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MG MGA - Front Tow eye

Colyn Firth..re recent post and your protruding rear 'tow eye'.
For longer than yonks I have been considering putting a tow eye on the front of my car or at least putting the structure in and keeping the eye in the boot.
The front end is so structurally weak that I always considered the load would need to go centrally back to the main chassis to allow towing and then have sideways strength to stop bending the front structure (as latter looks like it has poor lateral strength). I thought about going through my redundant starting handle hole .....or are you just considering the front tow eye as a mini bumper so above does not apply? Any ideas...
..and at the rear ..what is the "dumb iron" ? I note Mike Ellesmore has an eye at the same position.
Neil Ferguson

http://thesciencedictionary.org/dumb-iron/
On an A these are chassis extension studs that the front and rear bumpers attach to.
Mike
Mike Ellsmore

Mike..thanks .it is the first time I had heard the expression. I obviously have led a secluded life away from the cognoscenti.
I would not like to put too much varable direction load on either of the front ones. Maybe both if there was some cross stiffening to keep the shape ...
Neil Ferguson

Neil, i agree that the front dumb irons which the bumpers are usually bolted onto are quite a lot less substantial than the rear ones.
But you would think that if they are strong enough to attach the bumpers to, then you would expect that they would work well enough to use as a very occasional towing eye.

I plan to fit a towing eye to the front left dumb iron to act as a sort of minimal front bumper.

Maybe I should fit a bar across the front of the front chassis extension to spread the load between the two sides

Colyn
Colyn Firth

Colyn..from the way I see it the tow eye you propose is on one side of a what is essentially a portal frame and it is strongly x connected normally by the bumper ( whoops ..you don't have one ) . I your case it is just a cantilever .In any case the portal frame ( or cantilever )lack shape stability under any lateral load and needs a pinned diagonal connection ( capable of tension and compression) between a point close to you new eye and the rear end of the another piece of protruding 'dumb iron' on the other side of the car . NB I just
love the latter expression and will use in my lexicon..now on the lookout for 'speaking iron'
Neil Ferguson

I agree the dumb iron extensions (either front or back) are not a very practical place to affix a tow eye but it is a great way to cover the ugly stud extensions on a bumperless car without removing them.
I had call to use a front dumb iron tow eye on the track when I broke a throttle cable and after a 2 km smooth tow the stud need some straightening!
Also the dumb iron location is useless if you wish to winch a car onto a trailer as most winches are centrally located. I have found the best place to winch an A is to clip the hook directly into one of the holes in the base of the front subframe.
By threading a light chain through these two holes in subframe and fixing with a D shackle will provide a substantial front tow point.
Mike


Mike Ellsmore

..Away from car right now but really keen to get a structurally sound removeable tow connection on the car....this deficiency always been a niggle for me ( and now lasted 26 years ..time to exorcise that niggle )
I am considering the following see .. diag attached.
..It should be central
..use the starting handle hole ..so no new cuts.
..Take load back to main chassis front cross member
..Give lateral strength to tow point .
..keep the tow eye and threaded shaft as short as possible to avoid bending

The idea is to have two diagonal tension ties ( bar or tube )bolted to and coming from the main cross member vicinity. The ties would then also bolted to the small tubular front cross member and then to a plate or threaded boss . If a plate then weld on a nut to back side to accept the removable tow eye part. The whole beastie would be removeable as well...in parts .
I need to get the head under the car to see the simplest locations and joints .
The load would be well distributed and the whole thing kept fairly light ..and out of sight. I I can keep the bars as simple tesion memebers then they could be quite slim .
Thoughts etc ..


Neil Ferguson

Well, considering that you are away from your car Neil, that is a pretty good engineering drawing!
It also looks as if it is engineered more than well enough to do the job.

However, because I have installed an oil cooler beneath my cars radiator duct, your towing bracket would tend to obstruct the airflow into it.
So l think I would prefer to find a way to simply beef up the individual dumb iron.

Colyn


Colyn Firth

I like your idea Neil. Here is a nice tow eye to go with your proto type.

http://m.ebay.com.au/itm/Screw-in-tow-eye-point-hook-aluminium-red-CAMS-compliant-/151468466955

Trailer pic shows why needs to central.
http://www.mgaguru.com/mgtech/trailer/pics2/8013.jpg
Mike Ellsmore

Mike ..thanks for info....Away in Europe, mainly Italy, until mid august .When I get back to the car I will make up a wooden template and plan to have the unit totally removable (in 3 pieces) and to have all the joints as bolted/pinned so loads are simply applied. The 3 pieces will be the two tie rods with flats at each end and a threaded boss with two welded on ears ( for connecting to the tie rods) at front end to take the tow eye ). The dia. of each rod will only need be around 15mm if I keep it in simple tension..ie basically acting as a cable.
Neil Ferguson

I plan to do some work on my front suspension over the winter and whilst I'm doing this, I intend to remove both the front valence and the front chassis extension as they both need repainting. Plus my front oil cooler vent needs to be made a little wider.

At the same time I can have a look at ways of beefing up the dumb irons to see if I can fit a towing eye to one or both sides.

Maybe if I fit a towing eye to both sides, I could then make up an external bar with a central towing eye, which I could fit onto them (like a temporary bumper) whenever any towing was needed.

Colyn
Colyn Firth

Colyn...The dumbo irons need some lateral stiffening ..the plate is micro thin and the top and bottom flanges pathetic..good for straight line pull and holdng up a bumper but will bend easily. Suggest beefing up the width and thickness of the flanges ( adding a bolted on heavy angle iron?) if you cannot fit a angled tension tie in back to the chassis.
Connecting both sides obviously increases the strength and connecting a towing cross beam bolted to the two tow eyes will assist by ensuring they have to share load and bend together . ..but it is still is a weak portal frame and to my mind needs some the stiffening as per first para above.
...and I know you are a master at finding room for parts ..but a tow beam ...where would you put it and if you leave it behind sod's law says you will need it .
Neil Ferguson

Colyn..a supplementary to my last comment...

