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Re-drill hubs and rotors/drums?

12K views 35 replies 12 participants last post by  o2bad455 
#1 ·
I would like to put larger wheels and tires on my car and want the same size all around.
I have considered the wheel adapters (3 to 5 lug), but have heard that they are not really strong enough for everyday use. Has anyone considered simply re-drilling the hubs and rotors/drums for a different pattern? Are the hubs of a design that would even allow this?
I will be buying new tires soon and would like to do everything at once if possible.
 
#2 ·
This is the back side of the hub. There isn't enough meat to drill another pattern. Only in the raised cast areas where the stock holes are is it thick enough. On top of that if you superimpose another pattern you will find one or more of the existing holes will interfere with the pattern no matter how you turn it. There are whole threads on this, been beat to death. There are plenty of aftermarket wheels in almost any size you could need. You can get adapters for 5 x 112 Mercedes to 3 x 112 smart.
 

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#5 ·
I hate to dig up an old thread, but has there been any more information about redriling the hubs and rotors to go to 5x112? That seems like a good way to get to 5-lug without causing wheel offset issues.

I'm considering doing this to mine and just wanted to see if anyone else had tried it.

I'm not concerned about adding material on the back side of the hub for thread depth. That's not an issue.
 
#4 ·
I run 7.5x17 Brabus wheels with 215/35-17 Hankook tires all around on my '09 Brabus coupe. They are plenty big and I have no issues with rubbing or electronic nannies. I was told by Discount Tire if you come in with spacers, they will do no work on your car until the spacers are removed. Not even repair a flat. Just something to keep in mind.
 
#7 ·
Thanks for the reply, but I would like to hear some actual reasons that this isn't possible. From everything I see, it does not look like a lot of trouble, but I could be missing something, which is why I would like to hear from someone who has done or attempted to do this.
 
#8 ·
I haven't heard of anyone actually doing it. I think you would weaken the hub too much. It's surprisingly thin material.

If you look in the photo above, you will see that where the current holes are, there is extra material thickness. This provides strength as well as providing sufficient number of threads to hold the bolts - neither of which you would have if you drilled more holes in it. What would happen is the hub would deform and then effectually break under load and there would be a high risk of the wheel bolts pulling out.

Having worked in automotive manufacturing for 10 years and having worked in manufacturing R&D consulting for 8 years, I would say this is a bad idea! Under no circumstances should you try this!

The hub is made from a forging (not a casting), which is even stronger than billet. So, even if you were to have a custom made hub with 5 holes, it would have to be substantially beefier than the original design in order to meet the same strength characteristics.
 
#9 ·
I don't disagree anything you have said, but I still find it hard to believe that someone hasn't created a good, strong 5-lug hub/rotor/drum system for these cars. Broaching splines on a well built, quality hub is not rocket science.

I missed the initial Smart car craze and have only gotten into it now because of my need to transport one on the back of my "RV Hauler". However, I'm blown away that the 3-lug issue still exists after all of the years these things have been on the road.
 
#10 ·
A custom built one could be done, but not as a forging because it wouldn't be cost effective due to the small volumes - forging requires a skilled engineer to design the die to the proper specs, then you have to have the die made and find someone to do the forging. If you could find a 5 bolt hub with comparable dimensions, it might be as simple as a little machining to make it fit - that's if you can find one.

The adapters are just a more viable solution - very cheap and easy to make with very little upfront cost - almost anyone with limited CAD skills could do it - then you just send it to a machine shop to get made or make it in your garage if you have a lathe and a mill. I'm considering making my own because the available ones I've seen are just way overpriced.

Once you have a 5 bolt pattern, you have a wide range of options for offsets.
 
#12 ·
I don't see the back spacing as an issue. I shopped around for rims and saw ample offset choices.

Price is the only thing I don't like about the current ones on the market. They seem to be around the $400 mark, which to me seems absurd. The material for each set is probably about $10 + bolts and probably about 5 minutes machining time/pc + set up. I could probably sell them for $100 for a set of 4 and still make 30 points.
 
#13 ·
You lost me there. Personally, I don't want my name attached to any products that have to do with road driving. It's one thing to make something for myself, but it's not worth the liability to produce them for public sale.

I spend a lot of time in Solidworks. Drawing them is not an issue, but drawing a one-off set for personal use doesn't make sense if I value my time any. Cheaper to just buy a set.
 
#14 ·
When you refer to backspacing, are you referencing the affect on offset? This is the distance that the wheel mounting face would be moved out, which would be the thickness of the adapter - approx 20mm. Just want to make sure we're talking about the same thing here.

On stock offset rims, 20mm wouldn't be an issue for most people because the new fitment is typically preferred: the wheels stick out an additional 20mm which actually looks a little better.

When going to wider rims, then you would have to do a little math to figure out what would look best.

The other benefits of adapters are that you have one solution for both front and back, and it's a quick switch back to stock, which is good if you have stock rims for your winter tires.
 
#17 ·
Yes, we are talking about the same thing.

