Bob Tail

Happy New Year to all, I have made some progress with identifying all the inputs required and so far it all looks doable, maybe a few bugs to sort with road speed signal from speedo and not sure if diagnostics will work without the BECM but will hook up the K and L lines and take some advice from a local OBDII guru (who is mostly into VAG stuff but has a good understanding of the control and comms systems - I am more of blue spanner man!). Any links to other threads talking about reversing diffs? Is the P38 running gear worth preserving? I have all ashcroft running gear in my trials truck but not to keen to shell out on another set of CV's and axles to convert/reverse defender or disco axles if the p38 stuff is tough enough. I hear at least the rear diff is a 4 spider unit and supposedly the front open type CV's are strong enough. Any comment on this appreciated as have heard various accounts. Extra strong P38 gear is hard to find but I hear on the grapevine there was some purchased from a US company for a Whitbread racer. I will get my wiring diagram on paper over the next few days and post it for comments - it will be a combination of block layouts with just the tails of interest in any detail (the wires that used to interface with the P38 body and controls). Engine and gearbox looms will be standard. It won't be beautiful but I will try make it useful (if it works). I figure that since no one has come back with anything similar - maybe I am the first to go down this route? or maybe I am too naive to see the dragons! Keen to hear if anyone has remapped the original EPROMs in the GEMS ecu for better (richer mid range) injection map (rather than the rechip route). Just been to visit a mate who is doing something similar with a 4.6 in a winch trials truck but with aftermarket loom and ecu kits, He has binned the original MS set up after much frustration (and £) and is now on plan B with an Emerald system which has better local support from the rally fraternity. I think he would like to know more about ZIM's set up using the original bellhousing crank sensor. I will try searching the old posts. All the best for 2017. Bob Tail

Hi Tom, I know a few years have passed but are you still playing with the rear engine truck? I am just about to start a similar project but using a complete GEMS P38 4.6 driveline. I will need to use both Auto box and transfer case controllers and feed the rellevant inputs and get them to communicate with the engine ecu. How did you get on with your transfer case control? A pic attached of the wiring mess I have to sort out. Currently getting engine ecu unlocked so I can run without security (or any other inputs) from the BECM. I@m sure there will be some fun and games but it may make it easier if I can locate other folk who have gone the same route. Happy New Year to all. Bob Tail

Thanks Gary, With the engine in the rear the drive shafts will be on the wrong side. Current plan is to cut the front diff housing and flip the mid section and reweld, Flip complete rear diff and re fit mountings maybe for a late disco J radius arm (simpler under the engine than using the top link and A arm set up from a disco 1 or 90) Thought about a few different combinations including shelling out for a proper reversing transfer case (Milner maybe) as not likely to need 2 ratios or using defender axles and just flipping nuggets (bit of redrilling required) but want the strength of the P38 gear to save buying uprated CV's etc. Have not read enough about the wear issues about flipped diffs yet. Apparently they don't like being run backwards for any length of time. Is this caused by gear profile or old wear patterns or spacial relationship between crownwheel and pinion? High pinion shaft will mean they need more oil or a splasher for lubrication. For the gear box there is also an option to fit the manual valve body from an earlier ZF box but keeping an open mind till I see if I can get the engine ecu to talk to the gearbox and transfercase controllers. There is a 6 pin connector from the engine loom to to the gearbox loom which I think has the relevant links.I think the BECM just supplied power and a comms path but this can be replicated. I will lay out what I have salvaged from the donor. Check the pin outs from RAVE and see what I have and what I need (running without the BECM) and make a block diagram and post the results. Would like to hear if anyone else has done anything similar and maybe learn from their wiring diagram? In the process of getting ecu unlocked and considering re mapping at present. Will get it running first before I dive into chassis (eventually will be a full tube fabrication after some testing on ladder chassis) and driveline. Maybe I should start a build thread for this project? First I was hoping to learn a bit more from folks who have gone down some of these paths - simple Gems ecu management first, then gearbox control. Wes' project seemed a bit similar but not to keen on MS and it seems I have a pretty capable ecu already so why replace it? Eventual use in comp safari events (like short course racing but timed 5 to 10km runs over 2 days. Maybe 100km of fast rough stuff) if I can make it light enough to be competitive with higher powered land rover derivatives (Bowlers, Tomcats and Simbugginghis). I actually still think a light rear engine 2 wd buggy will do the trick but want 2 seater so weight goes up and 4wd becomes more desirable (but possibly lighter options than LR live axle). It is really falling over a good coscast 4.6 that has drawn me along this path other wise it could have been a Lexus V8 mid engine onto a Fortin transaxle (or a cheaper Renault transaxle). Also the events are run by Land Rover clubs so its not such good form bringing exotic kit along. Its more social and about thrashing similar kit around the hills than balls out performance. Hope Santa was kind. Bob Tail

Hi Guys, I am very interested to read of your electronics issues when converting to run on Mega Squirt systems. I am in the process of building rear engined off road buggy using a P38 Gems 4.6 as the donor vehicle for drive line. I know I am bucking the trend but what is wrong with using the original gems ecu (emc). I have found a company that will free the engine ecu (quite cheap) so it no longer needs input from the BECM and figure with a new power supply and fuse board (something like what they run in the Morgan plus 8) I can basically use all the standard sensors and engine loom. Not sure if I will be able to run the auto box and transfer case direct from the manual inputs and the 6 pin connection to the engine loom but I am currently laying out the controllers and bits I have salvaged from the p38 loom (with pin description inputs from the manual in RAVE) to see what inputs I need (earths power signal, comms and comms direction etc). I may need something like Ashcroft's compushift or fit a manual valve body (and hi lo control) but I am hoping the stock system can be made to work (without input from the BECM or ABS controller). I think road speed signal can be obtained from the speedo output (if not done as standard). I am a bit of a newby at this so the learning curve is steep but I wanted to learn something about electronic control while I build this project (other wise I could have bought a loom and ecu kit from the like of Lloyds or RPI). Has anybody else out there tried to do it this way? I wold love to get my hands on simplified wiring diagrams. Also pin references from the manual are great but it would save me some work if they also had wiring colors so I can identify the tails on the bits of stock loom I need. Any help and advice greatly appreciated. Also looking for non locked maps that I can get loaded on the original PROMS for injection and timing mapping to remove the mid range lean/over heating issues with the stock maps. I may yet stump up the cash and buy Tornado chips but I think there will loads of folk out there with maps that may be worth a try. If it all works I may develop the engine a bit but agree that, bang for buck, the LS engine conversion is probably the way to go for over 250HP. Currently it just a play thing but if I can make it light enough it may worry a few of the tail enders in the Scottish Comp Safari scene. Yet to find a stock wiring diagram with wire colors and would appreciate any links or leads, even simplified block diagrams (I will endeavour to post a block diagram of what I am trying but I think it will look like a Morgan +8 without the security input but these are all manual so no auto box controllers). Wes, I hope I am not hijacking your thread. What sort of off road toy are you building? Mine only needs a few lights (for the dark northern evenings), usual engine gauges, fuel pump, etc, and a big stop, go and crank buttons. If I get really keen I will make an independant front end for it a bit like Mathew Lee's earlier buggies (maybe a bit longer). I run mostly 2wd offroad rails (VW powered) but also play with a modified diesel rag top 90 for trials, orienteering and some winch events (like yr Southern Challenge trophy trucks). After dipping my toe in Landrover club Comp Safari racing I find myself drawn to V8's - mostly for the noise! Plus in my old age a 2 seater toy is bit more sociable in the local 4x4 scene. Bob Tail