be heading there late next week if you can wait until then?

[OrangeMax]

  Croc said:

Right now it’s 2 hours drive away from me but I should be heading there late next week if you can wait until then?

Yes, Thank you that will be fine.

[Croc]

It looks like my suspicion is correct - you seem to have the same ECU as a Caterham 7 CSR260, at least based on the exterior code - no guarantees that the original map has not been overwritten.

 

 

For tach, the part number on the back of my tach has the following label.

 

Edited February 17, 2021 by Croc

[Croc]

If the CSR tach is no longer available then this cross-referenced part number may provide another option.

TACHO 2015MY "BASE PACK" - Caterham Parts

[BruceBe]

We have both of these tachs (58055 and 71261) on the shelf.

 

I'm a bit surprised that the 71261 you have is 2-coil, but, there are clearly multiple generations of these tachs. To be specific, we have the 58055A, which is the current CSR tach listed on the UK website.

 

You can always reach us at info@beachmanracing.com

 

Cheers,

-Bruce

[OrangeMax]

  BruceBe said:

We have both of these tachs (58055 and 71261) on the shelf.

 

I'm a bit surprised that the 71261 you have is 2-coil, but, there are clearly multiple generations of these tachs. To be specific, we have the 58055A, which is the current CSR tach listed on the UK website.

 

You can always reach us at info@beachmanracing.com

 

Cheers,

-Bruce

 

Greetings Bruce,

 

I have been trying to get ahold of you for a discussion on seats. I've sent emailing including one with my phone number so we can have a chat. If you like please PM me with your phone number and a convenient time to call.

Thanks!

[OrangeMax]

This is Awesome! Question, is this an 8 Pin Tach? Thanks!

[Croc]

  OrangeMax said:

This is Awesome! Question, is this an 8 Pin Tach? Thanks!

 

 

My tach has a rectangular plug and not a square one like yours. I could not unplug my tach to check pin count as I have to dismantle the dash to do so which is a fairly time consuming effort on the CSR swoopy dash style - apologies. Guessing, I surmise yours is an older style plug. I think you will have to get a new plug and rewire your existing plug pin-ins to the new-style tach plug so it will connect to the new tach.

 

I doubt there will be an off the shelf solution but Bruce is sometimes good with miracles.

[BruceBe]

  Croc said:

My tach has a rectangular plug and not a square one like yours. I could not unplug my tach to check pin count as I have to dismantle the dash to do so which is a fairly time consuming effort on the CSR swoopy dash style - apologies. Guessing, I surmise yours is an older style plug. I think you will have to get a new plug and rewire your existing plug pin-ins to the new-style tach plug so it will connect to the new tach.

 

I doubt there will be an off the shelf solution but Bruce is sometimes good with miracles.

 

Well, there are a bunch more pins on the CSR tach. In the end, power, ground, and a tach signal make a tach a tach. What year is the chassis? Armed with two sets of schematics, and pins/shells from Caerbont, one could probably get most, if not all chassis side features working on the new tach.

 

Cheers,

-Bruce