Uprights - What would you do if you were making new ones?

[Richard48Y]

Anyone have a scrap upright I may section for educational purposes?
Been playing around a little with lost foam casting and how to make repeatable patterns.

[Richard48Y]

I know this is an old thread I have resurrected.
I've checked again and Lotus Supplies now show every version of the upright/bearing carrier as out of stock.
I have no idea if they will ever make more.
Apparently they are a wear item that is fairly frequently in need of replacement.
I've abandoned the idea of castings, partly as I now have a CNC to make them from billet.
After much thought I think most of the weight saving reliefs will be on the bottom.
If anyone has a good drawing of the originals to share that might save a lot of time.

It also seems I will be making matched stronger stub axles.
I do have nearly complete drawings for the stub axles.

This is not going to be quick*, but unless someone else does it first this is my plan.
I suppose I will have to put the "Racing purposes only" caveat on everything. 
I will also be using everything I do on my own "Race" car.

*But not six years!

[Richard48Y]

Two more old threads found.

https://www.lotuseuropa.org/LotusForum/index.php?topic=3085.30

https://www.lotuseuropa.org/LotusForum/index.php?topic=1283.msg11145#msg11145

I looked up Kelvedon too, it seems they do offer a setup, but over £1,470 per side plus shipping!
My hope is to be about the same, maybe a little less, in U.S. dollars.

I got a little bit of LOL! from the Japanese billet parts price.

I guess I am cheating, essentially no overhead and I work too cheap.

Back to my CAD practice now.

[EuropaTC]

Hi,
I'm not going to discourage anyone from opening up a new parts supply for our cars but if none of the mainstream suppliers are planning another production run then maybe the market isn't as big as we imagine ? 

If you think of the UK, there's Lotus Supplies, SJS, Paul Matty, Kelvedon as big players plus the guys on your side of the pond who could band together for a production run and share costs. The moulding will presumably be in place now so it's a casting program and you'd leave machining costs until someone actually wants to buy one, just keep the rough castings in stock.  If they aren't interested then maybe it's because they expect to have them on the shelf for years and prefer faster moving stock ?

I'm not convinced they are a service/wear item,  mine are the originals from '72. The bearing surfaces are good and the only issues have been one radius arm bolt needing to be helicoiled. That turned out so well that I did the rest and hopefully that's sorted for my ownership. I'd guess that my car isn't unique and the only time folks replace them is if there's been lack of maintenance, the car driven with worn bushes, bearings breaking up, loose lower link bolts, etc.

It's going to be tough to come up with something lighter or better designed for the OEM suspension, but you could consider a carrier with facilities for a twin link suspension for anyone fitting different transmissions. LIkewise somewhere to bolt on a rear caliper, maybe with an adapter to allow different caliper makes/bolt spacings/disc diameters ? 

I think you'd have a larger market with something like that rather than a straight replica of the OEM carrier. It should be usable with the OEM suspension/brakes but also for those wanting discs, etc.

Stronger stub axles and internal spacers are an entirely different case, I reckon you'd have no problem with that market. I think you'd need to sell as off road/race components, I don't know how product liability would work if you sold as road use parts.

Brian

[BDA]

I'm not familiar with the relative costs of cast vs fabricated parts but If you are to redesign the rear uprights, I would definitely include a way to incorporate EuropaTC's suggestions. It may end up that a fabricated piece might be a lot stronger and easier to include twin link suspension and brake caliper mounts.

On the other hand, I agree with EuropaTC that I don't consider them to be a wear item either but it has attracted some attention (e.g stainless steel "lined", I guess you'd say, bearing seats). If the bearing seats do get damaged, I would think it would be a pretty simple task to press in some heat treated aluminum or even steel seats to repair them.

[Richard48Y]

Uprights.

I am certain that what I am drawing up will be much stronger then the original.
I intend to remove metal from the bottom side for weight reduction.
There may be shallow relief on the top and sides as well.
I may forgo that in the interest of shorter machine cycle times.

