stevengerard

I've done some searching but can't find anything specific about putting in a relay for the convertible top switch. The shop that was doing my car put in two switches and both blew out. I've had the car for almost 15 years and the original one never had a problem. Are the new switches just poorly made or should I look to install a relay as I have heard about. I'm guessing I would need two relays, one for up and one for down, but don't know where to start. Supposedly there was a draw of 25-27 amps on start up and 22 amps as the top continued up and down - all well within normal range.

67442nut

Don't know about a '70 convertible, but, I have '67's and the circuit breakers for the convertible tops are all 40 amp.
I suspect your '70 is also a 40 amp.

If you install a relay(s), you should make sure it has the same rating as the factory circuit breaker.
You should only need a relay for the "UP" function. Raising the top is going to draw more current than putting it down.
I don't know what type of switches your shop used, but, repros of the original switch are available.
The switches your shop is using may not be rated for the proper amperage if they're not the original type.
This could shorten the switch life.

If you're burning out switches that quickly, you may have some resistance in the top mechanism.
You might want to check that by disconnecting the hydraulic cylinders from the frame and working it by hand.
You may also have a pump motor going bad and drawing excessive current to do the work.

70Cutrag

Just wondering if you were successful with your relay modification? My 70 cutlass melts switches like crazy. Now, I just jump the socket from the back of the switch w/ 12 gauge wire to save my last remaining OEM switch. Seems to draw a hell of a current without relay protection. It did this before with the original motor, pump, and top frame. Hoped replacement used parts would stop it, but the melting continued. Seems like this would be a very common problem.

Bobac455

There is a place in California called "Convertible Service" and the high quality top shops in Chicago use their stuff. They have a heavy duty toggle switch that mounts into a round hole (for under dash use if you don't want to damage your dash) and it is rated at 50 amps. I kept burning out dash switches too and this has resolved that problem. I left the old dash switch in the dash for appearances sake. Their phone # is (800) 333-1140. They tell me only one person out of the Midwest is making the replacement dash switches for all supply houses and has them made in China. I'm guessing they are not the same quality as OEM by any stretch.

stevengerard

I'm still in the middle of doing it, I found the relays at radioshack and have started to rewire it, I was supplied some wiring diagrams and instruction from others that have done this. Fur now I just jump the wires, - before the body shop ruined my original switch it worked fine. What I noticed is when they put in the new wiring harness nobody checked to make sure the new wires were a tight connection and they went through two switches and charged me for both and the labor.

So I now have a repo switch but you really can't tell. This switch bobac455 talks about sounds like a nice alternative too, instead of messing with all the relays, mount it under the dash under the real switch.

Bobac455

Hi Steven,
I may want to install relays in the future only because I would really like to use the original looking dash switch. Any chance you can scan the wiring diagrams and e-mail them or perhaps post them to a web site where we can view and print them? Thanks

allyolds68

There's a good sketch in this thread from ROP:

http://www.realoldspower.com/phpBB2/...ible+top+relay

and to answer your question, yes, two relays are required. My top motor strains pretty well going down as well as up. I haven't figured out exactly what brand relay I should use yet. There are a bunch of postings about how most 30A relays aren't really up the the task (including the radio shack ones) but none that recommend a good one.

Here's another thread I started trying to find a good relay but didn't have much luck:

http://www.realoldspower.com/phpBB2/...ic.php?t=76812

edit:

I should have just linked it. Here it is:

Tom442

Any relay Guru's here?? So I am bound and determined not to fry another convertible top switch on my 68 442. I found a Buick guy with a relay set-up on his site http://members.shaw.ca/timcr/elec.html ...he says it works fine. So there are two different ways of setting up the relays...one shows the power into the relay on pin 30 and the other (Buick) shows the power in on pin 87. Would it make a difference? I am thinking of going the Buick guys route since he says it is working. He sourced the relays and brackets out of a 90's Pontiac...I found quite a few different GM cars in the yard with similar relay sets! Should be capable of 40A. Input??
Thanks
Tom

MDchanic

It's the exact same circuit.

Just hook it up like whichever of the two ways you like best.

And those relays are available from many places including auto parts stores, junk yards, and electronic supply houses. You can buy them new for less than $5 - just grab whatever's cheapest.

For your further perusal and confusion, here is my version of the same diagram:



Here is a fancier version of the same thing:



and here is another thread on the same subject.

- Eric

droldsmorland

Steve,
Get into a commercial supply house...McMaster Carr, Grainger’s at minimum and look for a good Ice Cube relay and base, not radio cracks house of china. Allen Bradley, NTE, Dayton etc…Get one with the correct ratings. Go a little over vs under. You want a 12vdc coil with maybe 60 amp contacts. Also you might want to check out some of the reproduction harness vendors they often have upgrades for these known trouble circuits already in kit form.
First check motor amperage draw. I’ll bet the grounds bad somewhere. Think about it the engineers did their homework and the original OEM stuff lasted quite a while. Why did it fail...higher then rated current. That’s most likely due to a bad ground; bad pump motor or the mechanism is binding all due to age. The engineers didn’t really account for that. Sure you can improve the circuit with the latest electronic stuff and slave relays are a great way to pull the high amp primary power off the delicate switches allowing the salve relay to take the hit (they are cheap). Many people are converting their headlights this way. But first make sure the rest of the circuit is up to snuff and the tops not binding before going through the trouble of altering/improving.

MDchanic

When I did my Delta, I used Tyco T92P11D22-12 from Mouser.

- Eric

stevengerard

I bought all new harnesses, the real reason for the witch not working well is the new harness wasnot secured tightly enough onto the pin of the convertible top switch. It being loose craised the resistance and built up heat. beleive it or not I have yet to finish this job. I take the top down in spring and it goes up soon. I just touch one wire to the other and bingo it does what I need it to do. But yes I plan on fixing it but I end up cleaning or doing something else on the car instead.

Tom442

Thanks Eric and others, I was just confused on the pins on the relays and either way works then I will wire her up and see what happens! Thanks again for the input.

Tom

Lady72nRob71

I disassembled my old original switch (which was working fine), lightly refinished the contacts with a dremel, reinstalled, and not one problem in 5 years.

If the switch still moves ok, then try this. Works well for window, lock, and seat switches, too.

MDchanic

I linked to your thread in Post #9 above, Rob .

- Eric