S3 relays

[garypTVRS3]

Hi all, been advised to consider swapping out my 30 years old relays for new, for the sake of reliability. TBH I think I've only ever had to change a relay once, maybe twice in over 30 years... Although I do get the wisdom of the advice... So, are there any that are more susceptible to aging, possibly being located somewhere sensible where they're more likely to get excessively hot or wet...? Those I should prioritise!

Planning to do this over the winter, hence just getting my ducks in a row for now.

Ta much!

[phillpot]

If it ain't broke don't fix it


Originals are probably better quality than anything you buy now? Just keep a couple of spares in the glovebox.

Probably more important to know what is what so if you have an issue you can go straight to the correct relay

Between using the diagrams in Steve Heaths book and cross checking by pulling them out one by one and seeing if the lights or whatever stop working?

[v8s4me]

I'd say leave them alone but carry spares. The old relays are likely to be of much better quality than new Far Eastern ones and so the old adage of "if it aint broke, don't fix it" applies. Disturbing the wiring tends to cause more problems than it solves. The only OE relay I've had fail was the fan one which caused a problem but that was more because I failed to diagnose the problem properly. The smell of over heating plastic should have been the clue! I now have two fans running on separate fuses and relays.

[Penelope Stopit]

Replace all the metal cased relays if there are any as they are prone to problems caused by condensation and moisture ingress

You could....................

Gently prise the cases off the bases of any plastic cased relays. Using a very fine wet&dry paper, fold the paper so that you then have a double sided narrow length of abrasive material, place the abrasive paper in between the contacts and gently apply pressure to close those contacts but not too much pressure as the contacts will grab the paper too tight, push and pull / slide the paper in between the contacts several times to clean them

I would replace all the relays, my reasoning being that even when the relays contacts have been cleaned there is nothing to guarantee that the relays coils are going to be of good condition and they could fail at any time in the near future

Please note that I am a perfectionist and carry out automotive electrical design, build, testing and rectification work with classic, old, new and prototype vehicles, this is my profession, hence you may not wish to take my advice

Edited by Penelope Stopit on Monday 12th August 11:00

[phillpot]

Well there you have it, the opinions of two guys who have both been running an S for more than ten years or a " perfectionist and automotive electrical design"... whatever one of those is

[Penelope Stopit]

If cost is important to you.........

A way of obtaining very good relays at a cost effective price is to visit a breakers yard and search for newish German, Jaguar and Land Rover vehicles that you can remove relays from. Siemens and Tyco relays can be relied on

Edited by Penelope Stopit on Monday 12th August 13:46

[garypTVRS3]

Thanks for all the replies!

I reckoned there would be two schools of thought.

My usual way of tackling a 'planned' job (i.e. not the unplanned, oh-st type jobs) is:
1) research and glean knowledge from others (e.g. this post and Steve Heath's book)
2) armed with the knowledge from 1) go look see (e.g. check physical locations - not always where expected - and pull/check as appropriate)
3) make plan to renew / refurb / replace / upgrade as appropriate
4) ensure all known parts and tools are available, then get on and do it...

...somehow things don't always go as planned...

I intend to do this over the winter, that way I have time to re-plan if things don't go as planned...

I've just got my car back on the road after a lengthy lay-off for a full body off chassis restoration (surprise, surprise), I don't want to pull anything just yet, want to enjoy the car as is for a couple of months first!

Is there a list of relays in Steve Heath's book? Pulling spares from newer German cars sounds like a reasonable idea, could do that whether I carry them as spares or use them to replace old ones...

[Penelope Stopit]

The number of relays fitted does vary from car to car and also the relays layout differs from car to car

The biggest mistake people tend to make when replacing relays is to fit the wrong type, the relays terminals configuration is what matters, although many relays look the same they differ

Terminals 30 and 86 are the relay terminals that differ in position and need checking before buying

30 to 40 Amps current rating is the norm

Relays with an internal resistor wired across their coils (in parallel with) are good

Relays with an internal diode wired across their coils (in parallel with) can be troublesome if TVR have not wired the relays to a certain standard

See below for different relay terminal configuration




The above shows 4 terminal relays yet five terminal relays with the same different layouts of terminals 30 and 86 do exist

Here is a link that covers much of the various combinations and relay sizes
https://www.hella.com/hella-us/assets/media/HINC_E...

[v8s4me]

garypTVRS3 said:

Hi all, been advised to consider swapping out my 30 years old relays for new,.............

If you do decide to chuck out all your old OEM relays, can I have them please?

As for the old metal relays, if they are still working after all this time, leave 'em alone.

[Oldred_V8S]

v8s4me said:

garypTVRS3 said:

Hi all, been advised to consider swapping out my 30 years old relays for new,.............

