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MG Midget and Sprite Technical - frontline front suspension instructions

Hi,
My car was fitted with the Frontline front suspension system, with AVO adjustable shocks, some 20 ish years ago. I would like to remove it for refurb: can anybody supply me with fitting instructions, including pictures please?
Also, has anybody been able to discover the specs for the AVO dampers, or sourced a replacement?
Finally, has anybody replaced the oilite bush with an IGUS bearing? If so, part numbers would be helpful.
Many thanks,
Andrew
aj robinson

I think I've still got my instructions Andrew, for what they are worth. I'll look.

I don't have the spec of the avos, but I'll look at them and see if there is a model number or anything on them.

Nope, I looked too, but never found an igus bush to fit as a direct swap. But I have considered boring in deeper, to fit a longer oilite bush. I'll look up the size, it's a standard off the shelf item here.

I'll dig out the pictures of my strip down too.

anamnesis

AVO are three miles from where I live and so too are igus.

I have the later set up with igus bearings I believe.

At the time I enquired about buying the dampers from AVO they said (the) FL had it stitched up so only FL or their suppliers could sell the damper (unless things have changed since). Gaz or others may be able to match the FL spec.

I've attached a PDF of the (later) fitting instructions but I'm not sure it'll help for repair but a mate had to strip the hardly used s/h set he bought as they were seized from rust, and he said mine would probably be the same.

igus do lots of bearings, and other stuff, and just need the sizes to match up, I found them to be very helpful.

https://www.igus.co.uk/info/product-category-overview

https://www.avouk.com/

https://www.gazshocks.com/


Nigel Atkins

Who can dig out the MASC article where someone recently IIRC, maybe last year, replaced the bushes with Delrin and a new shaft. MASC online seems to have been reorganised so the later magazine PDFs are no longer available online. If I was modifying the FL units I'd add replaceable wear washers to take the thrust so the body bracket doesn't wear, would mean narrowing the upper arm by a few mm. Be nice to see drain holes in the front to rear web as well, I have them in the original so water doesn't pool in the body bracket.
David Billington

Those look like the same instructions as for the mk1 set Nigel. I'll look up the oilite part number later, maybe you could ask igus if they do a match now.

Yep, exactly my thoughts when I stripped mine David. Wear washers to take the thrust, at the front really, as I found the rear wasn't worn much if at all.

I'd also slot the base mounting holes, to enable a reduction in negative camber to the same as the mk2 igus bushed set.

But if retaining oilite, I'd bore deeper for a longer bush, plus drill in to fit additional grease nipples, and probably add internal grease paths/grooves to the oilites.

Plus previously, someone, possibly you David, mention a harder material for the pin; chrome bar?
anamnesis

David, the article you metioned from Mascot
was in Mascot Januari 2021 page 23
It was written by Mike Pearson from Kent
He used a material called Delrin where he made the new bushes from.
Got the article here but my scanner doesnt work at the moment... :(

Im actualy at the point of reconditioning my old type Frontline front suspension.
Got a set on my car and my old set somewhere in a box, thinking of improving this one as experiment but im not realy in a hury :)
Also have a spare set of Frontline bronze bearings.

Mine seems to also have play/movement on the bold and boldhole in the bracket, hopefully the boldhole hasnt worn out to much and made the hole to big....
A de Best

many thanks everybody, all great stuff! It's been a while since I asked for any assistance, and as usual, it has been first class.
aj robinson

Andrew.

I was, still intend to try a linger oilite bush. This one.

http://www.bearingboys.co.uk/AI1218-20_Imperial_Plain_Oilite_Bearing_Bush_3_4_x_1_1_8_x_1_1_4-42726-p

Here are some stripped down pictures. Not in order, but should be self explanatory, hopefully.





anamnesis






anamnesis

Trouble uploading.

Try again.




anamnesis

And again




anamnesis

And again

And that's all I have.




anamnesis

I’m not familiar with the F/L units but I assume that the tube is a fixed spacer (when the through bolt is tightened) ?
In the article referred to Mike made ‘top hat’ bearings that were pressed into the arms from Delrin having reduced the width of the arms to accommodate the flanges of the top hats.
The original bearings were ‘olilites’ and these can be bought cheaply from most of the bearing suppliers in top hat form.
I haven’t checked the sizes are what’s required but very likely. I recently reduced the flanges of some for a friend as they are used in the folding system of Moulton bikes but not with standard flange thicknesses available.

