EDSRX3

I have this RX3 that wants a new life. I've had it for 20+ years, parked for the last 10. The car is complete, little rust, with original paint.

I want to upgrade drive train, suspention, and brakes. I am seriously suffering from lack of infomation.

Will the original RX3 dif take an upgrade in power? Can it be upgraded to disk brakes, is there a better alternate(first gen RX3 dif???)

Is there a common front suspension/ brake upgrade?

The original twin distributor engine runs, but poorly(suspect apex seal problem). Does this poor old engine have any value?

I'm hoping to find someone with practical experience with this kind of upgrade.

Thanks - ED

D3rELiC

i've heard about some ppl using 1st gen rx7 suspension in front and rear, but im not sure how,

you might wanna get a 13b if ur engine is wasted, but go carb, not EFI

a compression test will reveal if you have apex seals issue,
Jeff20b also wrote a very complete writeup about direct fire ignition, u might wanna try it if ignition is your problem.

is your rx3 a coupe ? 4 door or wagon ?

EDSRX3

Its a coupe. nice condition, originally from california, my second RX3. It was originally an automatic, but I changed it to standard some years ago. it has factory air conditioning that I have never seen in any other RX3's. I've tried a couple of different carb set ups. A holly 650, then a set of webbers. The webbers gave me the best performanace and runnability, but I want to forget about keeping it more or less stock and make a bit of a rod out of it. The body is sound, but I don't know if a serious increase in power will cause any structural problems.

Any and all advice is welcome.

ED

jm93rx7

iTrader: (7)

do you have any pictures of the car ??

SS124A

the rear suspension/diff/brakes is the first upgrading you should be doing..

I have just gone through all this with mine.

to convert to rear-disc there is a kit made by Jeff at rotary power USA (e-mail me and I'll get you an e-mail address)

I retained my long pinion rear diff and bought a 4.375 ring/pinion set from Racing beat.. a bit steep for you maybe..

I would consider using a 4.10 rear ratio ring/pinion.. or steal the ring/pinion from a GSL-SE which will be 4.07. then come up with an 81/82 LSD..

change the ring/pinion into the 81/82 "pumpkin" and bolt it into your axle housing.. your original axles will work with all this..

the cheapest way to do all this is to find that GSL-SE ring/pinion from a junkyard or via someone selling one here. then buy a COMPLETE 81/82 rear axle assembly so you have the brake parts etc.

then flat spring your leafs, new shocks (i have Koni's) and weld in a pan-hard bar.

if i ever find a alfa romeo GTV or 97 Miata rear I may graft that in..

Wankelguy

RX3 axles are notoriously wimpy.
If you're going to be making any serious power, I'd look into using an 8.8 Ford rearend.

EDSRX3

My plan A would be turbo. I want the most power without limiting the drivability of the car. My first RX3 experience goes back to 1978 in the cold winters of Edmonton Alberta. I've been through the hard to start and difficlult to keep running game with this car and don't want to go there again.

I'll over build the car so I can stay off the wrenches when I really want to play.

Is there a more common dif conversion than others?? Anyone with the best and worst story?

Is the body strong enough to take the extra stresses at the leafspring mounting points? What kind of suspension modifications will best impove handling?
When upgrading rear drums to disk brakes, what modifications are needed to the master brake cylinder?

Thanks for the help!! I want to do this right the first time (or close to it)

13BT_RX3

I had a J-Bridge 13B in mine for a while. It wasn't enough for me so I added a turbo. This combo didn't last too long, but was really fun. I had a Blow-through Holley 650, see pic. I had slapper bars on the car, but took them off because they screwed the handling up. Major instant overstear. It wasn't long after that when I noticed how warped my leafsprings got. Pinion pointing upwards more than normal.

I would recomend using the 81-83 GSL Dif housing over the RX3 housing. It bolts right up and is lighter. Better ride comfort. The downside is the driveshaft needs to be shortened. Or you will need to push the engine back.

13BT_RX3

[QUOTE=SS124A]the rear suspension/diff/brakes is the first upgrading you should be doing..

I have just gone through all this with mine.

to convert to rear-disc there is a kit made by Jeff at rotary power USA (e-mail me and I'll get you an e-mail address)

What did you do for a parking brake cable?

