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MG MGB Technical - gear reduction starter don't fit

I am trying to help out a fellow club member who purchased a gear reduction starter from a Isuzu trooper part # 16878S for his 65 MGB. I had to elongate the mounting holes to get it to bolt up but the pinion would not mesh with the ring gear. If I remove the top bolt and move the starter towards the block I can get it to work. This means I need to drill and tap the block plate to bolt it in place. I have read in the archives that this is a bolt in application. What am I doing wrong?
Jim Pelletterie

I'm curious about all these Denso starters that are being used on LBC's nowadays. On Triumphs, and others (maybe MGB too), the starters are being sold with an adapter plate. Maybe the MGB doesn't need this plate, but your description makes me think that at least you have the wrong amount of teeth on the pinion gear. From pictures, it looks like there are 9 or 10 teeth on these starters, could it be you have 9 teeth and need 10?

I defer to those who know more, but the guys that are selling them would rather we didn't know the details, I'm sure. If we still had an auto electric shop in town, I'd go there and ask questions. There are probably 100 different models of car that would provide a starter from the junkyard, maybe even my '94 Dodge minivan. The starter looks the same.
Tom

Jim,

Moss sells two gear reduction starters: one for '62-67 cars and the other for '68-80. My guess is that your friend got the wrong one. There is a difference in flywheel size, type of starter and starter mounting location between '67 and '68 models. The correct starter for '62-67 is Moss #541-545.

FWIW,
Allen
Allen Bachelder

the starters are different...as mentioned above you will need one for an early MGB which is also interchangable with spitfire or a sprite if you see one of those for sale
jjralston

4-cylinder MGB inertia starters i.e. MkIs have 9 teeth and pre-engaged i.e. MkII and later have 10 teeth. Inertia starters engage the pinion from the back of the flywheel whereas pre-engaged do so from the front, but this doesn't matter, geared starters all engage from the front and work fine with the earlier flywheel.

There are also very many adapter plates that fit on the front of the standard starter to mate with the various engine back plates, I'm not surprised one from an Isuzu Trooper doesn't fit. If it works fine by moving the position of the starter it wouldn't seem to be the pinion that is wrong, but the adapter plate.
Paul Hunt 2

Paul, I agree. But does Jim's problem starter here even have an adapter on it? Or is it just an Isuzu replacement?

Is there a standard Denso starter used for all of these LBC high torque ones? Do they use different pinions?
Tom

OK, for 'adapter plate' read 'mounting flanges'.

For after-market use I think the *base* starter is relatively standard for a wide range of applications, with different pinions and adapter plates for specific applications. This adapter plate is what contains the mounting flanges, and means that Denso can manufacture millions of the expensive starters, and small numbers of the individual cheap adapters to attach to the starter as required. Extending the range is similarly cheap and easy. Even with the MGB there seem to be different adapter plates/mounting flanges used, some that have a captive bolt inserted during manufacture as the motor covers the hole, and some where the original bolts can be removed and inserted easily.

For volume OE applications they may well have a one-piece casting including the mounting flange, in which case the question is where did Jim fellow club member get the information that an OE Isuzu starter would fit an MGB? Having to file out the mounting hole should have been the first warning, although having said that I have had to file out the mounting holes on a copy alloy water pump many years ago. A pump which is still working some 17 years and 40k miles later (despite a very slight weep during warm-up for most of that time) probably because I have been carrying an OE cast-iron replacement in the boot for most of that time.
Paul Hunt 2

I ran across the website descibing how to convert an Isuzu starter a couple years ago. But if I remember right, it did include drawings of the adapter plate that was made by the author.

Another twist on this is Bosch starters. I have 2 nearly identical minivans, they came with Bosch (1991) and NipponDenso (1994). I haven't gone to the trouble of trying to exchange between vehicles, but instinct says they would exchange. This correlates with some suppliers of Lucas high torque replacements for LBCs. Some of them use Bosch too. I think I'd prefer the Denso if I ever replaced my Lucas.

But I'm still looking for more specific info on converting a junkyard Denso.
Tom

The specifics would depend on what it came from and what you wanted to fit it to. The generalisation is that the flanges have to be positioned so the pinion comes fully into contact with the flywheel when the solenoid operates (which seems to be the bit that wasn't happening with Jim's), and the tooth pitch must match which is usually where the number of teeth on the pinion come in.
Paul Hunt 2

Hi Folks:

Just a note: be mindful that the newer starters may not correctly mesh with an aftermarket ring gear. The aftermarket ring gears have a machined step on the side that is facing the front of the car. The newer starters engage from that point. In addition, there is no gear tooth lead in the stepped area. If an OEM type is being used, then the mesh should be OK.

