H5->H4 upgrade, relays, bulbs - question about fuses?

[jdbunda]

I am about to take on the headlight upgrade, replacing the H5s on my late '86 with H4s (I thought they were H4s, but no, they have the telltale "DOT" and aiming beads on the lenses). I have the JWest relay kit, Euro H4s, and 80/100w bulbs. My question is this - do I need to also uprate the headlamp fuses in the process? 60w is ~5 amps, but a 100w bulb is closer to 8a (certainly at least 7 at 14v). I think the fuses in the panel are 5 amp? I am thinking all four headlamp fuses should be replaced with 10amp in doing this upgrade.

But - I haven't seen this mentioned in any of the myriad threads I've read when searching on H4 and bulb upgrades, nor in the instructions that came with my relay kit - but I do recall this being an issue when I upgraded lights on an '89 BMW a few years back.

Is there some Porsche magic or something else I am missing that makes this unnecessary? Am I overthinking this?

John

[Flat Six]

No; leave fuse ratings as-is. Once you install the relay kit, the only current running through the fuses will be to drive the relays themselves -- not the headlamps. That's why you're installing relays in the first place: to isolate the current draw of the headlamps from the battery through the relays to the headlamps, bypassing the fuse box, turn signal stalk, etc.

You might want to clean up the fuse contacts and for kicks and giggles install new fuses of the same (stock) rating.

HTH

Dale

[j911brick]

+1

Originally Posted by flat six

no; leave fuse ratings as-is. Once you install the relay kit, the only current running through the fuses will be to drive the relays themselves -- not the headlamps. That's why you're installing relays in the first place: To isolate the current draw of the headlamps from the battery through the relays to the headlamps, bypassing the fuse box, turn signal stalk, etc.

You might want to clean up the fuse contacts and for kicks and giggles install new fuses of the same (stock) rating.

Hth

dale

[jdbunda]

Originally Posted by Flat Six

No; leave fuse ratings as-is. Once you install the relay kit, the only current running through the fuses will be to drive the relays themselves -- not the headlamps. That's why you're installing relays in the first place: to isolate the current draw of the headlamps from the battery through the relays to the headlamps, bypassing the fuse box, turn signal stalk, etc.

Hi Dale,
Thanks for the reply - but are you sure this is right? I went back and consulted this diagram that I found on another Pelican thread:



I downloaded the jpg and zoomed in with a photo viewer to get a better view.

Based on the location of the cuts in the diagram to insert the relays, it seems to match the method used by the JWest relay kit. It appears to me that the switched side of the relay is connected to the lights through the "normal" fuses for each bulb - power comes from the relays to the fuse block, through the fuses, and out to the bulbs. It is, in fact, the (now low-current) dimmer switch side that is unprotected with this mod.

It does show 8a fuses on the high beams - but all the fuses still seem marginal for 80/100w bulbs.

Am I completely missing something?

[Flat Six]

Ah, I see the difference. I installed relays, though Daniel Stern's kit not jwest. Rather than running headlights' +12VDC through the fuse box I isolated the power circuit this way:

Battery (+) --> in-line fuse holder (10A) --> Relay --> Headlamp (hi or low) --> chassis ground

I use the current running through the fuse box for the sole purpose of triggering the relays. To me, it's cleaner overall to avoid running the heavy load through the fuse box with its sometimes suspect connections.

So yes, I too have fused the load circuit to the headlamps (though it's not really necessary to protect the relays which are rated at 35A or -- in my case -- 50A). Probably reflects my bias to over-engineer; belt and suspenders kind of thing. Really, though, adding a fuse in this headlight load circuit doesn't provide any protection I can think of.

Hope this helps.

Dale

[rattlsnak]

The whole point of running the relays is to avoid having the current run through the switch and burning out the contacts. It has nothing to do with protecting the fuses or wiring on the headlamp side of the fuse. The diagram is correct.

[jdbunda]

Originally Posted by rattlsnak

The whole point of running the relays is to avoid having the current run through the switch and burning out the contacts. It has nothing to do with protecting the fuses or wiring on the headlamp side of the fuse. The diagram is correct.