R.
richard b

The original oilite bush is :
Inside Dia: 3/4" Outside Dia: 1.1/8" Width / Length: 3/4"

This is the direct replacement from bearingboys.
https://www.bearingboys.co.uk/Imperial-Plain-Oilite-Bearings/AI121812-Imperial-Plain-Oilite-Bearing-Bush-34-x-1-18-x-34-42724-p

I can't find a top hat oilite with an external o/d of 1.1/8"






anamnesis

These are the size I used originally https://www.bearingboys.co.uk/Imperial-Flanged-Oilite-Bearings/AJ121620-Flanged-Oilite-Bearing-Bush-34-x-1-x-1-14-42886-p , the tube they fit in being 1" all the way through the 1.5" ones are an option but then the oilites didn't tend to wear the shaft did as I only used readily available stainless steel bar at the time .

Just looked at Bearingboys and the price for the 1.5" length top hat bush is half the 1.25", maybe more common.
David Billington

That's great info everybody. I'm not too technical so will probably replace like with like. Which will hopefully be easier.......!!
aj robinson

And I would just like to say again, how useful this forum is and the willingness to share information and experience is massively beneficial.
I am a very grateful, not very technical, owner of an old car. Which is not an ideal combination!
aj robinson

Hi Arie,
did you manage to scan the article from MASCOT please?
aj robinson

Not yet but my neighbour is suppose to help me tomorrow getting the scanner "connecting" again, hopefully.
A de Best

Inspired by Anam's photo's ive doug up my old FL set and took it appart.
Still need to get the old oilite bushes out.
Is it just smacking with a hamer&metal cilynder on the oilite bushes so they come out the otherside?
On this I was wondering: how many of those are in there, 2 or 4? (spare kit comes with 4)
If 2 then what is in the middle bit where the greasenipple comes in?
Feels like its solid metalcilynder, is it part of the armconstruction and do you place the oilite bushes against it?


Other question: what is suppose tho be the weakest part of this setup, the actual part that wears the most?
the oilite bushes?
the metal cilynder inside the oilite bushes?
the bolt? (mine has worn a bit on the thread that is in the outer bracket)
A de Best

That's great Arie. Although I'm not a technical person, I'm very interested to see the article because I have a friend who has a plastics/3D printing company and he is interested in helping out
aj robinson

AJ,

Use your grease gun to push the bushes out, as in this picture. Block the ends, and the grease pressure does the work.

There are two bushes in each arm.

Yep, a gap in the middle.

When you push the byshes in, they bottom out on a ledge, as the arms ar not bored to the same diameter all the way through.

It all wears a bit.

The bushes wear, and so dirs the steel pin.

The front of the bracket wears, as the oilites grind their way into the inner face.

The pins wear mostly on one side, where the thrust from road wheel pushes the pin against the oilite bush. I turned mine round and tht helped, but it's not a solution.


anamnesis

AJ.

Instructions for removing the bushes. Courtesy Anthony Cutler.

"The problem is there's no exposed part of the bush which to clout (with suitable bar on an inside edge). The solution is to put the steel shaft back in, break out the grease gun and pump some grease in. This will start one of the bushes moving.

Whilst continuing to operate the grease gun, stop the moving one from ...errrm... moving so the other one is encouraged to move. (I found this particularly easy since I have 3 hands ... no really, I'm on my own in the workshop.)

Once they've both moved a litte, you can drift them out in the normal manner (they aren't that tight)."



anamnesis

@arie.... if you to sell one of your FL sets, please let me know
a.o. arnold

That all looks like a right faff! Why not just a good old lever arm shock with a triangulating link ;-D

(Couldn't resist the opportunity for a shameless plug!)

Best of luck with the rebuild.

Cheers,
Malc.

Malcolm

Where can you get a ***good*** old lever arm these days?
anamnesis

Touché Anam ;-)
Malcolm

Lol.

I should have said cheap too. Moss sell new ones at 125 quid each, but they are on back order anyway.

Anybody remember JL HEAP's kit that he was developing? That looked really good. I was very tempted by that. But it doesn't show on his website, so it must have been dropped.
anamnesis

This was the JLH kit in prototype form.




anamnesis

And these.