Thanks: Rich Boris 67B roadster
R Boris

Paul Hunt is right, there seems to be a "base" starter that is universal. From the one I have you could deduct that they must be machining a different mounting flange for each different vehicle, that attaches to the base starter with hex head screws.
I had some trouble with my starter and took it to a local shop, and all the internals were the same. The shop even had a few parts bins with the replacement parts.
The version I have is for the later MGB, and the solenoid is rotated so that the positive cable is on top. When you pop the tabs that hold the distributor cap in place, they drop down onto the positive terminal and can get red hot if you don't move them! On the other hand, if you're tracing starter problems or using a remote starter button, it's easier with the terminals on the top of the starter.

About 5 years ago my son had many starter problems on his 1970 midget. He bought the Izusu starter and it fit just right. I had to bang in the firewall a little with a hammer to make some clearance, but it was already a rustbucket and is now salvaged. We removed the original type solenoid and replaced it with a new cable, and the starter worked great.

It's a bit of irony: I always thought MGB starters worked fine with very few problems, but I always had serious problems with the brake master cylinders. So, the aftermarket makes improved starters but not improved master cylinders.

Regards,
Ken
1974 MGB
Kenneth Thompson

"aftermarket makes improved starters but not improved master cylinders"

That's because the guts of these aftermarket starters are identical to the OEM units for modern cars, and motor manufacturers wouldn't tolerate the warranty returns. After-market master cylinders (and most other stuff for the MGB) is only made for the MGB or cars of its era and hence low volume, and cost-pared often beyond useability. Without a volume user to lean on the manufacturer it's only when word gets round and people stop buying it that stockists might look elsewhere. Unless we each do our own work-around, like for the dodgy brake-light switches, which actually perpetuates the problem.
Paul Hunt 2

Sorry I did not get back to you guys but I did make it work. Just don't tell anyone I did the job. The starter did not have an adapter plate on it as it was a replacement type starter. I got it to bolt in but would not mesh with the ring gear. without redrilling the backing plate I moved the starter towards the block and made a bracket that utilized the original upper hole. It held the starter tight to the backing plate and stopped it from rotating outward. I know its rube goldburg but it worked and our clubmember is very happy. the starter meshed perfectly and sounded good
Jim Pelletterie

Jim,

Now all you need to do is make up a bunch of those brackets, package them with the Isuzu starters, and sell the package at a "bargain" price!

Somehow, I suspect I won't see this arrangement on a car of yours at a car show anytime soon. But having seen your work, I'd guess that you made a pretty neat job of that bracket.

Congratulations on finding a solution where none existed before. Sometimes, that's the most fun, right?

FWIW,
Allen
Allen Bachelder

fwiw, I just completed a cross country journey. The worst experience was with my new gear reduction starter. The adaptor plate had gradually come loose and torn off one of the screws. The result was the ugly sound of gears tearing apart the flywheel. This happened over time, of course. Sometimes, the starter would just lock up, leading to the 'click' sound of a dead starter. For the longest time I was wondering which electrical element was keeping my car from starting properly.

I ended up purchasing new Allen head screws (not easy to find in that length, btw.) and using Locktite.

There is nothing more aggravating than brand new parts failing.
Philip

The only gear reduction starter I tried had the adapter plate secured to the starter with just two self-tappers and some super-glue. When I first fitted it and tried it all I got was a faint whine and I thought it wasn't even engaging, then the engine burst into life! All seemed well, but only a couple of days later I noticed the starter was hanging at an angle. When I cranked it it actually pulled the starter into the correct position, but obviously the risk was that sometime soon the pinion was going to move to far to pull itself into the flywheel, so off it came and I fitted an standard unit instead.

Hunt's Fifth Law states: "Many break-downs occur soon after a car has been worked on; 'new' parts can be faulty when you receive them; 'new' parts will sometimes fail soon after fitting; 'new' parts almost certainly won't last as long as the originals."
Paul Hunt 2

Yes, the new starters are not as bulletproof as we would like to think. On mine, where the terminal for the solenoid wire from the relay goes through the housing, there are 2 copper wires that solder to that terminal on the inside. One of them broke from vibration, and caused the starter to go dead. When the wire vibrated into place, it made contact and the starter worked fine. When it vibrated out of place, the starter was dead. It took a year of tracing wiring harnesses to find the problem. I soldered the wires back into place and now it works fine.
So beware of the man with the magic starter!
Ken
1974 mgb roadster
Kenneth Thompson

This thread was discussed between 19/09/2007 and 05/10/2007

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