Lotus Elan

Rebuilding +2 door hinges

PostPost by: js43lotus » Sun Jan 25, 2009 6:49 pm

I am wanting to rebuild the door hinge assemblies on my +2. I read the technical article posted by C. Adkinson on this subject, but I still have a couple questions for the group.

The bolt that holds the bottom of the hinge pin in the door shell is frozen and one of the previous owners destroyed the straight blade slot on the head in both doors.

Can someone tell me what size thread is on this bottom bolt? Is it 1/4-28 as the bolts in the top hinge pin mount? Also, does the hinge pin sit on top of the spacer with the bottom bolt slip fit through the spacer and thread into the hinge pin end? Or, does the hinge pin go all the way through the spacer and rest on the bobbin molded into the door?

I cross-drilled an 1/8" hole part way through the spacer hoping to get penetrating oil to the bolt threads, but that did not help. Should I center drill the bottom bolt and try an easy-out? If so, I need to know the bolt thread dia to avoid using too large of a center drill.

Thanks in advance for advice from the group,
Jerry
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PostPost by: JJDraper » Sun Jan 25, 2009 10:32 pm

I'm afraid I have no idea of the bolt thread, but my guess is that you are very unlikely to get them out whole! I have tried four time to remove these bolts after they have seized in place, without success. The threaded part goes over one inch up the centre of the pin, so unless it has been moved recently, and been well greased with anti seize compound, it is unlikely to move.

The only solution I have come up with is to procure new hinge pins (expensive, but should be available). Cut through the hinge pin at the point just above the lower spindle bush - time consuming and helps if you have a sharp and flexible hacksaw blade in a holder - see pictures. Then punch out the remains of the screw and remove the hinge pin. Note that you will also need to move the window motor out of the way slightly to allow you to rotate the pin 90degrees to allow removal through the top hole - again, see pictures.

I have heard of using a TIG welder to weld an extension to the pin to allow more force to unscrew it, but this is beyond my capability and I worry about the heat...If you can remove the pin without the destructive process I've described, good luck!

Jeremy
PS I have four good hinge pins waiting for some process whereby the screw remains can be removed - any thoughts?
Attachments
New pin 4.jpg and
Job done - now clear up the mess before wife gets back from Christmas sales...
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PostPost by: JJDraper » Sun Jan 25, 2009 10:38 pm

Sorry missed off the other pics...
Attachments
Removal efforts 1.jpg and
This completely failed and wasted loads of time!
Removal efforts 2.jpg and
Using a hacksaw blade in a special holder
screw remains removal.jpg and
I had to use a punch to push out the screw, and use mole grips to pull
Pin removal.jpg and
I found it impossible to do this without dropping the window motor a little
Pin removal 2.jpg and
New pin 1.jpg and
New pin 2.jpg and
New pin 3.jpg and
New pin 4.jpg and
Job done, now clear up...
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PostPost by: gerrym » Mon Jan 26, 2009 8:28 am

Jerry, 99% certain from when I had the same issues as you that the bolt was 3/8" UNF. I will check tonight for certain against my hinge assembly which is out of the car.

I do know that I replaced the fasteners with a countersink cap screw in stainless. Bernie the Bolt sourced this special fastener for me. The idea of the internal hex is to provide a greater torque capability than the slot drive.

Separate point, the hinge pins will probably be pitted which will mean a very short life for any new bushes you fit. SJS sportscars did a great job of replacing the pins with Stainless (303 grade)

Regards

Gerry
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PostPost by: gordonlund » Mon Jan 26, 2009 11:58 am

Can confirm the hinge pin bottom fixing is a 3/8 UNF countersunk set screw. I took mine out many years ago by drilling out the countersink portion of the screw and the remaining bit of screw in the door bobbin. This enabled me to strip and remove the door and then tackle the hinge pin on the bench. I used a lathe to drill out the remaining screw and remove remaining bolt threads carefully. I replaced the screws with 3/8 UNF c'sunk screws made from 10 mm c'sunk HTS Allenscrews of sufficient length to enable the plain portion to be turned down to 3/8, cut to length and then a 3/8 UNF die used to provide the new thread.

Reassembly involved load of copper grease to prevent reoccurance of original problem.

Gordon Lund
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PostPost by: davidj » Mon Jan 26, 2009 10:15 pm

I had this problem, and came up with (what I think) is the ultimate solution! At the base of the door there is a ali spacer. I very carefully drilled radially through this and the screw with a drill just less than the diameter of the screw. With a very slight twist of the screw head it sheared and the rod assembly could just be lifted out! I then held the rod in the vice and with a pair of mole grips quickly removed the remains of the screw. Because I only drilled through half of the spacer and did not damage the faces, I could reuse it and Mick Miller provided a new screw.

