Subject: Collector Edition Hatch Hinge Installation Instructions Rev 4

Subject: Crossfire tech - fixing failed attempt to repair broken off screws.

FIXING A FAILED ATTEMP TO REPAIR BROKEN OFF SCREWS

Initial Release 06/16/08

REVISION 01 – 06/16/08 For Clarity, added ‘F’ designation to ‘fix procedure” steps. Added caution and changed procedure for drilling out throttle plate holes in Step F7.

REVISION 02 – 06/17/08 Changed photo in Step F7.

REVISION 03 – 07/25/08 Added links to and updated article references

REVISION 04 – 08/05/08 Add ref to REAMED bushings article

Difficulty level: Moderate

Special Machines required: drill press (or mill) with vice.

IMPOTANT NOTE: These tech articles go thru periodic revisions to add or update info. The link does not change, so check back before you use the instructions to be sure you are using the latest version.

** I want to add my thanks for the excellent feedback I have gotten. There’s no point in doing this if I’m not providing the info people want, so the contributions from readers are all valuable. **

Note: use the browser back button after viewing links in this document. Adobe .PDF versions of these articles (that can be printed including the pictures) will be available soon

This is a special addition to the series of tech HOW-TO articles on maintaining and improving the crossfire injection system. This article is in response to requests made by readers and it is specific to Crossfire, but the principals can be applied to any shaft or other part with a failed attempt at screw extraction.

Articles released so far:

Crossfire Throttle Body Rebuild including Installation of standard Shaft bushings Difficulty Level: EASY – Special machines required: NONE

http://www.thecubestudio.com/CrossfireThrottleBodyRestoration.htm

A special follow-on article by request is here:

http://www.thecubestudio.com/CrossfireTechFixingFailedAttemptToRepairBrokenOffScrews.htm

Crossfire Throttle Body Rebuild including Installation and REAMING of accurate Shaft bushings Difficulty Level –MEDIUM – Special machines required - Drill press with vice

http://www.thecubestudio.com/CrossfireThrottleBodyRestorationREAMEDBushings.htm

Straightening bent shafts and arms. Difficulty level: EASY – Special machines required: bench Vice.

Above operation IF arms are loose on shafts. Difficulty level: Moderate – Special machines required: Brazing torch.

http://www.thecubestudio.com/CrossfireThrottleBodyStraigteningBentThrottleShaftArms.htm

Building your own water manometer for $6 in materials from any hardware store. Difficulty level: EASY – Special machines required: NONE

http://www.thecubestudio.com/CrossfireHomeBuiltManometer.htm

Correctly and accurately balancing the Throttle bodies. Difficulty level: EASY – Special machines required: Water Manometer, air passage plugs (home made)

Above operation IF balance screw if still welded. Difficulty level: Moderate – Special machines required: Rotary cut-off tool or hacksaw

http://www.thecubestudio.com/CrossfireThrottleBodyBalancing.htm

Follow on articles will cover:

Adding sealed stainless ball bearings to the TB shafts instead of simple bushings. (best) Difficulty level: Advanced – Special machines required – Lathe

Note: After some thought and discussion, I have concluded that this is NOT a do-it-yourself project and this article may not be released. Feel free to comment on that.

Rebuilding the injector POD. Difficulty level: EASY – Special Machines required: NONE

This will be the next article released and the article now contains some optional special performance modifications which will require machining. Standard rebuild is still EASY no special tools.

Porting the crossfire manifold. Difficulty level: Advanced – Special Machines required: Die Grinder (not a Dremel tool), Non-ferrous carbide cutters, Sawzall or rotary cut-off tool, Milling machine. Metal forming skills.

One additional article specific to the 1982 Collector Edition Rear Glass Hatch is here:

http://www.thecubestudio.com/CollectorEditionHatchHingeInstallationInstructions.htm

FIXING A FAILED ATTEMP TO REPAIR BROKEN OFF SCREWS

You need these items available from your own tool box or any hardware store:

A piece of 1/8” (minimum) thickness by ¾” to 1-1/2” wide steel. This can be a new piece from the hardware store for a couple bucks or an old door hinge or heavy shelf bracket . . whatever you have lying around.

Drill bits

#6-32 specs a NUMBER 36 drill bit (.1065”) but you probably have a 7/64” (.1094”) which will work fine.

#8-32 specs a NUMBER 29 drill bit (.1360”) but you probably have a 9/64” (.1406”) which will work fine.

#6-32 and/or #8-32 tap . . do not need fancy, just plain old hardware store taps (Vermont or Hanson) – couple bucks.

#6-32 and/or #8-32 screws over ¼” long. – OK now you need fancy - do NOT use slotted screws that you find hanging in little packs at Lowes/Home depot, etc. Get good button head cap screws from the specialty nuts and bolts section . . you now the ones in the little partitioned drawers that they burn you a buck each for. These fasteners usually are allen head and are high strength. I use torx® because I despise allen heads, but you probably won’t find torx ® at the hardware store, so allen head is the next best thing. And yes, I’ve gone to the hardware store myself and paid an outrageous $1.15 for a single stainless M4 x 25 screw to use for a Crossfire Idle stop. In a box of 100, they cost me 17 cents . . so no whining, just buy the screws already.

