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MG MGB Technical - BGT Rear tubular shocks - Australia.

73 BGT currently has 10 year old tired Monroe Gas tubulars with part # 150378. For now, I plan to replace them with new tubulars to make use of existing fitting arrangement, but am conscious of the tendency for tubulars to give a harsh ride. Monroe no longer list 150378. I'm keen to hear what Aussie BGT drivers have fitted and found satisfactory.
Relevant info:
Ride height - Rear 14.5 ins. Front 14 ins.
Front shocks - rebuilt Armstrongs.
Tyres 185/75 R14.
Use - everyday country roads.

Thanks for any input.
John.
J P Hall

Monroe sensa trac is the go for a road car--
If you measured the compressed and extended lengths of your shock eyes they should be able to match them up with a sensa trac the same
Not 100% sure but I believe the Moss kits have these shocks now

willy
William Revit

Agreed, Willy - sensa trac looks like the best value for money. Koni offer their general purpose 80-1244SP1 at about $200 EACH as being suitable for both roadster and GT. The Monroe sensa trac is about half that price, IF I can find the right size/specs to fit the B - and even better if anyone actually stocks it!
If anyone knows with certainty which Monroe part number suits the BGT, I'd be more than grateful. Of course I'm asking Monroe, but a user's experience would be invaluable, rather than just "the book says ...".
Sorry if that sounds cynical, but I'm just about over so-called "specialists", who all too often seem to be happy to repeat what their wholesaler says.
Over on the T Series side of things, I would nominate NTG as being exceptions in that they have an intimate understanding of the cars and their idiosyncracies. A dying breed.
John.
J P Hall

There was an MG specialist firm in Penrith, west of Sydney called "Nepean Classics". Different ownership now, and no longer MG specialists.
Many years ago they worked in with Peddars one of the Australian suspension specialist firms, to come up with a tubular shock to use with the MGB. Their development "mule" was an MGB GT,( which are a little heavier in the back than the roadster. However both versions of the MGB are very light cars in the back).
They discovered that no matter how hard they tried to configure gas filled shocks to suit the MGB, they all gave a very harsh ride, presumably because of the aforementioned lack of mass at the back.
Ultimately they came up with a fairly short dumpy oil filled shock absorber/damper.
Their conversion using this form of damper was so successful, that they sold hundreds of them through Nepean Classics. I believe Peddars were amazed that there would be such a demand for them.

I fitted a set of these Peddars/Nepean Classics shocks to my MGB roadster many years ago now. The difference was amazing. It rode much softer, yet, paradoxically, leaned less in the corners. You could also instantly sense the elimination of the "lost motion" through the linkages that the lever arms types required to actuate the damper.

The usual, and I suspect well deserved criticism of rear tubular shock absorbers is firstly that they result in a harsh ride. But this is likely because all, or virtually all are intended for heavier cars.
The second criticism is that the problem is not the type of shock absorber being used, rather that after forty to nearly sixty years of use, you can, very reasonably, assume the original shocks are "clapped out". The advice is to get the original lever arm units (competently) rebuilt. Peter Caldwell, Worldwide Imports, in the USA has an extremely good reputation for rebuilding the Armstrong lever arm shocks to better than new. His prices are extremely reasonable. But postage is the killer for that for those of us in Australia.

Maybe check with Peddars to see if they can still supply their shock absorbers that they developed for the MGB ?
T Aczel

By the way John. How did you go with your stainless steel MGB bumpers. The question of course is, "did they fit well?"
The steel reproduction bars I have seen are all pretty terrible. Wrong profiles, and generally poor fit. You can pick the difference between repro and original from 5 metres away.
T Aczel

Thanks TA - your comments on tubulars are most helpful; I have been in touch with Jane Caldwell, and will probably revert to lever-arms in the fullness of time. For now, $100 per side for tubulars will be fine - that seems to be the going rate for Monroe out of the US. I have a mate up here (North of North Queensland) who had a family connection with the old Nepean Classics I believe - Doug Head. Or maybe he was in Melbourne. Old age.
As to the stainless bumpers: I've only fitted the front one so far; the appearance (shine) seems to me very good; the fine detail is, as you say, not exactly the same as the original presses produced (but for this particular car, a BGT daily driver, I'm comfortable with what they produce), and the fit is "OK" - I did have to loosen the support bar, assemble all the fixings loosely, and then carefully work everything up to full torque - but then I would expect to do that with any new bumper. When I've fitted the rear, with original good rubber overriders, I'll get a couple of photos up.
Yours,
John.
J P Hall

