prodracing.com

Unofficial SCCA Production Racing Forum
It is currently Sun Oct 21, 2018 7:26 am

All times are UTC - 8 hours




Post new topic Reply to topic  [ 20 posts ]  Go to page 1, 2  Next
Author Message
 Post subject: Wiring Help
PostPosted: Mon May 28, 2018 9:59 am 
Offline

Joined: Mon Oct 14, 2002 6:08 pm
Posts: 620
Location: Raleigh, NC
Getting ready to wire up the MGB. What is the collective wisdom on the use of relays for brake lights, fuel pumps, etc.? Last car I wired was my Crossle 32F – pretty straightforward.

I am now looking at 2 fuel pumps, brake and tail lights, a fan (likely), starter, ignition, tach, etc.

Do I go the KISS route (one less thing to fail), or build in the additional circuit protection of the relays?

Rick

_________________
#27 FP MGB
#0 ChumpCar TR6


Top
 Profile  
 
 Post subject: Re: Wiring Help
PostPosted: Mon May 28, 2018 11:52 am 
Offline

Joined: Wed Jul 06, 2011 3:48 am
Posts: 559
Location: Florida
Of the five Sprite race cars we've bought or built only the first one had relays in it. Second weekend out the one on the fuel pumps died. Wasn't smart enough to have a spare and there wasn't any place to buy one... Sunday at Hallett. The only relay since was on the fan for our autocross car. The crappy Chinese made relays (Bosch) have failed numerous times on our other cars, another great reason we don't use them on the race cars. Put the wires in protective looms, tie them down so they don't flail around, solder your terminals to the wires and you shouldn't have any problems. Don't tie the wires together in the looms. If something does short out usually the wire carrying the load gets hot or burns. Usually the other wires survive just fine.

If a pump shorts out it will be in the pump itself. Brake light bulbs are fuses themselves. Only reason we used the relay on the autocross car fan was to get full voltage to the fan. Ignitions don't use much voltage so no problem there either. Used a fuse on a Tach we paid too much for until the manufacturer told us we didn't need it as it would burn up a dollar three ninety eight wire in the unit if it shorted out. Hard wiring doesn't fail....

Bob

_________________
Bob Hess 165947
HP 13 '59 AH Sprite FP
HP 49 '60 AH Sprite LP


Top
 Profile  
 
 Post subject: Re: Wiring Help
PostPosted: Mon May 28, 2018 12:53 pm 
Offline
User avatar

Joined: Fri Oct 01, 2010 9:21 am
Posts: 1136
Skip the relays and run switches with higher amp ratings.

Obviously separate circuits for fuel pumps vs fans etc

Summit sells some nice 40a switches that will give years of trouble free service.


Top
 Profile  
 
 Post subject: Re: Wiring Help
PostPosted: Mon May 28, 2018 4:45 pm 
Offline
User avatar

Joined: Fri Aug 12, 2011 4:03 pm
Posts: 191
Location: Northeast PA
All circuits in my car come through a 8 circuit switchable breaker panel.

I have my fuel pump on a relay which triggers from the ECU, that 12v line is fed from a breaker.
I have my 2 speed fan on 2 fused relays. These are fed direct from a bus bar, direct from kill switch.
Those are the only relays I used.

_________________
Jimmy Pettinato
88 BMW M3 - SPU #98


Top
 Profile  
 
 Post subject: Re: Wiring Help
PostPosted: Mon May 28, 2018 4:51 pm 
Offline
User avatar

Joined: Thu Mar 27, 2003 7:43 am
Posts: 594
Location: Pueblo West, CO
FWIW - I ran my Fiat 20 years hardwired (14 ga per Carroll Smith), quality switches and no fuses - never a problem.

_________________
Bob Cancellieri


Top
 Profile  
 
 Post subject: Re: Wiring Help
PostPosted: Mon May 28, 2018 9:37 pm 
Offline

Joined: Mon Oct 14, 2002 6:08 pm
Posts: 620
Location: Raleigh, NC
Bob:

Thanks for the Carroll Smith reminder. It's been while since I read that section of his book.

Rick

_________________
#27 FP MGB
#0 ChumpCar TR6


Top
 Profile  
 
 Post subject: Re: Wiring Help
PostPosted: Tue May 29, 2018 4:40 am 
Offline
User avatar

Joined: Thu Oct 29, 2009 8:31 pm
Posts: 129
Location: West Chester Pa
Rick

My $.02

I recommend using fuses and relays, mostly because they protect expensive hardware, and limit the amount of trouble shooting needed in the event of an issue.

A few options i found with a quick search:

https://www.amazon.com/Universal-15303- ... B07CB2JCN2

https://www.ebay.com/itm/Littelfuse-HWB ... 2404187922

When wiring use high quality switches, Weatherpak or Deutsh conectors, heat shrink, "Tessa Tape" wrap or "braided sleeve" skip any spade connectors in favor of ring terminals.

_________________
Bill Ball
2017 Sunoco Hard Charger GTL


Top
 Profile  
 
 Post subject: Re: Wiring Help
PostPosted: Tue May 29, 2018 5:18 am 
Offline

Joined: Fri Nov 06, 2009 5:08 am
Posts: 1177
Location: Philly
Brake lights; no need for a relay. Use LED bulbs. Get good ones. Its amazing how high the draw is on incandescent brake light bulbs.

Fuel pumps; it depends. EFI or carbs?

EFI, you have to use a relay. The ECU will not handle the load from the pump(s).

Carbs, I skipped the relay and used a high amp rating (30) switch. I was careful to use the correct load rated fuse to protect the pump. Check with the pump manufacturer for the right fuse. Separate switches and fuses for each pump.

-Kyle


Top
 Profile  
 
 Post subject: Re: Wiring Help
PostPosted: Tue May 29, 2018 5:17 pm 
Offline
User avatar

Joined: Mon Oct 26, 2009 1:45 pm
Posts: 225
Also, color code is really helpful. Batt. hot-red switched 12v -black ground- brown. Design it with fixing it at the track in mind. Terminal blocks are helpful.

_________________
Dick Gagliardi
Chicago region
H Production VW Scirocco


Top
 Profile  
 
 Post subject: Re: Wiring Help
PostPosted: Tue May 29, 2018 7:58 pm 
Offline
User avatar

Joined: Fri Aug 12, 2011 4:03 pm
Posts: 191
Location: Northeast PA
Buy the best components and materials you can swing.
I like Tefzel wire, but some people dont, it only comes in white so you have to be good with labels.
Stein-Air is the best source for Tefzel.

I personally never use any insulated crimps, always good non-insulated metal crimps with heat shrink.

Terminal blocks and buss bars are huge helps. There are places that sell jumpers to convert terminal strips into bus bars, as well as spades to allow plugging spade connectors to a terminal strip.

Digi Key has a limitless inventory of high quality switches and a great assortment of LEDs for warning lights, etc.

Some resources:

http://order.waytekwire.com

http://www.parts-express.com

https://www.vtewarehouse.com/content/el ... tb/ttb.php

http://www.kayjayco.com

http://www.steinair.com

http://www.delcity.net/

http://wefcorubber.com/

http://www.digikey.com/

_________________
Jimmy Pettinato
88 BMW M3 - SPU #98


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 20 posts ]  Go to page 1, 2  Next

All times are UTC - 8 hours


Who is online

Users browsing this forum: No registered users and 9 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
Powered by phpBB® Forum Software © phpBB Group