Standard starter vs 'slimline' starter - help

[vincematthews]

I am trying to replace a 924 n/a Bosch starter motor and the one (also Bosch) that has arrived is a so called 'slimline' one.
It's apparently specified for the car but is physically smaller and lighter.
The problem I have is that the terminals are differently numbered.
Old starter = 30, 50 and 15a
New starter = 30, 50 and 30h

The question is where do I connect the (black) wire that went to 15a? The other end apparently runs to the coil +ve.
The car seems to run without it but as I haven't spent the 1-1/2 hours necessary to get the heatshields back in place,
I haven't run it for long enough to be certain.
Are there any downsides to not connecting that wire.

Also what is terminal 30h for?

This car has points ignition.

Thanks

 

[tref]

Have you looked at the wiring diagrams at all? Some of them include the internal circuitry, and may possibly show up if there are any internal differences (which I somehow doubt.

I ran into the big/little starter motor difference a while ago, and seem to recall that on the 944 S2 or Turbo there wasn't enough room for the original "big" starter motor, so it was shrunk to fit... I also seem to recall hearing it became more powerful at the same time, so a "better than original" replacement.

I know I replaced a "big" one with a "little" one previously without problem, but didn't check the terminal numbers... That said, I cannot recall ever connecting more than two terminals on all the various 924/944s I have played with, but then I don't ever recall taking the starter motor off any which have points.

My guess for that wire is that it is a way of feeding power to the points (and thus ignition) when the "X-contact relay" is out - that being the one which switches everything off that isn't required when winding over the starter motor... That shouldn't cut the power to the ignition anyway, but maybe there is a voltage drop, or maybe it is bypassing a resistance in to give the ignition an extra "kick" when the starter is operated.

Just suggestions for stuff to look at or consider - I cannot say for sure.

Hope this helps,

Tref.

 

[vitesse]

Vince,
This is all to do with the use of coil resisters & their use on the various 924's where points were used before the Hall effect distributors.

I have a useful Bosch publication which defines all the terminal ref nos ,relates them to the electrical device using them & gives a bit of descriptive text so it could help & can be associated with a relevant circuit diagram (the corresponding nos are shown on the circuit diagram)

Quite useful when confused by the nos on the base of relays!

If you let me have your email address,I'll send it to you.

 

[vincematthews]

ORIGINAL: tref

Have you looked at the wiring diagrams at all? Some of them include the internal circuitry, and may possibly show up if there are any internal differences (which I somehow doubt.

I ran into the big/little starter motor difference a while ago, and seem to recall that on the 944 S2 or Turbo there wasn't enough room for the original "big" starter motor, so it was shrunk to fit... I also seem to recall hearing it became more powerful at the same time, so a "better than original" replacement.

I know I replaced a "big" one with a "little" one previously without problem, but didn't check the terminal numbers... That said, I cannot recall ever connecting more than two terminals on all the various 924/944s I have played with, but then I don't ever recall taking the starter motor off any which have points.

My guess for that wire is that it is a way of feeding power to the points (and thus ignition) when the "X-contact relay" is out - that being the one which switches everything off that isn't required when winding over the starter motor... That shouldn't cut the power to the ignition anyway, but maybe there is a voltage drop, or maybe it is bypassing a resistance in to give the ignition an extra "kick" when the starter is operated.

Just suggestions for stuff to look at or consider - I cannot say for sure.
Hope this helps,
Tref.

Thanks Tref

Yes, '79 in the Haynes is close but not close enough, there don't seem to be many 924's with points ignition now.
Mine doesn't have ballast resistors though I haven't checked for high resistance wire.
According to a Bosch website, my new starter has less power 0.85 vs 1.10 (presumably KW?) for the old one - however they failed to list terminals.
I might have a trawl through 928 circuits as that car is contemporary with the 924 and might have had extras on.

ORIGINAL: VITESSE

This is all to do with the use of coil resisters & their use on the various 924's where points were used before the Hall effect distributors.

I have a useful Bosch publication which defines all the terminal ref nos, relates them to the electrical device using them & gives a bit of descriptive text so it could help & can be associated with a relevant circuit diagram (the corresponding nos are shown on the circuit diagram)

Quite useful when confused by the nos on the base of relays!

If you let me have your email address,I'll send it to you.

Thanks Vitesse, PM sent.

 

[924nutter]

except that in Vince's case test whilst cranking produced 9v on 30h as you would expect for a ballast resistor bypass, but connecting the 15a wire to 30h made the engine start and stall and run very badly indeed. We had quite a discussion about it via email and we are both none the wiser. We have theories but nothing else. If you have had a 944t starter apart it has a pair of epicyclic gears which slide and rotate as the pinion engages and the armature runs at a rough guess twice normal to give the motor the torque to turn the engine at the necessary >200 rpm. Clearly doing it that way allows the motor to draw less current but there is not a lot of difference, witness the 9v at terminal 30 h when cranking so that's still a heck of a current draw