EDSRX3

I'm in the process of mounting the RX7 pumpin into the RX3 dif housing.

There is conciderable difference in the housings as the RX7 diff is set up for coil springs instead of leaf springs! Did you modify the RX7 housing first??

I understand that I need to grind down the RX3 axles by 1/8 inch and that the diff bump stop needs to be relocated as well as the drive shaft needs to be lengthened.

Have you seen a RX7 diff transplant into the RX3?? Any pics??

Thankls for the reply??

13BT_RX3

Sorry for being unclear. I used the stock RX3 Axle Housing and Axles. I simply installed the complete third member from the RX7.

Siraniko

iTrader: (13)

No need to grind it down but be sure its pre-83 to ensure that you have the right of spline and use pinion flange from your orig diffy to match your driveshaft. Im using a kia 4.44 R&P in a 81 GSL 3rd member in my RX-3. I have abused this so called small axles on slicks but still in good shape.

13BT_RX3

I did not grind my axles and they looked perfect on inspection 6 years after I installed the diff.

EDSRX3

Who would know???

The information you get from the internet!!!

I have a Question regarding the brake backing plates on the diff;

It looks like the axle bearings need to come off to remove the backing plates, How have you dealt with them?

I've seen brackets to adapt the disk brakes over on the RX3. Very simple in design. I was planning to manufacture them myself(some cutting, heating and bending). I was also planning on cutting the backing plates off the RX7 axles and just modify them to match the adapter plates I make and avoid disturbing the axle bearings at all on the RX3 axles.

What do you think??

13BT_RX3

I left my old backing plates on. I mounted the caliber bracket to the Axel Housing using custom laser cut bits. The stock Axle bolts were long enough for 1/4" thick bracket.

Siraniko

iTrader: (13)

No need to pull the axle all the way--just enough so you can use a tin snips to cut the backing plate. besides, what do you mean by disturbing the bearings when the entire axle comes out. In fact, its even better so you check the condition.

BTW, buy the adapter plate from RESpeed. Got to support a RX7Forum member.

EDSRX3

Cool! Thanks for all the feed back!!

What about rear shocks??? What are you running in your RX3??

Siraniko

iTrader: (13)

koni reds

13BT_RX3

I used rear shocks from an '83 RX7 (KYB). They required a spacer to fill the gap of the axle attachment point though.

I have attached a few pics:
Front susp and brake, rear end, rear brake (kind of a bad shot)

Siraniko

iTrader: (13)

On the front suspension, is that the spacer from REspeed?

13BT_RX3

No. I made it. I have a few extras since laser cutting was a batch job.

13BT_RX3

Oops, you meant the strut spacers. Those are Racing Beat 1st gen RX7 Bumpstear spacers.

EDSRX3

Can you help me understand what the spacers you are using do to improve handling??

Are there other alighnment adjustments needed to make them work??

13BT_RX3

They help maintain the rollcenter when you lower your car. If you lower your car too much your control can go level. When this happens you loose camber gain in roll. Not an efficient use of the tire.

I believe you want to increase caster quite a bit 3-5deg is normal for a sport feel. Negative camber is important too. I like a minimum of 1 deg for normal around town driving. I hear people run camber a lot more agressive than that on the track. I have a fixed caster position on the tower, but can adjust it at the swaybar by repositioning a stack of washers between the Control arm and the machined lip on my bar.

I have seen a few RX3 that ran the 2 bolt hats of a camber kit without the kit's mounting/adjuster plate. They mounted one bolt in the inner most of the 3 strut mounting holes and modified the strut tower accordingly to allowed their 2.5" race spring to be mounted as far in and back as possible without rubbing on the inside of the strut tower.

I have heard that RX7 struts don't allow as much camber as the original RX3 struts. So keep this in mind if you opt for them.

davidleonardi

Hi,

I'm David from indonesia. I'm planning to do engine swap on Mazda 808 sedan with 13BT engine. I'm still blind about the brake and the suspension conversion. Do you have the photos of your suspension and the brake conversions ? If you do, I'd be highly appreciate if you could send them to me ? It's my first tiome doing this conversion and I have nobody to ask from here.

Thanks a lot.