Thread: Planned Upgrade of Stock Standard TD5

I'm looking forward to hear your feelings about that diff ratio with 32" wheels. I'm running D2a TD5 auto (medium torque converter, slightly chipped, stock turbo+IC) with 32" wheels and 1:3.8 KAM diff gears and sometimes think I should have kept the stock 1:3.54.

Originally Posted by pojir

I'm looking forward to hear your feelings about that diff ratio with 32" wheels. I'm running D2a TD5 auto (medium torque converter, slightly chipped, stock turbo+IC) with 32" wheels and 1:3.8 KAM diff gears and sometimes think I should have kept the stock 1:3.54.

interested in why you choose the 3.8, assume it was maintain the standard gearing against using the 32"s. Looking at the figures the speedo would almost be spot on (allowing for the inherent under reading) whereas I am definitely looking at the off road low ratio. The 4.7 was preferred but the extra rpm's on the road against where i am trying to get my torque developed once I do get the tune (got the Nanocom ordered and got onto Jose for the tune, not in a particular hurry due to the lockdown but Do want it done!) that now having seen graphs, looks like 400 Nm's at 2000 rpm gets the torque peaks out around 2300-2400 rpm corresponding close enough to the 100 kph cruise... As I noted in my email to Jose, would rather drive by the toes rather than the foot.

For me the fact I got the gearing between 1st and 2nd Low in the TDi manual with 32"s which I thought would be optimum for the step descents with minimum brakes (before even worrying about using HDC). Now knowing the TC locks up in first was the deal breaker, elsewise would have gone to 4.7 and suffered the gearing on road.


Just putting the 3.8 into the Ashcroft calculator for comparison

Ratio	TD5	TD5 4.37	TD5 3.8
First Gear	29.15:1	35.98:1	31.29:1
Second Gear	17.39:1	21.47:1	18.67:1

100 kph	TD5 Stock	TD5 3.8 32”	TD5 4.37 32”
Third Gear	3089	3005	3456
Fourth Gear	2294	2188	2516

RPM @10 KPH	First	Second
D2 TD5 3.8 32”	2043	1219
D2 TD5 4.37 32”	2350	1402

No matter how I rationalize it on paper, it remains just an opinion and one that until it is on the road and off, neither right nor wrong LOL

I chose 3.8 because I was getting Ashcroft's ATBs fitted front and rear and the 3.8 gearings are much stronger and were very cheap at that time. I also expected it to allow TC lockup on 4th a bit sooner (at same speeds as stock), which it did. I lost the capability to drive 160 km/h on highways though Even on steep descents, I find the combo of HDC + locked 1st gear in low manual mode to be enough. CDL+ATBs+TC don't allow much wheel slip, manual mode locks the torque converter for best engine braking and HDC takes care of effective top speed of around 6.5 km/h. I have yet to see a situation where I'd need lower descend speed. On the other hand I find myself often limited by the top speed of transfer case low range and with 4.37 diffs it would be noticeably lower.

Speedo definitely isn't spot on, with those wheels it always shows around 7.5 % more. Speedo signal comes from ABS sensors unfortunately, so no matter the diff and transfer case ratio, the reading will always be the same.

Originally Posted by pojir

I chose 3.8 because I was getting Ashcroft's ATBs fitted front and rear and the 3.8 gearings are much stronger and were very cheap at that time. I also expected it to allow TC lockup on 4th a bit sooner (at same speeds as stock), which it did. I lost the capability to drive 160 km/h on highways though Even on steep descents, I find the combo of HDC + locked 1st gear in low manual mode to be enough. CDL+ATBs+TC don't allow much wheel slip, manual mode locks the torque converter for best engine braking and HDC takes care of effective top speed of around 6.5 km/h. I have yet to see a situation where I'd need lower descend speed. On the other hand I find myself often limited by the top speed of transfer case low range and with 4.37 diffs it would be noticeably lower.

Speedo definitely isn't spot on, with those wheels it always shows around 7.5 % more. Speedo signal comes from ABS sensors unfortunately, so no matter the diff and transfer case ratio, the reading will always be the same.

The target speed I read for where HDC kicks in is 7kph so your 6.5 is pretty much right.

From the figures with a locked TQ the engine at this speed would be at roughly 1400 rpm with the 3.8 or 1600 rpm with the 4.7, not sure exactly at what revs the 'lock' would disengage and reduce the amount of engine braking versus HDC and brake control. Hey also saw that the gearbox locks up in 2nd low as well which is pretty useful.

