Mud-club
Vehicle & Technical => Defender => Topic started by: Jimbo on May 14, 2007, 16:42:37
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I'm trying to figure out why my 110 Td5 won't go much over 65-70mph, it's running on BFG muds 265/75/16's and we believe has a standard transfer box (43D******G).
Dave Ashcroft is certain that the t-box is the standard 1.410 ratio - but without stripping it apart, there's no way of telling whether the 'innards' have been swapped for different ratios.
On the Ashcrofts site there's a formula for working out your MPH per 1000rpm - but you need to know the diff ratio.
I've tried a couple of numbers (4.7, 4.11 and 3.54), but these all give bizarre results - with 4.7 in the equation, I get a figure of 57MPH per 1000rpm..........so in theory I should be doing over a ton at 2000rpm :shock:
Anyone know what ratio my diff should be - just realised, the formula doesn't say front or rear diff :?
Jim
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All the diffs are 3.54:1 in coil sprung disco, RR & defenders except that is the disco 2.
Hope this helps!! :wink:
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All the diffs are 3.54:1 in coil sprung disco, RR & defenders except that is the disco 2.
Hope this helps!! :wink:
Hmm, putting 3.54 into the equation I get a result of 104mph @ 4200rpm in 5th gear - think somethings amiss with my truck somewhere :(
I don't have a rev counter fitted, so can't be absolutely sure what rpm the engine is doing - but it sure sounds like its screaming, and the speedo (checked with 2 different GPS's) reads around the 70 mph mark. I've been reliably informed that a Td5 Defender will easily pull 90mph (not that I want to !), but I would like to be able to keep up with motorway traffic and not rag the nuts off the engine.
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Wow, i have a disco 200tdi engine in my defender and that'll do 80 on the motorway with the pump turned up so i'd say something is definatly not right a standard TD5 you sit at 70mph a piece of ****!
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Wow, i have a disco 200tdi engine in my defender and that'll do 80 on the motorway with the pump turned up so i'd say something is definatly not right a standard TD5 you sit at 70mph a piece of ****!
I also have a Td5 Disco, and that sits quite happily at motorway speeds, at about 2500rpm, I know the engine in Discos has a different ECU tune, but somethings definitely up with the Defender.
I'm guessing that maybe the t-box ratios have been messed with - its not as if the engine is lacking power as it pulls like a train up to 60.
Is there anyway of checking what ratio the diffs are for definite ?
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Diffs are 3.54 unless they have been changed, only way to check is pull them. As Dave A. says the T-Box is 1.4:1 unless thats been changed.
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Diffs are 3.54 unless they have been changed, only way to check is pull them. As Dave A. says the T-Box is 1.4:1 unless thats been changed.
OK then, if we assume that the diffs are 3.54, and the t-box is a 1.4, and knowing that the truck pulls well up to 60mph.........what can be causing my lack of top end ? - could the ECU have been 'played' with to restrict top speed ?
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All the diffs are 3.54:1 in coil sprung disco, RR & defenders except that is the disco 2.
Hope this helps!! :wink:
disco 2's have 3.54 diffs :wink:
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I have a cunning plan :(scared):
What if you remove the front propshaft from the transphere case, apply the handbrake, stick the gearbox in 4th (1:1 ratio) and whalst someone else counts the number of turns on the front output of the transphere case, you turn the the engine over manually for a number of turns. The more turns you can bear to do this for the more accurate the result will be provided neither of you lose count. Marking both crankssft pully and transphere case output with a bit of paint would make it easier.
Knowing the number of turns of the of the engine (ecentially the number of turns of the transphere case input) for a number of turns of the transphere case output you can work out the ratio of the transphere case.
Because of the action of the diff and the lock rear output the number of turns of the front output would bave to be halved to get an accurate figure or altenitively chock the wheels, disconnect both propshafts from the transphere case and engaged the difflock. But this would mean more work.
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Diffs are 3.54 unless they have been changed, only way to check is pull them*. As Dave A. says the T-Box is 1.4:1 unless thats been changed.
OK then, if we assume that the diffs are 3.54, and the t-box is a 1.4, and knowing that the truck pulls well up to 60mph**.........what can be causing my lack of top end ? - could the ECU have been 'played' with to restrict top speed ?