I agree, it is all about reducing current through the switches and panel wiring. I'm a little surprised that the kit leaves the switches and panel wiring effectively fused only by the relay coils, but relays are easy to replace at least.

The original question was whether I will need to go to bigger fuses for 80/100w bulbs. It seems to not be an issue based on the lack of confirmation of that. It may well be that the bulb power ratings are a little "conservative," but I think I may pick up some spares just in case, and bump up the rating if they blow.

Dale, looks like you have in fact effectively gone to 10a fuses on the bulbs with your setup, which is what I would expect. Your setup requires new wires running to the headlamps, correct? It appears that the Stern approach is probably more robust, but requires additional wiring.

[jdbunda]

I got the JWest relay kit installed without drama, then I went to swap the H5s out. I must be a complete bozo, I removed the screw on the painted trim ring, but then what? That doesn't seem to loosen anything, and without knowing how it all fits together, I have no idea what to do next. I tried both sides, but I could not even figure out how to get the trim ring off (let alone the rest of the assembly). Bentley, Haynes, searching searching here and with Google, I can't find anything more helpful than "remove headlight assembly". All I can do is laugh, someone please tell me how to disassemble! How does one remove the H5 trim ring?

[schumicat]

the painted trim ring should just pull off when you remove the screw (which just provides some tension to hold it in place).

[Flat Six]

Originally Posted by jdbunda

Dale, looks like you have in fact effectively gone to 10a fuses on the bulbs with your setup, which is what I would expect. Your setup requires new wires running to the headlamps, correct? It appears that the Stern approach is probably more robust, but requires additional wiring.

One of the main reasons I did it this way was because I wanted to run larger (14g) wire throughout the circuit (including grounds) and install hi-temp ceramic H4 sockets without cutting OEM wiring. Also, I'm running the dual 87 relays in order to run two separate 12V+ power leads (L/R) from each relay (Low/High) rather than the single 87 relays in your wiring diagram and JWest kit.

Interesting reading here Sensible Automotive Wiring regarding wire sizing.

BTW, I was able to run 14g wiring alongside factory wiring (even through all grommets, with some patience and lube) so didn't have to cut anything.

HTH

Dale

[hcoles]

@John, how did this go? Are the H4's much better than H5's. I have an 89 and assume I have H5's, they are not impressive in terms of providing light. I need to read more threads on this I guess but was just wondering. The other idea is to go all out and rig up a projector light system but that is involved.

[jdbunda]

I am just about finished, I had to wait on some parts. I was thinking of doing a full thread on this since I ran into several blocks along the way. If you are thinking of this upgrade and you haven't done the relay kit, I would suggest doing that first. At least for my car, getting the light switch wiring out of the circuit seemed to make a big difference in brightness. Still not exactly an ecode beam pattern, but MUCH improved. They are now good enough that if I didn't already have the h4s, I might be tempted to just leave it alone, especially since the mounting of the H5s is so much more solid.

Obviously, the relay kit's improvement will vary depending on the condition of one's switch and wiring. I used the Jwest kit our host offers, which uses the original fuses and doesn't require adding any wiring - I think there are perhaps more robustly engineered ways to go (more fusing and heavier gauge wiring, etc) but I like the simplicity, reversibility, and stock look of the Jwest kit. At $25 and 30 minutes to install, the bang for the buck is huge.

So the H4s are ready to go in, but I ran into two issues that caused me to delay. First, I decided to replace the gaskets. Mine were original, cracked, and shrunk, I couldn't get them back in and looking decent after removing them to clean. So I ordered new ones. Also, I bought the "adapters" from our host, but they are really just h4 sockets - using them as is would require cutting the wires on the H5 sockets, so I ordered some connectors from Susquehanna Motorsports that will allow me to make true plug adapters so I can leave stock wiring and sockets intact.

[ben parrish]

Are you going to sell the h5's? I might be interested.

[hcoles]

@John, if you can take a few pictures of the before H5 parts/assemblies and H4, this will help see what I might be dealing with. Thanks.

