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Author: Subject: Choices - Driveshaft, hubs and PCDs for a middy
GRRR

posted on 26/9/24 at 08:28 PM Reply With Quote
Choices - Driveshaft, hubs and PCDs for a middy

Hi all,

Many moons ago I started designing my scratch built mid engined sport car. 20 years later Im starting to make some progress on the details, such is life. Hoping to build up some momentum now and I'll post progress here as this site has been a regular go to for most of that time. LCB also seems to have an unusually high number of clever and resourceful people on it, and I hope you can impart some of that with this issue.

Engine and transmission is Alfa V6.

My brake size calculations need roughly 280mm vented front, 280 solid rear.

I'm resigned to custom alloy wheels (like Image Wheels) as I want 16" in 7" width front, 8" rear and there's not really off the shelf options I like. Therefore PCD choice shouldn't be a major issue but should match front to rear.

Minimising custom machining is preferable. I will design custom uprights to get the geometry I want so bolt on hubs is something that makes life easier. Hubs with matching brake discs in the right size is also preferable.

Option 1, use alfa driveshafts, alfa hubs, which means having to work out the dimensions of the rear Alfa 156/166 knuckle/spindle to get new spindles machined to mount on a custom front hub, using the rear alfa bearing on the front, and front alfa bearing on the driven rear.

Option 2, BMW Mini bolt on rear hub on the front, front hub on the rear and have custom driveshafts with Alfa one end, Mini on the other. Correct size discs are available. A bit of googling suggests that after market Mini CVs are terrible quality though, and genuine are expensive.

Option 3, BMW mini bolt on rear hub on the front, Fiesta/Puma front hub on the rear, custom driveshaft, ST170 rear disc on the rear, hubcentric spacer to convert Ford 4x108 to 4x100 to match the mini front. Cheap parts, but spacers are a bit of a bodge if everything is being designed with no constraints (within reason)

Option 4 Mini rear on the front, Alfa front bolt on hub on the rear, with a custom hub machined to suit the alfa driveshaft but with a 4x100 PCD and flange to suit a mini 280mm disc.

There's probably other options too but does anything jump out as being far more sensible than the others?

Thanks and sorry for the essay!

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gremlin1234

posted on 27/9/24 at 07:54 AM Reply With Quote
I am surprised MX5 is not on the list
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GRRR

posted on 27/9/24 at 09:04 AM Reply With Quote
I think i had discounted MX5 as most of the matching centre-bore rear discs are pretty small, but have just noticed there's 276mm discs available which is probably close enough. On the MX5 fronts I'd need to machine a spindle for my uprights, and again off the shelf discs are available little smaller than i wanted at 276 being the largest. The NC mx5 has 280mm rear discs but the rear hub and bearing don't seem to be a convenient bolt on type.

I'll look and see if there's other mazda model discs in a good size with matching pcd and centre bore.

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nick205

posted on 27/9/24 at 09:26 AM Reply With Quote
Nothing in the Audi stable worth a look?

No doubt parts might be more costly, but they might have the sizes you're are without having to machine them.

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JimSpencer

posted on 27/9/24 at 11:20 AM Reply With Quote
Hi

Option 2, all day..

Not heard of the BMW Mini CV joint quality issue (original mini yes..) but a quick Google suggest that OE ones aren't 'that' expensive to be worth spending a shed load of cash on custom components to avoid, I'd suggest a quick chat with somebody like Lohen would confirm one way or another?

Hence, on option 2, the driveshafts being the only custom component make that the no-brainer for me as they're easily available from several sources for not a lot of £'s.

HTH

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GRRR

posted on 27/9/24 at 12:09 PM Reply With Quote
Thanks for the replies, Audi is a great suggestion as there's bolt on hubs front and rear and plenty of disc sizes, and parts prices are low.

Good to hear a vote for option 2 as well, I appreciate the input.

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anonymouse

posted on 2/10/24 at 10:58 AM Reply With Quote
Have you thought about using the Ford Mondeo V6 / Focus Turbo alloy hub with bolt on bearing?
The CVs that fit to those will be much much stronger than anything on the little BMW mini.

That should allow standard similar Ford stuff front and rear.

Have you thought about the twin wishbone setup on the front of the Volvo XC60 / 90 ?
It also uses a bolt on bearing and alloy hub with Ford PCD IIRC.

;-)

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pigeondave

posted on 2/10/24 at 12:31 PM Reply With Quote
Don't Saab do a bolt on 4 stud hub with a 108mm pcd?
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GRRR

posted on 5/10/24 at 06:22 PM Reply With Quote
quote:
Originally posted by pigeondave
Don't Saab do a bolt on 4 stud hub with a 108mm pcd?


They do for the front of the saab 9000 but not the rear (which id be using on the front of my car)

However looking at Mondeo parts, the rear bearing and hub for up-to yr 2000 estates is bolt on 4x100. So looks like reasonable to have options for 4x108 all round (Ford/Saab) or 4x100 all round (Mini).
I did think about the strength of Mini driveshafts, joints etc but my car should be under 800kg inc driver and with 190bhp, and the Mini parts were the same on the heavier Cooper S and JCW with 200-odd bhp so should be fine on a lighter car with a much lower 'duty cycle' i.e. low mileage.

I looked at the Volvo stuff but it's quite specific to the volvo and doesn't look too relevant to my setup. Thanks for the idea though.

[Edited on 5/10/24 by GRRR]

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