There is of course one advantage in the weak dumbness of the front frame..it will fold backwards easily in a collision giving about 20in or so of distortable metal( incl. radiator ) to absorb impact before the engine starts to caress the drivers legs. You would not wish to lose this I would suggest so any extra strength should only be in tension.
Neil Ferguson

Some really great points there Neil, particularly about maintaining a collapsible safety zone.
I must admit that this is something I hadn't really considered.

I will have a look at making something more along the lines of your design, so that it will be strong enough in tension for towing but still collapse on impact.
Cheers
Colyn
PS
Are you going to visit the UK during your European trip?
Colyn Firth

Colyn..
Not his time except one night in London between flights. I am now single again so in charge of my own itinerary and given this freedom I am planning an extended time in Uk next year when Uk exits from the frost ( June?) catching up with La Famiglia and friends around uk and seeing some new sights ( preferably during the day and in the countryside and old towns ).
Strange about the front crush zone is it not? I never thought about it ..bemoaned the weakness .until now ...but now it seems it is the mga equivalent of an airbag. I even now like the way the front bumper would be stopped by the tyres/wheels as it is pushed back..
..but not much use in a true high speed..best not to think about that ..
Neil Ferguson

The next time you are over here let me know and I will try my best to get to see you, ideally in my MGA (assuming you can escape from the "rellies")☺.
Loads of MGA stuff to talk-about on your next UK walk-about!

It's weird on an MGA, how a small project seems to mysteriously escalates into a large one.

I noticed last year that the left side of the front chassis extension had lost most of its paint due to the rad overflow pipe being too short and dripping antifreeze over it. So I was about to paint it but realised that the front suspension could use some paint also.
Then I saw that the kingpin dust seals had all but dissolved away.

So it has now become a major winter project where the front end has to virtually come off to do all the other stuff I have been thinking of doing over the last few years including:-

Raising the suspension ride height a little as my race set up is so low. (Probably have to remove the rear lowering blocks too! So an even bigger project!)

Cut a bigger vent in the Sebring front vallence to get more air into my low- mounted oil cooler.

Re-paint the front vallence.

And so it goes.

Looks like another busy winter for me!

Colyn
Colyn Firth

This all seems to have become rather complicated.

I took 6 feet of 1/2" polypropylene rope heat sealed one end and spliced an eye into the other end.

The eye goes through the starting handle guide on the chassis extension, round the back of the cross tube, and the sealed end goes through the eye.

The sealed end then goes through the starting handle hole in the front bumper to be tied on to a tow rope.

You can do it all without jacking up the front but you may get your shirt dirty, and no problem to store in the boot.

Job done?

Cheers

Dave
small

Dave, thats a nice simple solution.

Unfortunately I would first have to re fit bumpers and move my oil cooler from where I re-sited it underneath the radiator duct panel for it to work on my car.

Also, would a tow truck driver agree to recover a car using a rope these days?

Colyn

Neil, can you email me when you get the chance.
Colyn Firth

Dave..all ok and for a short low speed pull to get you out of trouble ..I have such a rope and have done it.. but you ignore the loadings . The thin walled cross tube is vey weak and transits through the thin front extension without reinforcement. Much, very much better to get your shirt really dirty and take the rope back to the main cross frame member. I would also add that if there is any angle on the tow rope you will exert lateral load on the bumper and hence the weak front frame and most likely bend it.
Neil Ferguson

A thought.. based on daves comment and looking at my tension tie proposal earlier on there is no reason why the two angled tension ties could not be replaced by good towing rope/cable ( latter probably better ). When I get back under my beastie I will examine whether it may be simpler to have two shackles arranged on the main front cross member near the inside of the front frame ( ie the same place as the tensions bar ties and then a pre-made sling made to connect the two angled ropes/cables from the shackles to just behind the bumper/body shell at the starting handle hole . ..with a very short tail coming through the hole for connection to the main elastic tow strop...but think on paper at least I still prefer the tie bars ..
Neil Ferguson

Neil

In your first response, hitching onto the crossmember will impact on the front number plate and put a crease (creases) in the aluminium valance. It has to come out of the starting handle hole.

You say the extension is weak, but it is connected to the radiator duct plate via the cross tube and must gain lateral stiffness from the duct plate which has its X stiffener and a turned down edge all round.

In your second response, I would suggest connecting a bridle across the lugs on the crossmember which carry the rack mountings. Your shackles could connect to these lugs and fix the angled slings. No detriment to the crumple zone, if that was ever the designer's intent.

Still get your shirt dirty.

Cheers

Dave

small

dave... My proposals use the starting handle hole as the focus for the pull whether from a tension bar or strop arrangement ...I never suggested putting anything under the bodywork.
The front extension is weak and the front part ahead of the radiator is extremely weak in lateral load .
It may not have been the designers idea to provide a crumple zone ..but there is one and for me I would like to keep it.
re your last proposal I agree that the radiator support etc does provide some lateral support ..but for me nowhere near sufficient when pulling a ton a long distance . The dynamic load will be a huge multiple at 30 kph . I like the strength of meaty frame cross member.
I intend to detail up the tension bars and central threaded boss...and it will not weigh much so, if practical I will design it to be left in position and held in the right attitude/place by support only from the light tubular cross tube.
I have never used the starting handle and since I put the Judson in there is no way to connect it ..so no loss of function..
Neil Ferguson

This thread was discussed between 22/07/2016 and 30/07/2016

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