John
Got rained out today so got into the Monroe catalogue
The shocks you have--150378--are indeed superseded by--
D7018+
They fit a NISSAN -Dualis, S/Wagon, 2WD,4WD10/07-12 Rear
483 extended length
325 compressed

Haven't finished looking yet
willy
William Revit

Interesting, that part number is for Monroe Magnum shocks which are a tiddle heavy duty but probably fine
Don't know if you can get that particular shock as a sensatrac but if it's a direct supersession for what you have now it should be fine-
There's a writeup at the bottom of this ebay ad-

https://www.ebay.com.au/itm/Pair-Rear-Monroe-Gas-Magnum-Shock-Absorbers-for-NISSAN-DUALIS-ST-Wagon-07-12/232962952141?fits=Model%3ADualis%2FDualis+%2B2%7CMake%3ANissan&hash=item363dac8bcd:g:~dAAAOSwTQFgWbmT
William Revit

Hi John,

When you find out which brand/model, I would be grateful, as I am going to fabricate my own conversion kit. The prices of some of the conversion kits are getting out of hand and the costs of restorations/rebuilds are becoming bottomless buckets!

Cheers,

Maurie Prior
R M Prior

ETA: Moss UK use Koni, Spax and GAZ, they also offer Bilstein conversion kits (Bilstein were often on fat heavy German saloons cars over here). Frontline use AVO (3 miles away from me) the rear ones used on Spridgets are only just soft enough for real world UK road use, I know as I have front and rear conversion sets on my Midget.

John,
my mate contacted GAZ in the UK for an alternative GAZ damper to the one supplied by Westfield (the vehicle manufacturer) and was told the one that was specified and fitted by Westfield was not the one GAZ wanted to specify and offered him a standard alternative, that was a better suited and also less expensive model.

I've no idea if the GAZ website is up to date with their Overseas Authorised Distributors but if so you could ring the distributor and ask if the specified BGT rear damper in the usual kits is the best one for the job.

https://www.gazshocks.com/distributors/overseas-distributors

Australia

DVS Performance
13 Alan Street
Grovedale
Victoria
3216
Australia
http://www.dvs.net.au (this don't work)

Tel: +61 412709695

V&A Spiteri Jaguar Pty Ltd
34 Joseph Street,
Blackburn North.
3130
Australia
Tel: +61 (03) 9899 4851 / (03) 9899 4851
http://www.vicspiteri.com.au/ (this does)
Nigel Atkins

Nigel
be careful who you are recommending, there are sharks circling--

Also' the shocks from one manufacturer's kit might not necessarily fit another manufacturer's kit, everyone has different ideas on how to mount them on various designed brackets
On my v8 conversions I use the std.shockers from the front of TC/TD Ford Cortinas, mount the top eye to a fabricated bracket bolted through the original shocky holes'etc' in the body and the bottom eye to a modified (mounting angle) original bottom spring plate (inverted for lowered suspension height cars)
None of the kits available have the shock mounted correctly

cheers
willy

Also, just out of interest, I've noticed a few companies here now have given their websites the flick and are operating off facebook instead, seems to be the trend
William Revit

Now this is getting interestng.
Nigel: I thought I'd read that Koni, Spax and Gaz, although all adjustable, gave a very harsh ride in the B roadster and GT. But I will definitely call Gaz over here and see what they say.
Willy : I'll try to get a pic today of the mount used on my existing setup. You mght well have a view, and your input is appreciated.
Have you ever heard of an Escort tubular damper being used on a B? - I know Tony Slattery spoke of Escort dampers in connection with Y Types.
John.
J P Hall

I've looked at the images on line of the various dampers suggested in this thread. They all look remarkably long and spindly compared to the Peddars units I have in my conversion.
The mounting however is similar to that which Willy describes, with a fairly simple bracket using the original body holes, and the bottom plate inverted, but in mine, without a modification to alter the angle of action.
As stated before, the resulting ride is supple and well controlled, without the slightest suggestion of harshness.
T Aczel

John; If you're going underneath for a pic, it'd be interesting to know the centre to centre length of the shocky eyes at normal ride height and the distance between the axle and the bumpstop
William Revit

The PO fitted Spax to my V8 and they nearly shook my teeth out over some surfaces at his setting. On the softest they were just about OK, then one started leaking and I felt obliged to replace both at several times the cost of a single lever-arm. Some years later I became aware that the rear ride was getting softer and almost bouncy. Went to harden them up a bit - even though the indication was that they were probably on the way out, to find the adjuster seized! At that point I got a set of used lever-arms and drop links from Stoneleigh and no more issues.