Speaking of whining, let’s talk repair psychology. These types of repairs can be very frustrating and any normal person is going to become less and less patient as things go from bad to worse. Then the concept of a ‘destroyed’ part floats into the scene and adds another layer of anxiety. So, to avoid all of that, keep in mind that it takes a lot to ‘destroy’ a part to the point it cannot ever be repaired. In the case of throttle shafts, even a loose arm or a very nasty hole can be brazed up and the shaft re drilled and tapped or even an entire new shaft can be made up fairly easily. Here is a new custom shaft I made for a current project. The steel arm is a modified Crossfire piece:

http://www.thecubestudio.com/pictures/Dually/ShaftNewEndPeenedWEB.jpg

And the completed shaft.

http://www.thecubestudio.com/pictures/Dually/ShaftNewCompletedWEB.jpg

So worst case is not that bad. Take your time, follow the steps here and you CAN fix a very jazzed up shaft.

First we’ll look at

The correct way to repair a broken off screw and then the way to fix things up if the repair goes badly, of if you get a jazzed up shaft from a ‘friend’ that needs fixing.

STEP 1

Assess the damage. Let’s see what we have here:

http://www.thecubestudio.com/pictures/FixTBshaftHoles/LookDownBoreWEB.jpg

OK, that’s ugly . . let’s fix it up.

STEP 2

Get the shaft out. That is covered in another article here:

http://www.thecubestudio.com/CrossfireThrottleBodyRestoration.htm

However, in this nasty case, we could use a tip to turn that nasty stripped out screw head . . self explanatory:

http://www.thecubestudio.com/pictures/FixTBshaftHoles/TurnScrewWithCuttersWEB.jpg

STEP 3

Center punch the broken off screw. Unless you have a mill and a spotting drill bit, you MUST have a good center punch mark for the drill bit to follow. A bit this tiny will wander all over the place. Trying to drill out an broken off screw without a center punch mark or ‘choking up’ on the bit (more on that later) is how most repairs attempts go south.

Tips:

Take your grinder and make a very slight depression or ‘bowl’ on top of the broken off screw. Note we always attack from the broken side, not the bottom of the screw.

http://www.thecubestudio.com/pictures/FixTBshaftHoles/GrindBrokenScrewInsideWEB.jpg

Now center punch right in the middle of the screw shaft:

http://www.thecubestudio.com/pictures/FixTBshaftHoles/CenterPunchUsingWEB.jpg

Oops! Get a little off center? No problemo. Did you know you can actually ‘move’ a center punch mark? Here’s how; just put the punch in the old mark, angle it as if the punch can ‘push’ the hole sideways and whack it again. OK, it’s redneck, but it works:

http://www.thecubestudio.com/pictures/FixTBshaftHoles/CenterPunchMoveWEB.jpg

Don’t even think about drilling until you have something that looks about like this:

http://www.thecubestudio.com/pictures/FixTBshaftHoles/CenterPunchMarkWEB.jpg

If your punch mark is hopelessly off center, grind the ‘bowl’ a little deeper and try again.

STEP 4

Drill out the screw.

http://www.thecubestudio.com/pictures/FixTBshaftHoles/DrillFor6WEB.jpg

Tip:

Ever play baseball? You can ‘choke up’ on a drill bit just like you did on the bat. This is another trick that stabilizes a tiny drill bit and helps it not wander over to New Jersey as soon as it touches the work piece. With a collet, this does not harm the drill bit. With a drill chuck as shown here, you can easily crush the tiny drill bit into oblivion because you are actually clamping on the flutes. Be gentle and you can get away with this trick, but even if you destroy the bit in the process, it’s a $2 bit and you may save your crossfire shaft so the sacrifice is logical.

http://www.thecubestudio.com/pictures/FixTBshaftHoles/DrillFor6ChokeWEB.jpg

If you want to go Pete Rose and increase your odds, you can use the ‘choke up’ trick on a 1/16” bit and drill a tiny hole in the middle first. The smaller drill will follow the center mark better and then the larger drill will then follow the small hole.

http://www.thecubestudio.com/pictures/FixTBshaftHoles/DrillFirstHoleWEB.jpg

STEP 5

The shaft is drilled out, so you simply run the #6-32 tap thru and viola, Miller time:

http://www.thecubestudio.com/pictures/FixTBshaftHoles/New6ScrewInShaftWEB.jpg

Properly, the hole should be countersunk, which helps the tap and also the screw start into the hole better. If you choose to do this, keep it absolutely minimal as we want as many threads as possible in this thin bit of shaft.

