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View Full Version : Disco 3 S & Hayman Reese weight distribution hitch



Gypsy_Pete
6th June 2008, 06:54 PM
I have been warned by Land Rover that using a Hayman Reese weight distribution hitch on my Discovery 3 when towing my caravan is not recommended and can cause damage.

All they say is that it is not an approved accessory and it may result in the ball height being beyond the approved height. They won't say if anyone has had a problem. I can see a potential problem with the air bag suspension model but mine is the "S" with coils all around.

So I contacted Hayman Reese and again they were non committal. However they did say that they have designed a replacement towbar for the Discovery 3. This is another $1,000 fitted - an expense that I really don't want to have.

Overlander has proclaimed that the Discovery 3 TDV6 is one of the best towing vehicles in their test of large 4WD Wagons, so I am surprised at Land Rover's concern.

To you knowledge, is there a safety issue using the Hayman Reese 550kg hitch attached to the standard Land Rover tow bar?

Bushwanderer
7th June 2008, 01:22 PM
Hi Gypsy Pete,
Welcome to the forum.

You have raised a very controversial question. I suggest that you raise it in the D3 Zone (in the Pinnacles).
Edit: Wow, already moved. Thanks Mods. :-)


I also want to tow using my D3 with coil suspension. However, I was unhappy with the loss of departure angle & low towball height with the LR towhitch. As a result, I have bought a Mitchell Bros towhitch receiver (rated for 350kg towball load & 3500kg tow load). It is also suitable for using weight distribution hitches (WDH) (although I would hesitate to use them on D3s with airbag suspension). The Mitchell Bros tow hitch receiver, does NOT compromise departure angle (unlike the Hayman-Reese towbar).

I have yet to fit the Mitchell Bros bar, but will be testing it without WDHs first.

Do you KNOW that you will need WDH with the D3, or is it a case of "I have always used them"?

What unit are you planning to tow with the D3?

HTH,

CaverD3
7th June 2008, 06:37 PM
Someone on the D3 site used a WDH on a coiler D3 but it the DSC kept cutting in when cornering. Not sure why this should be. IF LR are saying could cause damage rather than it could be a safety issue it would appear to confirm the suspision that the LR tow hitch is too weak to take the torsional loads of a WDH?
As bushwander says the engineer who approved the Mitchell Bros hitch said the hitch would take the load of a WDH.
It will be interesting to see how the Mitchel Bros hitch goes with air suspension and a WDH.

johnc18
7th June 2008, 09:33 PM
Fellas
CaverD3, by saying - "the suspicion that the LR tow hitch is too weak to take the torsional loads of a WDH" brings up an interesting point.

I have a reasonable general knowledge of things mechanical, but I don't know what he means by "torsional loads" (in this context).

I'll bet I'm about the same as 99% of LR/Disco owners.
I know what meant by-
Tare
GVM
GCM
Max towing capacity
Max ball download etc
And I understand the basic idea behind WDH's. Transfering weight from the rear axle to the front axle.
But I have never come across any detailed explainations of the physics involved.
For my ( and 99% of LR/Disco owners) benefit, is there anybody out there, who can either
1) point me in the direction of articles (with diagrams/pretty pictures) that explain the physics/maths/engineering behind WDH's, or
2) explain the above directly here on this post. Note: I'm quite happy with physics and maths providing you don't get into quantum physics or somesuch, and have some diagrams.
Thanks John
PS If someone out there can come up with a simple, easy-to-understand explanation of all this (as above) it could be put in as a permanent feature.
I'm sure that there'd be plenty of LR owners who'd refer to it.

Will
8th June 2008, 06:45 AM
I have been using the Mitchell Brothers hitch since it came out, towing a Golf Outback. So far it has proven to be a superb unit. I do not use the WDH and use a standard tongue and ball, which gives me the normal pre-hitching height for the van when all connected up. The rear of the D3 drops about 5mm when connected, with no difference in front measurements.

Have a complete heavy duty HR WDH for sale if anyone is interested - as new.

gghaggis
8th June 2008, 01:36 PM
See the thread:

http://www.aulro.com/afvb/d3-zone/50412-weight-distribtution-bars-disco-3-a.html

where this point was thrashed out ad-nausem ......

It was mainly to do with EAS D3's, but some of the points (diagrams etc) would apply to a coiler.

Cheers,

Gordon

Bushwanderer
8th June 2008, 04:59 PM
CaverD3,
I think that the activation of DSC would be independent of whether a WDH is employed or not.

What DSC does (by black magic, I think:)) is to determine when the D3 is outside the stability limits (say when cornering at speed). It then activates to bring the vehicle back within those limits.

One can imagine, that "pushing" from a trailer when cornering may also cause the DSC to be activated & act to bring it back within "limits".