[jdbunda]

I am happy to take some pics, but it will have to wait, just took the car to the body shop to have my rocker rust repaired. If you can wait a week, I will snap some pics. If you search for H5/H4 conversion threads, you might be able to find what you need meanwhile.

But here is some more detail. The first thing you will notice is once you have the trim rings off, the H5s are mounted with screws onto tabs in the bucket. Take out those screws, and the assembly lifts out. You might notice some rust in the bucket, if any moisture gets in there, it has no place to go - I used some rust converter to clean mine up a bit.

The rubber gasket between the light assembly and fender was grimy, so I removed it to clean it up. Unfortunately, at least on my car, it was not a round ring, but a strip. It was kind of hard and cracked, and had shrunk, like most 30 year old rubber, and didn't really seal very well even with trim adhesive, so I decided to replace them.

The next thing is connecting the lights. As expected, the H5 bulb connector is completely different (9004 I believe), and the Pelican "adapters" are really just sockets, you need to either cut the H5 sockets off, use spade-lug pigtails, or what I did, buy connectors that look just like the H5/9004 bulb, and make your own harness adapter.

The next thing you will notice is the crummy mounting system for the H4s, which use only the small lip at the top of the fender opening and the bottom screw at the front of the assembly to hold everything onto the car. Not the greatest scheme - I am tempted to try to see if I can somehow use the same tabs the H5s screw into. If that isn't possible, I may use the tie-wrap method others have described to keep them from departing the car.

[Jesse16]

Just completed this upgrade to H4's on my 87 this weekend. I used the Daniel Stern recommended method, not sure I would if doing it again but I'm always up for a project. Send him a message and he'll advise. My reason was that I really wanted to have Cibie brand H4's in my car and Daniel sells them.
He sent me these photos.

I bought the buckets for $110 and the kit from Daniel which is lights, bulbs, and relay kit for about $220. All in, it looks like this.
I like the old school clear glass lense covers.
This project is not for the faint of heart and is not a simple bolt in project. You gotta make em fit. Most of the cutting/grinding is on the VW Buckets but I had to do some significant fitting of the trim rings to get em to accept the new clear glass cover. (that means cutting metal). They are sturdy now though and the light is amazing compared to the H5's. I'll put them up for sale soon.

[hcoles]

@Jesse16
Re. bezel cutting, you are referring to changing from the VW chrome ring to the painted 87 Porsche ring. correct? To get clear lenses I need to get these VW assemblies like you picture (small image), correct? Thanks.

[Jesse16]

This is just one way to do this as recommended by Daniel. I had to open up the painted ring as it wouldn't take the clear glass cover, basically the chrome VW ring is a bit larger and shape is a bit different. I spent alot of time tracing the shape on paper to understand what I was going to do. Then I kinda built a crude jig to mount my dremel with a carbide burr and opened up the painted rings inside opening. Maybe took 1/16" off all the way around. To be exactly right, I'll need to do some touch up painting. The other issue is the adjustment screws sit out proud of the painted ring. Not very pretty right now but I'll think of something cool to do eventually. The VW rings have a crudely punched in countersink to sink the screw heads closer in. If I try that, its bust the paint everywhere.
Then lots and lots of grinding on the buckets to cut of everything that hits the 2 upper H5 mounting tabs. I also cut the tabs back some as they are much broader than they ever need to be. I didn't touch the threaded hole at all though.

[Jesse16]

Last, I believe that the assy's sold at this site have an optional lense cover. Don't know if its plastic or glass. Not sure of how it all mounts but it has to be mostly the same.

[jdbunda]

Nice Jesse -
Your post brings up one of the great causes of confusion in all of the discussions of this topic - there are H4s, and then there are H4s.

The Hella or Cibie H4s (like what you are showing here) are H4 bulbs mounted in 5-3/4" reflector housing, drop-in replacements when used with the old "sugar scoop" style mounts.
As you discovered, when you don't have scoops already in place, it's a little bit more involved. I kinda like the look with the VW parts and clear lens - I recall a thread a while back where someone used this approach to build some HIDs.

My car is getting the "other" H4 i.e. Bosch Euro H4 assembly, which looks VERY similar to the H5 with its fluted, flush lens design.