At the time I also had a ZS180 which was also pretty hard, but changing to a Golf7 which is significantly more compliant (and how I prefer things) we now find particularly the V8 rather harsh again over the traffic calming measures we are surrounded by. I seen reference to adjustable valves for the lever arms, did some digging and found these https://www.fourashesgarage.co.uk/parts-for-other-marques-besides-astons/adjustable-damper-valves-for-armstrong-lever-arm-dampers
An enquiry elicited a price of £65 each + VAT + P&P with good stocks. Pondering.
paulh4

The off-the-shelf conversion kits may have a damper that are too hard for a classic car, certainly the AVOs I have need to be at their lowest settings for ride comfort and to stop any more modern made fixings coming loose too often.

My thought was not to use the dampers that are provided on those kits and to ask the damper manufacturer(s) if they could recommend more suitable units. There could be very many reasons why a particular damper is used in a kit but things can also move on and a different damper may be more suitable but not used for many reasons.

Most, certainly modern, cars are heavier than our old two-seater cars, having said that Westfields are light by even these standards.

I've also seen here before that those in Australia seem to run with much higher tyre pressures than over here. Then there's the type of suspension bushing generally and to dampers.

I realise the different kits have different mounts but Maurie at least is going to make his up so the world, of dampers, is his lobster.

My Midget came with a Spax rear conversion which lean back more than the FL kit that replaced it, I thought the FL seemed better but who knows as I wasn't able to do any tests just comparing the two conversions in isolation.

I like a more compliant suspension as it suits the cars I feel for road use.

Not sure what sharks Willy's referring to but I'm not recommending anyone or any damper just suggesting that phoning, and talking to the right person, can sometimes gain you improvements.

I don't know the authorised GAZ suppliers in Australia that I copied into my last post or any of the dampers manufacturers, none, all or some might be great or just con-artists for all I know.

I can certainly tell you a few people and companies to avoid in the UK from my 30 years experience of using 'classics' as dailies. 😜
Nigel Atkins

Armstrong lever arm adjustable damper valves.

This maybe already known but in case not, adjustable damper valves have been sold for a while now.

(if available?) These are more expensive from MGOC Spares at £79.95 each - AHH7217Q.

These might(?) be the manufacturers of those, and IIRC(?) sell at same price -

A.J.B. Engineering. - https://ajbengineering.com/products/armstrong-lever-arm-adjustable-damper-valves/
Nigel Atkins

The email came from AJB.
paulh4

£78 (inc VAT), perhaps things have changed or moved on as they often do with time, or perhaps it's just round numbers or perhaps they're not the same (doubtful?).

This was the MGOC I remembered (back in stock at the time) - https://www.mgocspares.co.uk/pdfs/hlarchive/HOTLINE-OCT-2020.pdf
Nigel Atkins

Right Willy : crawled under the normal-height car today, held a torch with one hand, had a beer handy, and my best estimate is:

Fitted length, eye centre to eye centre - 395mm.

Axle top to lower edge of bumpstop - 12cms.

Bottom mount plate - 10mm

Bottom mount thread diameter - 12mm.

To my untrained eye, the bottom mount assembly looks like a home-made or maybe professional but not from the Big Guys - what do you think?

What I don't know yet is the extended and compressed specs of these tubulars. I don't think Monroe had that info when I rang them, but I'm going to try them again tomorrow. More soon. Hope the pictures help.
John.








J P Hall

Those bottom mounts are way more substantial than any of the conversion kits the main suppliers sell over here sell. Like some others it puts the damper at quite a lean.

