Vlocity

I am wondering if any of you electronic gurus out there can point me to a heavy duty relay. I tend to fail the stock ones on track.....(Number 53 style)

I've been through the grounds and they are all pristine.

I am wondering if I can make a heat sink that will help the relays survive.

Last week I went through turn one at Nelson Ledges, rolled on the throttle to pin down the left rear and the car went DEAD. Not good timing for complete throttle off oversteer. I caught the car and coasted to a corner worker stand. The car refired at the end of the session and I was able to drive back in.

I'm guessing it was the ignition relay since I have the Fuel Pump relay run right off the battery and located in the battery box. Run with heavy gauge wire.

So, looking for any direction on the best replacement relay out there.

Thanks,

Ken

Landseer

My replacement 53 relays seem fine. Your use may be more severe. Wonder if anybody else has issues.

Have you had your CE panel out recently for close inspection / cleaning?

Where I have had problems is where I had corrosion and also partial wire melt/merges behind the panel, twice involving electric defrost wires, that apparently create alternate paths for electrons, robbing voltage in some cases down to threshold operational levels. Contact was intermittent in a couple of the wires, it seems.

(My data set is limited to a couple 84 rescues, and 85 and 86, and am not running on a track. The 85 was the most frustrating, with a host of problems behind the panel that I found little by little)

Vlocity

Thanks Lanseer,

I will pull the panel and have a look, it's been a couple of years since I have taken a look behind there. The last time I pulled everything apart, cleaned it and used dielectric grease on all of the tabs for the fuses and relays.

I'm WOT for long extended periods of time. The relays involved are almost too hot to touch after a long session.

Ken

dr bob

Just a reminder: Dielectric grease is an INSULATOR. Its sole purpose on the car is to keep water out of high-tension leads to the spark plugs and coils. Everywhere else, it's the devil when it comes to keeping connections working. If you want to protect a connection from corrosion, try to eliminate the source of moisture that's damaging the connection, and then use one of the spray contact protectors, but only after the connections are established mechanically and electrically.

Ken, I'm interested in your thought process that points you to relays as the problem. The ignition (EZK) relay sees no greater load at the track than it does driving to the supermarket, for instance. Telltale of no EZK relay would be that the tach is completely dead during cranking. Is it more of a vibration issue?

Vlocity

Bob,

I understand the Insulator aspect. The car is in storage for long periods of time in an unheated building, so moisture is an ongoing concern. I used a light coating and plugged and unplugged several times hoping to make a good contact and leave the grease there as a "sealer" around the connections, not between them.

I'm not familiar with the spray contact protectors, but that's what I was trying to accomplish with the routine above. Where can I find that if you know?


My only observation is that the relays are HOT after extended track periods, so there may be some high resistance causing this (36 pound injectors running at 90% ?)...I just don't know where to begin to look.

Thanks for the input, it's appreciated.

Ken

John Speake

So did the car start again when you replaced some relays ? Which ones ? Did you check any relays chenaged in (say) the horn position to see if they were dead ?

In terms of current loading, highest is fuel pump relay, then LH relay, EZ-F last. They usually fail in that order.

Vlocity

Hi John,

Hope all is well with you.

I didn't get a chance to replace the relay....I was setting by the flag stand and told them to let me try a restart before they sent a tow truck. It refired and ran fine on the way back in and that was my last session for the day, so I don't know which one might have been the culprit. I will replace them all before going to Putnam Park next weekend, but just trying to see if anyone else had some ideas on the subject or a BEST relay. Over the years I've bought relays from multiple sources and I'm sure that they are not all made to the same specification with their windings etc.

One additional clue was that there was a lot of black smoke on fire up that made me wonder if the ignition had stopped prior to the fuel delivery being stopped.

Thanks for any help you can provide.

Ken

Vlocity

Bob,

I did have Tach RPM despite the engine being dead, I remember glancing at that during the coast down to get off track. So would that point then more likely to the fuel pump relay? That's a very helpful observation.

Thanks

Ken

John Speake

Hi Ken, all's well here, thanks !

I measure stock 53 relays as having a coil resistance of 77 ohms. That means about 2 watts is being dissipated due to the coil alone, so a warm relay is quite normal.

Any good quality 30A relay should be adequate.

