invacar LightBulbFun's Invacar & general ramble thread, index on page 1, survivors lists on Pages 24/134 & AdgeCutler's Invacar Mk12 Restoration from Page 186 onwards, still harping on...

[Andrew353w]

30 minutes ago, Remspoor said:

A peek over the wall. Location unknown.

With added Wartburg too. Just smell the two stokes.

Two strokes~YEAAAA!~ 

[LightBulbFun]

so today, @egg very kindly, just for the cost of his travel, came down to help me with some bigger jobs on REV, aim of the game was look at the CVT system/possiably change the drive belt and in a fashion, fit the head lamp relay kit I have, and then also adjust up the brakes for good measure since its been a few hundred miles now since getting her back, nothing felt particularly wrong per say, but I figured since it has been a few hundred miles of stop-start going, it would be good to give them a twiddle

and this is where things went a bit Autoshite, in that we figured lets start on the brakes first, and that just ate up all of the time so we could not get the other jobs done! the front was easy enough, but the rears where a real ball-ache, just because of how they are permanently coupled to the CVT system, so they are *never* free of drag and trying to get a feel for when  the brake shoes themselves actually dragging or not was quite hard, it was clear when it was locked up sure, but trying to find that sweet spot felt impossible, especially on the offside rear right, in that with the front, you adjust and the wheel locks, you back it off and the wheel is free, you give it a spin and hear the gentle "woosh woosh" as it spins and the shoes lightly brush the drum,, pretty decisive, but trying to do that with the rears, especially the rear right felt much hard, especially with after a few rotations of the wheel or brake application it would change how much resistance it would have 

at one point we did get things nice very nice and sharp, (which is where we should of left it!) but she would pull to the left slightly when breaking harshly, so we tried twiddling things adjusting the right brake, but then she was obviously labouring due to drag on the brakes, so we ended up backing things off a bit which  at that point we ran out of time, so the brakes are kinda back to square 1 I think there about as good as before we started messing about, certainly I can lock them up, or at least lock one of the wheels up! (I am not actually sure when I hear skidding, if its the front or the rears or all 3 at the same time), but they are certainly not as good as we had them in the middle of the day, and there is still a pull to the left slightly under hard brakes, so im not sure what thats about exactly

all in all could of certainly gone better, but I very much appreciate @egg's assistance no less  in-fact I feel bad for wasting his time in what just turned out to be a bunch of pissing about with the brakes, if I had know it would of been this much of a palaver i'd of left them be and done one of the other jobs instead, so we had something to actually show for all the work!

I suppose I should look on the bright-side that REV's not been immobilised LOL

[egg]

It was all good fun, cheers Dez! 

On my way home from Londinum in very nice Spring time light. Perfect day for tinkering. At one point REV was stopping on a sixpence. Hard to know if the pull to the left was brake imbalance or another suspension/drivetrain factor?

[Andrew353w]

I sympathise with you-adjusting the brakes on a car with C.V.T. can be a pain! According to the workshop manual when adjusting the car brakes on a Daf 33 the procedure involves removing the belts, to enable the wheels to be turned. However, in practice there's enough slack in the gearing to permit the wheel to be turned just enough to ascertain the closeness of the shoes.  With my Daf 33 I've done this a number of times and never had to remove the belts to do it. 

Isn't there any (enough?) slack to allow the rear brakes to be set? 

[LightBulbFun]

2 minutes ago, Andrew353w said:

I sympathise with you-adjusting the brakes on a car with C.V.T. can be a pain! According to the workshop manual when adjusting the car brakes on a Daf 33 the procedure involves removing the belts, to enable the wheels to be turned. However, in practice there's enough slack in the gearing to permit the wheel to be turned just enough to ascertain the closeness of the shoes.  With my Daf 33 I've done this a number of times and never had to remove the belts to do it. 

