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SP250 remote control door locking mechanism

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heh101353
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SP250 remote control door locking mechanism

Post by heh101353 »

Another call for help ...

There was an intermittent problem since I own my SP250 when opening the RH door from the inside . Sometimes it would not open on the first try.
I did not put this onto the list of the most pressing issues and maybe now I have to face the music …
While opening the RH door from the inside the other day I noticed a snapping sound and the door would not open anymore.
The car is still in the workshop so we went right at the problem. We removed the complete door locking mechanism.
Apparently the remote control assembly “snapped” after 58 years of operation.

1. One of the two springs inside the mechanism snapped.
Image

2. The pin which protrudes at both sides of the casing should move in a perpendicular up and down movement as the handle is actuated.
The guidance of this pin is pretty much worn and the pin sits somewhat crooked and it does not travel the whole length.
This limits the amount of travel of the linkage to the lock preventing it from actuating the unlocking mechanism as necessary.
Image

I already contacted BT and he promised to look what he can do.
Apparently this is not a “take off the shelf and replace it” kind of thing, so I decided to bring this to the attention of this forum.

Any help would be very much appreciated.

Thanks,
Hans
Last edited by heh101353 on Sun Jan 26, 2020 11:46 am, edited 2 times in total.

Vortex O'Plinth
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Re: SP250 remote control door locking mechanism

Post by Vortex O'Plinth »

Thanks for the pictures Hans. These sort of problems with the SP door lock mechanism are quite common nowadays - lots of use and minimal service have taken their toll. I believe the Club has plans to reproduce these linkages when an economically viable source can be found.

It's a shame they're handed, since the passenger side units are usually in much better condition.
Nick

"Don't bother with the Air & Space Museum - there's nothing to see.......".

smithgor
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Re: SP250 remote control door locking mechanism

Post by smithgor »

Vortex O'Plinth wrote: Sun Feb 25, 2018 1:37 pm It's a shame they're handed, since the passenger side units are usually in much better condition.
Conversely a LHD car would tend to have the right hand door mechanism in better condition so I suppose an option might exist to find and do a trade with a supplier in the US or Europe.

Vortex O'Plinth
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Re: SP250 remote control door locking mechanism

Post by Vortex O'Plinth »

smithgor wrote: Sun Feb 25, 2018 5:59 pm
Vortex O'Plinth wrote: Sun Feb 25, 2018 1:37 pm It's a shame they're handed, since the passenger side units are usually in much better condition.
Conversely a LHD car would tend to have the right hand door mechanism in better condition so I suppose an option might exist to find and do a trade with a supplier in the US or Europe.
Good point! :idea:
Nick

"Don't bother with the Air & Space Museum - there's nothing to see.......".

Sydsmith
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Re: SP250 remote control door locking mechanism

Post by Sydsmith »

If it's any encouragement, I have fixed one of these twice, though in my case the spring was OK and I guess you could have a problem sorting a new spring.

On the first occasion with the unit intact and some padding I used a sharp centre punch to stretch the metal round the pin channel, it worked for a time but wore out very quickly.

Second time, I drilled out the rivets and added weld to the channel and filed it back to fit a new pin. I turned the new pin on the lathe and with lots of filing, fiddling and fetling, I managed to restore mine. I put it all back together with nuts and bolts with the bolt peened over the nut to stop it from shaking loose.

It has lasted six years without a hitch, but it is a fiddle, you do need loads of time and patience and it is not an easy job, but it is do-able.

Good Luck if you try, but what have you got to lose? Syd

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migray
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Re: SP250 remote control door locking mechanism

Post by migray »

I believe these mechanisms are the same as those on the Conquest New Drophead Coupe - though that doesn't particularly help.
They are also the same as the MGA Coupe ones and there is an article on refurbishing them on MGA Guru website http://mgaguru.com/mgtech/coupe/cp113d.htm .
Unfortunately I cannot find anyone who supplies replacement parts.

Mike

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heh101353
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Re: SP250 remote control door locking mechanism

Post by heh101353 »

At close inspection it turned out, that
  • the wear of the slot is not too dramatic
  • the travel limitation of the pin is/was caused by the a fractured piece of the spring which got stuck inside
  • the cause of the crooked positioning of the pin is because only one spring applies tension on the pin
All in all not too bad.
I guess the problem could be solved by
  • get hold of a spring (the trickiest part)
  • drilling the rivet that holds the broken spring (following the advice from the MGAguru article)
  • replace the spring
  • put the rivet back in and secure it with a carriage bolt (filing the bolt head more or less flush)
Thank you all for your assistance and guidance.
Hans
:o owner since 2015 :mrgreen:
https://www.wyhe.ch/

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heh101353
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Re: SP250 remote control door locking mechanism

Post by heh101353 »

Took a while but at last mission accomplished.

It’s not that easy to find a shop which does springs without an order of thousands or more.
But I was lucky I found a spring manufacturer who is quite sympathetic to requests from somebody in need of a helping hand …
He looked at the task, said “peace of cake”, give me two weeks and it’s done. So I ordered a few “left” springs and “right” springs.
Today I went there and the result is really nice. The “right” ones even have the bend that’s necessary to accommodate both ends side by side on the pin that moves up and down.

Image

To hold the mechanism perpendicular to the drill press I took a block of wood and drilled a hole to accommodate the stud for the door handle. Another hole on the side of the block allowed to use a clamp to hold the mechanism securely while drilling

Image

I started with a 8mm drill bit on the end of the rivet, then switched to a 10mm drill bit until there was just a very thin rim of the rivet left.

Image
Image

With a 3.5mm drill bit I drilled through the rivet but not all the way through.
Just to the point when the tip of the drill bit breaks through.

Image

I flipped the whole thing upside down and now with a 4mm drill bit went all the way through the rivet.
Image
At this point the I could pull the broken spring and the remains of the rivet out of the casing.

Image

Put the new spring and the part of the rivet back in.
Image
Took a M4 bolt and a nyloc nut to secure the spring.
Made sure the springs lined up correctly and tested the whole thing
Image
Image
Image

Did put a drop of epoxy on the thread and screwed the nut back on.
Image


Ground away most of the head of the bold and quite a bit of the nut as well.
Image

Everything ready to be put back into the door.


I have some springs left so if somebody needs such a thing he may contact me.

Hans

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