DIY top mounts

No problem at all. The value is in the discussion!

Anyone else got an updated pic? I thought they looked pretty similar, although not identical. the shape of the plates is different, although the bolt holes look the same layout.

I think your second suggestion is probably right.

 

I'm taking one of my front struts off this afternoon so I'll take a photo of the underside of the Ground Control..

 

Great - any pics would be a big help. Thanks!

 

Here's a few I took earlier

 

Thanks for sharing. That's very different to the other pic. You can see why they cost more, as there's a lot more work gone into them.

Are they from a Mk1 golf?

 

The are great pics, lots of work goes into each one, however we could simplifi the idea and come up with a design that will work with both mk1 and 2 and I guess3 as well. Just need the mk1 measurements.

 

Took some pics the other night... Mk1 and Mk2 Scirocco Turrets. Similar but different. I think the Mk1 Rocco are the same as Mk1 Golf.

Mk1 Rocco


Mk 2 Rocco - hole is the same but the turret top is smaller, and a different shape. The Compbrake top mounts on my Mk2 track car are cut down to fit this shape.


The lip on the turret is about 5-6mm high, in both cases, but I assume this needs to go anyway.

 

I think first, we need to agree on a target price, that folks are ok with. No point designing uber mounts, and them costing 350.

So, what do people want to pay, and lets work it back from there.

Theres a few steps to the part cost - excluding design, as we are taking that as our free time.

Material, rough cost Idea, 12mm aluminium, 350mm, x 1200mm costs around 90euro, in 5 or 6 series, 7 series will be a bit dearer, and the strongest for this application since there is no heat involved.
For a piece 32mm thick, 550mm, x 400mm, is around 150euro.

Jigs and fixtures for machining - these are one off, but a factor none the less, say 80euro total for some 20mm steel jig plate.

Fixtures and fittings - bolts/circlips and washers for each kit - 5euro

Bearing - can range from 10 to 50euro, 10 being the worst, 50 being the best/certed. Something midway, that guys are prepared to changed out I guess?

Machine time, Ill do first one/s r+d batch free for tests if nobody else wants to/can, but when it comes to batch, someone will want money, at I dont know, 40 pounds per hour? These vendors will need jigs too, and Im not sure if thats factored in, or has to be paid for/design time covered too/separate on a job like this.

Anodizing/surface treatment, at a rough guess, factor in say 25-30 per pair incl shipping to and from plater for whatever coating.

Ill have a think about the design in the mean time, but first, a final shipped price HAS to be agreed on that everyone is happy with.

Brian,

Edit, bolt or weld is a major factor too. So answers on a postcard there as well!

 

Great to have some real numbers to work with!

A piece of ally that size would do about 3 or 4 pairs of mounts, assuming 2 plates per mount, doing sums in my head, (if they're no more than 170mm wide), and probably getting them wrong?

Smudge was planning to draw up a design, when he's back from a break. Maybe you two can get your big brains together and figure it out.


Questions to provoke discussion... in no way criticising your design.


My initial thought was a 2 plate design. Bottom plate holds the bearing, and has slots for adjustment one way. Top plate has the big slot for the bearing carrier to slide in for adjustment the other way, and clamps the whole lot to the turret. 6 bolts?

EDIT... no I don't think that's right. Need to sketch it out to get my head round it.

EDIT 2 - think the slots both way need to be in the top plate, as per some of the other designs. If the top plate is bigger than the bottom plate, to reach over it and clamp it down, then as a minimum we need spacers of the same width.

You could mount it either way... big caster adjustment for the track toys, big camber adjustment for the show ponies? Rough overall size 150-170mm Square? Will do some more measuring this weekend. Will have access to a Mk1 golf and Mk2 golf as well.

I'm assuming the top lip of the turret gets removed to simplify machining of the mounts.


- If it's ally then it needs to be bolt on I guess. Is 12mm thick enough for the bearing carrier?

- Assume that bearing price is each? I don't mind going for a mid price one and buying some spares.

- I have to say I don't care about pretty colours or finishes. If it needs corrosion protection I could always paint it, but I'd probably leave it 'raw' or spray with WD40

- All the mounts I've seen have a little headed bronze(?) bush or two (top hat bush?) to protect the bearing from the strut. Were you including that in your thoughts.

- Do you think this sort of spec is strong enough to top-mount on the turret, rather than the under-over type? Gets you a free turret extension of a few mm that way!