Isn't there any (enough?) slack to allow the rear brakes to be set? 

there is a little bit of free play in the system/enough belt slack (which im not sure should be there mind LOL) that you can jiggle the wheel backwards and forwards and somewhat get a feel for whats going on, but I was just not sure if that was enough or not to accurately assess things, you could certainly tell "yes this is very much dragging" or "yes this is very much not dragging" but trying to find that middle ground, you know where its just freely spinning going "woosh woosh" felt very hard to do,

 we did talk about removing the CVT belt so as you say there would not be as much drag (since that was on the list of things to do anyhow) but sadly there was not enough time to start that major job in itself

perhaps @Zelandeth if you have any tips or tricks?

[Noel Tidybeard]

one thing that was always advised on 4w drum braked minis is to file a chamfer on the leading edges of the shoes to stop snatching/pulling to one side

[Blake's Den]

Hey @LightBulbFun here is something that might interest you

https://www.ebay.co.uk/itm/186903502591?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=-6Jl9ywLQwS&sssrc=4429486&ssuid=PJQO1AMYSTG&var=&widget_ver=artemis&media=COPY

It is some kind of stock car but with what looks like the Steyr Puch flat twin engine. Could be useful for parts for another invacar owner? I wonder if the distributor turns ...🙂

[LightBulbFun]

13 minutes ago, Blake's Den said:

Hey @LightBulbFun here is something that might interest you

https://www.ebay.co.uk/itm/186903502591?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=-6Jl9ywLQwS&sssrc=4429486&ssuid=PJQO1AMYSTG&var=&widget_ver=artemis&media=COPY

It is some kind of stock car but with what looks like the Steyr Puch flat twin engine. Could be useful for parts for another invacar owner? I wonder if the distributor turns ...🙂

hah interesting! its not just a Steyr Puch engine but its a whole Model 70 drive train, Gearbox and CVT system inclusive, looks like it would of been from an earlier Model 70 (cartridge oil filter), but that heat-exchanger/silencer looks a bit worse for wear! 

in-fact I wonder if there might be some Model 70 chassis under all that?

 

 

@Six-cylinder/ @Mrs6C a toy for the FoD that we can then rob for bits for Dolly?  

[Mr Pastry]

Surely that has to be worth having at that price?  Ad says Imp front suspension, but the top wishbone looks like Fiat 126.

[richardmorris]

12 hours ago, Remspoor said:

A peek over the wall. Location unknown.

With added Wartburg too. Just smell the two stokes.

Wigan?

[richardmorris]

6 minutes ago, richardmorris said:

Wigan?

 

[High Jetter]

5 hours ago, egg said:

It was all good fun, cheers Dez! 

On my way home from Londinum in very nice Spring time light. Perfect day for tinkering. At one point REV was stopping on a sixpence. Hard to know if the pull to the left was brake imbalance or another suspension/drivetrain factor?

You're a good @egg. Cracking assistance, shame you didn't get further.

[richardmorris]

22 hours ago, Mr Pastry said:

Surely that has to be worth having at that price?  Ad says Imp front suspension, but the top wishbone looks like Fiat 126.

And only in Amersham - not a world away.

[Mr Pastry]

3 minutes ago, richardmorris said:

And only in Amersham - not a world away.

A frame it home behind Rev?

[richardmorris]

19 minutes ago, Mr Pastry said:

A frame it home behind Rev?

I was thinking more of another owner of a blue plastic thing with access to a Range Rover with a tow bar.

[LightBulbFun]

speaking of REV, I am wondering is there a good video anywhere, (or set of pictures) showing exactly how the adjuster on these borrowed-from-a-triumph 7 inch girling brakes work exactly/how things/the shoes are meant to move when you turn the adjuster? for example people talk about "clicks" but none of the adjusters really had clicks they had stiff points which I assume was meant to be a click, which has me wondering are these adjusters analog, so to speak in that, is there is still adjustment, between Clicks, or do they only move the shoes when they go click? they felt pretty "analog" to me, in that you would be turning the adjuster and before there was a click the wheel would go tight, and if you twiddled the adjustment spanner just a smidge backwards the wheel would release, but im not sure if this is "safe" or is the adjuster in some sort of position its not meant to so could ping back either way?

