Range Rover Sport GVM Upgrade Question

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Originally Posted by Tombie

The common D4 upgrade is RRS arms ;) Only difference is the bushings - So for engineering purposes neither could be identified on vehicle.

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Is this commonly done on the rear control arms too too? My understanding is the fronts are often swapped for this reason but I couldn't find much on the rears. Are the rears definitely interchangeable, upper and lower?

Interestingly, the only number I can find on my lower control arms is this one - RHI500225. It doesn't match the part number for any LR control arms, but does sort of look like a LR part number. Can anyone shed any light on what this means? Maybe an aftermarket arm? I'd be interested to know what numbers are on anyones Discovery rear control arms.

Attachment 192810

I fitted the 31" GG 255/60R19 LI 113 to D4 rims on my L322 over Brembos which has 30" wheels but might be too oversize for the L320. I also have them on my L405 on D5 19" rims.

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Originally Posted by felix.loten

Yes I have - depending on how far I go with it it could get problematic. I will most likely limit my rear axle load to the limit of 111 load index tyres (2 x 1090kg) which seem to be readily available. I am stuck with 19" or larger rims to clear the Brembo brakes and heavy duty tires above 111 load index in 19" or 20" seem to have very limited options.

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a load index of 111 is above anything you'll ever get approved for, with d4 about 1855kg, id read somewhere different limit between 5 and 7 seater, but i cant find it now, but it def wasnt over 1900

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Originally Posted by felix.loten

Is this commonly done on the rear control arms too too? My understanding is the fronts are often swapped for this reason but I couldn't find much on the rears. Are the rears definitely interchangeable, upper and lower?

Interestingly, the only number I can find on my lower control arms is this one - RHI500225. It doesn't match the part number for any LR control arms, but does sort of look like a LR part number. Can anyone shed any light on what this means? Maybe an aftermarket arm? I'd be interested to know what numbers are on anyones Discovery rear control arms.

Attachment 192810

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That’s an RRS Rear right lower [emoji41]

And the other upgrade is the Top rears to RRS - tougher bushing!

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Originally Posted by haydent

a load index of 111 is above anything you'll ever get approved for, with d4 about 1855kg, id read somewhere different limit between 5 and 7 seater, but i cant find it now, but it def wasnt over 1900

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I think I have a case for more than that... I've got 2 options:

1 - Early Disco 3's had a special provision in the owners manual for 15% overload on the rear axle when towing. This gets you to 2151kg.
2 - The Armoured Discovery variants have a rear axle capacity of 2350kg

I'd like to try for the whole 2350kg but wheel options are very limited and really I don't need all that extra weight capacity anyway.

Attachment 192832

Yeah id love that too, but might be more difficult to try and equate and possibly hard to use without going over the other limits. As you said not really necessary id love 1900, was that manual spec Australian or OS ? Ive seen another nice note in some manuals that say when towing limited to 100kmh you get extra capacity :)

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Originally Posted by haydent

Yeah id love that too, but might be more difficult to try and equate and possibly hard to use without going over the other limits. As you said not really necessary id love 1900, was that manual spec Australian or OS ? Ive seen another nice note in some manuals that say when towing limited to 100kmh you get extra capacity :)

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This was a manual I purchased from someone wrecking a vehicle in Australia. I guess it's possible he or a previous owner lost his manual and purchased a new one from overseas, but seems unlikely. It is an early D3, a 2005 model.

There are provisions in the European type approval requirements (Euro equivalent of the ADR's) for 15% overload on the rear axle provided the speed is limited to 100 km/h which I guess is likely where this has come from. Refer 2.7.2 in the attachment.

Attachment 192912

I just got my approval in principal from the WA DOT to do this so now need to pay an Automotive Engineering Consultant to write this all up in a report and get it inspected. Would you be interested in joining my exercise and splitting costs? Or if anyone else is interested in joining?

im in nsw so not sure how much use it will be, but def would be interested in payment for this upgrade ! what increase are you going for on what basis ?

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Originally Posted by haydent

im in nsw so not sure how much use it will be, but def would be interested in payment for this upgrade ! what increase are you going for on what basis ?

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My understanding is vehicle modification approvals are generally accepted in different states once accepted. But whether they will accept a report from a WA engineer for a modification lodged in NSW might be a different matter, it would be interesting to try. I'm going for a rear axle load of 2148kg - the limiting factor is the standard wheels which I think I have a means to uprate to this figure - it will be interesting to see whether the WA DOT accepts it.

The amount the WA DOT gave conditional approval for was 2350kg rear axle load based on the armoured Discovery variant. Uprated wheels required for this, for which there are very limited options, and none of them cheap, hence shooting for a lower figure.

I'll PM you with costs once I have them all bottomed out.

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Originally Posted by felix.loten

My understanding is vehicle modification approvals are generally accepted in different states once accepted. But whether they will accept a report from a WA engineer for a modification lodged in NSW might be a different matter, it would be interesting to try. I'm going for a rear axle load of 2148kg - the limiting factor is the standard wheels which I think I have a means to uprate to this figure - it will be interesting to see whether the WA DOT accepts it.

The amount the WA DOT gave conditional approval for was 2350kg rear axle load based on the armoured Discovery variant. Uprated wheels required for this, for which there are very limited options, and none of them cheap, hence shooting for a lower figure.

I'll PM you with costs once I have them all bottomed out.

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2350kg is only 1175kg per wheel.

CSA does one that exceeds that - they’re not that badly priced.