What cars are the Monroe 150378 usually fitted to?
Nigel Atkins

John
Thanks for that--
I had a setup exactly like that on my old MGC, don't know what brand the kit was but a few guys round here had them on B's--just like that
Couple of things,
First off the shocky looks dry so no leaks, if it's a rattle you're after the obvious place to look first would be them badly worn spring saddle rubbers and them loose 'U' bolts, you can actually see a gap between the rubber and the spring, it's very loose would be working up and down with every bump, Your shock absorbers might be fine

Shockabsorbers-
With the earlier Monroe part no. you gave the shocks in your car are quoted as 483 ext -325 comp
So with your measured ride height length of 395 there's heaps of available droop 483-395= 88mm dr.
and plenty of compression395-325= 70mm comp
BUT the bump stops are 120 so it's going to bottom out in the shock 50mm before it gets to the stop
It won't be quite that bad as the shock is on a bit of an angle but will still bottom out in the shocky first

Really it needs a shocky undone and measure exactly what you've got, you only have to let one end go to measure

There's a Monroe list online but be carefull with mountings, I take it that yours have eyes on both ends
I'll go through them and see if I can find something suitable, but you might be ok with them rubbers done and the U bolts tweeked up---

Page 181 onwards

https://www.monroe.com.au/images/pdf/Monroe-Catalogue-2019-20.pdf

Cheers
willy

I'll go through the list tomorrow
William Revit

Good spot about the rubber to spring gap Willy; I'll get one damper off tomorrow and report the measurements, plus see what state the damper eyes are in.
I hadn't noticed any rattles or squeaks, but an annoying thrum which could otherwise be fuel tank mounts (another topic for another day). Thanks as ever for your input. I know Maurie Prior is interested too.
John.
J P Hall

A quick update, having extracted one side today.

1. Monroe helpline confirm the measurements for the old 15-0378 are 442 and 285. On the bench today, mine measure 440 and 285 - so close enough.
Monroe say they were for Suzuki Sierra - but obviously fitted my GT with the brackets as pictured.
They have been superseded by D7014, which are again listed for Suzuki Sierra but will fit my car.

2. In various archives I have read that a more appropriate range for B/BGT would be something like 410 extended and 275 compressed - but Monroe Man said they don't offer anything in that range. I tried to check on their website Willy, but couldn't make it work. Do you have a view about that smaller range? I think that might be nearer what Koni put on MGBs.



3. My top mount by the way is the plate bolted to subframe - see pic. Bottom mount is the offset stub on plate - see additional pic.

On the bench, my Monroe 15-0378 self-expanded when compressed - not sure if it's meant to! Will try to add video.

Thanks for anyone's input.
John.

John.





J P Hall

John
If your shock still expands/extends on it's own then that means the shaft seal is still good and that it's a gas pressurised shock
I'm starting to think there's not much wrong with your shocks and the problem is worn/loose hardware
With that bottom bracket having loose U bolts as it was it would be flapping around and causing all sorts of handling/noise issues
440/285 travel, will be fine with your brackets
heaps better than the 480/325 that the supersession number that i got
I've been searching for something around 445/275 but if the chart i posted up is out of whack which it sounds like it then we're in nomans land with that
You mention 410/275 in the archives but they would be too short for your particular brackets having 395 at rest it would only have 15mm extension from normal ride height----not enough

willy
William Revit

John,
I almost put the damper looks like it's off a truck, so wasn't that far out.

I must admit I thought the pad gap was just it squashed out and highlighted by the camera flash.

I'd follow Willy's lead and put the damper back on and check the u-bolts are all well snugged down, if they not then just tighten and see if you're happy with the results of just that. You'll need to check and possibly nip up after a good road test or two.

Depending on their present state just changing the bushes to the rear springs and dampers may give the improvements you want until the dampers really need replacing, they're probably a lot less stressed than intended.
Nigel Atkins

So Willy it looks as though the nearest we're going to get in new shockers to fit my existing bracketry, stub size etc. is Monroe's D7014. And the travel seems to be pretty good for the weight etc, of the B. The kerb weight of the Sierra is listed as ....kgs, and the BGT ... kgs.
I will now dig out my new rear suspension rubber set, spring-eye bushes etc., sort out the spring baseplates, and ... put back the existing shockers first. At only about $160 the pair (compared to $200 EACH for the Konis), I'm quite happy to then put on new D7014s for the long run, and compare the two.
Thanks heaps for your input along the way, especially on things like the travel characteristics.
Nigel - thanks also for your interest. I'm basically doing what you suggested all along!
I will of course post my findings - probably won't get it done til next week now.
John.
J P Hall

It'll be interesting to hear the results. You could possibly experiment with the tyre pressures too later.