Test criteria - needs to support a 1.25 ton car kerb hopping at 100 mph, compressing on 700lb springs. 70/30 weight distribution, so that's roughly a 500kg static load on that corner? I'm doing basic arithmetic here, not engineering calculations, so feel free to shoot them down.

 

All great stuff Brian, we need to write a specification on here including people's specific criteria, then we can start to design around these specific points. I can very quickly make wooden CNC cut pieces for people to test fit on different platforms, to make sure the fit is right before commiting to more expensive materials/processes, I wont charge for this either, all for the club and community.

 

Mike just seen your post great stuff too. Let's get a spec sorted and design from there, easy to come up with multiple ideas and materials and then we can judge each one a test and develop from there.

 

Any thoughts on pricing? If we start with a target of... say 120 for a pair, and see how it works out?

Obviously if it's less that's brilliant, but... If I could get top-mounted 2-way adjustable mounts for the price of Compbrake ones, I think I'd be happy with that. It makes more sense to do a batch though, with the setup costs that Brian is talking about, for jigs and so on, so it's the group opinion that matters....

 

This is a point that needs to be defined, price will effect all processes of maufacture and materials oused for the final product. Therefore what are the to upper end other people want to pay? We can then design around this criteria!

 

To many beers in the south of France and that post is a little bit wrong, so I shall enjoyyholidaysnd beer and add to this thread next week.

 

There's two ways to do it I think.

1. Set a target and see if we can meet it.

or 2. Try to cost it out to do it to a good standard, and see if we like the number. If not then we go back and look at where we could save something.

 

Number 2 is just design and development! Set out a criteria that includes a price and idea of durability and function and we can design within it, challenge is part of the design process.

Rain is very heavy, just nipped next door for food avoiding lots of rain! Got to love Monico!

 

Thread has come some far. Thanks for the input.
I know how expensive the bearings can be. My Dad has his own design of top-mounts for the clios and the bearings are around 50 I think, but then there are track/road cars that have never had to change one in 4+years.

I would be willing to spend 200-230 personally.

I guess weld-in ones would work out cheaper, and easier?

 

A few further notes on the ground control tops I posted pictures of above.

They don't make a MK1 specific unit, that's their universal one.

I order to not have to cut the body work I used spacers to lift it above the pressed lip.

The stainless steel plate goes below the turret to spread the load. The bolts are loaded in extension regardless of the spacer.

Spacing it upwards also gave me a few more mm of spring travel.

This position also allows for the greatest range of movement in the camber and caster setting as the thinnest part of the spring perch is at the same height as the panel opening.





I did initally mess with the pressings a little but found a better way by contouring the spacers to match the panel for the other side.



Perhaps a design consideration should include thoughts on how to align the units.
I had to do some serious head scratching to figure it out.

Some reference markings or at least a straight edge will aid in initial setup.



With this setup I can get from 0 to -3 of camber adjustment.

Castor I measured at +4 with the bearing in the stock centre position. It's set up so I can add more by pulling the plate rearwards using the fore/aft slots.

A design feature of the GC top mounts which is not obvious is that the spherical bearing does not support the weight of the car.

There's actually two bearings in these.

The first bearing is obviously the spherical bearing in the mount which serves to locate the strut laterally.

The second is visible below and is pressed into the top of the spring perch.

Even when you've got it in your hands it's hard to see that it's actually a proper raced bearing and not just a bushing.



The spigots in the spherical bearing are to compensate for different strut shaft diameters. You have to tell GC which struts you are planning to use.

Likewise you have to specify the spring diameter for the perches.

 

Is everybody happy loading a spherical bearing sideways?
When applied to an upper mount of a front drive car doing the steering?
I'm an electric type guy, so not qualified to comment, but I want an extra bearing in there that is designed to take a load in line with minimal friction, so my
steering works with minimal friction
Worth discussing?
Jon

 

Spherical bearing sleeve spigot could incorporate a needle thrust bearing, but thats more work/cost.

Jon, Not as much sideways load as you think there, since its so high up, its mainly axial load.

As mentioned, price defines bush, and layout complexity.

B.

@ Peter, like the design on red car. I think many get afraid when they have to chop loads off. Ferrules could get you the ability to lower too, design is common, dare I say copyable, its the same as a 1000 google images I have open here, and looked at the last hr.

Lets not re-invent the wheel,

ps, id prefer to see splined bolts used there, so when adjusting, you wouldnt have to also hold bolthead - like a merc wheel stud, or any stud, diff studs, etc.

Dont get you with two bearing idea, one must be a needle thrust as mentioned.

B