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29 Buick Current Limit Relay

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I'm looking for a replacement source for the current limiter relay for our 29 Buick. I'm also interested to hear if anyone has rewired a car and replaced the relay with a conventional fuse block.




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Steve the current limiting relay is a fairly difficult piece to find. Do you not have one at all? If you do it can usually be reconditioned ,if they aren't in too bad of shape. Relays from other vehicles besides the 1929 can sometimes be used.

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Posted (edited)

Steve- If you do have a relay you would do well to post a picture as several styles were used over the years.  It could be the one you are looking for is common to 30 and 31 models.  My car is a 31 and had no relay and I took one from a 30 as they are identical.

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Edited by Str8-8-Dave (see edit history)
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Many years ago, a previous owner replaced that relay in my 29-27 with a single fuse...  I may be wrong, but I think it was a 20 amp fuse.


It is now my son's car.

29 Buick.jpg

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Sorry guys,

This is the car that has been sitting since 1954. It runs great, so I'm in the process of re-wiring the car. Unfortunately, the previous owner removed all of the wiring including the relay. I'm n ot sure what happened to it  so, I'm looking for one I can use or maybe mount a fuse under the dash.

As always , Thanks

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Here is what a 29-25 owner did in Finland.  <https://www.29buickphotos.com/Information/29-25-Restoring-after-55-years/i-Lcf6vCB/A>


He used fuses and put them on a board with a hinge so it folds up, out of site, under the dash.


Send me your email and I'll send you some places you may be able to get a Current Limit relay.


Bill McLaughlin

1929 Silver Anniversary Buick Club

Bill at 29Buick.ca

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I just re-wired my 29-27 sedan and I bought a refurbished current relay from Old Schoolhouse Restorations (Tony Bult) in Whitewater, WI.  He should have one available because I sent my old one back to him so that he could refurbish it for some future customer.  My old one was functionally OK, it just was rusty.  Tony has a lot of parts for 1927-1930 Buicks.


It states in the 1929 Service Manual that the current at which the relay activates is between 30 and 35 Amps.  Personally, I think the relay vibrating is better than using a fuse for a couple reasons.  First, you get an audible warning that there is a problem.  Second, if the overload (short circuit) is corrected, the relay stops vibrating and you don't have to replace a blown fuse.  Third, the 30-35A trip point on the relay is going to be more consistent than any thermal automotive fuse.  The actual trip point for a thermal fuse is very temperature dependent, and they usually are rated to blow in amp-seconds, so if you use one rated at 20A it might need to see 20A for several seconds or minutes before it actually blows open.  Finally, the relay limits the  overload current to 30 or 35A, while a fuse will not limit the current at all.  Limiting the current is much more friendly to your battery and generator.



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Thank you for your response........After listening to all, I've reached out to Tony and I'll be going back with the relay in the harness.

As always, I appreciate everyone's time and input!



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