Odd Starter Issues on my 68 850 Spider

GarageTimeTV

GarageTimeTV

Garage Time TV
Hello all!
You have been wonderful help in the past and I seek your knowledge once more!

I have a 1968 850 Spider. 843cc Engine. All stock components.

I have replaced the solenoid on the starter and bench tested it. (Side note, I also cleaned all the internals of the starter to shiny metal surfaces) Works well! Responds instantly, spins fast and is relatively quiet for its age. The problem I have is when it gets into the car. (Luckily these are easy to get in and out on these unlike my 124)

Once in the car I have it wired up. I use a jumper wire to spin in from the rear and I get nothing. Initially I got some slow spinning of the engine, but now nothing at all. I used my multi-meter to confirm 12v are getting to the solenoid post. I even plugged in the red wire (from the ignition switch) to test it from the key and got nothing, even though I get 12v there too when in the "crank" position on the ignition switch.

The battery is brand new. I just got it an hour before this test. Bench tested with the same battery. The ground wire for the battery is clean. I took a wire wheel and cleaned the mounting surface and the end of the mounted terminal. (the side that attaches to your car)

Out of desperation I added an extra ground wire from the bottom start bolt and still got nothing. I attached an alligator clip to the body of the starter and grounded that too with no luck. I thought maybe I have a neutral safety switch, so I tried again with the clutch fully depressed. Nothing.

I feel like I am at a dead end unless I am missing something obvious. This car is bone stock and a true survivor, as I can see no visible hacking of the harness. Any insight is appreciated.
 
Any of the wires warm? I wonder if the negative battery cable is not getting a good ground? maybe a jumper cable from battery neg to starter, something more beefy than an aligator clip and wire

There is a heavy ground cable from the rear frame to the passenger side transaxle mount. Did you replace when you but the transaxle back in?
 
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I haven't touched them, but I will. I will also run a longer pair of jumper cables to the starter to see if that helps. They are much thicker. Ill run it from the negative terminal to the starter body.

As for the wire, I actually didn't reattach it. I set it to the side and you know how stuff gets mixed in by accident. I will definitely reattach that! Is there a specific bolt it attaches to or just any close by the transaxle? I was thinking from the mount attached to the trans going to where its mount where the rubber on the underbody is. I'd attach it to the all metal side though as to not insulate it with the rubber.
 
the aft ground strap attaches to the transaxle mount bracket on the stud that comes out of the transaxle case. Across from the transaxle is a bolt/nut holding the trailing arm, 17mm I think. Don't ask how come I know so much about this ground strap!
 
Well, I attached the ground strap and still got nothing. I then ran my jumper cables directly from the battery neg side to one of the bolts holding the starter. I would think that would be the ultimate ground! I still got nothing. I am getting sparks when I try to jump it in the rear, but nothing else. I took it off and bench tested it again, thinking maybe I am crazy.... works awesome on the bench. So I reinstalled it and set it up in the car the same way I bench tested it. Bother jumper cables on the battery, negative on the case, positive on the stud and then tried to jump it this way and still got nothing! I am so confused! Exact same set up on the bench and it works, but in the car nothing happens.
 
Jamming? Rather than bench testing, take to a starter/generator specialist. Maybe failing under load. No load on the bench.
 
I recommend the new high torque starters rather than waste time on a rebuild. As a bonus they are half the weight of the oem and crank much faster all while drawing less power through the 50 year old electrical system.
Available from Midwest Bayless and others.
 
I didn't think about the load issue. The rod doesn't even extend while installed. Nothing.

I do want a nice gear reduction one that MB has. I have a gear reduction starter for my 124 and has never caused me a problem. I just was trying to troubleshoot before dropping $250. I think I can mail in my old ones for core credit though, so that will help.

Thanks everyone!
 
Chances are that at some point some one tried starting the car with a low voltage battery. Low voltage current draw goes up, more current draw more heat. Often on these starters enough heat to melt the solder that holds the windings to the armature. Go with the gear reduction unit and be done with the issue once and for all. Even 40 years ago when I was playing around with these cars the starters were not the best.
Jay
 
I'm just going to get a gear reduction starter. I appreciate it though! If someone has one they want to part with I am interested!
 
By hand. There are new rings, so there is a little resistance from that. I am going to take the starter to get looked at first, then we can go from there. I don't want to be shooting questions into the dark without doing the steps
 
Update:
Went to a trusted starter shop, and was told that its more worth your time to get a gear reduction starter than to take the time rebuilding or putting effort into an OEM one. He also said the turn around would take awhile since parts would have to be ordered. So, I will be getting a gear reduction. Thank you to everyone who contributed!
 
Did you run jumper cables from another car and did you try to turn the starter motor by connecting neg. clamp to the engine and touch the pos. on the starter stud (not the solenoid stud)? That will eliminate anything to do with the 850 battery, cables & connections and solenoid. Watch what the voltmeter shows at the starter terminal and also solenoid terminal and see what it reads and if there's a difference in the readings as you try and turn the engine over. I assume the body of the starter is bolted on tightly and is making a clean/solid connection to the bellhousing. You could try connecting the neg. jumper cable to the engine and to the transaxle and see if there's a difference. Jumper strap terminals need to be sanded clean and bolt/engine/bellhousing contact surfaces should be clean.

Does the solenoid try and engage with a clunk or does it barely move? Does the starter turn much or not at all. Did you clean the brushes? They can sometime be dirty and glazed over. Are the springs holding the brushes snugly against the armature? You could bench test it by clamping the starter in a vice and then use vice grips on the pinion gear teeth and give the starter a quick zap to see if it wants to turn hard under load. A motor can spin nicely under no-load but bog down under load if armature and/or brushes aren't clean and making proper contact or if all windings aren't connecting to the armature. With the motor apart, you could measure continuity of the windings by touching an ohm meter across the armature segments (at 180 degrees) to see if a winding has failed. Sometimes the braided wire to a brush or the connections at each end of it can be damaged .

Sometimes the contacts inside a solenoid can be dirty and/or pitted and not make a proper connection. If you've isolated it to a solenoid problem, they can be taken apart to clean the contacts.

Note that using a lead with alligator clamps and small gauge wire has too much resistance and can even burn out the wire at one of the clamps. Automotive jumper cables can also be defective due to a poorly manufactured connection at a clamp (under the plastic cover). Not long ago I tried to use a brand new cheapo jumper cable on our lawn tractor and it wouldn't turn the starter. Turned out there was only a few wire strands connected at one clamp causing too much resistance. I have heavy duty jumper cables that I normally use and then I got the lawn tractor starting fine.

Last thing you want is to buy an expensive new starter and find you overlooked something. I also have several 850 starters available. All have been bench tested and run properly. That shop doesn't sound that great to me.
 
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FWIW, I had a similar issue. Everything looked fine, had 12 volts everywhere, but it would not crank. Turns out there was corrosion on the battery terminal wire clamp. It would let through enough to trick the voltmeter, but not enough to spin. Cut off the old clamp and installed a new one. Problem resolved. I doubt this info is useful, but you never know.
 
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