Do you find the 'lock' comes off at around the time HDC kicks in or the TQ remains firmly locked with max engine braking?

in the standard tyred TDI it would go down to around the slowest crawl speed at just over 1000 rpm, almost jump out and do your own spotting at this speed, but second was great for everything I encountered, going to 32" and 2nd was at times a tad too fast down some of the steep shalely stuff, but 1st was still too slow, sure it was safe but still too slow. Its why I think the 4.37 with locked TQ and 32" will give me the sweet spot based on previous experience (and I dont have the capability of trialing all combinations so it came down to numbers!!!) and comparing the numerical data.

I should add that I don't have the experience with the engine braking of the TD5 in steep descents versus the known TDi and certainly wouldn't have chosen the same diff for the TDi unless I was looking to come down vertical walls, the

Originally Posted by RRT

The target speed I read for where HDC kicks in is 7kph so your 6.5 is pretty much right.
...
Do you find the 'lock' comes off at around the time HDC kicks in or the TQ remains firmly locked with max engine braking?

6.5 km/h is the real speed with 32" wheels when the ECU/SLABS thinks it's going 7 km/h

In low range manual mode the torque converter is locked all the time unless the car would stall (which would be under around 1000 rpm I believe).

Originally Posted by pojir

Speedo definitely isn't spot on, with those wheels it always shows around 7.5 % more. Speedo signal comes from ABS sensors unfortunately, so no matter the diff and transfer case ratio, the reading will always be the same.

Here in Australia you can buy a unit that gives you the option to adjust the actual speed (and hence km) to be accurate. I think it now retails around $250 and is easy to fit and adjust to whatever ratios you might have.

Took the advice and have now ordered the Serck intercooler along with a straight through pipe and for good measure, front and rear diff and steering guard (as it all has to come off to fit the diffs and bullbar makes sense to me!). At just over a grand (+$19) feels money well spent, just have to wait for it all from England now and once here, then the installing so hopefully if we down here in Melbourne will be out of lockdown by the end of this month and can head out of town, the plan has come together pretty well.


So all up to date the parts accumulated and ready to fit

• Ashcroft 4.37 Diffs
• ARB rear air locker
• CDL lever
• Serck IC
• V8 Torque Convertor and Ashcroft kit
• EGR blanking kit
• Silicon Hoses for Air and Water
• EGT and Boost Gauges
• Replacement XYZ
• Uni Joints in propshafts
• Front Alloy Bar
• Winch
• Recovery Points for front
• Dual Battery Kit
• Inverter and Anderson Plugs
• All Fluids
• SLS rear bags and 2" Spacers
• Snorkel
• 3"+ Shocks
• D2a airbox
• D2a Slabs and NNN ecu

Still important to get but can wait almost to the day before fitting starts
Front Springs - Still not sure how heavy and which ones to get


So this leaves me with just a tune to go, oh and the trickster thingy for the boost. The VNT I can see the merit, just having difficulty to justify the price at the moment, want low down torque and yes it will improve this- suppose once tuned will be better able to tell.


Actually just thought of something, should i look to deweb the manifold before tuning or even put in one those manifolds that grace ebay so prolifically?

Is there anything I am missing, seems reasonably complete but if you were wanting to drive to the Rock and back what else would you do?




Sort of got my beating ventricles on this which I think will be gotten before the VNT, more about getting back rather than getting back quicker!!!

fff disco-2-rock-sliders.jpg

full-cover-kicker-rock-sliders.jpg

Discovery Rock Sliders: Land Rover Discovery Rock Sliders, Step kits, and Rockrails

Any of want to try for group deal??????

Originally Posted by Bluetoes

Hi
I have a 2004 TD5 auto with 2” lift on 32” muddies and you will want to get a tune if towing anything. Still have the airbags using spacers and for what I do they are great. (Now carry spare bags when on long trips but that’s another story)
Have contacted Empire Tuning in the uk and they have been very helpful, quick to respond and seem well priced depending on what you are after.
I have found the auto to have plenty of engine braking and is a pleasure to drive long distance sits at 2225 rpm on 110kph. The muddies are noisy on road but it doesn’t bother me and work great off-road.
I use a sat nav for accurate speedo (vms cause I got it cheep)
I find the hill decent to be fast for my liking in most off road situations.

Thanks for this, read some nice reports of the tune but was a bit disconcerted at a graph I saw last night and thought I had saved it, NOT! Showed the level of torque (maxed out at 416Nm round 2300) I want but unlike others was only showing about 360-370 Nm at 2000 rpm, rising sharply from about 1600 rpm to the max around 2300 rpm.

Have you gotten the tune? If so does it feel a little soft below 2000 rpm or can you as I want, drive it with your toes rather than your foot at low revs?

Re the SLS, got a reasonable set of Conti's but have purchased a set and a half of cheap bags for on the 'road' and will pack the set of coils insitu in the back for the long trips, sure they will be a nice carry case for the belts. What set are you running and what set caused the grief?