Best Wishes,

Gypsy_Pete
8th June 2008, 05:51 PM
Thanks Peter. I've been towing a 17 foot single axle caravan and have so far had no problems. I don't go off road so departure angle is not a problem. Its just that LR put the wind up me by just advising against using the WDH without being willing to tell me why. Now, I'm trying to find out. Is there a chance that the LR hitch will just fail and my caravan, complete with WDH will go wandering off to the side of the road?

Bushwanderer
9th June 2008, 01:31 PM
Hi Again Gypsy_Pete,
You're not the only one that LR doesn't give reasons to. :mad: In the lack of that, NONE of us can be sure of the consequences. :eek:

I SUSPECT that their reasoning is mainly to do with the air bag suspension, but in their wisdom, LR don't elaborate.

I think that LR is generally conservative in the performance limits of its vehicles. This helps stop the "but you said that this would be OK" liability issues.

All I can say, if you find that you don't need a WDH, don't use one.

Enjoy your travels,

geoffo
9th June 2008, 05:20 PM
I tow a 25 foot van with bikes and 2 kayaks (bikes also sit on the hitch) and I've just been 3000 k's and guess what? We made it. I use a hayman reese
hitch and apart from weghing 3 times as much I can't see how this can possibly affect the sleeve it slides into. The torsional effect would be minimal in comparison to the loads already placed on the hitch. My guess is that LR won't comment because they don't know the answer. Don't panic because you attach your chains to the GREAT chunk of metal that is firmly attached to the back of the car. If mine breaks I'll make sure I post it here first. Trust me this car is magic when towing. As an interesting aside: I met a LR owner who mentioned they used the manual overide to change into 6th gear because the auto was often reluctant. I tried this on the way home and my fuel consumption was way worse. When I let the auto work its magic it slipped from 5th to 6th as required and fuel consumption improved.

Gypsy_Pete
9th June 2008, 07:11 PM
Thanks again Pete and Geoff for your posts. Yes, I do need to use the WDH in order to level the load. But it looks like I should be OK.

Geoff, I have always let the auto select the gear when towing and I have noticed that at 95 km/h on a level road, if I just back off the throttle a tad, the auto will slip nicely into 6th gear and the engine ticks over at about 1,800 rpm. When it needs a lower gear, it does so. I'm getting about 12.8 litres/100 when towing. (10.5 litres/100k country not towing) How does that compare with your findings?

Peter

Phantom
10th June 2008, 09:38 AM
My 2 cents worth
I have a 2006 S model and tow a 6 metre caravan.

On this issue of WDH, LR are the masters of double speak and circular discussions. Despite many phone calls, emails (and at least 1 letter to the GM) I could not get any advice on why I couldn't use WDH and whether it applied to all models or only those with air suspension. It always ended up with 'talk to your dealer' or 'that is what the manual says'.

On the other hand the Haymann Reese dealer who supplied the WDH said that they were not aware of any problems. (Because I specifically asked)

I drove to Adelaide and back and around North NSW with the WDH with no problems.

My other issues were that the receiver was too damn low (over 10 cm below the coupling) and the receiver regularly plowed up driveways. The new HR receiver accepts WDH but was unsuitable because the receiver is the same height as the LR original

Anyway I bought Mitchell Bros receiver. It is a great piece of engineering - better height, easier to fit chains and hitch and very easy to install. I will probably paint it black to match the bumper but that is my issue.

That feels better
:soapbox:

Bushwanderer
10th June 2008, 02:44 PM
I tow a 25 foot van with bikes and 2 kayaks (bikes also sit on the hitch) and I've just been 3000 k's and guess what? We made it. I use a hayman reese
hitch and apart from weghing 3 times as much I can't see how this can possibly affect the sleeve it slides into. The torsional effect would be minimal in comparison to the loads already placed on the hitch. My guess is that LR won't comment because they don't know the answer. Don't panic because you attach your chains to the GREAT chunk of metal that is firmly attached to the back of the car. If mine breaks I'll make sure I post it here first. Trust me this car is magic when towing. As an interesting aside: I met a LR owner who mentioned they used the manual overide to change into 6th gear because the auto was often reluctant. I tried this on the way home and my fuel consumption was way worse. When I let the auto work its magic it slipped from 5th to 6th as required and fuel consumption improved.

Hi geoffo,
I'm moving even further into the realms of speculation now:(, but the LR receiver has a small lateral spread, meaning that it is possibly more susceptible to torsional loads (as I believe are applied by WDH). This, I think means that the applied loads MAY break the LR tow hitch. The Mitchell Bros tow hitch receiver has a wider spread & is made from thick (12mm?) steel & so could be expected to accept the torsional loads more readily.

Best Wishes,

geoffo
10th June 2008, 08:25 PM
I was getting about 120 km's per quarter tank on the way there (up north).
which equates to about 17.7 l/100k's if my maths is right. But I have a big van and water tanks were full. On the way home it was closer to 145 kms per quarter tank.(wish I got the trip computer)which is 14.6 l/100k's. Tanks were empty and wife had drunk all the beer. She insists it's because were driving downhill.