 | Home > My Defender > Putting a discovery transfer box in a defender |
 
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| EMPI748 Member Since: 15 Dec 2012 Location: Penicuik, Midlothian Posts: 50   
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oops was meant to be in technical
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13th Sep 2013 1:03pm |
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| blackwolf Member Since: 03 Nov 2009 Location: South West England Posts: 17378  
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Very few Disco2's had a fully functional centre diff lock, however some did have the internals fitted and were just lacking the linkage to operate it. If the lock is fitted, there will be a threaded spigot protruding from the top of the front output shaft housing.
Those without the internals will just have an unmachined boss in the aluminium casing in this location. A popular route for upgrading a Td5 Defender is to fit the transfer box gear clusters from the Disco box into the Defender box and leave the reast alone. An alternative would be to swap the fron output shaft housing from the Defender box and fit it to the Disco box, fitting the result. Given that Disco boxes without the lock are generally much cheaper than those with, I suggest buying one without and swapping the internals. I am sure that someone who's actually done this will be along to advise. I bought a Disco2 diff-lock fitted t-box to strip the front output housing and diff-lock to retro-fit to my Disco2, I then sold the remains to a friend with Td5 Defender who took the gear clusters to fit his Def box (which he fitted without problems and without the need to remove the box from the vehicle). |
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13th Sep 2013 1:21pm |
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| appaloosadude Member Since: 17 Oct 2012 Location: Buckinghamshire Posts: 630 
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I have a feeling you will not be able to do a straight swap with the overdrive onto the Discovery transfer box, as the output gear has a different number of teeth to a Defender...
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13th Sep 2013 6:59pm |
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| geobloke Member Since: 06 Nov 2012 Location: Nottinghamshire Posts: 4410
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Yes a Disco 1 transfer box will fit your defender, however and it is quite a big however the transfer box will not have the low box switch nor a space to have one. This means your ECU will not adjust the sensitivity of your accelerator pedal when in low box.
If you would like to retain the low sensitivity pedal when in Low Box you will need a Disco 2 transfer box from 99 - 02 which all had the CDL peg, just not the linkage to use it. I have a transfer box from a 2001 auto disco 2 with 70k miles and it works perfectly with my 2002 110. Plus it also has the low box switch so the accelerator pedal does what it should do. Benefit of an auto box is that the transfer box is usually still very tight as the auto is much more kind on the transfer box, gentle gear changes and all. You should be able to get a good box from someone like Equicar in Wolverhampton. I do not know if the GKN will fit the disco box but I would be very interested to hear if it does and if the defender is capable of pulling it. Have heard that it might lead t over gearing... |
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13th Sep 2013 7:24pm |
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| EMPI748 Member Since: 15 Dec 2012 Location: Penicuik, Midlothian Posts: 50
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Thanks for the replies some good points. Hadn't even considered the change in throttle setting, would be a shame to loose that.
Found a nice how to on ashcrofts site for swapping the gears inside the case, looks relatively straightforward and as far as i see it should allow the overdrive too. Reasonable price considering what some people are asking for the discovery boxes... http://www.ashcroft-transmissions.co.uk/in...oductId=44 Also found a gear calculator. Based on mine using the stock td5 ratios with 265/75/16 tyres, tables below shows road speed to RPM. I don't have a rev counter, but I'm wondering now if it is infact standard. It will pull in 5th with overdrive engaged from about 28MPH (OD drops out at ~25 with ecu), speedo is spot on with GPS speed too. Should a TD5 pull from that low? Will have a look to see what the transfer box code is, i guess it could have a 1.6 ratio fitted? It also suggests it should do ~25 i first, maybe i just change way to early, but 8 seems to be about it. 
Been considering a nanocom, perhaps should be getting that first to see what the rpm's are. That said if it pulls from so low extra gearing shouldn't hurt? http://www.ashcroft-transmissions.co.uk/calc/ratio_calc.html Normal Speed/Gear First Second Third Fourth Fifth 10 MPH 1958 1131 741 530 408 20 MPH 3916 2262 1482 1061 817 30 MPH 5874 3392 2223 1591 1225 40 MPH 7833 4523 2964 2122 1634 50 MPH 9791 5654 3705 2652 2042 60 MPH 11749 6785 4446 3182 2450 70 MPH 13707 7915 5187 3713 2859 80 MPH 15665 9046 5927 4243 3267 In overdrive Speed/Gear First Second Third Fourth Fifth 10 MPH 1410 814 533 382 294 20 MPH 2820 1628 1067 764 588 30 MPH 4230 2442 1600 1146 882 40 MPH 5639 3257 2134 1527 1176 50 MPH 7049 4071 2667 1909 1470 60 MPH 8459 4885 3201 2291 1764 70 MPH 9869 5699 3734 2673 2058 80 MPH 11279 6513 4268 3055 2352 Thanks Stu |
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13th Sep 2013 8:24pm |
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| Pickles Member Since: 26 May 2013 Location: Melbourne Posts: 3784  
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Ha Ha Ha....15665RPM @ 80MPH!!!!...Gotta love that.
Cheers, Pickles. |
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13th Sep 2013 10:02pm |
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| geobloke Member Since: 06 Nov 2012 Location: Nottinghamshire Posts: 4410
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Interesting Stu. So when you overdrive is engaged your revs drop by a good 800rpm... With the disco box installed my rev gauge says I am now running a good 500rpm less than with the defender gears... I always thought the disco gears and overdrive were comparable but obviously I must be wrong.
Any idea what mpg you are returning using the overdrive?? The disco gears and a steady foot are giving me an average of about 29.5mpg... |
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14th Sep 2013 5:46pm |
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| EMPI748 Member Since: 15 Dec 2012 Location: Penicuik, Midlothian Posts: 50
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It's actually quite good on fuel, been averaging 33MPG and have got about 37 on long trip at a constant 60. Did adding the disco gears improve yours by much?
Will try look for a code on the transfer box as the gears still seem way to short. |
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15th Sep 2013 6:49am |
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