but I realise, having never really done this before I was not sure what I was supposed to be feeling exactly!  the front wheel was pretty decisive between "yeah thats dragging" and "yeah thats just right" but the rears felt a lot more gradual for lack of a better word? you would spin the adjuster and it would maybe bind a bit, but not so definently and you would wind it back and maybe it would feel like it freed off a bit but you where not sure if it was actually free or not

it also felt like the amount of twirling to get the rears to bind up was different from the amount of twirling to get them to then free off again or vice versa, (ie for example using random numbers, it felt like it took 3 turns for them to lock, but only 2 turns for them to free off)

also along similar lines, I was not sure how much drag is acceptable, part of me was wondering should I have the rears dragging a bit so that way I *know* there is no gap between the shoes and the drums and then let them bed themselves in so to speak, but you obviously dont want to do that too much or you will cook the brakes! 

I also note that between the 2 rears, each one had a different feel to it, the nearside left wheel felt more "decisive" in its adjustment then the rear right offside wheel, that one felt particularly vague in its adjustment, and was the one was spent the most time messing about with!

i'd like to have another stab at adjusting the brakes and I *might* be able to rope my brother in to help with the heavy lifting, but i'd like to try and get a better idea on WTF im doing/whats going on/a better handle on things, so I dont go through another round of faffing about with no good end result!

 

as you can tell it rather bothers me that I have not been able to decisively be able to say "yep thats all sorted" especially with something like brakes, not that she is lacking in breaking performance, but especially after all the faffing about I do wonder if it could be better, did we actually manage to set things back to how they where or not, and that Im not sure about, it does somewhat feel like theres a little more travel in the handle bars then before, but I dont know if im just imagining things or now hypersensitive)

[richardmorris]

3 minutes ago, LightBulbFun said:

speaking of REV, I am wondering is there a good video anywhere, (or set of pictures) showing exactly how the adjuster on these borrowed-from-a-triumph 7 inch girling brakes work exactly/how things/the shoes are meant to move when you turn the adjuster? for example people talk about "clicks" but none of the adjusters really had clicks they had stiff points which I assume was meant to be a click, which has me wondering are these adjusters analog, so to speak in that, is there is still adjustment, between Clicks, or do they only move the shoes when they go click? they felt pretty "analog" to me, in that you would be turning the adjuster and before there was a click the wheel would go tight, and if you twiddled the adjustment spanner just a smidge backwards the wheel would release, but im not sure if this is "safe" or is the adjuster in some sort of position its not meant to so could ping back either way?

but I realise, having never really done this before I was not sure what I was supposed to be feeling exactly!  the front wheel was pretty decisive between "yeah thats dragging" and "yeah thats just right" but the rears felt a lot more gradual for lack of a better word? you would spin the adjuster and it would maybe bind a bit, but not so definently and you would wind it back and maybe it would feel like it freed off a bit but you where not sure if it was actually free or not

it also felt like the amount of twirling to get the rears to bind up was different from the amount of twirling to get them to then free off again or vice versa,

also along similar lines, I was not sure how much drag is acceptable, part of me was wondering should I have the rears dragging a bit so that way I *know* there is no gap between the shoes and the drums and then let them bed themselves in so to speak, but you obviously dont want to do that too much or you will cook the brakes! 

I also note that between the 2 rears, each one had a different feel to it, the nearside left wheel felt more "decisive" in its adjustment then the rear right offside wheel, that one felt particularly vague in its adjustment, and was the one was spent the most time messing about with!

i'd like to have another stab at adjusting the brakes and I *might* be able to rope my brother in to help with the heavy lifting, but i'd like to try and get a better handle on things, so I dont go through another round of faffing about with no good end result!

