Clocking Alternators

When I first started the restoration of my car back in 2011 I had no working electrical parts at all when I bought the car. Firstly there was a fire under the dash were the nutter who owned the car before me had wrapped a fuse with tin foil for some reason. Secondly the original alternator had rusted up and I didn’t trust it. So the only option I could see was a replacement wire loom from American Autowire for the Ford Mustang. Their recommendation is to use a one wire alternator. The choice was limited at the time as a result, so the best option I found was Tuff Stuff. I purchased a standard v belt in chrome with a 100amp rating at the time.

However there was a problem with the terminal for the single positive wire. The stud it connects to sits about 1/4″ away from the block even at the maximum distance on the standard alternator bracket. These pictures of the stud in the normal position for Tuff Stuff alternators.

Initially I had my alternator bracket custom-made to move the alternator much further away from the block with a longer belt to make it work and be safe.

This was fine at the time, but the step for the belt clearance was now in the wrong place which meant that the bracket was just a millimetre away or so from the edge of the belt. This occasionally rubbed as you can see below. I kept a very close eye on the belt for signs of fraying or any damage to the belt. None of which has happened as a result of this modified bracket I might add.

Later on while browsing the net I didn’t realise that the case on these alternators could be adjusted by ‘Clocking’ or ‘Indexing’. Basically this means that you can move the body case around to where you want the stud to be by moving the front fittings. Nowhere could I find a step by step guide on how to do it.

Note: not all alternators can be ‘Clocked’ and you should check before you try doing it.

The only thing I found was these instructions from Tuff Stuff. Note ‘point 7’ mentions the use of torque settings for tightening the centre pulley nut. Interestingly Tuff Stuff use both terms ‘Clocking’ and ‘Indexing’ in the same document.

Nowhere is this ‘torque’ setting documented on the Tuff Stuff website, so I contacted Tuff Stuff for their ‘help’ and advice via their message process, for what good it was. Their automated response said I would ‘get a response within twenty-four hours’. After a few days nothing, so I tried again with a different email address. They responded the next day where they just sent me the instructions above with no words within the body of the email. My response was immediate back to them, stating that I already found the document on their website and asked again specifically for the torque settings. Their response with the following:

On 4 Oct 2018, at 14:12, Matt Oliver <matt@tuffstuffperformance.com> wrote:

We use an air wrench to put on all of the pulleys here. Thank you for your business. Have a great day!

Matt Oliver
Tech Manager

Hardly helpful when they say you should “torque to settings” which they obviously don’t do themselves. Not exactly confidence inspiring by any shape of the imagination, not to mention poor documentation.


So, with the lack of information I decided to do it myself!

As I had already fitted the alternator, the process below also shows the removal. If you have a new alternator you can skip these first few steps on removing the alternator and go straight to the ‘Clocking‘ process below.

  • First things first is to disconnect the battery.

Disconnect the single wire from the back of the alternator. Remove the tension bolt for the alternator which fits inside the bracket’s slot gap. Then loosen the hinge bolt at the top for the alternator. Unhook the v belt and remove the hinge bolt fully, taking the weight of the alternator remove it to a work bench.

Figure 1


My research and a warning;

If you read some of the forums out there on this subject, they say that you can undo the four case bolts and move the back around then retighten. This saves the hassle of undoing the rotor nut. WRONG. This could damage the springs and brushes internal components within the rear housing. You should only clock/index the alternator by moving the FRONT housing part of the case only.


‘Clocking’ process – also called ‘Indexing’

With the alternator on its side we will need to lock the cooling fan in place. I used a long-handled probe between the fins and resting on the bench surface. A screwdriver could also do the job.

The fins are not evenly spaced, and you will need to find the best place to wedge your locking tool in place. This should be on the same side (left) looking from the front of the alternator when you are undoing the rotor nut counter-clockwise.

The best way to remove the rotor nut is to use an impact wrench. I used my cordless Snap-On 3/8 impact driver with a 15/16ths impact socket. It’s for this very reason that people incorrectly move the back part of the case around, just because it’s easier.

Holding as much of the unit still as you can, buzz the nut until it’s undone. Once the nut has been removed take out the locking bar you have used.

With the nut fully removed depending on your pulley type, (remove the parts one at a time, taking note of how they fitted together). Remove the spring washer next, then remove the v pulley from the face plate, followed by the polished face plate.

The final part is to slide of the fan itself. You will notice it has a key way cut out, but there is no key way on the rotor shaft itself, just a plain round shaft as shown. You can clearly see the uneven fan spacing here that I mentioned earlier.

There are four case bolts 5/16th which need to be loosened from the back of the case, I used a ratchet to break them free before using a cordless screwdriver to undo the rest. The bolts are quite long seated into the front half of the casing.

Once the four bolts are removed, hold the case together while resting the alternator on its back with the rotor facing up.

Gently separate the top from the stator (the black plates between the top and bottom half of the case). Lift up the top part of the case to a max of 1/4″ without disturbing the stator. Turn the front case by 90deg increments to where you need it to be. The pics I have marked below showing the gaps between the case during the indexing process.