I do intend to incorporate disc brake caliper mounts.
For simplicity some version of Wilwood is most likely.
If there is space I will try to provide mounts for a separate Wilwood parking brake.

I need to see examples of what would be needed for twin-link suspension provisions.

These are not large parts, space is limited to add too many features.
I think that if I design them to take my own stub shafts it should be possible to make them "Universal" to S1-TC?

[Richard48Y]

One more thought.
If I may cram enough features into these it may be possible that they will be of interest to home builders of other vehicles for a wider market.
I do not expect to sell hundreds, a couple of dozen sets would suffice.
Once I have the program and tooling making more is not too difficult.

[EuropaTC]

I do intend to incorporate disc brake caliper mounts.
For simplicity some version of Wilwood is most likely.
If there is space I will try to provide mounts for a separate Wilwood parking brake.

I know the Willwood calipers are a popular choice but if it means a separate parking brake then personally I wouldn't go that way. It's more complex and for UK road use you've got to have a separate emergency braking system.  There are loads of mainstream rear calipers that incorporate separate park/emergency brakes and that's what I'd look at. I've used Renault and BMW Mini rear calipers, I've heard of Mazda being used as well and their big advantages are cost, availability and spare parts.

With that in mind I would look at just having a mount system on the carrier which you bolt into an adaptor for whatever caliper and disc you prefer.  I think it was Fred Puhn's book that showed a caliper adaptor, if not there then I've seen the idea elsewhere.  That way you can have a wide range of caliper bolt spacings and solid or vented discs with a range of offsets

I need to see examples of what would be needed for twin-link suspension provisions.

Can't help with that, the variations of twin link that I've seen look to be custom designs and I'd be surprised if there's a "one size fits all". I think you'd have to sell a package of the upper link & inboard mount to go with the carrier unless you manufacture to fit one of the existing twin link offerings.

I think that if I design them to take my own stub shafts it should be possible to make them "Universal" to S1-TC?

The radius arms are different IIRC, I seem to think that the S1/2/TC have one set of radius arm bolt patterns and the TCS is different because of the rear drum plate ? Making the stub axles the same would be a good move for S1-TC because you'd get the more commonly available bearings, in fact you could use the same bearing for inner & outer, another good move IMO.

Brian

[gideon]

I agree with Brian that a mainstream rear caliper makes more sense than two Wilwood calipers.  It'll be cheaper and simpler.  There was a discussion on the email group which indicated that the BMW Mini R50/R53 rear caliper is a good candidate because it has the right size piston and is a lightweight alloy casting.  Most of the other options are cast iron.

Here's the relevant message

https://groups.io/g/LotusEuropa/message/174354

[EuropaTC]

 

that's the one I've currently fitted with 260mm discs although unlike the post I went for the 36mm piston. I'd say the caliper body is the same and they are alloy so I suppose they are lighter than the steel versions although it's not a dramatic saving. They look nice though and were ridiculously cheap !

[Richard48Y]

For my own car I am working with the MGF rotors as they are so simple to use and not expensive.
I will run Cosmic wheels too.
I should get some blue foam and just carve out a rough sample.
I had some VW GTI alloy calipers but they did not work out for Cosmic wheels.
I really prefer dual or quad piston over the slide type calipers.
Still a work in process so I have time to configure mounting lugs.
I will look into the BMW Mini R50/R53 rear calipers.

[EuropaTC]

I had some VW GTI alloy calipers but they did not work out for Cosmic wheels.
I really prefer dual or quad piston over the slide type calipers.

I didn't look at the VW calipers but it wouldn't surprise me if they are similar to the BMW Mini ones.

I think most folks prefer dual opposing pistons instead of single piston/sliders but given how many cars these days have this arrangement you'd be opening up your potential market by making provision for a lower cost caliper with different mounting points.  And there's nothing to stop anyone going up in spec if you offered different adaptors. (that'd be an easy make on your machine)

Was clearance the problem with the Cosmics ?  I know when I first looked at rear discs the Cosmic wheels I had were making life difficult and was one of the reasons I moved to 15" wheels  - I was also using MGF 240mm rear discs the first time around.

Brian