*= Mmmmm, not necessarily - you can do a rough count of the turns on the prop and the wheel to work it out close enough to be able to tell the difference between a series diff and a latter one........
**= As torque is what gets you up to speed but horse power is what keeps you there, you may have something as daft as a lift pump on the way out that is only starting to show up at higher speeds by starving the engine just enough to slow it up high in the revs - friend of mine had a 200Tdi that was doing the same - it got gradually slower over a couple of weeks then it just refused to start - new lift pump and it fired up and was suddenly back to its old top speed again......
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I have a cunning plan :(scared):
What if you remove the front propshaft from the transphere case, apply the handbrake, stick the gearbox in 4th (1:1 ratio) and whalst someone else counts the number of turns on the front output of the transphere case, you turn the the engine over manually for a number of turns. The more turns you can bear to do this for the more accurate the result will be provided neither of you lose count. Marking both crankssft pully and transphere case output with a bit of paint would make it easier.
Knowing the number of turns of the of the engine (ecentially the number of turns of the transphere case input) for a number of turns of the transphere case output you can work out the ratio of the transphere case.
Because of the action of the diff and the lock rear output the number of turns of the front output would bave to be halved to get an accurate figure or altenitively chock the wheels, disconnect both propshafts from the transphere case and engaged the difflock. But this would mean more work.
To check diff ratios - jack up one rear wheel and turn rear prop by hand, counting number of revolutions of the diff flange to acheive 2 (cos of open diff) revs at the wheel - much easier, don't even need a spanner for that.
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I have a cunning plan :(scared):
What if you remove the front propshaft from the transphere case, apply the handbrake, stick the gearbox in 4th (1:1 ratio) and whalst someone else counts the number of turns on the front output of the transphere case, you turn the the engine over manually for a number of turns. The more turns you can bear to do this for the more accurate the result will be provided neither of you lose count. Marking both crankssft pully and transphere case output with a bit of paint would make it easier.
Knowing the number of turns of the of the engine (ecentially the number of turns of the transphere case input) for a number of turns of the transphere case output you can work out the ratio of the transphere case.
Because of the action of the diff and the lock rear output the number of turns of the front output would bave to be halved to get an accurate figure or altenitively chock the wheels, disconnect both propshafts from the transphere case and engaged the difflock. But this would mean more work.
To check diff ratios - jack up one rear wheel and turn rear prop by hand, counting number of revolutions of the diff flange to acheive 2 (cos of open diff) revs at the wheel - much easier, don't even need a spanner for that.
that would give in-accurate results :wink:
friction between bearings and hub, break pads against disc
everything has to be free so no friction to variate results
best way is to only have the h/s in and count the no of turns on that :wink:
you have checked wheel balance aint you ?
cant see it bein but our old 200 disco wouldnt do anything above 55 turned out be the wheels bein so off balance and no the steeringwheel didnt wobble
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I have a cunning plan :(scared):
What if you remove the front propshaft from the transphere case, apply the handbrake, stick the gearbox in 4th (1:1 ratio) and whalst someone else counts the number of turns on the front output of the transphere case, you turn the the engine over manually for a number of turns. The more turns you can bear to do this for the more accurate the result will be provided neither of you lose count. Marking both crankssft pully and transphere case output with a bit of paint would make it easier.
Knowing the number of turns of the of the engine (ecentially the number of turns of the transphere case input) for a number of turns of the transphere case output you can work out the ratio of the transphere case.
Because of the action of the diff and the lock rear output the number of turns of the front output would bave to be halved to get an accurate figure or altenitively chock the wheels, disconnect both propshafts from the transphere case and engaged the difflock. But this would mean more work.
To check diff ratios - jack up one rear wheel and turn rear prop by hand, counting number of revolutions of the diff flange to acheive 2 (cos of open diff) revs at the wheel - much easier, don't even need a spanner for that.
that would give in-accurate results :wink:
friction between bearings and hub, break pads against disc
everything has to be free so no friction to variate results
best way is to only have the h/s in and count the no of turns on that :wink:
you have checked wheel balance aint you ?
cant see it bein but our old 200 disco wouldnt do anything above 55 turned out be the wheels bein so off balance and no the steeringwheel didnt wobble
Sorry, was something lost in translation, Iwas on about the transphere case ratio, not diffs.