I would think there's some other reason for the cut out on the track other than a relay.

Not sure if the igntion cutout theory stands up. As soon as the EZ-F stops sending rpm pulses to the LH, the fuel pump is shut off. Also, you observed the tach following engine rpm coming down, rather than dropping instantly the engine cut.

I owuld suggest you have a good look at temp 2 connections in case the car went so rich it cut out ?

Vlocity

Hi John,

I'll test a few of these relays and see what I get.

I don't think the car went rich an cutout, I just observed a lot of unburned fuel when it did refire and thought that might be a clue.

If it is some other random connection failure it may be very difficult to locate.
Not to mention scary when you are depending on the throttle to be there.

Best regards,

Ken

dr bob

Ken,

The higher duty-cycle on the injectors along with higher RPM's typical would all cause higher contact loading on the LH relay when racing. Coil resistance stays the same regardless since the relay is continuously energized whether driving slow or fast. So a better/higher contact current rated relay might be a solution if that's the problem.

I bought a few 53B relays from 928 Int'l to keep as spares in the car. They have 40-amp contact rating. The LH relay in the car carries some of the primary power used internally by the controller, plus the injector current, guessing in the 2 amp range for load. The injector circuit is a net 2 ohms, so somewhere in the 7 amp or so range for current draw to the injectors themselves. This is very safely within the safety limits of a 40-amp contact rated 53B relay.

Glen McCartney

I believe there is a difference in the quality of some of these 53 relays. When I bought my car in 2002, I replaced the critical 53 relays as preventative maintenance, as all the relays were original form 1985. I have had 2 of these relays fail, both intermittently due to heat I believe. One was the fuel pump relay last year and just recently the starter relay. They were purchased form one of our vendors, can't remember the manufacturer. The cases were grey with schematic printed on them.

Fogey1

Here's a link to a discussion of a CE panel with hot components and links to some products that are purported to clean, maintain and/or improve connectivity.

https://rennlist.com/forums/928-foru...l-smoking.html
1980 model fuse panel smoking

Heat buildup may well be high resistance in the connectors. Cleaning all of the connectors in the relay base, fuse connections, etc., and then using something like Stabilant (Google is your friend) or Corrosion Block (Google again) might help.
Wally Plumley

http://www.learchem.com/C.B.Page.htm
Corrosion Block
http://www.nocorrosion.com/corrosion-control.htm
Corrosion Block
http://www.nocorrosion.com/how-corro...trol-works.htm
Products

http://www.stabilant.com/

http://www.classiccmp.org/pipermail/...ne/081354.html
In my quest for more reliable repairs I have been using
Dow Corning #4 Electrical Insultating Compound
for a number of years on all our high current (>1A) plugs and sockets. I find that it reduces or
eliminates corrosion, plus it also reduces contact resistance and a connector that was warm to the touch is now cool.Not very expensive either...
John's Jukes Ltd. 2343 Main St., Vancouver, BC, Canada V5T 3C9
Call (604)872-5757 or Fax 872-2010 (Pinballs, Jukes, VideoGames)
www.flippers.com

http://www.skygeek.com/dc4.html
Dow Corning® DC4 Electrical Insulating Compound (5.3 oz. tube) is a moisture proof seal for aircraft, automotive and marine ignition systems and spark.
Grease like material containing an inert silica filler in combination with selected polydimethyl silicone fluids

http://store.caig.com/s.nl/ctype.KB/...1977/KB.215/.f
DeoxIT® & DeoxIT® GOLD vs Stabilant 22
What are the advantages of the DeoxIT® and DeoxIT® GOLD vs Stabilant 22?

Alan

I have no idea why you would guess this - I wouldn't...

To be sure I'd suggest you wire up some tell tale indicators to the Relay supplied powers so you can see from the cockpit what is powered and what isn't for when this happens the next time...

I suspect you have a loose connection problem somewhere - but probably not caused by a relay dropping out. Certainly swap them all for new but I don't expect this is the cause and as others have noted track use doesn't stress these relays electrically much more than normal driving. Mechanically it may be a little more demanding but not by very much.

Are you sure it wasn't the fuel pump dropping out...? I'd suspect changed wiring more than the stock wiring...?

You might consider swapping out the ignition switch as a possible culprit (assuming you still have the stock switch).

Alan