R33 Manual Swap: Speedo Reading Over Double

[Tys_Skyline]

Hey guys,

I've recently manual swapped my RB25DE Skyline and have put a RB20E gearbox in. 

The RB20E gearbox is out of a series 1 R33 and my R33 is a series 2.

Since doing the swap, I've noticed my speedo is reading just over double and the odometer is rolling the ks over faster. I have kept the original auto cluster in for now untill I can source a manual one.

Could this be because of the transducer/speedo sensor? If so, which one would I need to get to get an accurate speed? An RB20E as this is what the gearbox is, or a RB25DE?

Or could the issue be something else entirely?

Cheers

[GTSBoy]

Surely they're the same skinny gearbox? Just put the sender from the original box into the new one?

[Tys_Skyline]

13 minutes ago, GTSBoy said:

Surely they're the same skinny gearbox? Just put the sender from the original box into the new one?

The original one from the auto gearbox is bigger in diameter unfortunately. That was the first thing I checked out

[GTSBoy]

Ah sorry. I totally vagued on the point that it was a manual swap.

So yes, you just need the correct speed sensor to suit the dash. So skinny box sender. Probably the same S1/S2 anyway.

[Tys_Skyline]

39 minutes ago, GTSBoy said:

Ah sorry. I totally vagued on the point that it was a manual swap.

So yes, you just need the correct speed sensor to suit the dash. So skinny box sender. Probably the same S1/S2 anyway.

No worries. So do you reckon a RB25DE speed sensor would sort the speedo out? As there is already a RB20E speed sensor in the gearbox causing an inaccurate reading. Would a RB25DE speed sensor fit straight into a RB20E gearbox? Also, are maunal and auto speed sensors the same size?

[GTSBoy]

4 hours ago, Tys_Skyline said:

Would a RB25DE speed sensor fit straight into a RB20E gearbox?

Well......you would have to hope so, otherwise your only fix is going to be electronic. That's doable, but, non-trivial. We can address that later, if need be.

The problem is that the speed sensor relies on 2 gears. One in the box, one on the end of the speed sensor. It would obviously be impossible for them to have 2 different gear ratios without BOTH gears being different. The fact that the error is exactly 50% (or 200%) of the expected/required reading would suggest that the difference is in the number of poles inside the senor. A 2 pole generator would produce half as many pulses per rev as a 4 pole generator. I'd be willing to bet that that's the difference. Problem is, I don't know that they actually did that.

Anyway, assuming that the difference is internal to the sensor, then the pinion gear on the two sensors should be the same and yes, either one would physically fit into either box and turn at the "right" speed.

[AutoTrust]

Manual cluster fixed that issue for me. 

[robbo_rb180]

Or try one of these, have used both in the past and work fine.

https://www.jaycar.com.au/speedo-corrector-module-for-cars/p/AA0376

https://www.dakotadigital.com/index.cfm/page/ptype=product/product_id=1192/mode=prod/prd1192.htm

[Duncan]

20 minutes ago, robbo_rb180 said:

Or try one of these, have used both in the past and work fine.

https://www.jaycar.com.au/speedo-corrector-module-for-cars/p/AA0376

https://www.dakotadigital.com/index.cfm/page/ptype=product/product_id=1192/mode=prod/prd1192.htm

I've been using the Jaycar one in the stagea for more than 10 years, still working perfectly

[soviet_merlin]

Haha, @Kinkstaah's recent post on this comes to my mind:

 

[Kinkstaah]

TBH in my experience with the Jaycar module was a little different. I was using it in the middle of the car ECU to the cluster. It worked, but it only kicked in at about 30-40kmh. So anything under that would read 0kmh. It was also delayed. It may work for something int he same family that it just needs to do something like 'halve'

The dakota digital one worked perfectly in my application, and can be used for many, many, many different inputs and outputs.

[Tys_Skyline]

Just thought I'd post an update for anyone reading this thread in future that may have the same issue. I have the odometer reading correctly now after sourcing a series 2 speedo sensor (RB25DE) and putting it in the gearbox (RB20E). Cheers for all the imput guys 👍