Mk1 Stag 1972 Alternator

[Lagnakeil]

Hello,
i have a pre-73 stag with an alternator fitted. It is underpowered and I am wondering about changing it for a 65amp 18ACR unit. Would this be ok?
lagnakeil

[tvrgeek]

Why replace a POS with a POS? At least do the Fiesta/Bosch. I much prefer the CS-130. Just put one in my MK II. Another gentleman just fitted one in hos MK I. I had to file the case just a tad and go to a 15194 belt.

[Lagnakeil]

How many amps does the CS-130 put out?

[Phil S]

105 Amp but at twice the price of an acr unit, not needed in my opinin

[Lagnakeil]

Hi Phil,
Would a 65 amp alternator be ok on a pre- 73 car?

[mallardstag]

65amp should be fine unless You've added lots of high current accessories (electric fan etc). You will need to rewire a bit to disconnect the external charge relay and control units if they are still fitted.
Simon

[tvrgeek]

Yes, 105 is overkill. They quit making the 83 A version and quit making the CS-121. But it is no additional load as it only puts out the current the battery can take. The advantages of a stud-output, better regulation and diodes that don't start leaking and kill your battery make it a good choice.

In the picture below, it shows the changes. The part circled in red is where I tied everything together on a power stud as I do not like the Triumph block with big Lucar connectors. Very bad design IMHO. From alternator to this point should be a 6 gauge wire at least. MK 1 charge0 CS130.jpg

[KOY 23]

IMHO the Triumph design is fine for the original alternator and upgrades to 60-70 amp alternators, if you're going to use 100+amp alternator, then you should upgrade wiring and connectors. I have never heard of anyone having problems with the Mk2 power distribution terminals on main battery lead. As said above the alternator will give out what the battery needs so 100 amps may only be for a very short time. As a rough approximation a 50 amp one will take twice the time, maybe a few minutes. Do a current budget by adding up all the current consumptions of each device, this will give you the current rating of alternator required. Providing the current demand is lower than the alternator output you will not drain the battery. You probably won't need an alternator this rating as you're unlikely to have all loads on at once, especially if you don't go out at night or in the rain!

[tvrgeek]

10 years in failure analysis causes me to differ, so the viewpoints are all out there and everyone can make their own choice. You have probably not measured the voltage drops in use . I have. Ever wonder why you can "fix" an intermittent connection by just reseating the connector? It has to do with breaking the fretting corrosion. If a connection is more than a couple of amps, I want a gas-tight connection. Actually, I want a gas-tight connection everywhere which is why I recommend using dielectric grease in all the connectors. This is what modern cars do.

Personally, I am building my car as a daily driver and might just be driving in the rain on a cold night.

[fussydave]

The wiring on the Stag is a very simple, crude, 12 volt point to point system employing very little control, a couple of relays, a circuit breaker and minimal circuit protection. The plug and socket connectors may be of a low quality by today’s standards but have served most people well for 40-50 years (probably three times their expected life span) without giving much issue, especially considering some of the harsh environments that some are exposed to. So as and when these connections fail replacing with like for like (with some consideration for the ones that are more exposed) should give another 40-50 years service (well beyond the expected service life of the majority of us!!).

The standard Stag will draw a maximum of around 40 Amps with all lights on, heater blower on and other bits and pieces so the original spec alternator is more than adequate. Uprating to the ACR18 is desirable if you are fitting an electric fan. The most obvious reliability improvement is to move the alternator to the upper LHS of the engine away from its low down position to the RHS where the risk of water and crude ingress is high. As to the reliability of the 18ACR, this has been fitted to many cars for many years and seems to be absolutely fine. If there is any drain through the diodes, if the car is being driven daily this should not be noticeable. If you are using the car more infrequently, you would need to maintain the battery or charge it up regularly anyway so that should not be a problem.

Modern car breakdowns are more likely to be caused by ECU and sensor failures rather than mechanical issues despite modern technology and supposed better designed parts and practices. The Stag was designed for everyday driving and I know of people who had the car in its day and used it as a daily without any issues – least not electrical! Many SOC members have also clocked up high mileages without issue.

Dave

[tvrgeek]

Fine to move the alternator Unless you have AC, in which case there is a great big compressor in the way. You also have an additional 6.5A blower fan and two 8 amp radiator fans.

I have no problem with hind-sight. Doing something a long time ago as it was SOP is not justification to do it poorly again. A personal choice. Connections that may have been fine for the first 5 years expected life does not make the came bad design reliable 45 years later. Sorry, but that is what it is.

[KOY 23]

10 years in failure analysis causes me to differ, so the viewpoints are all out there and everyone can make their own choice. You have probably not measured the voltage drops in use . I have. Ever wonder why you can "fix" an intermittent connection by just reseating the connector? It has to do with breaking the fretting corrosion. If a connection is more than a couple of amps, I want a gas-tight connection. Actually, I want a gas-tight connection everywhere which is why I recommend using dielectric grease in all the connectors. This is what modern cars do.

Personally, I am building my car as a daily driver and might just be driving in the rain on a cold night.

Maybe your 10 years in failure analysis have given you a negative view on a 50 year old British car, I think this is borne out by your previous comments on bad design of almost everything on the car. Many of us look from the perspective that it’s 50 years old and a part has just failed so replace it, or it’s working fine so leave it alone. The Triumph engineers were not idiots and specified components to work within their design parameters. Most of the problems I have had are down to substandard replacement and aftermarket add on parts, or changing a part without knowing the consequences such as changing the carb to another which does not have the capability of dealing with crankcase breathing5hat the originals had, or removing the viscous fan and wondering why they have fuel vaporisation issues, there could be a link IMHO.

I am still running the original alternator with no problems or lack of electricity.

Yes I do measure voltage drop as it’s the most reliable method of electrical fault finding.

[Lagnakeil]

Thanks for your input guys. My preference is to increase to 65amps as it coped admirably with both MK2 cars that I had. I had upgraded the headlights where all four came on on main beam, fitted kenlowe fans and a modern stereo to the cars and it worked well so I shall leave it there. The 45amps standard alternator struggled abit and made the alternator belt squeal so I know assistance will be required.
Kind regards,
Richard