Lower Alternator Bracket Upgrade

When I fitted the Denso alternator I fabricated a new top bracket.  For the bottom bracket I reworked the original Lucas ACR bracket from Tiger.  I removed the mounting pieces and had the local welding shop add new ones for the Denso.

After fitting I did worry a little that this bracket had no lateral bracing and may be weakened by the sideways forces combined with it being 'pulled' across the front of the corner of the engine.
A week after returning from the 1,500 mile Euroblat trip I was having a general check under teh

It is not surprising that it failed as it did.  I was just lucky I did not breakdown.  Here you can see where the edge of the engine was contacting the bracket.

It it probably a bit over the top, but for a replacement I used some 5mm right angle steel and got some mounting pieces welded on.  All painted up and ready for fitment.

It is perhaps possible to lighten this further, but I didn't want to unwittingly introduce any weak points into this new bracket.  It was mounted with spacing washers slightly proud of the engine so as not to have the corner of the engine pressing against the bracket where the failure occurred on the old bracket.

FIA Kill Switch

I'd been meaning to fit a battery isolator for a while.  Partly as a safety feature for when the car is stored in the garage and partly in preparation for possibly taking part in formal motorsport events, e.g. sprints.

There are simple isolators available that just cut the positive connection to the battery.  They achieve the goal of isolating the battery, but if turned off whilst the engine is running, will very likely kill the circuit in the alternator, as the load has nowhere to go.  Also, if the ignition coil/ECU is not isolated from the alternator, it is possible for the engine to continue running even after isolating the battery.

The solution to both of these issue is to use the more advanced model of isolator switch.  As can be seen below, this not only breaks the supply to the coil/ECU, but also dumps the alternator load to a resistor for the short period after the isolation switch is activated and before the engine ceases to rotate.

The main challenges to fitting the switch to an Avon with the bodywork fitted was finding a suitable location for the switch as well as routing the wiring.  I had some bespoke cables made up by a seller on eBay.  These were 170 amp rated and had the appropriately sized ring connectors fitted on each end.

I decided to locate the kill switch in a hole that was used for a side mirror before I fitted the cage.  The one on the other side of the car still has as blanking bung.  This location for the switch should also comply with the MSA regulations, i.e. it can be activated by the driver whilst strapped in to the car, as well as a marshal from the outside of the car.

Alternator Upper Bracket

Whilst on the return from a Southern Kit Cars trip to Bletchley Park, I thought I could hear a metallic rattling when the car was idling at junctions.  When it was safe to do so, I pulled up at the side of the road and took off the bonnet.  I discovered that the upper alternator bracket had failed.

Thankfully, the new bottom bracket is very robust and bolted up very tight.  This single bolt was holding the tension in the alternator belt.  Aside from worries about the alternator not charging, I was concerned that if the belt started to slip, then the water pump might not function correctly, with the engine potentially overheating.  For the rest of the return trip I kept to a steady speed on the main roads.  I made it back home, where I was able to look at the bracket failure in more detail.  It can be seen where the failure started, from the outside rusty edges and then it has spread across the middle, to completely separate.

For a replacement, I fabricated a new bracket out of a single thick piece of L-section mild steel.  It is a little overkill, but I really don't want to have any more alternator bracket issues.  Even if I'm carry just that little bit more weight than is necessary.  In the future I may trim off some more of the excess metal.

Denso Alternator

I'd been having some more issues with my Lucas alternator, so I took it apart and ordered a service kit, which included bushes, bearings, rectifier and regulator.  I started to overhaul the alternator, but during the process I decided that I was not really happy with the situation.  I wasn't convinced that I would not have further problems in the future, so I finally took the plunge and ordered a genuine Denso alternator.

The new alternator is rated at 40 amps, so should be more than sufficient for the modest electrical loads that my Avon can generate.  It weights about 2kg versus the 3kg of the Lucas, so there is a nice weight saving too.

When I removed the Lucas alternator I discovered that the lower mounting bracket had failed.  The front lug had snapped off and it was just the rear lug that was holding the alternator on.  It was lucky that I discovered this in the garage and not at the side of the road!