If you do decide to chuck out all your old OEM relays, can I have them please?

As for the old metal relays, if they are still working after all this time, leave 'em alone.

I'm with Phillpot and V8S4Me; just carry a few spares.
My 1992 S still has the original relays which are working perfectly, despite the previous owner using it as a daily driver in all weathers and storing it in a damp barn. Never had a failure.

Beware of new spares; like the guys above said, there is so much crap out there now; you might be replacing good items with inferior ones.
Don't get me started on that discussion, I could bore for hours on parts I have replaced just because they were original items and better to have something newer. Not any more.

[Penelope Stopit]

These are very nice, it's just a case of wating 10 years or so for a reduction in their price



https://www.amazon.com/HELLA-H41773001-Solid-State...

[GreenV8S]

Penelope Stopit said:

These are very nice, it's just a case of wating 10 years or so for a reduction in their price

Unless you are trying to PWM something, I can't see the benefit. They cost more, are fussy about getting the polarity right on all connections, generate more heat and unlikely to be any more reliable than a mechanical relay.

[garypTVRS3]

GreenV8S said:

Penelope Stopit said:

These are very nice, it's just a case of wating 10 years or so for a reduction in their price

Unless you are trying to PWM something, I can't see the benefit. They cost more, are fussy about getting the polarity right on all connections, generate more heat and unlikely to be any more reliable than a mechanical relay.

Oh, I better not get to involved! However, having spent most of my working career in semiconductors including being a Reliability Engineer (back in the days when I did real work instead of directing!) in terms of reliability I'd put a solid-state relay up against a mechanical relay any day... that said, like all things, it's all a cost-benefit argument...

...and of course there's the fear of breaking into the thirty year old electrical system and having it spit the dummy...

hence I'll probably throw some spares in the boot and replace them as I need to!

[Penelope Stopit]

garypTVRS3 said:

Oh, I better not get to involved! However, having spent most of my working career in semiconductors including being a Reliability Engineer (back in the days when I did real work instead of directing!) in terms of reliability I'd put a solid-state relay up against a mechanical relay any day... that said, like all things, it's all a cost-benefit argument...

...and of course there's the fear of breaking into the thirty year old electrical system and having it spit the dummy...

hence I'll probably throw some spares in the boot and replace them as I need to!

Interesting, I have gained much from viewing mixed opinions about circuit control methods

I do chuckle away to myself when those that knock progress become momentarily oblivious to what makes their car engines tick

I guess those that knock progress never fly

I've been looking into incorperating transistors into a circuit for low current switching but have come unstuck due to the activating part of the circuit needing to handle variable voltages from as low as 11 volts and as high as 15 volts

I wish I had your knowledge

[phillpot]

garypTVRS3 said:

in terms of reliability I'd put a solid-state relay up against a mechanical relay any day...

I think the point myself and other long term S owners are making is that the original relays are good quality and from lack of problems reported on PH over the years are not anywhere near the top of the "TVR Electrical Gremlins to sort out" list

[garypTVRS3]

That's why I posted in the first place... as I said, I don't necessarily want to intervene in the electrical system and cause the gremlins to appear...

On the other hand there may be e.g. water ingress which isn't visible hence there could be a problem lurking under the surface... having had all of two weeks actual use from my car in the two years of ownership it's hard to say what the risk is.

Anyway, I have a servo + master cylinder to replace (would be nice to have brakes that work properly)... then a distributor + coil + leads... then I'll maybe take a closer look at the relays... maybe I'll just pop some spares in the boot...

[phillpot]

garypTVRS3 said:

... maybe I'll just pop some spares in the boot...

[GreenV8S]

garypTVRS3 said:

Oh, I better not get to involved! However, having spent most of my working career in semiconductors including being a Reliability Engineer (back in the days when I did real work instead of directing!) in terms of reliability I'd put a solid-state relay up against a mechanical relay any day.

I don't have your experience, but I've seen what happens to MOSFETs when they aren't adequately cooled. A couple of Amps through a MOSFET cooled by an ECU case is fine, as every modern car ECU shows us. Tens of Amps through a MOSFET with that tiny heatsink in an enclosed air space does not strike me as fine.

[Penelope Stopit]

GreenV8S said:

I don't have your experience, but I've seen what happens to MOSFETs when they aren't adequately cooled. A couple of Amps through a MOSFET cooled by an ECU case is fine, as every modern car ECU shows us. Tens of Amps through a MOSFET with that tiny heatsink in an enclosed air space does not strike me as fine.

I suggest you contact the manufacturer to inform them that they are clueless

What do you think about SSD's?

[Penelope Stopit]

Getting cheaper - $9


https://www.amazon.com/Ogrmar-SSR-40DD-Solid-5-200...