D1 Disco wheelbase measurements

[72pug]

Hi Folks,
Just a question for those with a D1 Disco,.....just wanting to know IF, When you measure you're wheelbase,( not track width) hub centre-centre, do you get the EXACT same measurement for both sides of your vehicles, or is the driver-side measurement marginally shorter.

Just to pre-empt other questions.....NO the vehicle is not accident damaged .

I know that back in the UK years ago, the POLICE force sent a heap of their highway patrol cars back to LR as they were as above, and wandered dangerously on the highway, and pulled to one side under brakes.

Thanks in advance for any replies,

Cheers,

Pug.

[DaveS3]

Obviously you should get the same each side, at ~100inches.

The biggest factor in this is how you measure the wheelbase and what error you introduce.

Other major factor is both chassis front and rear control arm bushes. Subject to major compression and they compress greatly and they often deteriorate at different rates.

If you don't get the same measurements +-5mm (this is acceptable) i would start changing bushes.
If its more than that the car will probably tracking or crabbing down the road stressing the other bushes.

Dave.

[langy]

The last wheel alignment I had was on a reasonably new device which measured the relationship of all four wheels to each other ( I was able to watch the set up and talk to the operator).

I have heard discussion ( here actually ) of changing aspects of suspension distances to correct other problems, but I'll stick to saying it should be the same.

Of course, if yours wanders under brakes, go talk to a tyre place and get them to check it out with equipment. It may cost you $40 - but it will answer the question without doubt.

[72pug]

Hi again,
Should have siad, that bushes are aok, or have been replaced.

wheel alignment is done regularly, and is curently good.

Tyre pressures are smack on and exactly the same, and tyres themselves are near new.

Had New steering box and adjustmentslast year........
as for measurements ( and accuracy of course) by my calculations there is approx 4mm( -) difference on RHS.

I understand that squish between radius arm bushes / rear control arm etc can all take a role, and also castor correction. ( this vehicle is'nt lifted above 40mm)....

I suppose it kinnd of intersects a thread placed on this site recently regarding slotting swivel hubs( with regard to CASTOR)......not that you'd have such a (mm) difference in that area.

Must take a closer look and get some Really accurate measurements,

Cheers,

Pug.

[72pug]

Will be interesting to see how many D1 owners have a difference in theirs........and if so by how much.........:question:


Pug

[Bush65]

I doubt that we would get accurate measurements as left to right side measurement will change if the front wheels are turned, ever so slightly, one way or the other.

Perhaps on a good wheel alignment machine, as Langy used, the results would be more reliable.

[DEFENDERZOOK]

if there are such problems as described above.....and the panhard rods and radius arms are all the same length......
and there is no damage anywhere.......


then i would be doing a chassis drop test to makes sure the chassis is 100%......


what you need to do a drop test is......

a plumb bob......
a marker pen or piece of chalk........
a chalk line......
and a flat bit of (preferably) concrete......big enough to park the car on.....




procedure......using the plumb bob.....make a few drops at various points along the chassis down one side of the vehicle......
and then repeat in exactly the same locations on the opposite side of the vehicle.......
and make a chalk mark on the ground for each drop.......

once you have made approx 5 drops on each side of the chassis.....remove the vehicle......
then using the chalk line......make some nice straight lines between the marks on opposite sides of the chassis......
but make the lines diagonaly across.....ie..use the first mark on the left side and the second or third mark on the right......
and vice versa......you should end up with some crossed lines on the ground......

these should all intersect along the centreline of the vehicle......
using the chalk line again...mark out a line where they all intersect.......

if any of the intersections are out of line you either have a problem with your chassis.....or you werent accurate enough with the plumb bob......



it is very important to make sure you use exactly the same drop points on both sides of the chassis.......

[DEFENDERZOOK]

i should add.....you could also check diff alignment using this method as well.....

take some drops at the brackets on the diff housings for both diffs.....
these should also intersect along the same centre line.....unless one of the diffs is out of whack.....

[72pug]

Thanks to all for suggestions above.............will get into 'proper looking'...., feel it's something simple though.


Pug

[DarrenR]

Your talking 4mm difference between centres.

X = left side between centres.
X +4mm = right side between centres.

If each hub centre on the left side is moved OUT 1mm and on the right side each hub centres move IN 1mm, then both X left and right are now the same.

1mm of hub centre movement for 2 ton of coil sprung rigid axle truck.... my guess is general suspension movement, as in the way it is currently sitting on the driveway, the way the coils/shocks have settled when you stopped due to turning in, uneven load, braking pressure from one side to the other.

I'd find it more than difficult to believe there is a problem.

Best regards
DarrenR

[camel_landy]

Remember that's also possible to have a bent axle casing... ;)