I recently purchased a 1991 n/a coupe and I have some questions I could not find through searching

1. My car has a replacement hood on it that is aluminum. Would this have been stock? I assume it's a very item for weight savings. We're there other alum body parts made?

2. Wtf does the "security" thing on the center console actually do, if anything?

 

Answers.

1. Yes, certain trims in certain years had an aluminum hood, consider yourself lucky.

2. The security light indicates that the factory security system is armed. They tend to go screwy after 25+ years so maybe it does something, usually that something is triggering false alarms in the middle of the night.

 

Convertibles and certain NA models (GTUs) came stock with non-vented aluminum hoods.
Some clever PO probably snagged a vert hood for his coupe.

The center console security light goes through a long, protracted series of flashes to indicate it is armed and ready to false alarm at any moment.
When it does, the headlights will raise, the horn will honk and the hazard lights come on.
It's quite a show.

It's main strategy is to paralyze thieves with laughter.

 

^ Truth.

It's caused by a variety of things going wrong all at about the same time. On the S5 models, the factory hood pin will start to fail and randomly trigger the alarm. The CPU will also start to fail due to the electrolytic caps going bad and eventually, the highbeam switch stops working followed by the factory alarm ceasing to function.

You can permanently disarm the factory alarm by doing this...

S4: At the factory alarm module behind the glove box. Ground the Light Green/Black wire.

S5: At the CPU in the driver kick panel, ground the Light Green/Black wire.

 

Not meaning to Jack this thread, but my high beams don't work! Even the nifty blue notification in the dash board doesn't come on. Is this a CPU issue?

 

Edit...

Posted to wrong area.

Cheers,
Bull

 

Yup!

You have 3 options...

1) Fix the CPU.

2) Buy a latching relay from eBay and wire it up to receive the negative trigger pulse from the factory switch and then wire that relay to turn the high beam relay on. This can all be done in the driver kick panel easily.

3) Buy a dummy switch to apply ground to pin 85 of the factory relay until you can accomplish options 1 or 2.

 

This is why I enjoy this forum. Good info from knowledgeable folks!

Thanks again,
Bull

 

You mentioned that certain trims have the aluminum hood... Is there a for sure way to know if you have a GTUs? My 1990 has
-aluminum hood -the turbo wheels -turbo seats -no sunroof- no rear wiper- LSD - the alarm system - auto track seat belts- a/c - and crystal white color code .... But are all those features on other trims as well? Is it just that maybe someone put all those bits on? Or is there a sure way to know it is a GTUs?

 

Does it have manual windows and locks? Also 4 piston front brake calipers? If so it probably is. GXL, GTUs, and vert had the 4 pot calipers but the GTUs was the only one with manual windows and locks. GTU had single piston fronts. GTUs was the only n/a with LSD that year. Only the GTUs got the turbo wheels. Originally had a GTUs decal on the fenders. This thread says check the tire size on the door. It was the only n/a car with 16" rims. They also said on a '

https://www.rx7club.com/2nd-generati...-218481/page2/

 

Yes manual windows and locks... 4piston calipers front, rear vented rotors, and the door says 205/55/16.... I'm gonna take the rear diff apart to double check the ratio, but based off all that it should be a GTUs? I called Mazda and had them look up some info with the vin, they said it came up as a "GU" and they had nothing about a GTUs in the system... Not helpful at all... And if it is a real GTUs, there was only 100 of them marked as a 1990 right? Which would make this thing super rare right?

 

why take the diff apart to get the ratio?
just observe the revolution of the wheel compared to the driveshaft.Calculate from that.
And as a far as LSD..the stock LSD unit had a tag on the filler plug on the rear casing stating which oil to use..it said LSD in some kind of jargon on it.(brain fart.,.forgot what it says.!)

 

I don't think the '89 and up had a tag as they used a viscous LSD which is a sealed unit internally thus standard gear oil without the LSD additive is fine. Yeah no need to take the diff apart. Besides IIRC the GTUs was the only n/a with a LSD that year So it is either a GTUs or had an LSD swapped into it.

 

Well I was planning on changing the fluid anyways, what is the difference between the LSD and the Viscous LSD? Can you tell the difference just by looking at it? Sorry I'm fairly new to rx7 world and all the components associated with them

 

Read here for differences between the different types of LDS's: https://www.google.com/webhp?sourcei...0clutch%20diff

As far as looking all n/a use the same case so just looking under the car you won't be able to tell. If your car is in fact a GTUs you have the viscous diff unless a previous owner swapped it for something else. You don't have to open the case to change the fluid it has drain and fill plugs on it. The individual units look different but you have to drop the whole rear end to open the case.

 

Rear end dropped, counted the teeth 43 on the ring gear 10 on the pinion so a 4:30-1... Is this what the Viscous looks like too then

 

Unless I am missing something, that looks like a regular differential to me.