I took the old lower bracket to the local fabricator/welders.  They removed the old lugs and added strong new fixings for the Denso.

For the alternator tensioner I re-used the old upper bracket and connected it to the alternator with two rod ends and some 8mm threaded rod.

The main output connection is a threaded copper post.  I had a proper battery cable made up that had the correct size ring connector for the alternator on one end and the correct size at the other to connect to the starter motor connection (where the car's main loom terminates the +12v).  This arrange should be much better than the Lucas spade connections, which are prone to arcing.  The cable is more heavy duty than the original Tiger alternator output wire, so this can only help.

More Alternator Woes

Prior to my recent trip to France I noticed that the low battery light was coming on.  On my Acewell dash this is set to come on at 12.5 volts and off again at 13.0 volts.  The alternator warning light extinguished normally after starting so there was no issue with the excitement of the field, there was another cause.

I ordered a replacement set of brushes for my Lucas ACR alternator just in case they were worn.  When I took the back off the alternator and dismantled the brush box I discovered that the wire attaching one of the brushes to the terminal had broken.  I think that the current was being carried by the spring alone, hence the erratic charging of the battery.

Replacement of the brushes is a fairly straightforward task.  I also did a quick health check of the nine diodes with the multimeter.  Then a quick test drive proved that the full 14.2 volts had been restored.  Then it was off to France for the weekend.  All was okay until after arriving in France I noticed the low battery light was illuminated again.  Oh no.  Anyway, long story short I managed to nurse the battery through the weekend and I made it back to the UK without the need for a breakdown truck - phew!

So, alternator out again, back off and then I discovered this:

The red wire had snapped off from its ring terminal.  I suspect that I had trapped the wire when previously replacing the back cover of the alternator.  I soldered a new ring terminal on and carefully refitted the back cover.  Testing proved that the full 14.2 volts had been restored.  Hopefully, there are no more alternator problems.

Alternator Problems

I've had an issue recently with the alternator.  It was a new Brise 16004 alternator supplied by Tiger and its only done 1700 miles.  I noticed something was wrong when I could see the headlights flickering.  Only noticeable on side lights.  I checked the battery voltage with the engine running and it was erratic, sometimes above 15 volts.  If left this was going to damage my battery.

I checked all the wiring, the belt tension and the alternator plug, but everything seemed normal.  I decided to take the alternator to a local alternator and starter motor specialist.  I wanted it fixed quickly and I wasn't sure how long it would take if I sent if back to Tiger or how much the postage would cost.  I did contact Brise by email regarding the warranty, but I've still not heard back.

In the end it turned out to be a simple fix.  All the connections on the regulator had vibrated loose (or not been correctly tightened by Brise during manufacture).  The regulator had also failed, possibly as a result of working loose.  The alternator repair shop fitted a new regulator during the same day.  I've refitted the alternator and now I've got a nice steady 14.2 volts.

Alternator Problem Solved

I didn't have a charge indicator light for the dashboard (digital dash has a voltmeter and a low/high voltage light).  Without this in the circuit the rectifier in the alternator does not send a charge to the battery.

With the light connected the alternator worked perfectly.  It's nice when problems are fixed easily (and cheaply).

Here is another video of the car running.  Apologies for the terrible sound quality from the mobile phone.  It is much, much better in real life.

Alternator

Mounting the alternator with the Tiger provided brackets requires removal of one of the upper cambelt cover bolt mountings.  The plastic part must be sawed off the upper cambelt cover and the matching piece of metal cut off the back plate.

 Here is the upper bracket in the space where the upper cam cover bolt would have been.

The upper alternator mounting bracket can only be mounted by bolting through the inlet manifold flange, i.e. the alternator bracket bolts partly hold the manifold on to the engine head.

The finished article with the drive belt in place and tensioned.  The engine was turned over by hand a couple of times to check the drive belt was running freely and straight, i.e. on the right grooves of each pulley.