 

as you can tell it rather bothers me that I have not been able to decisively be able to say "yep thats all sorted" especially with something like brakes, not that she is lacking in breaking performance, but espicaly after all the faffing about I do wonder if it could be better, did we at least manage to set things back to how they where or not, and that Im not sure about, it does somewhat feel like theres a little more travel in the handle bars then before, but I dont know if im just imagining things or now hypersensitive)

Triumph owners club forum?

[Snake Charmer]

Do you have any brake spares Dez?

[Mr Pastry]

It is difficult to feel what the adjusters are doing especially if they haven't been moved for some time and may be partly seized.

The adjuster is a plain screw thread.  On the business end there is a wedge which moves a pair of plungers apart to expand the shoes.  The wedge looks like a cone but has flats on it every 90 degrees, so each quarter turn there will be a click when the flat aligns with the end of the plunger.  In theory, it is possible to adjust without even jacking up, so you screw in the adjuster until it is tight then back it off usually 3 or 4 clicks and that is about the right clearance.  "Tight" is obviously a bit subjective and in practice it is best to jack it up and feel as you have been doing.

How is the handbrake?  Increase in handbrake free travel will indicate that the shoes are wearing.  I wouldn't have thought you would have done enough miles to need adjustment yet.

 

[lesapandre]

I think you may have to take a brake drum off to see what's going on. The two sides may be set up slightly differently in any event - maybe best to have a look how they operate.

If they are not leaking and pulling to one side they may be fine in the interim?

Here is the Girling advice for the Austin A30 - it again just talks about 'clicks'. I think if you leave between clicks and it moved one way or the other it would not be adverse just mean the brake performance is slightly different.

But it all just goes to show how 'hit and miss' old engineering is in set up.

I'm basing the above on an A30 and an A35 I once had. My approach was as Girling advise and then road test and if the drum remained cool and brakes effective job was a 'good-un'.

But we are a long long way away from the kind of braking that they thought adequate in the past - thought modern shoe materials have improved things somewhat.

I think it a case of try it and see. But as long as you are not losing brake pressure or fluid should be fine?

[egg]

When turning the tyres, off the ground, it definitely felt loose-loose-tight for a bit-loose quite unevenly on both rears. At times we had both rears off the ground and I thought LBF had done a good job of balancing them.

We only did the front once - as that was much easier without the transmission drag (although it was also the adjuster that had most resistance to movement)

[captain_70s]

I think that's the same sort of setup as the Dolly's drums. Adjusted by a square drive on the back of the wheel cylinder through the backing plate?

Mine definitely lacked a firm click when adjusting, it was more like it felt lumpy - for want of a better description!

[LightBulbFun]

On 06/03/2025 at 20:01, Snake Charmer said:

Do you have and brake spares Dez?

not currently in hand, although its not hard to procure them thankfully as it is all just off the shelf stuff shared with Triumph cars mainly  (although the front Flexi is Land Rover funnily enough)

On 06/03/2025 at 20:18, Mr Pastry said:

It is difficult to feel what the adjusters are doing especially if they haven't been moved for some time and may be partly seized.

The adjuster is a plain screw thread.  On the business end there is a wedge which moves a pair of plungers apart to expand the shoes.  The wedge looks like a cone but has flats on it every 90 degrees, so each quarter turn there will be a click when the flat aligns with the end of the plunger.  

Ahhh! this would explain why as I turned *anti clockwise* to losen off the wheel would go tight again before then going lose, (as based on what you describe/looking at pictures of this wedge, it would rise the plungers back back up before it fell back down to the next flat right?) this was something that itself was bugging/concerning me a bit "why was it going tight again before going lose" so I appreciate your explanation on that that, it puts my mind at ease on that part at least  and that would explain the "fine" adjustment I was feeling also where there would be a point where just very small movements on the spanner would sometimes give a difference in brake drag feel, as I was obviously at a point where I just at that in-between point, where i was onto or coming off of a flat and it was moving the pistons accordingly

On 06/03/2025 at 20:18, Mr Pastry said:

In theory, it is possible to adjust without even jacking up, so you screw in the adjuster until it is tight then back it off usually 3 or 4 clicks and that is about the right clearance.  "Tight" is obviously a bit subjective and in practice it is best to jack it up and feel as you have been doing.

interesting! so there is a point there the adjuster will itself go tight and stop moving? I did wonder would the adjust itself stop turning once the shoes where firmly up against the drum, and I had a thought to try twirling it all the way until it stopped moving and then try backing it off, but I did not want to break anything so I never went that far, (as even with the wheel would locked up you could still farily easily turn the adjuster, so I was not sure if that was was because there was still dead space being taken out despite the wheel being locked or if somehow the adjuster was just turning/slipping in place)

On 06/03/2025 at 20:18, Mr Pastry said:

How is the handbrake?  Increase in handbrake free travel will indicate that the shoes are wearing.  I wouldn't have thought you would have done enough miles to need adjustment yet.

this was actually one of the reasons I wanted to have a poke at the brakes in general, as it felt like I have to pull the handbrake out quite far to get a positive lock so to speak, *but* I have not counted exactly how many clicks on the ratchet that is, reading through the workshop manual, I have notice it does give an exact "the handbrake should lock the rear wheels with 6 clicks of the ratchet",  so thats something I will be going back and have a look at, I did however also note that when testing things yesterday with Egg, that I cant actually lock up the rear wheels with the handbrake when im doing about 20Mph or so, maybe I just was not pulling hard enough, but I *think* one should be able to lock up the wheels while in motion with the handbrake right?

On 06/03/2025 at 20:28, captain_70s said:

I think that's the same sort of setup as the Dolly's drums. Adjusted by a square drive on the back of the wheel cylinder through the backing plate?

Mine definitely lacked a firm click when adjusting, it was more like it felt lumpy - for want of a better description!

aye, just like that, and indeed I would describe it much more of a lumpy action than any sort of clicking

[High Jetter]

3 hours ago, LightBulbFun said:

speaking of REV, I am wondering is there a good video anywhere, (or set of pictures) showing exactly how the adjuster on these borrowed-from-a-triumph 7 inch girling brakes work exactly/how things/the shoes are meant to move when you turn the adjuster? for example people talk about "clicks" but none of the adjusters really had clicks they had stiff points which I assume was meant to be a click, which has me wondering are these adjusters analog, so to speak in that, is there is still adjustment, between Clicks, or do they only move the shoes when they go click? they felt pretty "analog" to me, in that you would be turning the adjuster and before there was a click the wheel would go tight, and if you twiddled the adjustment spanner just a smidge backwards the wheel would release, but im not sure if this is "safe" or is the adjuster in some sort of position its not meant to so could ping back either way?

but I realise, having never really done this before I was not sure what I was supposed to be feeling exactly!  the front wheel was pretty decisive between "yeah thats dragging" and "yeah thats just right" but the rears felt a lot more gradual for lack of a better word? you would spin the adjuster and it would maybe bind a bit, but not so definently and you would wind it back and maybe it would feel like it freed off a bit but you where not sure if it was actually free or not

it also felt like the amount of twirling to get the rears to bind up was different from the amount of twirling to get them to then free off again or vice versa, (ie for example using random numbers, it felt like it took 3 turns for them to lock, but only 2 turns for them to free off)

also along similar lines, I was not sure how much drag is acceptable, part of me was wondering should I have the rears dragging a bit so that way I *know* there is no gap between the shoes and the drums and then let them bed themselves in so to speak, but you obviously dont want to do that too much or you will cook the brakes! 

I also note that between the 2 rears, each one had a different feel to it, the nearside left wheel felt more "decisive" in its adjustment then the rear right offside wheel, that one felt particularly vague in its adjustment, and was the one was spent the most time messing about with!

i'd like to have another stab at adjusting the brakes and I *might* be able to rope my brother in to help with the heavy lifting, but i'd like to try and get a better idea on WTF im doing/whats going on/a better handle on things, so I dont go through another round of faffing about with no good end result!

