Lotus Elan

Minilite style wheels - offset ?

PostPost by: Frogelan » Mon Mar 26, 2018 9:46 am

I am still slowly assembling all the parts for my project, but I'm nearly there! I plan to build up a 1965 S2 26R spec car, with FIA compatible minilights (5.5" x 13") to fit the following combination:

- 2.25" rear springs / perches
- Adjustable rear wishbones
- Standard rear brakes and Girling AR (aluminium) front brakes
- Bolt on (standard hubs) on Issue 16 strut carriers

Could any one clarify:

- the correct offset for what seems to me to be a fairly "standard" specification (this seems to be absent from the R&R book)

- whether the wheels sold by https://retroracecar.com/ (magnesium (4kg) or aluminium (just under 5kg)) have a good "track record" ?

Many thanks
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PostPost by: Craven » Mon Mar 26, 2018 10:54 am

Checked many years ago, IIRC 22mm outset. But if no one else can help I have a steel wheel I can check for you.
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PostPost by: denicholls2 » Mon Mar 26, 2018 10:32 pm

Magnesium wheels are wonderfully light, but they have a nasty habit of corroding invisibly that makes them potentially lethal with age. Unless you absolutely have to save that kilogram, I'd look to your waistline first to find the weight savings and go with aluminum.

I love my Panasports and they look great on the Europa. They look very nice on Elans as well. When I bought mine (quite a few years back now) RD had the right ones for Elans as well.
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PostPost by: nmauduit » Tue Mar 27, 2018 8:30 am

denicholls2 wrote:Magnesium wheels are wonderfully light, but they have a nasty habit of corroding invisibly that makes them potentially lethal with age. Unless you absolutely have to save that kilogram, I'd look to your waistline first to find the weight savings and go with aluminum.

I love my Panasports and they look great on the Europa. They look very nice on Elans as well. When I bought mine (quite a few years back now) RD had the right ones for Elans as well.


If unsprung weight has more or less impact on performance depending on one's driving style, when one is after performance one probably adds lightness everywhere he can, so I'm assuming there is not much to be saved around the waistline already... In addition, wheels also have a rotational momentum which adds to general inertia, so the added lightness there works even on smooth straight lines.

I have a spread sheet where I calculate the cost of saved kilogram to help me select where I should add lightness out of a tight budget: I use a multiplicative factor for non suspended weight, and an other for parts in motion. There is no way I could add as much lightness to my waistline as a set of magnesium wheels would to the compounded weight of my type 26 project...
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PostPost by: Frogelan » Tue Mar 27, 2018 12:12 pm

Amusing comments from "denicholls2" and here are some replies. I'm back out there running and did 10 km this morning.

To my knowledge, Panasports do not get across the Atlantic...

I understand what you mean by corrosion of magnesium, I'm personally more concerned about cracking, but I have done some reading up on crack detection. The same firm can deliver Aluminium wheels...

But my main question is for the offset...the available options will become clear once this is understood!
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PostPost by: el-saturn » Tue Mar 27, 2018 1:14 pm

.........how much does a magnesium rim (4 1/2 X 13) weigh?? my brand rims (4,5") weigh 4.4kg!! sandy PS-------almost 5 kgs less than the steel ones!
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PostPost by: Frogelan » Tue Mar 27, 2018 1:32 pm

The magnesium wheels are +/- 4.1 kg and the aluminium come in at ~5 kg.

Magnesium is not a good idea for thumping curbs and the air tightness is worrying. Whilst I agree with Nicolas above about upsprung weight, safety is an important subject and probably takes priority.
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PostPost by: Craven » Tue Mar 27, 2018 2:00 pm

Frogelan
From your post it seems you think wheel offset is a variable!!
Read up on the theory, offset is a design constant and is fixed by the bearings position within the hub.
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PostPost by: Frogelan » Tue Mar 27, 2018 2:11 pm

Hi Craven

I know that the offset is only variable...if the wheel is bent :D

You mentioned 22 "IIRC" and having searched I saw one online trace at 25...but I would prefer to be 100% precise, especially after reading the horror stories of K/O Minilites where no one ever seems to manage to get them to fit !

:D
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PostPost by: nmauduit » Tue Mar 27, 2018 7:29 pm

Frogelan wrote:I am still slowly assembling all the parts for my project, but I'm nearly there! I plan to build up a 1965 S2 26R spec car, with FIA compatible minilights (5.5" x 13") to fit the following combination:

- Bolt on (standard hubs) on Issue 16 strut carriers

- whether the wheels sold by https://retroracecar.com/ (magnesium (4kg) or aluminium (just under 5kg)) have a good "track record" ?


I was looking through their site and was wondering the type of wheels you were looking at... are you planning to use a 3.75" PCD (95.25mm) as you mention standard hub ? could only find 6" in the standard elan PCD... though I'm sure you can get whatever you need via custom order.

as it happens, I was also looking into hubs and wheels for my similar project (also not for 2018)... for what it's worth I checked the backspace on my 6" rims, which is 115mm.

I was also checking the wheel nuts since I'm missing one, and they've actually a 5/8' shank while the rims expect 9/16"... though they are 3/8 UNF, as the studs on the hubs. So I'm rather having 15 extra larger ones (look like I'll need something like Grayston SN28 http://www.graystonengineering.com/wheelnutmenu.htm, need to check shank length)

p1040985.jpg and
3/8" UNF nuts but 5/8" shank
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PostPost by: Frogelan » Tue Mar 27, 2018 8:11 pm

I spoke to them about 3 months ago, and I'll need to sell of some family silver to afford them !

Yes, they are happy to do a custom order for 13" x 5.5" x 3.75" PCD. I'm just stuck on the offset subject and I was hoping there is a documented figure somewhere !

As mentioned in another post, I think it makes sense to have some grouped purchases.

I have an idea for wheel nuts but we should discuss the techie side of this over a beer !
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