Looked very good. Are you still reading here JLH? Has this kit died a death?






anamnesis

AJ,

is this of any use (if you haven't spotted it already?). Only one picture though.

https://s3.amazonaws.com/frontline-developments/wp-content/uploads/2015/01/FS1.pdf
Jeremy MkIII

Anam, I missed a trick and should have retorted to your comment with another shameless plug...

Why not refurbish your bad old lever arm dampers and make them good again? Someone does a refresher kit for that ;-)

Cheers,
Malc.

Malcolm

👍
anamnesis

Scanner working again!
A de Best

Obvious wearmarks on the bolt where it goes thru the bracket...

Anybody knows a supplier of the these hardened bolts to order some new ones?




A de Best

Next job is to get the oilite bushes out.
Like the Ant Cutler method you linked Anam but at the same time I find it hard to imagine it would work... but if it worked for you and Ant then atleast I can try.

Alternative is pulling it out with the 7/8 tap screwing into the bush and tapping it out as described by Mike.

A de Best

My bolts didn't suffer that much water and wear damage Arie. Actually none at all.

I greased them heavily, plus, the hollow steel pin shouldn't be turning on the bolts. The hollow steel pin, and bolt should be locked up tight. Only the arm pivots, via the oilite bushes, around the stationary hollow steel pin.

The oilite bushes are VERY VERY easy to remove using ANTHONY CUTLER'S method. You put the pin into the bushes, and that creates a chamber. The grease you pump in easily shifts the bushes.

No need at all to 'destroy' the oilites by tapping into them. Although if they are very worn, it doesn't really matter. But I wanted to see if mine were reusable, and they are. I found most of the wear was on the pin, -- and the inner face of the front side of the bracket; which is where the endfloat comes from, and increases as the oilite cuts into the steel. Fragments of steel embed in the oilite and do the grinding I was told, innitiated by road grit and crud, because it's not sealed.

For an expensive system, it's pretty poor. But when new, it was very good.

I took mine off in 2011, after over 10 years of use. (So maybe I shouldn't grumble too much about wear? ). Anyway that was 11 years ago, and it's been on my shelf since then.

I went back to my lever arms which were in very good condition, and found I preferred the original handling. Hence I haven't done anything since to renovate my FL kit. If I could buy GOOD NEW ORIGINAL lever arms I would. I personally think the fl kit doesn't really improve on them.

Triangulating the original lever arms makes them last longer, and must also reduce wear on the outer wishbone fulcrum. No bad thing.

But I might just give that delrin conversion a go.

How long ago was that delrin conversion done? How well is it lasting?

Bonus head gasket descriptions.😆😆
anamnesis

The article was in Mascot Januari 2021 page 23
It was written by Mike Pearson from Kent.
So he should hav atleast 1,5 year experience with it now.

Actualy the bolt and pin had no/hardly wear between them, they are still very thight together.
so actualy need new fresh hollow steel pins.
Gonna replace the oilite bushes anyway as they are not that expensive.

oilite bushes: Bearingboys
New Bolts: ?
New hollow steel pins?

Defenitly need some rings between arm and bracket as there is some wear on the brackets which gives more play and therefore quicker wear...
A de Best

If I do the Delrin conversion, I'll make a couple of changes.


1). There is plenty of room to bore deeper into the arm and extend the length of the bush (Delrin, or Oilite as I already mentioned previously -- see link).

2). I'd cut back more on the front fave of the arm to allow for replacable thrust washers, -- which maybe available in igus ready made --, or have a batch made at the same time as the delrin top hat bushes. Because with the amount of thrust there is, the delrin is definitely going to wear.

3). I think some form of sealing is needed. Road grit and moisture are still going to make for a nice grinding paste at the ends of the pivoting arm.
anamnesis

See my link to longer oilite bushes Arie. Do you have machine tools to bore your own arms deeper?

Agree about the wear at the ends. It was that really, that made me take mine off in the first place.

Do you REALLY need new bolts then?
anamnesis

Thanks Arie and anamnesis
aj robinson

Arie,

You should be able to identify the bolt grade by its head markings, see https://www.constructionsupply.com.au/ebook/files/assets/downloads/page0076.pdf . Someone like https://www.namrick.co.uk/ will likely be able to supply them. The spindle you'll likely have to have made from your choice of material 3/4" steel round bar.

