4WD on 2WD Dyno

[cockie55]

Any mechanical reason why you can't use a 2WD Dyno by locking the centre diff (LT230) and lifting the front wheels off the deck ?????

[Psimpson7]

Removing the other propshaft would be safer!

[BigJon]

Potential for diff failure? Is it a salisbury rear or a Rover centre? The reason why Range Rovers were constant 4WD in the first place was because the diffs weren't strong enough for 2WD use with the Rover V8 powering them.

[cockie55]

I don't have any rover centres. Have always used a 4WD dyno but the waiting time and cost is a pain.

[GuyG]

Any mechanical reason why you can't use a 2WD Dyno by locking the centre diff (LT230) and lifting the front wheels off the deck ?????


We've never had any issues in the 20+ years of having it done with either the LT230 or LT95

[101RRS]

I don't have any rover centres. Have always used a 4WD dyno but the waiting time and cost is a pain.

Unless you have changed out the axle housings to something else you will have rover diffs (or a modifed version there of).

In would lock the center diff and take out the front drive shaft. As you will have equal traction to both rear wheels and no sudden application of braking force etc on the dyno there should be no issues doing it in 2wd.

Garry

[Dougal]

Potential for diff failure? Is it a salisbury rear or a Rover centre? The reason why Range Rovers were constant 4WD in the first place was because the diffs weren't strong enough for 2WD use with the Rover V8 powering them.

The rear diff sees more torque climbing offroad locked than it would in 2wd onroad.

[big guy]

When I did my 4.6 conversion, I rang around for local 4wd dyno places which can be hard to find.
My response was "Its a 4wd, go to a 4wd dyno place thats why they are there"
I did that and was very happy, although Yes I had to wait 4 weeks to get a time slot. ;)

[2stroke]

A bloke I used to work with had diesel gas fitted to his Tdi 130 and they put it on a 2wd dyno with the centre diff unlocked, not hard to picture what happened to the centre diff. They didn't want to know about it either and he had to fix it himself.

[mark2]

There is a plate riveted to the seat box of my 110 which states that the center diff must be locked and the front prop shaft removed before dyno testing is done.

This would have to be referring to a 2WD dyno....

[Zute]

Thats why they left the centre diff' lock in the first D2's. So they could be dynoed on a 2wd dyno.
But yeh, remove front drive shalf. dont just jack up the front wheels. Or we'll be reading about it in the Darwin awards.:o

[rovercare]

Thats why they left the centre diff' lock in the first D2's. So they could be dynoed on a 2wd dyno.
But yeh, remove front drive shalf. dont just jack up the front wheels. Or we'll be reading about it in the Darwin awards.:o

No...its not....It'll quite quickly ruin the centre diff;)

Pull the front propshaft at home, lock the centre diff and head to the Dyno, it will be fine and its the only correct way

[cockie55]

.... dont just jack up the front wheels. Or we'll be reading about it in the Darwin awards.:o

Zute thanks for posting but please explain your view (which is pretty pointed re the Darwins suggesting I am a very dead dickhead if I don't disconnect front shaft) as my thread seeks ie "why" (that is mechanical reasons)??

[cockie55]

No...its not....It'll quite quickly ruin the centre diff;)

Pull the front propshaft at home, lock the centre diff and head to the Dyno, it will be fine and its the only correct way

Hi Rovercare....providing front wheels are off the deck (as I state up front to this thread) ...why then will the centre diff be ruined as you say if front shaft is also not removed ????

[rovercare]

Hi Rovercare....providing front wheels are off the deck (as I state up front to this thread) ...why then will the centre diff be ruined as you say if front shaft is also not removed ????

That was in reference to the D2 and not having a centre diff lock, if you run without CDL on a 2wd dyno and your front wheels of the ground it won't work very well:D if you run on a 2wd dyno with front wheels on the ground and front prop in, without CDL you'll ruin your centre diff quick smart

I think it'd be a tad foolish to run with your front wheels happily whizzing around at 100+km/hr as opposed to removing the front shaft....but I am a believer in natural selection

[cockie55]

My originating post said...."Any mechanical reason why you can't use a 2WD Dyno by locking the centre diff (LT230) and lifting the front wheels off the deck ?????"