 

as you can tell it rather bothers me that I have not been able to decisively be able to say "yep thats all sorted" especially with something like brakes, not that she is lacking in breaking performance, but especially after all the faffing about I do wonder if it could be better, did we actually manage to set things back to how they where or not, and that Im not sure about, it does somewhat feel like theres a little more travel in the handle bars then before, but I dont know if im just imagining things or now hypersensitive)

It's been decades since I bought my Draper brake spanner. Yes it helps to see how things work with the drum off, as said, but it can be done on the ground, and by feel. It's a bit of an acquired art, but if you have any degree of mechanical sympathy (which I'm sure you do) it becomes natural. Involves lying on the ground though.

[Mr Pastry]

11 hours ago, LightBulbFun said:

not currently in hand, although its not hard to procure them thankfully as it is all just off the shelf stuff shared with Triumph cars mainly  (although the front Flexi is Land Rover funnily enough)

Ahhh! this would explain why as I turned *anti clockwise* to losen off the wheel would go tight again before then going lose, (as based on what you describe/looking at pictures of this wedge, it would rise the plungers back back up before it fell back down to the next flat right?) this was something that itself was bugging/concerning me a bit "why was it going tight again before going lose" so I appreciate your explanation on that that, it puts my mind at ease on that part at least  and that would explain the "fine" adjustment I was feeling also where there would be a point where just very small movements on the spanner would sometimes give a difference in feel

interesting! so there is a point there the adjuster will itself go tight and stop moving? I did wonder would the adjust itself stop turning once the shoes where firmly up against the drum, and I had a thought to try twirling it all the way until it stopped moving and then try backing it off, but I did not want to break anything so I never went that far, (as even with the wheel would locked up you could still farily easily turn the adjuster, so I was not sure if that was was because there was still dead space being taken out despite the wheel being locked or if somehow the adjuster was just turning/slipping in place)

this was actually one of the reasons I wanted to have a poke at the brakes in general, as it felt like I have to pull the handbrake out quite far to get a positive lock so to speak, *but* I have not counted exactly how many clicks on the ratchet that is, reading through the workshop manual, I have notice it does give an exact "the handbrake should lock the rear wheels with 6 clicks of the ratchet",  so thats something I will be going back and have a look at, I did however also note that when testing things yesterday with Egg, that I cant actually lock up the rear wheels with the handbrake when im doing about 20Mph or so, maybe I just was not pulling hard enough, but I *think* one should be able to lock up the wheels while in motion with the handbrake right?

aye, just like that, and indeed I would describe it much more of a lumpy action than any sort of clicking

You seem to be on the right lines with all this.  You don't need to screw the adjuster in beyond the point where the wheel locks, because of the wedge action it will go further but won't do any damage, just don't be too much of a gorilla on the spanner.

As you probably know the handbrake cable should not be adjusted until the shoes are correctly adjusted, so be cautious with that, but who knows what has been done in the past - it may just need tweaking to get yr 6 clicks.  I would say you should be able to lock the wheels at say 10mph, also try it very slowly in reverse a few times (where safe to do so, obvs), which may tell you something, and give the trailing shoes a bit of exercise. 

 

[Andrew353w]

Reading through the most recent posts I can see that the brakes here are basically as those on an early Mini (British, not BMW MINI!) and identical to those on the Daf 33. The adjuster's turned in 90 degree movements, each quarter turn moving the shoes outwards toward the drum by a very small amount. By spinning the wheel one can deduce when the brakes are dragging and then locking, so therefore by how much to undo the adjuster. As you say, the problem comes when you can't spin the wheel, owing to the belts. There should be a small amount of play nevertheless, to allow one to judge when the brakes are locking and so therefore when they're free.

[LightBulbFun]

17 hours ago, Mr Pastry said:

I wouldn't have thought you would have done enough miles to need adjustment yet.