Having read the article again his point about steel in bronze having no compliance is correct but ignores that the LA damper is the same and the rubber top trunnion bush is there for compliance and isolation.
David Billington

I wonder why F/L did not use top hat bearings in the first place as David did ?

Looking at the top hat Delrin top hat option, a smooth thick metal washer for it to thrust against would be good.
To stop the spacer rotating it could be trapped between the spacer tube and outer arms when the through bolt tightened (arms/tube adjusted to accommodate).
This would sort the problem of wear on the original arms.
Boring the arms deeper could be carried out but somewhat more difficult to set up - large vertical mill probably easier to hold / align etc.


R.
richard b

Would an ‘o’ ring around the perimeter of the top hat bearing provide sufficient sealing to at least reduce road dirt/ grit to a reasonable degree ?

R.
richard b

As I understnd it, fl knicked the design and for cheapness, selected off the shelf oilites. There isn't an off the shelf oilite top-hat bush, that fits the way fl finished the arms; -- I don't think. I haven't found one.

The ends of the arms, isn't where the thrust wear occurs. It happens to the insides of the brackets. Almost all on the front.

The oilites protrude at each end by about 15 thou inch. At the front, the greatest thrust, the end of the oilite eats into the inner face of the bracket. See picture.

If the arms were narrowed a bit, a wide flange could be fixed on the ends/sides of arms, so it can't rotate. A suitable thrust washer could then sit over the end of the oilite, and between that new flange and the inside face of the bracket. That could improve it a lot I think. And those thrust washers would be easily renewable.






anamnesis

With the delrin top hat bushes a shoulder could be added to take an O ring with a bit of nip to make a seal and plenty of meat in the arm by the look of it to do likewise if retaining the oilites. IIRC the early FL arms were closer to what I originally designed and may have used a top hat bush, the arms with the thick oilites not being the first incarnation from FL. My original design had replaceable thrust cups which retained an O ring to keep it all sealed and allowed use of oil instead of grease for lubrication which is as intended for oilite bushes.
David Billington

Yes that’s what I thought- should have said :-
‘To stop the Trust washer rotating it could be trapped between the tube spacer and the bracket arms by boring the T/w 1/2”.‘

The top hat solution was what I was describing.
Delrin bushes should be fairly easy to make.

R.
richard b

I don't think the replaceable thrust surface for the FL units needs to be anything special I'd likely use an off the shelf stainless penny/mudwing washer of suitable size and as Richard notes place it so it's clamped by the spindle when all done up tight.
David Billington

anam
bear in mind (non pun missed) that igus bearings tend to be 'plastic'.

From my personal experience of talking with one of the FL I can tell you they were not interested in any development of the mk2 version at least.
Nigel Atkins

Yep I remember the previous discussion about all this Nigel. I had no luck talking to them either.

David, yep , I understand, but that way the thrust surface wouldn't be made larger/improved would it?

A bigger thrust surface area would wear more slowly. I'll take a picture of the wear on mine.
anamnesis

Here's a question.

Why are they called mudwashers? Penny I get, but why mud?
anamnesis

I wonder if it's because they may be used to retain mud wings/guards. I was working at a racing company once and one of the guys referred to sh*t fight rivets so I had to ask what they were. He explained they are a type of pop rivet commonly used in a sh*t fight such as repairing broken fibreglass in a hurry, also called peel rivets as they peel like a banana in use.
David Billington

If you go down the top hat route 1/18” about 28 mm then add top hat flanges say min 3mm gives a diameter of about 34 mm - so significant additional area - assuming the plain steel or s/steel thrust washers are sized to match.

R.
richard b

" The spindle you'll likely have to have made from your choice of material 3/4" steel round bar."


David, it was steel, the new ones from frontline are aloy apparently
Any metall will do?
when frre of choice what would be best choice for wear and availability?
A de Best

David, ive found this code on the bolt: R S B S

Ill see if I can find some company here in Holland to order the bolts as ordering from the UK is a bit more complex and more expensive since Brexit.
But thanks for the links.

Actualy thinking of ordering a wee bit different bolts if available.
Basicly the sam bolt ofcourse but les trhead on it and a longer shaft length.
On my bolt now you see that the bit of thread that was in the bracket is worn, if the treadbit would start where the bold comes out of the bracket the bold would last longer.


