Thread: Highway cruising 300tdi

My 130 used to read 100 but only doing 90 until I replaced the blue cog with a yellow one in the speedo drive now when the speedo says 100 I’m doing 102 that’s with 235/85/16 tyres

There are online calculators which work out your speed based on original size road tires compared to new size. Possibly with ones which take gearing ratios into account too.

My manual D1 tdi has 245/75/16 and the speedo now reads about 94kmh when doing 100. Revs in 5th gear at that speed are about 2250. Before closer to 2500.

I find when i sit on 90 on speedo (so about 95ish real speed) I’m in the sweet spot. At 100 real speed i get an annoying rattle as well. So ruins the feeling.

Originally Posted by Rick1970

Manual. Speedo drive is on transfer output from memory, so shouldn’t effect readings. Tyre size and diff ratio changes will vary it.

Here's a couple of pics from ashcrofts website:

The only difference in the data enetered was the Transfer Gear Ratio 1.41 vs 1.21. There's quite a bit of difference in the revs at 100kms

That sounds about right.
In my case std @ 100 would be 2400rpm, 1.22 hi transfer and 29” tyres, 2500 with 1.41 trans and 32’s

I assume you know the vehicle is unroadworthy and insurance might be voided if the speedo reads lower than the actual speed. Just saying...

Originally Posted by incisor

my last two have their sweet spot around the 105kph mark

my 130 pulling a 1 tonne van has no trouble cruising at 105kph

the usual hills and headwinds caveats apply but in my experience the 300tdi pulls as hard / well as a 3.5 v8 or 4bd1-t county up the same long hill, if not slightly better... and you don't need a fuel stop half way up the hill

I'll second that.

Originally Posted by Fausto79

....

I find when i sit on 90 on speedo (so about 95ish real speed) I’m in the sweet spot. At 100 real speed i get an annoying rattle as well. So ruins the feeling.

LOL! those annoying rattles!
Easy one to fix was the transfer case lever boot covering frame. First rattle/zing I located and fixed. I wedge 4 slices of soft foam in all 4 edges and fixed that one.
Next one was the rattle from the centre console to base of dash interface, again some foam just wedged in between(screwdriver) fixed that, then the fun started!

I used to have one smack bang at about 1750 at the exact point where 4th lockup(TC) happened, at 80k/h(auto obviously).
This one was both rev and throttle dependent light throttle and 1750RPM, right on 80k/h.

Turned out it was the flapper thing inside the drivers central vent. had to pull the centre dash section out about 10 times to finally fix it.
Used all manner of stuff from cut rubber orings on the flap shaft, to duct tape, to straws .. and just about anything I could think of to stop it vibrating.
Only fix was to bash the bejesus out of it with a hammer and long tube to bend the flap on it's spindle just a little without bending it too much it didn't operate!.

sorted.

Only problem was that in stopping that vibe(now totally fixed) it masked the other annoyance .. the passenger seat vibrates(zings!) at about 90k/h now when no passenger. removed it, bashed it, thought it was the seatbelt clip, .. nup! it's the actual back rest. When I place my left hand on the grab handle, it stops.
So I'll have to remove seat again and bash the other bejesus out of the backrest to seatbase pivot soon.

my auto tdi has a sweet zone. anywhere between 80-100 now, depending on road surface more than anything else. .. Oh! and as long as I keep my hand on the passenger seat back rest(for now)

Wow! Cheers for the responses everyone.
I really appreciate the dialogue everyone has brought to the table (although i will admit i had a chuckle at the comment about doing 120 comfortably in a 300tdi auto D1). Maybe once, but not in recent history. .This girl has pulled a 3.5t van around australia 2.5 times (third time head failure somewhere in NSW) by the previous owner and had no mods except for a uhf. Now she’s heavy as a brick and i wouldnt dream of doing 120, ill be happy with 110 for overtaking, the sweat spot is between 90-100 imo.
BTW saying there’s something wrong with a 300tdi if it cant sit at 120 comfortably all day is a bit rich, thats 40km/h over the entry into 4th in an auto, you would not be able to maintain that on D’aguilar let alone Bruce highway on a long stretch of hill on the sunny coast (not to mention malany).
My hope of the double sized intercooler and tune at MR (Ireckon they would have told me or the previous owner (my old neighbour) if something major was wrong in its many trips in 24 years too with how it was running ) is to simply regain some of the drivability which has been lost with all the mods Ive made. For those who are somewhat interested in what kind of weight the vehicle has had added I’ll try my best to add it below
Bullbar - 65kgs
Winch - 35kgs
second battery - 35kgs
Light bar - 5kgs
4x 9”lights - for those who have seen my vehicle it is apparent that wind resistance is another feature with a huge rack and 4 9” lights strapped to the rack - 35kg
roof rack - 60kg
solar panel - 10kg
rock sliders - 35kg
rear bar - 40kg
water tank (full) -80kg
hot water system - 15kg
tools and recovery gear - maybe 50kg
draws, fridge and shelves - maybe 75kg
Theres probably more small stuff like gauges, aerials, uhf units and gizmos but its pretty far from stock. If your doing 120km/h with all this stuff kudos to you, especially if your doing it on stock intercooler and fuelling.