kiwi_110 Posted August 11, 2011 Share Posted August 11, 2011 I've been waiting for a VDO programmable Speedo from the US, but the supplier says it's on back-order with VDO. Decided to follow up an alternative as a backup and today a nice Td5 KPH speedo arived, all wound up to required distance and ready to go thanks to CwazyWabbit. When I got it home, I jury rigged it to a battery and my Britpart er... Bits and parts transducer and tested it with a battery drill. It ran up nicely, full speed on the drill registered about 175 KPH and it seemed to sweep up the dial without hesitation or jerking. I proceeded to wire it in to the truck, and then mounted the transducer in place of the speedo cable at the LT230 end. Took it for a drive and could immediately notice a problem. It's registering pretty high, 40 kph down my driveway and I'm really doing about 15... So I made a mental note that I'm going to have to tweak the pulse count register a bit. No drama, CwazyWabbit is doing the whole Bus Pirate thing and will soon publish the info I need to use mine to correct the pulse count on this speedo. Out the front gate and down the road and suddenly the needle is bouncing all over the show, gone is the smooth movement I noted with the transducer mounted on the drill. I switch off in case it's got it's knockers in a knit, restart and drive back up to the house. Little or no movement from the speedo needle at all now So I'm thinking the "Oh So High Quality" transducer has plop itself. Why am I not surprised? I'll pull it out tomorrow, fully expect it to be in bits... Ray. Quote Link to comment Share on other sites More sharing options...
mickeyw Posted August 11, 2011 Share Posted August 11, 2011 Yes, your transducer looks like one of the less useful type. Not surprised you're in a spot of bother. A Genuine one is what you need. Quote Link to comment Share on other sites More sharing options...
jbs Posted August 11, 2011 Share Posted August 11, 2011 Thats not a B******T one is it? Quote Link to comment Share on other sites More sharing options...
western Posted August 11, 2011 Share Posted August 11, 2011 you need a green one like this YBE100530 that's what all who have converted to td5 speedo have used. Quote Link to comment Share on other sites More sharing options...
kiwi_110 Posted August 11, 2011 Author Share Posted August 11, 2011 Ok, found the problem. The Poopart transducer did not fall to bits. In the near-dark last night I missed noticing that the square drive of the speedo shaft in the t-case is too big for the transducer shaft. I've built it up with a bit of heat-shrink. We'll see how long that lasts... Quote Link to comment Share on other sites More sharing options...
kiwi_110 Posted August 12, 2011 Author Share Posted August 12, 2011 Update: After the heat-shrink mod, the speedo worked fine and I was able to determine the extent of the innacuracy. It registers exactly twice the speed I'm doing. Three solutions present themselves: 1. Adjust the pulse rate on the speedo (requires Bus Pirate code from CwazyWabbit) 2. Build a simple circuit that chops every second pulse out on it's way to the speedo (requires some components I don't have) 3. Do something mechanical. The transducer contains a circular 8 pole magnet so it's flicking a reed switch on and off 8 times per revolution. I actually think the speedo counts a change of state as a pulse, so that would be 8 times on and 8 times off, 16 pulses per revolution. So I get out my dremel tool, open up my already flimsy Britpart Transducer and grind away 4 of the poles on the circular magnet, turning it from a donut, into a cross... Worked a bloody treat. The Speedo is now reading purfeck! I don't expect this POS to last, it's been an interesting experiment but I'm looking forward to doing a proper job with a green transducer and my programmable speedo. Ray. Quote Link to comment Share on other sites More sharing options...
CwazyWabbit Posted August 12, 2011 Share Posted August 12, 2011 Glad you worked something out The Speedo I sent you is set to the standard KPH pulse count (which I can't remember off the top of my head) as I had kept a backup of the original memory before my experiments. Nick Williams noticed when he did his speedo conversion that the BritPart sensor caused an incorrect reading as well http://forums.lr4x4.com/index.php?showtopic=69070&view=findpost&p=594388 So quite why do BritPart produce a transducer that outputs double the number of pulses it should? Quote Link to comment Share on other sites More sharing options...
western Posted August 12, 2011 Share Posted August 12, 2011 it's possible the britpart black sender is common to Rover cars & Discovery/RRC vehicles, but wrong for Defender/90/110 vehicles. Quote Link to comment Share on other sites More sharing options...
trulyalya Posted March 9, 2014 Share Posted March 9, 2014 Nice to see this hack ;-) Ray, so, how long did it last? Can't understand, this green plastic gear should be inside the transfer box? Is it the same what's used in purely mechanical speedos? Can I just pull out the steel cable and install this sort of stuff instead? (thinking of building my own transducer from scratch. do i need bearings for that, or some sort of seal is enough, i wonder?) Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.