FINISH

CLEAN the threaded holes and the fasteners with brake or carb cleaner before you do final assembly into the TB. Use blue or red or green Loctite on the screws. I use a drop of green on the protruding end of the screw after it’s tight. If you haven’t used this stuff before, be aware that the Green is designed to ‘wick’ into tight places so it is very thin (runny, watery) A tiny squeeze on the tube can make a huge mess . . and you definitely don’t want it running down the shaft into the bearings or bushings or whatever you used for the rebuild.

Next up. How to fix up a failed repair attempt.

OK, now for the fun part. Let’s say you just left a quarter on your workbench next to the shaft hoping to lure the screw extractor fairy. She shows up, but she was in a hurry and skipped the all important STEP 3 above so in the morning, the quarter is still on your bench and your throttle shaft now looks something like this:

http://www.thecubestudio.com/pictures/FixTBshaftHoles/BadlyDrilledShaftWEB.jpg

I took a perfectly good shaft and jazzed it up nasty in order to show an example of the worst mess that anyone could possibly make. So if we can fix this, we can certainly fix your tiny mistake, right? No problemo.

STEP F1

Locate appropriate material. Do not try to use wood, aluminum, rock hard pizza crust from last week or anything else except 1/8” thick steel (minimum). What you are actually going to build is a redneck drill bushing. Real ones that are used in manufacturing are made from hardened tool steel. You only need to use yours once, so you can get away with using soft steel, but even that is not exactly a guarantee of success. Using anything else is a guarantee of failure.

http://www.thecubestudio.com/pictures/FixTBshaftHoles/BushingMaterialFitUpWEB.jpg

STEP F2

Mark where you need to drill the bushing hole:

http://www.thecubestudio.com/pictures/FixTBshaftHoles/BushingMarkDrillPositionWEB.jpg

Do the deed:

http://www.thecubestudio.com/pictures/FixTBshaftHoles/BushingCreateHoleWEB.jpg

STEP F3

Very important step. If you don’t get this right, there will be no joy. Line up the drill bushing hole over the original broken off screw shaft and clamp it securely to the shaft with a locking pliers (Vice Grip).

http://www.thecubestudio.com/pictures/FixTBshaftHoles/BushingPositionWEB.jpg

STEP F4

Slap that baby back in the vise and slowly and carefully using the bushing hole as your guide, drill thru the shaft. This is why the bushing must be made from steel. If it were aluminum or something similar, the drill bit, which is sharp on the sides, would jump sideways into the incorrectly drilled hole in your shaft and simply hog out bushing hole in the process. The idea here is that the bushing is as hard as the shaft and screw and it will sacrifice a bit of it’s side, but will hold the bit in place enough to get a hole in the shaft where you want the hole to be . . which in this case is right over the broken off screw.

http://www.thecubestudio.com/pictures/FixTBshaftHoles/BushingAndShaftDrillThru8WEB.jpg

If you follow all of the steps exactly, this WILL work and your new hole will now be ready to tap . . BUT, do not unclamp the bushing yet. Leave the setup as it is.

STEP F5

Time for more sacrifice. Tap 8-32 thru the bushing itself AND the shaft. This will further align the new bolt with the original position of the old screw.

http://www.thecubestudio.com/pictures/FixTBshaftHoles/TappingThruBushingTopWEB.jpg

BTW, You do not need a fancy spiral tap like this. A plain old El Cheapo hardware store tap will do fine. I strongly suggest you drive the tap by hand. Even if you have it chucked up to keep it straight. Turn the chuck by hand. Use oil . . . preferably tapping fluid . . it makes a big difference here.

STEP F6

Oh wait, there is no step 6 . . you’re done!

This is what your new tapped hole will look like from the bottom. Half of those threads are in the bushing.

http://www.thecubestudio.com/pictures/FixTBshaftHoles/TapThruBushBottom01WEB.jpg

Because this was such an extreme example, there remains a bit of the badly drilled hole, but you can trust me on this; it will not effect the ability of the new screw to hold the plate on just fine.

http://www.thecubestudio.com/pictures/FixTBshaftHoles/RepairedHoleBottomWEB.jpg

http://www.thecubestudio.com/pictures/FixTBshaftHoles/New8ScrewBottomWEB.jpg

STEP F7

Well, we are done with the shaft, but since we had to go to a #8 screw, the holes in the throttle plate need some attention: #8 screw is .164” so 11/64” or 3/16” should ‘git er done’.

Hold the plate with a pliers by the top and bottom surfaces and just rest it on TOP of the vice jaws to drill it out. That way there is no chance of nicking up the edges which will effect the operation of the TB.

http://www.thecubestudio.com/pictures/FixTBshaftHoles/DrillThrottlePlateWEB.jpg

This is what you want to end up with. Looks a little Robo with the relatively larger screw heads, but it will work fine and will outlast the rest of the car.

http://www.thecubestudio.com/pictures/FixTBshaftHoles/PlateWithNewScrews8WEB.jpg

FINISH