I've searched and searched and what little info I find is not consistent.

I'm swapping an s5 motor into an s4 car. I know that I must use the s5 flywheel, so that is currently mounted on. I also know the s4 and s5 clutch discs are slightly different widths, but from what I read, I can use either one. Correct me if I'm wrong on that.

Here's my problem. I tried to bolt up my s4 clutch disc to the s5 flywheel and the holes didn't line up. But from what I'm reading it should bolt up. So if anyone knows 100% if I need to buy a clutch plate, disc, or both for this s5 motor, please chime in. I'd like to get this motor set in the car before weather gets bad.

One more thing while I have the gurus in here helping me out, I will need to use the s5 starter and slave cylinder also, right?

Thanks in advance for the help.

 

the S4 turbo clutch is 240mm DIAMETER, and the S5 turbo clutch is 230mm (or something, maybe its 245mm/235mm). the Na clutch after 1983 is 225mm, and all the NA clutches from 83-92 are the same.

so you can use an S5 disc on an S4 flywheel, but the other way around may not work. if you're using aftermarket stuff, they might all just supply the S5 style, as its the common one (rx8,fd, and other cars use it), and so it may be that aftermarket is compatible S4 and S5, but the OEM parts are not. i think my car has a flywheel that does FC and FD, but the PP and disc are S4.

not sure about the pressure plate, i think the S4 plate should work.

the turbo uses the same starter from 86-92. the NA uses a different starter, but it is also compatible 86-92.

the clutch slave is different between the turbo and the non turbo, but both use the same master cylinder and hose.

 

I totally should have specified that I'm going from turbo s4 to turbo s5. Neither the car nor the donor s5 motor are N/A.

I hadn't thought of the aftermarket flywheels possibly being universal. That would explain why all the parts store, ebay, etc just say the flywheel/disc/plate are all for basically the whole spectrum of turbo models. I'll hold up the pressure plate against the flywheel again and see if I'm coordinated enough to take a picture. If the universal flywheel theory stands correct, then I should be able to just buy an aftermarket s5 flywheel and have my s4 plate just mount up? The flywheel has pretty wicked surface rust, so if I had to replace anything it would preferrably be it.

Thanks for the help so far.

 

The lightweight aftermarket flywheels ARE swappable from s4 to s5.( must be turbo or N/A)
BUT they attach to a counterweight that is Specific to the engine's rotating assembly.
That means your rear counterweight must be an S5 on an S5 Engine..S4 on an S4.
Do NOTput an s5 counterweight on an s4 or vice versa.

 

Yeah, post the picture as you said. Maybe you're not lining up the dowel pins and bolt holes properly. Sometimes the pins are a 'lil bent or really snug to the holes on the pressure plate.

And it's a good idea to machine the flywheel smooth, especially if you're using a new disk on it.

I always thought all clutch assemblies (clutch disk, pressure plate) worked between S4 and S5, as long as you keep NA with NA and turbo with turbo.

As an aside, I've heard you can use a turbo throw-out bearing on the non turbos. Any truth to this?

 

if you look in the Mazda catalogs, they are different PP/discs per series. well the NA i think had something that wasn't that lead to easy interchangeability.

 

N/A is N/A, Turbo is Turbo. Applies to Clutch disc, pressure plate, flywheel and starter. RX-8 uses a S4T2 clutch & flywheel.
Call me when it's important.

 

why?....
you never call ME anymore...sniffle..!..sorry..gimme a minute.........(blows nose..eww!)


Ok..Nuthin to see here!
Back to abnormal.

There is a slight difference in Throw out bearings,The older models seem to be heftier than the newer ones.I got one recently that had a lip on it compared to the older one that had a more solid face to contact the pressure plate.

But the main BIG difference besides size on TII to N/A would be the spline on the TII and N/A Transmissions.
they need the corresponding clutch disc.(TII tran,TII Clutch disc),Otherwise it won't fit.

 

Well I got it figured out yesterday and I would have posted sooner but I was too busy beating my head against the wall.

The kid I bought the motor from either lied or didn't know, but I have an s5 NA motor, not s5 turbo like it was supposed to be. The reason turbo clutch plate wouldn't mount up is obviously the dowel size difference and slight different location. I double checked the motor and sure enough, rotor housings have knock sensor, but coolant port for turbo is blocked and exhaust ports have the little diffuser things inside.

Ugh. Back to square one.

 

Post PICS of the engine.
S5 TII's do have the threaded hole above the Trailing plug for a knock sensor.

 

S5 na's do as well...

 

I can remember taking a Block heater off my S5.(yep!)
Wasn't sure whether it had a knock sensor though.
Actually the damn car has been running so well I haven't been in the engine bay in a month!

 

I attached a picture of the housing. It sure looks to me like an s5 n/a, but I'd love to be proved wrong.

So basically these are my options. Turn s5 na motor into s5 turbo motor, rebuild the s4 turbo motor that I have, or sell all the rotary parts and v8 swap it. I don't know what to do.

 

its an NA engine

 

Is it more of a pain than its worth to convert the na housings to turbo ones? Drilling out coolant line, porting, etc.

 

You said you have an S4 Turbo car. I'd rebuild the S4 Turbo engine. Seems like the easiest route.