Looking for advice on a starter motor for a high compression (12.6 : 1) 16v 4age.
The standard starter copes ok until the engine is hot and then it is really slow to turn over, like there is too much ignition advance. All of the wiring is in good order.
Mine is an AE86 starter, were the later smallport starters better?

Alternatively here are the details of an uprated Denso for this application:
https://www.amp-starters.co.uk/WOSP-Red ... 35650.aspx

Thanks

Lot of stuff about starters here...
viewtopic.php?f=7&t=18729&p=124044&hilit=ae92+starter#p124044
I swapped an AE92 (16V smallport) starter for the original AE86 starter and it worked fine.
Without going back through everything I wrote, it is reduction type versus non-reduction type,
and reduction type wins

Mind you, it is still possible to "stall" the starter if your cranking pressure is excessively high or
your timing is over-advanced. Too much timing when cranking will stop the engine dead or even
kick it backwards. I think I dropped mine to 5 deg BTDC (aftermarket ECU) to take a bit of load
off the starter.

Cheers... jondee86

standard starter copes ok until the engine is hot and then it is really slow to turn over

my hi mileage bone stock 4AFE used to do that. Could be poor electrical cable contacts, or just a tired old warn starter

Yeah... never had the problem myself but I've read that the starter can be affected by heat
soak and not want to crank when it gets hot. Stock starter should have a heat shield to help
prevent that. OEM AE86 exhaust also has a heat shield on the 2 into1 section. If no heat shield
some heat reflective insulation wrapped around the starter and zip-tied on might be worth a try.

Cheers... jondee86

Here is some information l have just received from Wosp.
Can l assume the AE86 starter is 0.8kw direct drive?

4AGE:
LMS378 is 1kw gear reduction
LMS421 is 1.4kw g/r
LMS861 is 2kw g/r

Most cars received a 0.8kw direct drive starters but some got a 1kw gear reduction unit which is our LMS378

Good call about the heat soak and l will definitely be fitting a starter heat reflective blanket.

The starter on the right is an original AE86 RWD 4AGE starter. The small cylindrical item
sitting out to the right is a solenoid to engage the drive.. The starter is direct drive.

The starter on the left is an original AE92 FWD 4AGE starter. The small cylindrical item
sitting out to the right is the motor. This starter is the reduction type.

It appears from the factory manual that both types may have been used on the AE86. The
FSM gives the direct drive unit a rating of 0.8kW @ 5000rpm output and the reduction unit
a rating of 1.0kW @ 3000rpm. The reduction ratio appears to be around 2:1. So assuming
that the lower inertia rotor on the reduction unit spins a bit faster than the rotor on the
direct drive unit, I would expect the reduction unit to output about 100% more torque than
the direct drive unit.

This information appears to gel with the information from Wosp.

Cheers... jondee86

Thanks Jondee, l have found a couple of standard gear reduction starters and l'll give one a try.
The 100% extra torque approximation appeals to me☺

Oh dear. I f#@£ed up!
Stupid, stupid mistake.
The battery wire connection on the gear reduction starter is on the rear side closest to the engine block and is difficult to see, when l fitted the wire l managed to fit it with the bend in the terminal going the wrong way, upon tightening the nut the terminal pushed through its rubber insulation
Once l connected the battery l started the engine ok but when l tried a second time l guess heat made the insulation soft and the battery live went dead short to ground!
Since doing this, the only thing (l think) l have noticed is that the tacho seems to act a bit strange when trying to start the engine the needle goes up/down between 0 and 2000rpm.
Looking at the wiring diagrams l can't see any obvious faults that might occur from shorting the battery wire, maybe someone knows better?

Does the tacho work normally (no needle flickering) when the engine is running ?

Does the tacho signal come directly from the coil negative or from the igniter ? If
it comes from the igniter, do you have a spare igniter you can swap in for a test ?

Cheers... jondee86

Jondee, l will check the tacho post haste.
After sleeping on this l woke up thinking about huge ground spikes

Update.
Old starter back in and everything seems ok (including the tacho JD)
It appears that both of the RG starters l have are no good, or at least need a rebuild.
One does nothing but a small click and the other seems to draw a huge amount of power from the battery, enough to flatten it in a few start attempts.

All good then I was thinking that maybe the tacho was getting the full voltage spike from
the coil negative. There is a fancy diode somewhere in the circuitry that clamps the spike
voltage at 25 or 30 volts, and maybe if that wasn't dioding any more, the tacho could be
getting higher voltage. But dubious logic anyway, so glad it fixed itself

Try a DIY heat wrap this time.

Cheers... jondee86

Thanks Jondee, it was somewhat of a relief when everything went back to normal!
I can only guess that the big draw of power by the starter was having an effect on the coil output and then somehow affecting the tacho.

While I was digging around in my saved 4AGE stuff I found this info on starter motors.
Had it there all the time but had never actually opened the file before



Cheers... jondee86