DIY top mounts

The part I've circled in red below is a thrust bearing and rotates within the spring perch.

The concave surface bears weight onto the convex area below the spherical bearing circled in blue.

All weight on the spring sits on the blue circled area.

The mating concave/convex surfaces allow for misalignment through he range of travel.

They're not an easy thing to describe the function of, even with one in your hand it takes a bit of thinking to realise how the loads are carried.



This is the blurb from the GC website.

http://www.ground-control-store.com/products/description.php/II=148/CA=195

 

''articulating needle bearing''

Thought so, they are using it for thrust - its under the concave bit in red circle.

The convex form-circled,(blue) is a radius taken from the centre point of the spherical bearing.

Thanks Peter for that, turns out its pretty simple.

Ill do a cross section drawing tomorrow showing whats going on. I did always, and do like the idea of a thrust needle bearing in a topmount.

Hard anodizing would take care of the convex/concave seat area preventing fretting/galling if alum.

Costs rising though,

Brian,

BUT,

with car standing, or cruising on a flat road, the needle is taking the load, - through the spring seat,

BUT, on hitting a hard bump, or rebound, or any form of damping, the spherical is taking the load, as that's bolted solid to shock.

I guess its load sharing - not totally through the thrust at all times - some axial loads are seen in spherical.

I might be able to put spring, and shock axial load through the thrust bearing - Ill see tomorrow if there is room when I draw it up roughly.

Time to wind down for the night I think...

 

I have only ever seen 'rose' bearings loaded as 90 degrees to the hole through the middle in industry. Putting an axial needle roller in series with the spring is what I do when I play around making/modding top mounts. The bearings are cheap and 3 piece. The two outers just machined flat hard washers. Total is about 8mm thick. If this is rebated back into aluminium on a reasonably tight bore it keeps the muck out.
Has anyone thought about modding the old group 4 escort type? They had a roller bearing inset into hard rubber. I like them and have rallied with them for years. Have also used spherical rose types with the needle thrust in series on tarmac. Hope this is constructive, always good to see group buys on stuff
Jon

 

Thier universal top mount has three mounting bolt (and is pictured earlier in this thread). The one in you photo's IS the unit they sell for the mk1 Golf (Rabbit). It is machined to perfectly fit a Mk1 golf turret without spacers, I have them fitted to my track car.

However, like you say you want to avoid, some of the lip has to removed to get the full range of adjustment..

 

Ah yes, when I was corresponding with them Trevor said,

I took that to mean that they were generic, but perhaps I should have taken it to mean that they were as close as possible but there would still be modifications required.

 

How many bearings in a compbrake mount? My assumption is just one.

 

Just the one (but bearings do fail after time, car weight and bearing dependent). Two bearings added expense and complication? Is this not ment to be a simple design people can download/pass onto a fabricator to have made at a reasonable price?

With regards to price I would really only be happy to pay a bit more than the compbrakes top mounts, so my upper limit would be 150. Obviously this includes the price of the bearing so to make that a fair comparison to compbrake items the bearings need to be identified in the compbrake product and a price worked out? I would imagine some people would be happy with the combrake bearing, others may be happy to spend more on bearing/s. maybe there could be more than one design/overall cost that would give people a greater choice, ie one design with a single spherical bearing and another design that also includes the thrust bearings.

 

This all takes us nicely back to the price people are prepared to call ok.

 

I'm OK with Smudge's numbers, but it's a question of what you get for that as well. Obviously they need to be cheaper than the equivalent.

I don't mind if I need to change the bearings every year or two, if it simplifies the design. The core benefits for me are

- having independent adjustment of camber and caster,
- a solid mounting to hold everything in place.
- Mounting on top of the turret, to keep suspension travel while lowering the car.
- Significantly cheaper than other designs that offer the same features.

I could go out and buy GC ones, but I can think of a lot of other things I could spend the money on instead. As well as that, if doing it this way offers more options to other people as well, then that's even better.

 

Yes, just one spherical bearing..

 

Hmmm, maybe we just need to work out if we can actually produce something better than the competition for less money...

I suppose we are just trying to simplify the Ground Control Design to save money. The idea of creating a design that can take different (quality) bearings would be good.

I was just thinking something similar to what Razzer posted pictures of (but with the mentioned modifications) laser cut out of steel/aluminium. The basic laser cutting file is almost all we need.....?.. the countersinking, machining and fixings can be left to people sorting in batches or doing themselves.
A design for the machinist to work from would be good of course.

 

Following on from my post the other day, let's start a specification to give people a criteria to design from. These points are things that have been raised in the thread, I may have missed one or two so please copy and add them in. You may have other points and opinions, so copy the post and add them in as well.

We could rate how important each criteria are, give them a colour green for very important and orange and red for less important? Gives an idea of what has to be designed in when one or two points conflict.