Therefore I don't know where doing it with a D2 and or leaving centre diff unlocked came from??? Anyway seems the answer is removing front prop shaft adds nothing mechanicaly and drive line will be sweet.

Thanks all

[rovercare]

Thats why they left the centre diff' lock in the first D2's. So they could be dynoed on a 2wd dyno.
But yeh, remove front drive shalf. dont just jack up the front wheels. Or we'll be reading about it in the Darwin awards.:o


No...its not....It'll quite quickly ruin the centre diff;)

Pull the front propshaft at home, lock the centre diff and head to the Dyno, it will be fine and its the only correct way


My originating post said...."Any mechanical reason why you can't use a 2WD Dyno by locking the centre diff (LT230) and lifting the front wheels off the deck ?????"

Therefore I don't know where doing it with a D2 and or leaving centre diff unlocked came from??? Anyway seems the answer is removing front prop shaft adds nothing mechanicaly and drive line will be sweet.

Thanks all

It came from the above post and that post I was referring to, not your original post, to put it in lamens terms, you can lock your centre diff and prop the front wheels, but its 1. lazy and 2. a stupid idea having large amounts of rotating mass hanging of the ground spinning like ****, make sense?

[clubagreenie]

For those in Sydney, Unigroup Engineering has one. Sees all sorts of vehicles. Yavuz is an excellent tuner as well.

Pretty much most performance shops have them as Skylines/Evo's/Subarus NEED them. Any shop that didn't want your work I wouldn't worry about.

What are you having done? Anything performance related I'd rather tune it with full load on the whole system. I know it should be the same but...

[cockie55]

I did some ringing around today....seems a whole lot of respected 4X4 shops simply prop front wheels with centre locked and don't remove prop shaft........interestingly when I then said I was concerned about the front drive line having no load they imediatley agreed that dropping the shaft was preferable but that would take more time ...blah ...blah.

While I am only after comparative data on some alternative setups and therefore not that interested in actual outputs on a 2wd being out of wack, I have decided to put up with the extra wait time and $ and do it on a 4wd. All the same I would be interested to hear one day why removing the front shaft and not jacking the wheels is a must do?

[101RRS]

seems a whole lot of respected 4X4 shops simply prop front wheels with centre locked and don't remove prop shaft........

Sorry - do not understand if the front wheels are propped - I assume you mean locked - and the CDL locked then how do the rear wheels turn?

[rovercare]

Sorry - do not understand if the front wheels are propped - I assume you mean locked - and the CDL locked then how do the rear wheels turn?

Propped...off the ground;)

Running like this is still ugly, I had a rod the dude was selling for 55k on the hoist doing just this, sorting some speedo issues, as opposed to running up and down the road, stone chips, filth etc and its far from a pleasant or smart idea, it vibrates and once it hits resonant frequency:eek:

[Zute]

Cockie55, The Hand Book state's that to Dyno a D2 on a 2wd dyno. You must remove the front drive shaft and lock the centre diff.
If you where to jack the front wheels off the ground, and run it on a dyno, with the front wheels spinning. If it should fall off the jack or such, than we would be reading about your sorry tail in the Darwin awards. The premise here is that it would be dangerours. Did NOT call you a Dickhead. Lighten up we are all friends here.

[GuyG]

Any mechanical reason why you can't use a 2WD Dyno by locking the centre diff (LT230) and lifting the front wheels off the deck ?????

So for clarification to the original question - there are no mechanical reasons why a 4WD could not be dynoed on a 2wd dyno with the front wheels lifted off the ground and the centre diff lock locked.

Clearly there are some possible safety issues already mentioned in the thread. Wouldn't want to see the results of the front diff housing falling off the axle stands

Would be interesting to know how many workshops that test 4wd's on 2wd dyno's actually do remove the front shaft.

Obviously a 4wd dyno would get better results. But on a 2wd dyno wouldn't having the resistance of the front drive/diffs etc be better than having the front shaft removed and having no resistance at all.

[Pedro_The_Swift]

There are a few here that have used a dyno service it seems--
I am happy to wait for a 4wd time slot,,

what can i expect to happen in a normal dyno session?

[BigJon]

what can i expect to happen in a normal dyno session?

What is a "normal" dyno session?

[weeds]

The two dyno's I have been on we have removed the from prop shaft........I was never really looking at the real figures at the wheels.......I was more interested in getting the fuel just right to give best torque/power