Mind you, I spent a very long time trying to shift it beforehand!

David
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PostPost by: js43lotus » Tue Jan 27, 2009 1:28 am

David, what you described is exactly what I planned to do. I just did not know what diameter the bolt had and did not want to drill too large a hole through the spacer. Now that I know it is a 3/8" I will try a 1/4" drill.

Thanks to everyone that replied! All of the posts were helpful.

Now, has anyone considered machining bushings out of brass in lieu of using the plastic bits? My thought is that the brass might arrest any post-install door sag due to the plastic deforming under the weight of the door.
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PostPost by: john.p.clegg » Tue Jan 27, 2009 6:18 am

The plastic doesn't deform under the weight of the door it wears...that is one sign the car's well used-you can lift the door up and down when open (generally drivers side).

I managed to make one of the bushes out of PTFE (and a little longer-twice the length I think ) you can only do that with one of the bushes (the reason escapes me now)and as far as I can remember thay are trunnion bushes...


John :wink:
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PostPost by: gerrym » Tue Jan 27, 2009 8:17 am

David et al, spacer as fitted to my car (looked as though it had never been apart) was steel not aluminium. make sure you have a sharp drill, suggest you work your way up through the sizes starting with 1/4".

Recall in the end I used an Easi-out. This will of course involve drilling into the head of the screw.

The hinge wear in my opinion is down to some fairly bad design practice. John is right, with a nylon bush the issue is wear. The lack of seal and original steel surface means some corrosion and scraping due to corrosion product and pitting will result in a short life. Also the nylon swells considerably with water absorption making clearance control problematical. PTFE on its own makes a very poor bush because it flows. That's why for example Glacier DU bushes are thin PTFE/Metallic amalgams on a steel backing.

Suggest that any means of lubricating the hinge in situ (with a non-moly grease) would be an improvement. Does anyone have any ideas for this (eg hole down the centre of the pin lubed from the top). It's a bit ironic that for almost any new car that one buys, the only things that require grease are the bonnet catch and the door hinges.

Regards

Gerry
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PostPost by: gordonlund » Tue Jan 27, 2009 2:29 pm

Door hinge problems are not just a Lotus problem. At least they don't fail catastrophically like some modern cars. My wifes two year old hatch passenger door nearly fell off when the top hinge pin just dissapeared. Apparently the pin retention clip had come "unclipped" itself. If it was not for my son holding the door it could have been an expensive repair. Needles to say I had it repaired under warrenty after a lengthy argument with the service staff at the main dealership from where we bought the car.
They tried to worm out of the warranty by saying that that item was not covered and was normal wear and tear. Threatening to take my business elsewere in future they decided to do the decent thing and repair it at their own expense. They pointed out that that the warrenty details where not of their making.

Poor design is not just the premise of small companies. At least Lotus doors don't fall off! Come to think, they are pretty well designed compared to modern cars. Have a look at your new car and lets see how many are just held on with a split pin!!

Gordon Lund
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PostPost by: mikealdren » Tue Jan 27, 2009 5:32 pm

David,

I wasn't able to get the screw out on one door as the head had been damaged beyond recall. I loosened the top mounting then cut through the bottom bush and screw with a hacksaw. I was then able to remove the bottom hinge and withdraw the hinge pin.

The remains of the screw were firmly corroded to the hinge pin but heating the pin with a gas torch freed it up. Even though I managed to extract the screw, I ended up buying a new hinge pin from Paul Matty - quite expensive.

Gerry's stainless solution sounds just the job

Mike
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PostPost by: gerrym » Mon Feb 09, 2009 4:55 pm

Have a laugh...

Quote from Plus2 130 Introductory Brochure (copy on this website)

Although your LOTUS requires only minimal attention between its widely spaced services, accessibility is designed to the LOTUS +2S 130. Whether you wish to check the oil or change a wheel, inspect a fuse or oil a door hinge, serviceability is good, saving your time and money.

Regards

Gerry
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PostPost by: soccy123 » Sat Jul 11, 2015 7:21 pm

has anyone out there fitted poly trunnions for the hinges
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PostPost by: BullAndrew » Sat Jul 25, 2015 12:18 pm

An interesting thought, I was going to make new stainless steel pins and was thinking if making oilite bushes made sense, but poly bushes could be a thought.

Like you interested if anyone has tried this or has an opinion

Regards
Andrew
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PostPost by: McBiter » Fri Jan 18, 2019 4:42 pm

Just a note to say thanks.
I thought more force would solve the issue but evidently a more serious approach is necessary!
New hacksaw acquired.
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