starter relay, next gen modification |
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starter relay, next gen modification |
Tom |
Oct 25 2011, 06:31 PM
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#1
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Advanced Member Group: Members Posts: 2,139 Joined: 21-August 05 From: Port Orchard, WA 98367 Member No.: 4,626 Region Association: None |
Well, been meaning to get this done for a while. Didn't want the hot start kit from Bosche or the Ford relay, so I found one on line that I liked.
Installed the relay on a small bracket on one of the mounting screws for the relay board. Ran a new small yellow wire to pin 6 of the 12 pin connector and a brown ground wire to the bracket . Ran two 12 ga. wires fron the relay to the solenoid with the hot wire having an inline water resistant ATC fuse holder with a 30 amp fuse. Put some heat shrink around the normally used large yellow wire to protect it. On the solenoid side used tape to protect the connector that used to be hooked to the solenoid. This relay uses 140 mili-amp so not a very large inductive spike to worry about, but I installed a supression diode across the relay coil anyway. Also put a larger one across the solenoid coil at the relay ( 87 to ground). This supresses the solenoid coil inductive spike to protect the relay contacts. here are a few pics, and a link to more info: http://www.google.com/url?sa=t&rct=j&a...eg_6KDxZdKYQYGw This is the aeroelectric link Oh, I tested it several times and it works just fine. Tom Edit: changed back EMF to inductive spike, sorry if this confused anyone. Inductive or transient spike is the correct term for what is happening here Attached thumbnail(s) |
Tom |
Feb 9 2012, 02:10 PM
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#2
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Advanced Member Group: Members Posts: 2,139 Joined: 21-August 05 From: Port Orchard, WA 98367 Member No.: 4,626 Region Association: None |
Prospectfarms,
No starter relay in the 914. There is where the problem starts. The inductive spike from the collapsing field causes premature wear and damage to the key switch and eventually causes failure of starting when the engine is hot. I suspect this can be all boiled down to the carbon deposits building up in the key switch causing more and more voltage drop across that contact until eventually the voltage drop is enough that the solenoid will not operate via the key switch. During bench testing myself, I have found that 9 volts or more is needed to operate the solenoid, any less due to bad contacts/wiring and the solenoid does not operate. Replacing the key switch/cleaning contacts should fix that. I haven't had to replace my key switch yet, but reading threads where others have, it seems like a semi-hard job. To me, a small relay to replace that would take 10 minutes and cost 5 bucks seems like a better solution. Much of what I am repeating is in the article in the link in the first post if anyone cares to read it. Or you could go to the IEEE webswite and research relay contacts and why they use special alloys to reduce the arc damage on the contacts. key switch contacts are just copper I believe, or copper coated. I am just putting info out here for those who want to use it and I would hope that those who do will confirm this by researching the links for theirselves. I have no plans at this time to make kits for this as there are already vendors that supply this type of modification, minus the "bump" feature. Tom |
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