Re-align the two halves of the case again and lower the top part of the case back down.

With the top is in place, hold the case together to stop it moving and turn the alternator onto its side again, finger tighten the four long case bolts back up. Spin the shaft to make sure that there is no snagging and spins freely.

Check that he rear stud is where you need it to be, perhaps do a dummy fit to the engine if required. Once you are happy with the location, tighten the case bolts back up. Do not over tighten the four case bolts, I recommend using the manual ratchet for the final tightening.

Spin the shaft once again to make sure it’s all still free spinning.


While the alternator was apart I took the opportunity to clean the case and the front sections. I was not happy to find bits of the chrome flaking of. I used Auto Finesse metal polish to remove the marks on the chrome and then Auto Finesse mint rims wax to seal the chrome.

I didn’t clean the spring washer or the back of the locking nut too much. The simple reason is that friction is required for the hold all the components on the rotor shaft.


Refitting The Parts

At this point you could replace the pulley style if they is your intention to change the look or function to a Serpentine setup maybe.

Replace the fan onto the shaft first making sure the fins are facing backwards.

Next make sure the cover plate is fitted the correct way round with the dish section fitting inside the fan recess.

Next is the v belt pulley that will sit flush onto the face plate, again the raised section fitting into the recess of the face plate now.

Slide the spring washer into the shaft and into the v pulley recess. Finally the nut is fitted and finger tightened for now. Spin the rotor to make sure all is free and not snagged anywhere.

Now insert the locking tool you used earlier on the other side (right) between the fan blades to hold the section still once again. Now re-impact the nut clockwise back into place securely.

Remove your locking tool and recheck that the whole section spins freely again.


Refitting the alternator

Place the long pivot bolt and washer into the pivot section of the alternator and through any spacer required to align the pulleys up correctly to the lower crank pulley. Finger tighten the bolt for now into the engine block. See ‘Figure 1‘ above.

If you are mounting the alternator bracket for the first time, lightly tighten the bolt above the main crank pulleys to hold the bracket in place, but movable to locate the tension bolt.

Next insert the tension bolt and spring washer through the bracket slot into the alternator case. Slip the v belt over the pulley. See Figure 1 above.

Pull the alternator to tension and tighten the tension bolt just enough to hold the alternator in place for now. There should be 1/4″ to 1/2″ movement up and down on the belt. I prefer the twist method for the belt, twisting the belt 90deg in the middle between pulleys.

Once you are happy then fully tighten the tension bolt, Pivot bolt and the bracket bolt if needed.


At this point I took the time to clean up the cables up before refitting them. Connect the one wire back to the alternator stud and tighten up. Reattach the battery connection.

Start the car and make sure that you are charging correctly and that the belt is not slipping on the pulleys.

At this point I tidied up all the cables around the solenoid, the battery cable to the alternator, the cables for the engine block and starter motor so it all looks neat and tidy again.

That’s it, all done and took three hours in total which included the cleaning, rewrapping of cables, photos for this walk-through and tidying up of cables. I also have to clean all my tools after I have used them. It’s all part of my OCD problem regarding my tool box. I intend to get the proper bracket and belt shortly, but it’s not important right now as it still all works.

As far as I know, this is the only guide for a Tuff Stuff alternator clocking. I hope it helps somebody else out there. Apologies for the more tech styled post, but I had to share it. 🙂

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About One man and his Mustang

I'm just a man with a Classic 1966 Ford Mustang Coupe and a collection of tools that just keeps getting bigger in order that I could do the job right. When I first started this blog this is what I wrote: "I had bought a project car, that had been neglected, set fire to, rusted and abused. As a result of that she needed a bare metal strip down, a nut and bolt restoration." Four and a half years later the car was completed, on the road and shown at the UK's premier Classic Car Show, everything that was done to that car is documented here. I now have the privilege to drive one of America's most recognised cars and a true Icon, the Ford Mustang. I'm still sane after the blood, sweat and tears, so would I do it again? Oh yes!
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2 Responses to Clocking Alternators

  1. RichardReina says:

    Hi Mart,
    It took me a while to get to this one, but GREAT post. I personally enjoy the more technical posts, as I always find things of interest, or tidbits that could help me down the road. I also recently replaced my alternator (on my Alfa), and also went with the one-wire job. It works great! (And ironically, I buy most of my Alfa parts from a U.K. supplier.) Good luck with yours!
    Regards, Richard

    Liked by 1 person

    • Hi Richard, Thanks for the comment I appreciate it. This was a little more technical but there is nothing like it out there for the Tuff Stuff. There are videos where people bash the centre spindle through the case to make it move. But this is the ‘official way’ according to the sheet of instructions. One wire alternators do seem so much better to be honest. I have a chrome dummy voltage regulator that had blown in the front of the engine bay that is pigtailed into the loom to like it’s being use. But, shhh don’t tell anybody! 😀 same for my parts they are all from the UK. I’m not that happy with the chrome finish on the alternator now, so i think I have a project to rubber spray coat it to make it look better. coming soon to a post near you. 🙂

      Like

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