I agree that 20mm won't end the world, but if I could avoid that along with wheel spacer issues, that would be a win win for me.

I'm also still a little perplexed that you favor the strength of two very small (less than 8mm - bolt head is 12mm - McMaster-Carr) slices of aluminum and one bolt, holding on your wheels, using the spacers, over a larger chunk of billet steel, when using a properly machined billet steel 5-lug hub. The amount of aluminum at the weakest point on the adapters is pretty thin (under the adapter bolts that secure it to the hub).
 
#19 ·
The adapters are made out of steel, whereas spacers are often made out of aluminum. Adapters typically have two bolts holding the adapter to the hub and one bolt through from the rim to the hub; therefore held by 3 bolts. The remaining 4 bolts in the rim anchor into the adapter. I don't see any reduction in strength here.

Threads in the steel adapters should be roll-formed to maximize strength.

Aluminum is not a suitable as a material for an adapter, not enough yield strength.
 
#20 ·
So you're saying that less than 10mm of steel is not a reduction in strength as compared to the thickness of the hub for those same two bolts? Honestly, I don't care either way. I'm trying to avoid the adapters if possible. I will probably buy three lug wheels before going with the adapters. I'm not racing the car or driving it hard anyway.
 
#22 ·
In other words, the threads are likely to shear in the hub before the bolt pulls through the steel of the adapter.

thread strength is 170ksi - but the shear strength is only as strong as the weaker material - I don't what the yield strength of the forging is, but not likely as strong as the bolt

1080 steel is 110ksi - which is less, but it has greater thickness to shear through.
 
#26 ·
I am new to this thread, I just recently bought a 2015 Smart and am looking for new wheels,
Do you have any pictures of how these look on your car?

I may be the strange guy since after reading through this thread and people are worried about 20mm wider.... LOL

I currently have 15x4.5 ET24 fronts and 15x5.5 ET22 rears and OMG the car is overhanging the tires a full 50mm (2")
I have been searching for wheels that can be used with small flares and sit flush with the flare. I think the Genius 17x7.5 still needs a 25mm spacer.
To achieve rims with the same backspacing as stock and sit flush with the body would require an 8" rim with ET32 on top of the 19mm 3 to 5 lug Adapters plus an inch!
All 17x7 or 17x8 5x112 rims I find have ET32 or more which would require a 45mm adapter!
What a Smart Car needs are 17x7 ET0 front 3x112 and 17x8 ET-10 Rear 3x112.
 

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#29 ·
@Smart car. If you would like to take a look at my gallery, you will see what I have done to my '09 Brabus coupe. I have 7.5x17 Brabus wheels on all four corners with Hankook 215/35-17 tires all around. I have Eibach wheel spacers on both ends, with 20mm on front and 30mm on rear. The tires are flush with the fender edges and the suspension is all stock Brabus. I like the car you referred to, but that is way out of my pay grade.
 
#30 ·
Awesome loo!
Now you see what I was talking about. In the earlier threads guys were talking about 15x6 rims sitting out too far????

I se what you have 17x7.5 with 30mm spacers, Just what I was talking about, actually I fell in love with this HotWheels looking Smart at the 2016 LA Auto Show.
It has a Wide Body and 17x9.5 fronts and 17x12 rears! I want to re create this look on my 2015
 

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#31 ·
The wide body looks really good and I would like to do something like that to my car, but being on Social Security and 72 y/o kinda prevents that in this lifetime. I don't care for some of the mods on that car, especially the two color wheels, but all in all it really is well done. Please keep us all posted on what you decide to do on your car. We all love pics of mods around here. Good luck with the project.
 
#33 ·
I have just completed my STAGE ONE Mods to my 2015 Smart ED.
It is hitting high likes on Instagram from @ExtremeWheels_

Check out my garage and gallery pics, Be honest and LAUGH about it. I intended to take the silliest car in the world (Smart Fortwo) and turn it into a rolling hit around town.
This is my daily driver and after only 1 week of driving it I broke several peoples necks as they gawked at it!

I have the Mod listed in my gallery but feel free to ask.
 

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#35 ·
Strelnik, I do not know what size tires you have on now.
My Smart came with 15 x 4.5 rims and 155/60-15 front, 15 x 5 rims and 165/55-15 rear.
I used an online calculator like this one:
It helps with tires choice by keeping the diameter the same you don't effect the speedometer or mileage.
 
#36 ·
RE: 3x112 to 4x100 hub conversion (NOT adapters)

Need to convert our 2006 450 from 3-lug to 4-lug tomorrow (Friday) afternoon so we can ice race on Saturday. How easy/difficult to swap to the 4-lug hubs from a newer (e.g., 453) model? I believe there's at least one at a boneyard within striking distance, but won;t have much time so a complete parts list would be ideal. This is mainly just for 13/14" wheel fitment, but don't have adapters and really don't want them (as certain ice conditions have vibrated even properly torqued lugs loose during an event, and adapters can make that worse). Thanks in advance!
 
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