Range Rover Sport GVM Upgrade Question

[felix.loten]

Hi

I am looking seriously at doing a GVM upgrade on my 2007 Range Rover Sport TDV8. The main basis for this will be demonstrating that the rear suspension components are the same as the Discovery which has a greater rear axle weight capacity and then presenting this in an engineering report to the department of transport for approval. I have been able to do this for the majority of components by comparing part numbers between the 2 models, however have got stuck on the rear control arms, both upper and lower, which are not the same part number.

Does anyone know:
1. Are there any physical differences between the RRS and Discovery 3/4 rear control arms
2. Are they interchangeable, even if there are identifiable differences - i.e. do they share the same geometry.

[haydent]

Ive definitely thought about this myself too, The limit im hitting is the rear axle one, and 5 vs 7 seaters have different limits, yet there's no mention of different parts between these seat versions afaik ....

[Graeme]

The RRS may have firmer rear suspension bushes as it does for the front for tighter cornering control, which would make for different complete arm part numbers.

Look into armoured D3/D4 parts too as they should have firmer bushes so might be the same as the RRS.

[felix.loten]

The RRS may have firmer rear suspension bushes as it does for the front for tighter cornering control, which would make for different complete arm part numbers.

Look into armoured D3/D4 parts too as they should have firmer bushes so might be the same as the RRS.

Yes, this was my thoughts too and is true for the upper arm, but the lower arm has the same bushes yet a different part number.

The rear control arm part numbers on the armoured D3/D4 match the standard D3/D4.

[felix.loten]

Ive definitely thought about this myself too, The limit im hitting is the rear axle one, and 5 vs 7 seaters have different limits, yet there's no mention of different parts between these seat versions afaik ....

Yes, there seems to be no rhyme or reason behind the axle and GVM limits Land Rover has placed on these vehicles.

[Graeme]

Have you considered tyre differences, particularly the load index?

[cjc_td5]

Could you just swap in the "higher rated" D4 arms in to the RRS then? Even if they are the same, at least they are "rated" higher for GVM purposes...

Chris

[Tombie]

Could you just swap in the "higher rated" D4 arms in to the RRS then? Even if they are the same, at least they are "rated" higher for GVM purposes...

Chris

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

[felix.loten]

Have you considered tyre differences, particularly the load index?

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.

[felix.loten]

Could you just swap in the "higher rated" D4 arms in to the RRS then? Even if they are the same, at least they are "rated" higher for GVM purposes...

Chris

Hi Chris - yes, that is the fallback if I can't prove equivalency. And also one of my questions - to confirm that they are in fact interchangeable.

[felix.loten]

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

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.

192810

[Graeme]

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.

[haydent]

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.

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

[Tombie]

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.

192810

That’s an RRS Rear right lower [emoji41]

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

[felix.loten]

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

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.

192832

[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 :)

[felix.loten]

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 :)

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.

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?

[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 ?

[felix.loten]

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 ?

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.

[Tombie]

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.

2350kg is only 1175kg per wheel.

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

[haydent]

re armoured, last time i looked into it, its different spring(bag), have you found a source for this ? im sure it will be pricey if even available any more ?

also where are the stats for this variant ?

i know a qld engineer, so will ask him regarding crossover between states.

I feel like getting all of the parts for the b6 armour version might be too hard if even possible, and you might be better going for something more achievable and affordable like the d4 rear axle weight, but id be interested to see if you think there is a a way and the cost/availability. [bigsmile1]

[felix.loten]

re armoured, last time i looked into it, its different spring(bag), have you found a source for this ? im sure it will be pricey if even available any more ?

also where are the stats for this variant ?

i know a qld engineer, so will ask him regarding crossover between states.