I also meant to put I'm not sure what that shiny black thing is but if it's a cable I'm not sure about its routing on the cage.
Nigel Atkins

Sorry - that should have read that the kerb weight of the Suzuki Sierra/Jimny is very similar to that of the BGT!
J P Hall

Just out of interest and for Maurie's benefit,seeing as he's going to self manufacture a kit ,the TC/TD Cortina front shocks that I mentioned I used earlier measure up at 335/230
These shocks will fit nicely if you make up a spacer and use the rearmost original top mounting bolthole through the chassis for the top mounting and use the original spring plate hole at the bottom for the bottom mount--As mentioned before the spring plate needs to point upwards for std. height cars and downwards for lowered cars
The shocks come with metal fittings through the rubbers which either can have their ends cut off and used as tubes through the rubbers if the fittings are hollow---some brands have solid fittings so will need pressing out of the rubbers
I've never fitted them to a higher rubber bumper car so not sure if they'd be long enough there
willy
William Revit

John,
same weight but for harder use, don't Jimnys have to pull Landies and Jeeps out when they get stuck. 😁
Nigel Atkins

And Maurie, if you go the Corty shocks you need to aim for around 295 or as close as for your normal ride height fitted length
William Revit

John,Willy, Nigel, Paul,

Thanks for the images - tells me heaps and I remember those bottom and top brackets well, as I used exactly that same kit on my first ever BGT restoration almost 25 years back.

I bought the kit from a company called Pickards in Melbourne back in 1997, and they worked fine from my aged memory. My next resto was a 1977 rubber bumper roadster and I bought that rear damper conversion kit from MG Heritage in Sydney (I think) and it was different to the earlier one, where it was required to re-use the bottom spring plate up-ended and swapped from left to right etc.

My third conversion kit was in 2015 and that kit also came from MG Heritage in Sydney with the same fitment as above (here is an image of the tech docs as supplied)

Cheers,

Maurie
R M Prior


I found an image of the product however it is a small image but shows the detail enough.

Maurie

R M Prior

If you're going to make up your own brackets Maurie, you have the chance to set the shockies up at the correct angles. The top brackets need to be further inboard to get the action right, The brackets can go further accross and bolt to the floor up behind the battery boxes as well as onto the original shock holes. It takes a while to measure it all up to get the bracket right but it's worth the effort if you're going to all the trouble of making brackets anyway--
William Revit

Thanks Maurie.

My thoughts were why the bracket didn't go further back to get the dampers more upright (Willy you need to worry as we're thinking alike again).

I thought by the drawing that the dampers look stubby but in your photo they're not that short. I can't remember if it's front and/or rear or Spridget and/or B but Mini dampers are used which makes sense for size and Minis take car plus 4 peoples' weight.

The bottom bracket arrangement is used on other kits IIRC.

Perhaps making your own bottom brackets that extend the other direction would help with alignment too.

With your present set up I did wonder about ground clearance under the bottom of that bracket.



Nigel Atkins

Would something like this make sense.


Nigel Atkins

Sorry Nigel, we're not thinking the same--
That mounting angle isn't really an issue, it's the angle relative to looking from the front/rear of the vehicle--If someone is going to make their own kit they should be up to speed on the correct mounting points, otherwise why bother, just buy an ordinary kit-
William Revit

Willy you must be so relieved that we're not thinking alike! 😊

I thought they meant vertical upright, I didn't realise there was much er camber(?) to these. As long as Maurie and John know what you mean I can be away with the fairies as usual.

I see I also mixed in John's damper ground clearance on to Maurie, sorry Maurie (and sorry about that).

Give me a little slack as I've not had an ale since the start of November when our micropub had to shut for second lockdown or whatever they called it then.
Nigel Atkins

All good Nigel--Happy Easter-don't eat too many chocolate eggs---we're half a day ahead here so the egg count is getting very low
lol
willy
William Revit

During my research, I have found that most kit suppliers have a common top bracket shape with a built-in spacer/threaded fixing point at the top - Spax- Koni - Gaz - Sensatrac. Gaz uses a spacer at the bottom only, Spax use an additional spacer at the top, Koni on both fixing points and Sensatrac rely only on the inbuilt spacer at the top.

So, where each has a similar top bracket along with all re-using the bottom spring plate in reverse mode, they all are having an almost identical fixed top spacer/threaded fixing point. It would appear then, that the north/south attitude of the damper,is identical to all suppliers, however the east/west inclination varies by the use of a bottom spacer, with each supplier/manufacturer.

When I get to that stage of attaching (6months away at least) I will follow the average and see how it fits then.

Maurie
R M Prior

This thread was discussed between 23/03/2021 and 05/04/2021

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