Repairing GT Headlight Rotator Mechanisms

[kwilford]

One of the best features of the Opel GT is its rotating headlights. And its one of its most troublesome features as well.

A very common problem (so common that many cars have it and the owners don't even know) is broken rotator bolts. These are the three wee little M5 bolts that clamp the headlight buckets, via a set of three spring steel strips, to the rotator gear. When one breaks, (and its not "if", but "when"), the headlights usually still rotate and lock in both the up and down position. But when two of the three break, the bucket is no longer "fixed" to the position of the rotator mechanism, and will often lock open, but not shut, or vice versa.

Many articles have been written about the general repair and trouble shooting of the GT headlights. We have a section here DEVOTED to the topic, with 31 threads to date already. But a recent thread related to repairing the rotators when the old bolt is broken off inside the rotator gear, and I thought I would create a thread dedicated to the topic. So here goes.

[kwilford]

Here's a photo of a rotator which has two of the three bolts broken. You can also see the spring strips (sometimes called "swivel strips"). Often these get broken as well, but at least they are easy to repair (if you can find a replacement set). In this case, I labelled this rotator "PS" for Passenger Side, which will prove to be important later on

[kwilford]

Here is the Drivers Side, which had all three bolts broken off inside. And that is the problem. These wee bolts are Grade 10.9, which is equivalent to a SAE Grade 8. So they are pretty much impossible to drill out using conventional means, and unless you remove the old bolt, you can't install new bolts. A true Catch 22. So I am going to show you an almost fool-proof way to repair these. This photo also shows the three roll pins, which was all that held these rotators to the spring strips.

What REALLY ticked me off here was that I bought both of these off eBay, and the vendor ASSURED me that all the bolts were intact (I knew enough to ask). But he also broke one of the rotator rod pins off when he disassembled them, so he refunded me the cost excluding shipping. But as it turned out, I needed the parts anyway...

[kwilford]

Here are a couple of useful photos for later when you go to re-install the rotators. It shows which wire goes to which terminal on the micro switches

[kwilford]

Next, remove the rotators from the car. I have heard about folks using bolt extractors, but since the M5 Grade 10.9 bolts are SO hard and SO small, I have never been successful at it.

Remove the micro-switches and whatever rotator bolts are still intact, and the swivel strips, front washer and rotator roll pins. You might be inclined to leave the roll pins in place, but you are almost certain to push them in all the way while you are working on the gear, and then they are a BUGGER to remove (I found that a small taper tap, #40 I believe, can be threaded into the roll pin and then the tap can be pried out with the roll pin). Here's a photo of how I removed the roll pins

[kwilford]

Clamp the rotator in a vice as shown (upside down, so you are looking at the back), and carefuly grind away the five rivet heads. You can use either a dremel, or a right angle grinder (which is what I used)

[kwilford]

Pry between the backing plate and the front plate with a large screwdriver or pry bar. If you have removed the rivet heads, it doesn't take much to pry them apart

[kwilford]

Here is what you will see

[kwilford]

Be careful NOT to mix up the centre or outer gears from one side to the other. They are DIFFERENT. Easy to tell the difference if you know what to look for. The first three sets I rebuilt, I DIDN'T, and managed to switch only one set of gears. Here are the differences of the inner gear, with the PS for Passenger Side, and DS for Drivers Side. The outer gear has the rotator rod pin at different places from right to left. I believe the gears are actually identical, but the pin is located at the fourth tooth on the Drivers Side, and the sixth tooth on the Passenger Side, by merely being driven in from one side or the other (back to back, the outer gears are identical).

[kwilford]

OK, on with the repair. The first photo shows the centre gear, with one bolt broken off. The first few times I tried to repair these, I thought I would just drill out the old bolt from the front and re-tap the hole. But the bolt is hardened (remember Grade 10.9), and the gear is even HARDER. Bloody hard, in fact, so you can FORGET about using a taper tap to re-thread the holes. And the biggest issue is the bolt holes aren't threaded right through. Only the front three quarters of the hole is threaded. So turn the gear OVER and drill it out from the back. Use a 5/32 inch Titanium or Cobalt bit, and if possible, use a drill press. You want to spin the drill bit as slow as you can, and place LOTS of downward pressure. You don't actually drill the old bolt out. You SPIN it out the front! Works every time. Guaranteed! That's the second photo

[kwilford]

Here's a photo of the little bolt that causes all this grief. They are unique, in that they have a self locking feature (the small strip of plastic that can be seen along the length of the bolt) and a taller head than normal. When you replace them, make sure you get a Grade 10.9 bolt, and use a drop of Lok-Tite to ensure that they don't come loose (which probably contributes to their susceptibility to break). The Grade 8.8 might be easier to drill out, but I am quite certain they will break much more easily. It has been pointed out to me that a SAE 10-32 thread is the same as the standard M5, so if you are having problems finding a Grade 10.9 M5 bolt, try asking for a Grade 8 10-32 bolt. Better yet, ask for the Socket-Head cap screw version (Allen head), as that would be easier to install than the standard hex-head bolt. (Thanks to our resident Kiwi, GTJim, for the bolt info)

[kwilford]

Another thing to watch for is a bent outer gear. When the Previous Owner (not YOU!) slammed the headlights open and closed repeatedly to try to make them lock, they may have damaged the outer gear. If it has too much clearance between the inner gear and outer gear, as shown below, you can CAREFULLY bend the outer gear to reduce the clearance. Use a large bench vice as shown, and take small steps. Much easier to bend them smaller than bigger. Especially watch the clearance at the middle of the outer gear.