I feel like getting all of the parts for the b6 armour version might be too hard if even possible, and you might be better going for something more achievable and affordable like the d4 rear axle weight, but id be interested to see if you think there is a a way and the cost/availability. [bigsmile1]

The armoured variant has a different strut assembly part number, so we can't verify by part number alone whether it is the same, although I suspect the air spring part of the it is and that the difference is in the damper. What I am planning to do is use some information available in the D4 workshop manual that gives us burst pressure for the air bags (35 Bar), and working pressures for front (10 Bar) and rears (8 Bar). I can calculate what the working pressure on the rear bags will be at 2350 kg (9.4 Bar) and then you can compare this to the stated burst pressure (35 Bar) to get a factor of safety. We use the factor of safety from the front springs (3.5) to show that the rear spring working pressure is OK.

192917

Other than that, it's the control arms (once again different part number but we can see they are the same as the standard discovery ones which are easy to source). I've summarised the part numbers below:

192918
Another thing to look out for is I have the larger brembo brakes which have a different knuckle part number to the smaller ones - this conveniently aligns with the armoured variant, however if you don't have these brakes it could be another hurdle to overcome.

I've downloaded an owners manual for the armoured variant from Topix - weights section below:

192928

Thanks for the various challenges, its good to find out if my logic is watertight before I go spending a bunch of money on this.

[felix.loten]

2350kg is only 1175kg per wheel.

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

Well spotted - I hadn't seen those ones. Good to have options, I also trial fitted some 18" American Outlaw rims and they fit, but they'd need the centrebore enlarging a bit.

[haydent]

I have non-brembo brakes.

You realise those rear strut/bags are like $3k each without shipping or import duties ?!

Also the actual sway bar and bush is a different part number. And RRS have a dynamic sway bar ?

[felix.loten]

I have non-brembo brakes.

You realise those rear strut/bags are like $3k each without shipping or import duties ?!

Also the actual sway bar and bush is a different part number. And RRS have a dynamic sway bar ?

Yep, those struts are expensive - if I had to go down that path I would probably choose another vehicle. As I mentioned before I'm planning to use the existing struts and demonstrate that they are up to the task.

I did notice the sway bar was of a different type as well and queried this with my Engineer - it seems that as its not directly load bearing they don't consider it in the assessment.

[felix.loten]

I have non-brembo brakes.

What year is your vehicle? 2010 onwards RRS seem to have been fitted with the right knuckle part number anyway (LR045824).
Range Rover Sport 2010 - 2013 (l320) / Rear Knuckle And Suspension Arms (rear Knuckle And Hub)((v)fromaa000001) | Jaguar Land Rover Classic Parts (https://parts.jaguarlandroverclassic.com/parts/index/part/id/23.52938.52988.27378/brand/land-rover/_gl/1%2A62fzwd%2A_up%2AMQ..%2A_ga%2AMTU2NzU3OTgwMC4xNz QzOTgwMzYz%2A_ga_6WEX61NFXZ%2AMTc0Mzk4MDM2Mi4xLjAu MTc0Mzk4MDM2Mi4wLjAuNzQ4ODMzNTA2/)

[haydent]

Hey im back interested in this again, have mine all fixed up and running smoother than ever, turns out i had a couple of leaking injector return orings hiding behind the covers.

I also not ready to rush into buying a 50-60k LC200 and then have to spend another 10k on the gvm & fit out and switch over.

So im back to trying to lighten the load in our caravan and going to test weight distribution hitch, and call an engineer to see if any options for an upgrade.

I even had the idea to ask about air bag deletes, as there are coil kits available, i know its drastic and blasphemy to mention it, but if it meant you could turn the l320 into a much better towing machine with HD springs/shocks it might be worth it and pretty cheap.

Mine is 2010 tdv8 with non-brembo brakes.

[Graeme]

With the van attached, do you have enough spare front axle capacity for a WDH to be of any use?

[haydent]

last time i checked with a weight bridge, i had enough appx 100-200kg spare

[haydent]

found this thread about armoured too DISCO3.CO.UK - View topic - armoured version - suspension details??
(https://disco3.co.uk/forum/topic102988.html)
interesting details about differing parts & reduced travel shocks, and that limit being programmed into the ecu, i guess to not raise anymore, or too high....