Gear Reduction Starters #1, #2, and #3

Starts up nice and fast. Similar to my first GR starter. Sounds a little faster cranking, but could be my imagination.

Tried a few more times. This GR3 definitely spins faster than GR1. I guess it makes sense? If they both spun the same revolution, 9 teeth turns the flywheel faster than 11 teeth? The car is firing up a little faster too when cold

Opposite way round, the starter turns more revs with the 9 teeth to turn the engine over than with the 11 teeth.


Nothing wrong with being proactive. The original starter does not necessarily last forever. I changed to a GR starter after the starter on my 78 XJS literally died in the parking lot of my bank.

as Robin : gearing will be the other way round, but final rotation speed depends on the motor speed

Thanks Bernard, for saying that. I always looked at your posts and website for great advice and solutions to some of the flaws (let’s say) in Jaguar design. I’m sure some of the evolution was great in the day, but if I wanted a more reliable XJ-S why not take a few liberties. I’m no Concours person, as it turns out.


And the epicyclic gear ratio.

Seems, then, the next question should be “How many years of reliable service will a GR starter give before I proactively replace it?”


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Give it about a year, then replace it … just in case.

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Brushes and bushes will probably last twenty years? A question of proactivity…

I’ve learned my lesson. Mine is staying in until the day i need to tow it home!


I’m guessing that most modern cars have GR for a reason. Lighter more torque and dissipate heat better.
But let’s be honest a lot of product was over engineered in the day to last longer. Heavier materials, maybe better workmanship? But less effective methods on a production line. (Maybe). I’m sure I can fly in a pretty good reliable airplane across the US with a bullet radial engine in a DC-3.
But at the end of the day are you not hopping on a MAX 8 or some wide bodied Boeing. More efficient faster better suited for the job.

GR starters are a lot cheaper and smaller. That’s why. They’re like a turbo three cylinder. It makes sense.

Direct drive are overbuilt but they use a lot of iron and copper to be this solid.

My ‘92 XJ40 was suffering from the excessive cranking due to the failed fuel pressure return valve failing, this was before I knew about priming the system.
One day it failed, on dismantling it the plastic gears had disintegrated, when I checked on the Bosch web site for compatibility the starter fitted all the XJ40 models from the 2.9 through to the 4.0.

Seems like there is no agreement on …

For what its worth, had a Reduction starter installed in my XJS- HE about two weeks ago, works well, I can tell it is drawing far less power on start up. In my opinion it is a big + on the original Tank starter.

Bruce d

Three days now with Lucas Classic GR starter from SNG, I have to say the car starts up faster than I remember. Faster than GR1 starter, and definitely faster than old Lucas starter.

I sense it is spinning the flywheel faster, hence the quicker starts?

I’ll add, when i bench tested my Lucas starter, it took about 1-2 seconds to reach full speed. GR starter was instant. Don’t know if that’s normal, or my Lucas starter was old and tired.

I’m going with old and tired , my car always started. I never had the luxury or money to afford to buy my car back in 1988 ($69K) considering I bought a brand new VW Jetta for $13.5K back in the day, but I can almost guarantee you if my brand new XJ-S cranked and whined like it did , when brand new I would be at the Jaguar dealer every other day telling them to fix it.
For whatever reason just was not performing.
Next 20 lb behemoth to come out is the old Sanden AC compressor for a newer better one.

A battery drill will also spin up faster than a mains drill, but until recently the mains drill was better…

Besides that it’s like comparing a 70 year old to a 20 year old.

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