Shorted My Gear Reduction Starter

I am in the middle of replacing my starter, which accidentally got shorted out when something fell and shorted the Positive terminal to the starter.

While I’m waiting for new starter to show up, what other damage should I check for? Would the alternator’s diode be fried for sure? What about starter relay? Ignition coil? (The car idled fine for 30 seconds when I saw smoke and shut down)


That damage looks VERY similar to that which occurred quite recently to the starter on my E-type S2 (4.2 6-cyl). In my case there was no precipitating event (nothing fell on it). It happened while driving and was quite dramatic, and resulted in a flatbed trip.

There is a short heavy cable between the two halves of the starter assembly. The insulation on this seems to have “perished”, resulting in a massive short-to-ground.

My (very competent) local auto electric shop said that there’s no hope for the old starter, so I am in the process of installing a new one from SNG. I don’t expect any collateral damage to have occurred, but we’ll see —

Bob Frisby
Boise, Idaho


Wow! What happened while you were driving? Sparks? Smoke?

Yeah, my old starter is definitely trash. $200-$300 for a rebuilt gear reduction starter, depending on where you go. I still have my working original Jaguar starter, but that thing is such a behemoth, I just want to say goodbye to it.

I am not 100% sure it was something that fell on it, unless that lump of metal next to the positive terminal is my old 8mm socket. Could be!

Either the way I clocked it with the positive terminal way too close to the engine block, or having it up top and creating a great spot for things to fall on it are the two possibilities for me. I will try to reclock a better position this time.

If you use it you will never have problems again and it’s not that enormous. Besides, it is not cheaply made, look at that fault prone little chinesium thing in comparison.

I don’t think anything of importance got fried. The battery will probably be alright, too.

What I think has happened is that the fallen socket started the short, that resulted on melting the insulation at the positive terminal, and then it was a irreversible and unstoppable process…
The socket is probably somewhere on the road.
The motor must still be good.

I also think that nothing else major happened, although your battery might have taken a beating.
Check that the insulation on the positive cable to the starter is still in a good nick and hasn’t melted away as well.

Experiences and opinions vary. I’ve had GR starters on two Jags and had problems.

Based on my experiences I think the originals are a better choice.


1 Like

They definitely look like a heavier more robust piece of gear.
So far so good with new GR starter. I don’t miss the long winding time for start up on a hot day. I was always wondering if if was going to eventually run down my battery and leave me stranded.

1 Like

I think both starters have their pros and cons. My original starter, although working when I removed it, is 36 years old. Last thing I want to do is put it back, and then a few years from now have it go out and I have to do this again. If we didn’t have to drop the exhaust and downpipe, I’d be more willing to experiment. I guess I could replace the solenoid, since the motor is probably bulletproof. But I’m sticking with gear reduction.

Also, the GR starter is made by Nippon Denso, which I believe is Toyota. So no way am I going to say a Toyota part is cheaply made. Correct me if I’m wrong, but I think this is simply a Toyota starter with a special clocking plate adapter so it will work on our V12s?

Also, it’s too late as I ordered a rebuilt GR starter, but I ‘think’ I could have just ordered a new GR starter for about the same price and just move over my clocking adapter. Doh!

One last PRO of the GR starter, if your battery is a wee bit low, you’ll be able to start your car. I think the original Jag starter required a fully charged battery. I remember when I had starting problems when I first got car, I had to keep recharging battery so that I could keep cranking it over. Old starter sucks a LOT of voltage.

I was trying to see a manufacturers name on the one I purchased but this is the one currently installed on the car not without it’s struggles.
Longer wiring required and mounting bolt.

Yep, bolt and nut for lower mount (instead of just bolt), longer cable for alternator. Not too terrible.

That is exactly same i bought first time. Its a Denso. Remanufactured by British Starters (NE USA i think?)

FWIW, i ordered GR starter from Terry’s Jag this time. Identical starter, but it appears this one is coming from Germany. More expensive too. Probably no difference, just how they rebuilt.

Of course it is, that in itself is not necessarily a bad thing as long as it works

My starter is 55 years old and I haven’t even looked inside, and it starts better than new cars. If your v12 takes ages to fire something else must be wrong??

Greg, maybe your battery is inadequate.

OK, we’re going off the rails…

My battery was and is fine. I said when I first got car and had trouble starting. It was because engine was in bad shape, causing it to take ages to fire.

Toyota cheaply made? I beg to differ. One of the most dependable and well engineered car today. And this particular Denso starter is well sought after for other cars, as well as racing engines.

Of course it’s cheaply made! That does not mean it can’t be a reliable part. As I said, not necessarily a bad thing. Nothing wrong with Nippon Denso either. But.
This is stamped parts, the Lucas is machined diecast parts. The housing is massive this one not so much. Even the bolts and wiring look cheap. So it is cheaply made, which we all want because most cars are not Rolls Royces where money doesn’t matter.

If engine and battery are good you don’t need to crank long so the problem has disappeared and you don’t need the GR anymore, right? I think you’re one who likes to improve things and get them right. In my opinion the way to do it right is to heave in the Lucas once and leave it in.

David to be honest, I changed out my old 20lb direct drive starter as it was 35 years old sealed unit that could overheat and put a major draw on battery.
It worked fine if listening to it whine for 30 seconds to ramp up to speed is acceptable. They will overheat and drain your battery at which point you may have to clean up brushes etc.
If I’m going to do that I might as well pull it out , get weight reduction and a vented cooler running GR starter that starts in a half turn(not 40 turns). By the way the engine is fine, the glass matt battery packs a punch for all the Jaguar electrics. I generally don’t skimp on this stuff.
My goal is not for a daily driver but a car that fires up in a heartbeat as a reliable Jaguar.
If I can make that happen due to more modern technology or parts that are available today that weren’t at the time , I’m all for that.

A debate about GR starter or not? Both are great choices, neither is wrong. It’s really down to one’s own opinion.

Anyways, I may take some photos in a week or so when I get the new GR starter in to show different clocking positions. May be worth discussing?

You should do that, I should save all my old starters and electric aux fans , FPR’s , fuel pumps and all that stuff for JL members that want to go down the concours road.
In fact (not that I have any authority here) we should open up a new section on JL’s called parts bin that we can donate parts to in order to preserve the hobby for people who are willing to go down the Concours road.
End of my rant.

1 Like

We have, it’s called the classifieds section.

Gary, That is a good idea. I would think though that one could place “ad” in classifieds as “free, pay postage” or some such. I imagine many of the Concours folks watch the classifieds

I was thinking a little something different than classifieds.
I was thinking start up a section with your Jaguar model, sub sections or titles, and if you need a part then you are able to contact the person who has no more use for it in order to restore a concours vehicle.
No monetary value exchanged just to gelp with the hobby of all the free advice we receive from this website.
And no I am not running for president of JL’s LOL.

Oh well, it was tired and in need of servicing. I skimp on stuff, but the AGM battery I got (and like very much) was the prettiest available and my starter is the best available.
If your car is even remotely in order you will need the starter for seconds, never half a minute. It only needs to pull mixture into a cylinder and when that ignites the job is done. Never more than a few turns. Vented starter??
New to old cars I had repeatedly and seriously misused a M100 to the point it smoked and was hot. Far too advanced timing, kick back and all. It didn’t die. You’re, perhaps successfully, curing symptoms with the wrong solution.

I made my point, don’t want to labor it and shall leave you alone, Greg. But keep the original starter for the next GR failure
There are free, pay postage (and even more generous) ads already. Seems to work fine!