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afink av worked to many hours today :oops:
even so, can see it being gear ratio's some how :?
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afink av worked to many hours today :oops:
even so, can see it being gear ratio's some how :?
PMSL
just do it the way previously described by puting it into 4th gear with difflock in & turn the engine over by hand,
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OK, in no specific order (cos I can't remember what order you nice chaps posted the responses in !).
Chris - I'll give it a go, but will have to wait until I can get down my mates place, as I can't see SWMBO turning over the engine or lying on the floor counting the number of times a flange rotates :wink:
Wheel balance - really :shock: , can't see it myself. But I do need to get the tracking done, so will get the balancing done at the same time.
Lift pump - Td5 so no separate pumps, and I used my 'spare' pump on the Disco a few months back......and on the Defender its a tank-out job to do the pump :evil: . If it is the pump - diags should show low fuel pressure I think, the guy who will be doing my tracking has the diags (Rovacom), perhaps I'll get him to come out for a run - assuming that you can access the diags in a real-time situation (ie, whilst driving along ?)
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Good point re the lift pump - must remember to read things more closely in future, D'oh.........
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Dave Ashcroft reckons that I should stick with the standard t-box (1.410) rather than swapping to a Disco ratio (1.222) as with my 265/75 MT's it might gear it too high !
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Dave Ashcroft reckons that I should stick with the standard t-box (1.410) rather than swapping to a Disco ratio (1.222) as with my 265/75 MT's it might gear it too high !
He might be right, but then again i did it on my old TD5 110 and it worked a treat, but then i did chip and intercooler it too :D
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He might be right, but then again i did it on my old TD5 110 and it worked a treat, but then i did chip and intercooler it too :D
A chip or re-map is on the cards, but not until it's running as a standard Td5 should !
Out of interest, what intercooler did you fit ? - I thought the Td5 one was the biggest that would go in there !
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LOL - you can fit bigger, much much bigger! Mine came from Allisport :)
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that would give in-accurate results :wink:
friction between bearings and hub, break pads against disc
everything has to be free so no friction to variate results
friction will not affect the gearing in any way.
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that would give in-accurate results
friction between bearings and hub, break pads against disc
BoBBins
Friction has got nowt to do with gear ratios. If there was friction present it would just be harder to turn, gear ratios stay the same.
In the middle of all this, we are assuming the CLUTCH ISNT SLIPPING......
Id guess either a rock crawling nutter was the previous owner and fitted 4.75:1 diffs, and a low ratio transfer gear set, or maybe....just maybe....the clutch is <edit> not very happy </edit> ?
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In the middle of all this, we are assuming the CLUTCH ISNT SLIPPING......
Id guess either a rock crawling nutter was the previous owner and fitted 4.75:1 diffs, and a low ratio transfer gear set, or maybe....just maybe....the clutch is <edit> not very happy </edit>?
The trucks done just over 15k miles, and was ex-leccy board, probably on the original clutch........and hopefully its not <edit> not very happy </edit> !! It certainly doesn't seem to slip, and infact, drives perfectly up to 60-65mph.
But, being ex-leccy I am wondering if the ratios have been fiddled with, or maybe, just maybe the ECU has been 'got at' to prevent leaden-footed sparkys driving it (and a large trailer) at warp-factor 10 :twisted:
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Wow, i have a disco 200tdi engine in my defender and that'll do 80 on the motorway with the pump turned up so i'd say something is definatly not right a standard TD5 you sit at 70mph a piece of ****!
So you are happy with it then Tinks?? :lol:
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I've got an hours worth of 'Rovacom' time at a local specialist lined up, the guy there can drive the Rovacom, but is not into anything other than clearing fault codes, and basic stuff. Is someone able to tell me what info I need to extract, in order to find out if the fuelling maps, speed limiter (if there is such a thing), etc has been 'played' with on my truck.
Once I've got the necessary info - i guess it will be in the form of file names maybe ?, is anyone able to decode said info, so that I can find out what stops the beast from going over 70mph ?
Thanks,