1971 mk1 replica sleeper with 180bhp

[gazwad]

Another successful day at the blyton park mk1 action day (thanks again mark & pete). Apart from a cv boot clip popping off at the end of the day (5 min fix with a cable tie) we had no problems at all. The cars were thrashed mercilessly all day and driven there and back (100 miles each way). Shaun's (beige with black roof) was better than before now the engine is tweeked some more and the suspension has been set up better but still torque steers a fair bit so we'll look at bump steer etc soon but I suspect it's mostly down to the wide 13" wheels, as I get almost no torque steer at all. I could feel the weight difference in mine, it handled quick direction changes better and generally cornered faster plus seems quicker to accelerate out of the corners and apparently I was on three wheels around most bends! The tyres are past their best so that limited grip but they still did ok, there's still a fair amount of body roll but the suspension is at standard height and standard rubber cones, red dot cones and a 2" drop would make the world of difference i'm sure but would be uncomfortable in a road car (which this is 99% of the time). Couple of videos:

https://youtu.be/sUW1sLh5uW0

https://youtu.be/pNJMMmVV0Dc

[foxy52]

Exel vid....enjoyed that ..!! foxy52

[Old English White]

What fun! A nippy little blighter isn't it! Mind you, that old Minivan put up a good fight didn't it? He must have been in a hurry to get to B&Q

[gazwad]

The mini tried to kill me last night. Went for a short drive and around 2 miles from home the passenger side lower arm completely sheared resulting in VAG scene camber and the tyre locking up against the damper:
DSC_0608 by garrywadey, on Flickr
although 'well stance bro', this is less than ideal for avoiding ditches and oncoming traffic. Fortunately I was only doing around 30mph so could still just about controll the car and get it into a layby until my fwend came to the rescue with a spare lower arm. The damage:
IMG-20190624-WA0010 by garrywadey, on Flickr
IMG-20190624-WA0009 by garrywadey, on Flickr
there should be the bush housing attached to that bit, it sheared at the thread. I didn't hit and big bumps and there was no sign of any previous damage. They were bought new from mini spares and have been on the car for around 4 years - It looks like just another crap quality part from the major supplier again. Luckily there was no other damage to the car and i avoided an accident (i dread to think what could of happened if i was doing 70mph!).

[timmy201]

WOW! I have those same arms on my car, makes me think twice now!

[mk1]

I'm really glad to hear that no real harm was done, & sympathise with you about the failure.

However, I think it is a bit rich accusing a part of being "just another crap quality part from the major supplier" when it has been perfectly serviceable & lasted for FOUR years in a 180bhp Mini!

Yes, there are some crap quality parts supplied by after market sellers, but people should maintain some sort of perspective!

[gazwad]

normally I would agree with you mark but I have asked around and have since heard of a few other failures of these arms. I have also have a few other poor quality parts from minispares in the last few years so have lost all faith in them. I know this forum is very pro-minispares but i am impartial. I am not singling out minispares on their own as they are still my preferred supplier as i do believe most of their parts are the best available and other suppliers are much worse, the problem being they are simply the best of a bad bunch. Also they don't seem interested in any feedback from customers, after purchasing some wheels from them a couple of years ago I phoned them to warn them about some serious safety issues with them (paint on wheel nut mating surfaces & incorrect wheel nuts being recommended) and they weren't interested in the slightest.
Yes they have lasted 4 years on a 180bhp mini but I don't see this as acceptable for such a safety critical component - the power is irrelevant as the car is mostly driven on the road like any other mini and only does blyton once a year - and surely by the fact that these are adjustable and aimed at more spirited road and track driving they should at least be as strong as the standard arms. I was lucky to get away with little to no damage and no injury to myself, this could have ended in a fatal accident quite easily and i'm sorry but I think i do have this in perspective and it is in no way acceptable. We have to have faith that these suppliers are making components that are safe and up to the job but unfortunately there is no independent control over what they can make/supply so we just assume they are of sufficient quality and designed by engineers who know what they are doing.
Anyway I didn't put this on here to have a go at minispares, i was just sharing my misfortune and hoping to maybe help others avoid the same problem.