[kwilford]

Other damage to watch for includes a broken tooth on the inner gear. Here is a photo of two gears, one damaged one not. By the way, the shortened first tooth is supposed to be that way

[kwilford]

Clean up the parts, and lubricate the moving parts. Make certain that the latching mechanisms aren't seized or sticky. I found that a few rotators just needed a good cleaning in my solvent tank, but three of the five sets I have rebuilt were quite rusty, inside and out. I gave then a little glass bead blast and painted them with a light coat of "Weld-Thru Hi-Zinc Primer", inside and out. Then, re-assemble and lubricate, making sure that the inner and outer gears are in the correct housing (passenger side versus drivers side), and properly aligned. Also ensure that the latch lever (the lever that is attached to the centre gear with the infamous M5 bolts) are on the correct side. They are side specific, as they have a hole in them that corresponds to the nut on the bucket assembly. I suggest that you don't go TOO wild with the lubricant, as every set I disassembled had a layer of dirty, solidified grease inside, which can't do ANY good at all. My preference was to lightly spray the moving surfaces with a lubricant called "Fluid Film", which is pretty tenacious, and doesn't leave a thick film that will attract dust and dirt.

Next, install the two bolts in the top holes to hold the pieces together, and use a pair of vice grips to hold the rivets in place. Apply a small weld over the rivets (I used my MIG welder, but a gas welder or small arc welder would work fine). You don't need a big heavy weld. Just enough to hold the halves together. Finally, spray a bit more zinc primer over the welds, and re-assemble.

HTH

[madhatterpdc]

Originally Posted by kwilford My preference was to lightly spray the moving surfaces with a lubricant called "Fluid Film", which is pretty tenacious, and doesn't leave a thick film that will attract dust and dirt.

Would the lubricants intended for use on bicycle chains be sufficient? I use Finish Line Teflon Plus Dry Lube on my bikes. It pretty slippery, lasts a good long while and resists accumulation of grime.

[houserc]

The other area to lube would be the lower pivot assemble. This is the pivot point opposite the rotator assemble.

I just pulled one side and lubed it yesterday and what a difference in the easy of flipping the lights now.

As far as what to use, I used the same white lithium grease I use on packing wheel bearings. It lasts a long time, is pretty resistant to heat, and won't eventually run off.

[jordan]

could a craftsman easy-out type "damaged screw remover" remove the little bolts, Im sure that they are above grade 8 and should have a good bite, and this would allow for bolt removal without separating the headlight rotator mechanism.

http://www.sears.com/sr/javasr/produ...id=00952154000

[namba209]

Jordan, those Craftsman tools are for recessed head type fasteners that have stripped out heads. If you can get a wrench on the bolt heads and the threads are in good condition, not rust welded in place, you should be able to remove them. To be on the safe side I would use a rust penetrant like liquid wrench, rust eater or PB blaster liberally and over a fair long period of time before attempting to remove the bolts. Keith has a real good thread on repair and maintenance of the rotater assemblies he has attached to this thread. Read it in its' entirety, there are a lot of good tips in this that can be very helpful. Lotsa luck in this endeavor, a lot of us, "have been there, done that". BTW, the bolts can be converted to a 10-32 SAE thread from the metric. They are very close in threads per inch and thread pitch so that one will work in either application. I plan to replace my bolts with 10-32 aircraft allen head bolts drilled for safety wire, and I won't have to tap out the holes to use them. HTH.

[jordan]

I was lucky getting these bolts out, one wasn't broken so that came out easily it backed off so it was loose. And one of the 2 left took about 5 minutes with a small sharp chizel and the other one took about 10 minutes; I was just working the small piece of bolt out counter clockwise.

[jordan]

I am now reassembling the light rotators but I only have 2 wires on the passenger side for the micro switch and I only ever remember there being too becuase I thought it pecular, any ideas? the wires are yellow/black and black.

[kwilford]

Originally Posted by jordan I am now reassembling the light rotators but I only have 2 wires on the passenger side for the micro switch and I only ever remember there being two because I thought it peculiar, any ideas? The wires are yellow/black and black.

Black wire to the "common" terminal, black w/ yellow stripe to the "NO" (Normally Open) terminal on the passenger side micro-switch. Which, according to my '70 FSM, are the correct colours and wires for the pre-'71 GT. One of several differences between the early and later GT's.

HTH

[jordan]

I reinstalled the headlight bucket and rotator but it won't latch in the open position, is there anything I can do to trouble shoot wiht out taking it apart.

[namba209]

Jordan, it takes the rotating mass for the arm and attached locking pin to impact the latches and force the latches to open against spring pressure. You can't just rotate the assembly slowly to get it to latch. Try to lube the area heavily, to see if that will help. You can also disconnect the rod at the cable attachment and operate the rod/rotating mechanism manually to see if that will help lock the mechanism, but you really have to use some force to get the latches to move. HTH.

[houserc]

The rotating force would be the first thing I checked out.

However, if you somehow got the rotating cogs switched, the latching arm will be out of position to latch properly when rotated.

One way to check this out, at least it worked for me. You will be able to latch them if your push hard on them. BUT, they will not come unlatched without having to trip the release mechanism inside the hood area.

I found out by installing a driver side cog in the passenger side rotator.

Hope that helps if force doesn't. There should be some good photos earlier in the thread showing the differences between the two cogs.

[jordan]

I have swung those open with plently of rotating force but the little locking arms and guts just go flush with the rotator mechanism housing.