I was wondering about that, what is the general recommend service interval for brake adjusting? I just figured here since she had done a couple hundred miles, of mostly stop-start traffic (and that I know the rears especially where previously taken to bits, rectified and put back together) that it felt like a good thing to (especially before a major trip) to have a look and see if there was anything that needed twiddling, now that things have had a good chance to settle so to speak since the work done, (and also since I know brake wear is one of those things that can creep up on you somewhat)

obviously I dont expect it to be needed just every two hundred miles like this normally, but yeah im not sure what the actual recommend interval generally is! and would it be different intervals for the front and the rears? (since I know the front does most of the work) or do you do em all at the same time

5 hours ago, Mr Pastry said:

You seem to be on the right lines with all this.  You don't need to screw the adjuster in beyond the point where the wheel locks, because of the wedge action it will go further but won't do any damage, just don't be too much of a gorilla on the spanner.

As you probably know the handbrake cable should not be adjusted until the shoes are correctly adjusted, so be cautious with that, but who knows what has been done in the past - it may just need tweaking to get yr 6 clicks.  I would say you should be able to lock the wheels at say 10mph, also try it very slowly in reverse a few times (where safe to do so, obvs), which may tell you something, and give the trailing shoes a bit of exercise. 

thats good to know! (tho out of curiosity  I am looking at the adjuster and am wondering, what stops you accidentally winding it all the way in to the point where it runs out of thread and falls out into the drum?

all being well, my brother has kindly said he will come round to help me with the heavy lifting , so I can have another go at things tomorrow , so ill investigate those points there (and yeah im not planning on touching the handbrake cable adjustments themselves, certainly not until I know 100% the rears are otherwise fully adjusted up good)

5 hours ago, Andrew353w said:

Reading through the most recent posts I can see that the brakes here are basically as those on an early Mini (British, not BMW MINI!) and identical to those on the Daf 33. The adjuster's turned in 90 degree movements, each quarter turn moving the shoes outwards toward the drum by a very small amount. By spinning the wheel one can deduce when the brakes are dragging and then locking, so therefore by how much to undo the adjuster. As you say, the problem comes when you can't spin the wheel, owing to the belts. There should be a small amount of play nevertheless, to allow one to judge when the brakes are locking and so therefore when they're free.

heres an exploded diagram from the workshop manual  

[Mr Pastry]

Service intervals in ye olden days were usually 3,000 miles or 3 months, whichever comes first, so you would check/adjust the brakes then. 

Generally the fronts will wear more rapidly than the rears, as they are doing more of the work.  Especially if you have only one front brake, though I'd expect the wear to be fairly even on an invacar as there is quite a lot of weight on the rear end.   They did not fit a 2LS brake to the front where they easily could have done, so this may have been deliberate to maintain the front/rear brake balance.

The adjuster can't be wound all the way through while the shoes and drum are in place, as the plungers/ links can't move out far enough.

[egg]

6 hours ago, LightBulbFun said:

all being well, my brother has kindly said he will come round to help me with the heavy lifting , so I can have another go at things tomorrow , so ill investigate those points there 

Glad to hear, that makes me relax a bit knowing that you can have another go to get it to a place where you are comfortable.

[plasticvandan]

I would suggest using the handbrake as a guide to help make it easier to tell what state of adjustment it is in with the belt drag.typically this is something I have "the feel" for ,like tuning carbs and engines by ear,but you are too far for me to do it. I would suggest one way may be to tighten the adjusters until the wheel is locked,then back off the same amount both sides,say one full turn.assuming the wheels are then free to rotate (with belt drag) pull the hand brake on in increments and compare how many clicks it is to what it was before,to get an idea of how much tighter the shoes are to the drums. As you know not having enough free play can cause the brakes to bind when hot.

These adjusters are pretty much the same as all reliant rears and I vaguely remember two flats back from locked up was the way I set them (or,look at where the square is on the adjuster,focus on one flat edge,then move that edge so it is two positions anticlockwise from where it was.this should get you close.its more important that they are fairly equal to each other at the back than being right up against the drums. Time scale wise,for your mileage probably once a year with an oil change would be sufficient.