A de Best

Arie,

If the bolt is done up properly clamping the spindle against the bracket sides it shouldn't wear as the bolt won't move. Regarding the later FL arms with the Igus bushes the spindle is hard anodised which is resistant to wear. I suggested in an earlier discussion about Mike Pearson's mod that if going the Delrin top hat route that 20mm chrome ground bar is readily available and would be more wear resistant than 3/4" bright bar, likely plain CRS (Cold Rolled Steel).
David Billington

That's what I reckoned earlier. The bolt must have been 'loose', for wear to occur.

David you mentioned chrome bar back in 2011, but I didn't persue it.

Who might supply it, and use it to make just two pins though? That triggers a memory, I seem to recall enquiring at a then local engineering place, and being told it was expensive to do that. Probably part of the reason I went back to lever arms.
anamnesis

https://www.ebay.co.uk/itm/284132754238 is just one of a number of sellers on ebay. 3/4" is likely available just far less common, maybe a specialist hydraulic cylinder place. I know a company in Brierley Hill that would likely do it but in 9m lengths last I bought from them although they did cut it down to 3x3m to fit in the car.
David Billington

So really the kind of thing for a number of people to fund, to get the price down. Not going to happen methinks. Not enough people with these kits who want to renovate them.

Here's a thought. Speedy sleeve the worn pins. But they don't make long sleeves.
anamnesis

The spindles could be built up with a hard surface material and ground back to size, I've had it done in the past for a worn lathe shaft, but if you're not doing a lot of miles then some 3/4" bright bar faced to length and drilled through 1/2"? is likely to appeal to more people cost wise.
David Billington

Is silver steel an option ?
Could machine spacers and flame harden as/if required.
Probably would not need to be very hard ?
It’s not that expensive and easily available in 3/4”.

Still grease to avoid rusting.
R.
richard b

Richard,

Silver steel would be a good option as the diameter tolerance is tighter than normal cold drawn steel so should ensure a consistent fit, using CRS is a bit of a gamble as it may be loose or occasionally too tight and it not always as round as it looks.
David Billington

Here's a thought.

This is one of my pins. Apart from a small bit of water/moisture damage which is very shallow and will polish out, the section inwards of the bushes is as new.

If I cut it into two in the centre, I could reverse each part, and use spacer/washer in between the two halves, to compensate for the length lost in the cut.

Effectively a new pin.

With new oilites, esp' the longer 1.1/4" oilites I mentioned below, it would reset the whole thing.

Then using the idea of the sacrificial penny thrust washers as described by David and Richard below, all the endfloat wear would be elliminated too.

Although the thrust washers wouldn't be very thick, it still represents a loss of bearing surface for the oilite/pin combination, unless the arms aren't bored deeper. So if having to bore anyway to compensate for that, it's another good reason to bore to 1.1/4" inch to provide an additional 1/2" of bearing surface.

Additionally, drill and tap for a grease nipple in the centre of each bush, instead of relying on the single grease nipple in the centre of the arm.

Summary.

Cut the pin in half, -- easy diy.

Need to find someone to bore the arms deeper, and ideally reduce their width accurately too.

That just leaves finding the simplest method of sealing the ends, although with sacrificial thrust washers, that becomes less important. And even when the ends of the oilites wear, they could theoretically be shimmed to move them outwards to compensate.


anamnesis

Anam,

What's the OD of the inner end of the top arm that the bushes fit in. Maybe you could do something like used on the classic mini see https://www.minispares.com/product/Classic/Suspension/Front/Hydro/MSK001.aspx a couple of simple rubber tube rings.
David Billington

I'm not sure David. Something over an inch, I guess 1.1/8th" ?

I'll measure it tomorrow. Sounds like a good idea.
anamnesis

O/D about 1.4 inch, 36mm.

But not much length to fit a rubber boot/sleeve. Only about 4mm before the weld, but a total of circa 8mm up to the arm, for a 'soft' rubber sleeve to mold around.

Actually I reckon just a bit of bike inner tube wrapped round, and held with a thin cable tie, would do enough to keep the muck away; esp' if it is grease filled.




anamnesis

This thread was discussed between 01/06/2022 and 10/06/2022

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