Critique my off road Rolls Royce project idea

[geekman]

As 2023 draws to a close, I’m looking for new ways to waste invest my money in 2024 and well, this seems like it could be a good one.

I’ve bought and sold several Rolls Royce Silver Shadows over the last year, and I currently own one which I occasionally use on weekends. As a result, Instagram often suggests photos of similar cars to me, which led me to see this, which is owned by Reggaeton artist Bad Bunny:

I did a bit of research on the build, and unfortunately it looks like it’s mostly for show. As far as I can make out, all they’ve done is lifted the car and done a few cosmetic modifications – it isn’t 4x4 and still retains the old, low powered Rolls motor and complex, unreliable braking and suspension system. So, I started wondering if there was a way to make it better.

A Silver Shadow has a wheelbase of 119.5 inches. A 2005 Chevrolet Silverado has a wheelbase of 119 inches. You can probably see where I’m going with this….

I could get a mechanically totalled Shadow like this https://www.facebook.com/marketplace/item/1433395390544984/ for around $2500-$3000 and a mechanically sound but body damaged Silverado for less than $5000 at a salvage auction. I’d like to keep the total cost of the project to around $30,000

The plan would be to only use the body and interior of the Rolls, and keep as much of the Silverado as possible. Unlike Bad Bunny’s car, I have no intention of chopping the roof off as it gets to 40c+ here in summer and I’d probably end up with skin cancer within a year.

A few things that might make this project feasible are:

I’m in Mexico, so the labour rate is far lower than it would be in the UK/US.
The car wouldn’t need to pass any kind of safety or registration inspection, although I obviously don’t want it breaking apart around me.
I don’t intend on using it on highways or long trips, this is more a fun off road type project.
It would be a great promotional vehicle for my business.

I’ve found a shop who are willing to do it, and they’ve previously done a 4x4 Smart car and a 1957 Bel Air on a Crown Victoria chassis / drivetrain. However, they’ve obviously never done anything like this before, so I would like to hear people’s opinions. First of all, do we think it’s possible? And if it is, what kinds of issues are we likely to encounter along the way?

I know there’s a lot of people on here far smarter and more experienced than I am, so I’d appreciate your input. Thanks for reading if you managed to get this far.

 

[geekman]

Wheelbase lining up is a good start, other simple things to check will be how the track and longitudinal engine positions compare.

The other big thing to consider will be what are you doing floorpan wise? Two real options, keep the Silverado floorpan complete and graft the Rolls body onto it This simplifies the mechanicals but may complicate retaining the interior (carpets and seat mounts will all need to be custom). Second option is to keep the Rolls floorpan and try to attach all of the Silverado running gear to it. I’m not really familiar with the construction of either vehicle (are both unibody or is one/both a more traditional separate body/chassis?) so would need some research, unibody will be tricky and need lots of custom mounts fabricating, separate chassis would make it easier.

That's really helpful, thanks. I hadn't really considered the floorpan, but it's a very good point. The Silverado is separate body / chassis and the Rolls is unibody, so I suspect keeping the Silverado floorpan would be easier. Custom carpet and seat mounts wouldn't be an issue, severely modifying the dash etc probably would be as it would lose the Rolls "look" which I'd like to retain as much as possible.

 

[geekman]

With that combination I’d probably start investigating the potential for sitting the Rolls body complete on top of the Silverado chassis. The fact that you’re doing a 4x4 (assuming you want a lifted look) will mean you can sit it on top of the chassis rails rather than having to try and hide them inside the body. Should be relatively simple work to attach the necessary mounting points onto the underside of the body.

Yes, that's exactly what I want to do - happy to sit it on the chassis rails and it doesn't have to look particularly polished / OEM, something a bit rat rod-ish would be fine for my purposes.

It would be good to avoid the wheel arches shown in the pictured example. Something more coach built worthy of a Rolls Royce.

I'm not sure what I could do about that though, it will need some sort of wheel arch, and anything welded would probably mean painting the whole car, or at least both sides. That would add quite a lot of time and expense to the build.

This is the route I would go too - keep the RR monocoque and either mount the Silverado frame to it directly, or via a kind of giant subframe. That way you are effectively retaining the Silverado as the running gear platform, and the RR is literally a box for people that's bolted onto it.

Then your interface considerations are the wiring loom, the steering arrangement, heating/ventilation, the pedals, handbrake, and your transmission controls.

Yes, I think that's the way to go. In terms of interface, I'd keep the wiring loom from the Silverado and maybe even the steering column which would solve the transmission controls issue, then just bolt a Nardi wheel to it so it doesn't look too out of place. Heating/ventilation I'm thinking of mounting the original Silverado controls under the dash and rigging it to blow through the original Rolls dash vents, handbrake I'm not worried about as I've spent so long driving cars that don't have working handbrakes that I never use it.

 

[geekman]

Do you really need the Silverado? Could you convert the RR drivetrain to 4WD?

But this is totally mad so, however you do it, you must do it!

I potentially could but I'd be stuck with an old, low power engine and an unreliable and fragile braking / suspension system. The idea is to be able to actually use it on trails which I wouldn't be able to do with the RR drivetrain.

 

[geekman]

Remember James May's RRSS from the India special?

They pretty much just fitted bigger tyres to that didn't they?

I'm sorry, why are you still here? Why is it not being built right this second? Why is there not a build thread? Get it done!

I'm in the US until mid January but once I'm back I'll get it started, assuming nobody gives me a good reason why it wouldn't work. Progress will be slow though - the last big job I had done was rust removal and painting of a 79 SS2 and that took almost 6 months, so I dread to think how long this will take. It did turn out nicely though.

Company I used to work for did something very similar for a member of a royal family from the middle east.

1970s brown Rolls with gold fittings instead of chrome. Ended up with quite a bit of ex military hmmvee underneath. Was very silly. 18" of ground clearance, could inflate and deflate the tyres from inside the vehicle and kept most of the Rolls interior.

Can't remember what we did with the engine though. But it did end up with 4wd. This was 25ish years ago now though.

That's very encouraging to hear, if you ever find any photos or more information let me know.

 

[geekman]

I would question if its worth the time and hassle as if you have the imagination and skills to pull this off there is probably a better use of your time.

But if its something you think you'd enjoy then it certainly looks interesting!

I guess I do have the imagination, I don't have the skills but I know people who do. I'm open to ideas for other stuff I could do, but bear in mind there are no decent country roads anywhere near where I live so building anything sporty is a waste of time, and I can't go throwing huge amounts of money at it.

 

[geekman]

@Diddums Fair to say that post blew up quite a bit I got some really good advice from that group - there's a few idiots but plenty of people who really know their stuff too and a couple have agreed to help me over the phone for when we hit the inevitable issues.

I posted it on a Rolls Royce group, another forum, and a modded cars group and with every post I've had people making great suggestions I hadn't thought of, so I've been building a plan and slowly working my way through the list of possible issues and solutions. There's no procrastinating on my end, but the guys who are planning on helping me do it won't have space for another couple of months so I'm using the time to try to plan it as best I can. I also want to take the time to source the right donor truck - people were recommending a pre 94 RAM because the body mounts can be made really easily but I'd really like something newer. I'd be gutted if I went for a particular option and then found out a month later there was a better platform that would have saved weeks of labour.