Aesthetics, it's going to be in full view within the engine bay so the shape and style is important and must fit in (not look out of place) within a range of mark engine bays. Golf 1 and 2 for example. Colour could be factor, I'm not very keen on galvanised steel or rust! But painting the part may hinder its operation when parts need to slide next to each other.

Client, mk1, 2 and 3 owners, but if it can be made to work with other series more the merrier.

Cost, 150 or less, this will be dependent on the quality and cost of bearings used.

Enviroment, it's got to be durable in construction to work within an engine bay, it will become wet and covered in grim, the bearing needs to be protected as much as possible from the underside spray and possibly the top side too. Materials used in construction should not corrode overtime easily and may have to be treated in one way or another to protect them. Ideally to keep sts down use materials that are self finishing in he respect.

Function, a solid mounting to hold suspension coil over unit in place.
Mounting on top of the turret, to keep suspension travel close to optimal while still allwing lowering of the car.
Have adjustment of camber and caster, independent of one another.
Include accurate markings to aid the user during setup. Have a baseline setting clearly marked.
to fit Golf Mk1 mk2 and mk3 cars off the shelf with minimum modifications required, also be easy to fit to other vag cars but more modification work may need to be carried out to chassis.
include a solid mounting point for a strut brace.
include a way of aiding the user to make setting up and alignment of first fitment, accurate. (when first drilling the turret)
Bolt in fitment to turret with minimum 4 m8 bolts. 6 m8 bolts preffered?

Materials, possibly a combination of materials cold be used for the different parts, however, keep costs down by limiting the amount of different materials used. Different materials will require different finishes and manufactured processess which all add to over costs.

Ring washer underneath top mount.
Stainless steel plate thickness to be calculated might need to be same as other plate used to keep cost down, CNC laser cut, plasma cut, self finishing.
mild steel, CNC laser cut, plasma cut, requires a finish.

Two adjustable top plates.
keep them both the same material as ring washer plate, how would a grade of stainless work for this? How thick would it need to be?
aluminium, one or both parts could be made from this, bearing housing could be welded in place, or solid billet could be machined to make bearing housing and top plate from one.

Bearing housing.
a grade of steel, could be easily welded to a laser cut top plate, or brazed for less distortion, keep weld on underside not supporting weight/pressure of car suspension.

Aluminium, would need to be tig welded to an aluminium top plate unless the design forms part if the top plate in which case it could be bolted in.

Durability is of a main concern to all and should be designed into he parts, however, would people be happy with aluminim alloy parts left as self finish? Or do they really need to be anodised? I'm happy to leave as bare but others may disagree.

 

Really enjoying seeing this thread and potential group-buy/design come together. Just my input, price wise, 150 sounds great and as mentioned, if they could be designed with a Mk2 Scirocco in mind also, that would be great!

Cheers

Andy

 

A Mk2 Scirocco is on the list, but the narrower shape of the turrets does make it a lot trickier to get something to fit (see pics earlier in the thread).

 

Yeh, I've been following the thread (eagerly), hopefully some of the CAD/Engineering geniuses on here can sort something out. Might be worth it if we go for a group buy as there's always the 'Register' guys too. Might help the price...

Andy

 

Im going to spend a few hrs on this towards end of the week, smudge makes great points,

One other point, if a piece is machined to accept bearing, then it will distort when welded, and will need a final finish machine, so another process.

Ive thought about threading it in from underside, to a shoulder, and staking, to save finish machine, but thats more work, and some funky threading(easy on a mill) The distortion of welded piece will be an issue I feel, if we want interference fit without finish machine/ream.

Spherical bearings are available with a teflon cage, or dust seal to save wear, but more

 

Completely agree about welding and distortion, I was thinking of silver soldering (if stainless however I doubt stainless would be used here) or brazing into place to reduce/eliminate the distortion.

I know the bearings can be sealed themselves with teflon which is great, but our lovely new MOT now says that all spherical bearings must be sealed, i was thinking, cover it up as much as possible, out of sight out of mind! Mine are covered by a carbon cap on the top and a piece of rubber on the underside! I'm sure that covering it up is only going to improve its life too.

 

Is soldering or brazing really strong enough?

MOTs say a lot of things that don't get enforced, like sliding seat mounts, and more

If we machine from billet aluminium to make the bearing housing, does that remove a lot of process steps, in return for a higher initial material cost, and more time on the mill? Insert bearing from underneath and circlip in place. As long as the strut and nut have clearance, the rest of the bearing can be shrouded by the ally - probably invisible from the top, with the right sort of washer, so it could well be 'sealed'

Billet ally also saves the need for any sort of cosmetic coating, IMO. Paint = dead weight and non-core expense

 

I wouldn't be keen on weld in. I think it would put a lot of people off as it's a skill not everyone has. Most of us can drill holes. Some can even drill them in the right place.

 

They're adjustable... you don't need to be completely accurate