[mk1]

Gaz,

I wasn't particularly defending Minispares. Only you know exactly how much hammer your bottom arms have had, no one else can know that. I would be very interested in hearing other examples of these bottom arms failing.

I have used them on both road & race cars for longer than I care to remember & they have been 100% reliable. However, in the past I have had cause to wonder about their reliability.

But any further info would be interesting.

I would like to think that a product like these bottom arms are tested & the design certified, but I do wonder.

M

[Peter Laidler]

Looks like it's been cracked and started to friction, ready to part - and finally sheared. If you're particularly interested, your local college with a small metallurgy lab/facility will positively identify the fault for you. The catch-all answer is metal fatigue

[gazwad]

yes that was my thoughts, there doesn't seem to be any obvious impact damage. I will probably replace them with the solid ones set at 1.5 degrees extra - at least i'll know they should be as strong as the standard ones.
Mark I have been privately messaged from someone on here who has said they had the same problem - but as they messaged me privately I don't want to share their information without their permission, my friend who helped me fix the car at the roadside also exchanged messages with someone whilst we in the process of fixing it, they also had had the same problem more than once.
Maybe we are just the unlucky few, I can only speak for what I have seen myself. I do recall when I bought them thinking I wasn't too keen on the design as any twisting or sheer loads could easily cause a failure on the threaded section, but assumed they were up to task as they seemed popular and I hadn't heard of any problems. I should probably learn to trust my own judgement more

[Exminiman]

I do recall when I bought them thinking I wasn't too keen on the design as any twisting or sheer loads could easily cause a failure on the threaded section,

looks like the base of the threaded area could be the source of a fatigue crack - not a sharp edge you can smooth out, so maybe a re-design required

Mind you, might not be an issue at 100bhp rather than 170bhp.....sorry 180bhp

[snoopy64]

That is indeed a fatigue failure but the root cause was the initial crack from which it radiated, caused by a particularly sharp thread overloaded , an impact, material defect like an inclusion or whatever...

[kit of bits]

Were you running rose joints?
I’ve had a similar problem in the past running solid type bushes..
D

[gazwad]

not rose joints, just rubber bushes. My thoughts are rose joints would be better as they allow twisting movement more freely whereas the rubber bushes have to deform so transfer more load into the arm.

I've just checked and with standard lower arms I have around 2 degrees of positive camber so i will order some solid lower arms with 2.5 degrees extra which should give me 0.5 degrees negative camber

[gazwad]

It appears 2.5 degree arms don't exist so it will have to be 2 degrees and some offset bushes should hopefully get the last 0.5 degree

[kit of bits]

I agree about the rose joints.
I’m using those adjustable arms on the moke but as it’s a road car I’m just using soft bushes.
I was also going down the 2.5 fixed arm route but could not find any in stock anywhere..
D

[1071 S]

It appears 2.5 degree arms don't exist so it will have to be 2 degrees and some offset bushes should hopefully get the last 0.5 degree

Not unless you can find offset bushes that are different from the normal kind.....

The offset allows for caster changes ... the hole is angled through the bush rather than shifted to one side.... so the inner end of the arm remains in the same location vis a vis the car centreline.... (the effective length of the arm, from inner pivot pin to ball joint, doesn't change).

You can.... or maybe its more like you "could" ... buy adjustable lower arms that use a reversed thread on one end so that A. they can be adjusted on the car and B. there are no shear loads on the threads..

Cheers, Ian

[gazwad]

I have ordered the 2 degree arms, that should get me just about into negative camber, could always drop the ride height slightly for some more but should be fine on a road car

[mk1coopers]

I run those arms too, but I use the rose joints with the protective rubber boots you can buy from them, not had an issue, the car is used on the road and for track work, it would be good to know if all the failures have been on the bush type ends or if it has been a mix of bushes and RJ's

[gazwad]

it seems to be the rubber bush ones from what i'm told. I don't want to panic people unnecessarily as it seems the failures are rare. But to me now it's not worth the risk and I will be using solid fixed arms in future.