Does anyone know the OD of the eshaft at the two rotor bearing locatoins? And what are their dimensional tolerances when brand new?



I'm thinking of running rx8 eshaft and rx8 front and rear start gears again. I want to know if I will need to purchase new rotor bearings to achieve the correct clearance between the rotor bearings and eshaft.



Thanks

the rx8 eshaft is the same as the rx7 the only diffrence is it is lighter causing you to have the rotating assembly balanced to your set up.

Thaniks for your opinion. Anyone else have anything accurate or at least "Right" to share?



From what I understand the E-shaft has neutral balance in the engine, just like the flywheel and pressure plate.

From mazdatrix:





These shafts are .6lbs. lighter than the earlier 13B shafts. The main journal diameters are approximately one-half thou smaller, and there is a one-half thou taper in the rear main journal.



Does the rotary journal lands also correspond to a 1 thou smaller diameter than a S5/S6 eshaft?

There are 4 different rx8 shafts, running the lo po ones will gain you pretty much nothing. Running an FC shaft in Rx8 stat gears, gains you well, nothing..

In order for you to make this an enhancment, you need the rx8shaft of the Ho model, the corresponding stat gears, and either the rx8 or FD front stack.

The rx8 is dimensionally similar to the FD shaft, which are staggered bearing designs. In truth most turbo motors power peak is so far below the reasoning for the rx8 stuff, the cost benefit difference really doesnt make it add up.. The RX8 gears arent any stronger than what its in an FC block..

The main thing I guess I was looking at the rx8 stuff was because the rx8 stuff is the same price as the FC stuff.

I totally agree with you, but the nice thing about the rx8 gears in the HO models they have a 10 window bearing, they are brand new, and I got both for $220cnd. The FC or FD Bearings would have cost that much to get pressed in, with the price of the bearings.

the rx8 ho/6port uses the same bearings as the fd, part number wise. rotor and main.



the low output engine uses fc bearings in the stat gears.

Yes it has the multi window bearing needed to feed the needs of the staggered shaft, which the FC doesnt have, so its not really implementing the whole benefit of the bearing/shaft design. The extra oil is needed for the looser tolerance of the outer rear bearing journal , which is wider tolerance to allow for some shaft flex due to flywheel weight and rpm, without wiping out the rear bearing. On the FC setup for rpm, the key to engine life is getting the engine oil pressure up, and flywheel wieght down and a .0005 cut on the e-shaft, thats where I would spend my money, thats whats also the direction I went with my P-port with a 9500 rpm shift point and also my bridged turbo car which I meant to shift at 8500 , but I couldnt always catch the shift fast enough. I read alot that people think that only s5 up and stat gears were hardened, but mazda says that all gears from 85 on were hardened, makes sense, I have never seen a stat gear failure in an s4 turbo and they have the heaviest rotors.



Btw your getting hosed for bearings, I think I pay 11.00 a piece and I own a press.. https://www.nopistons.com/forums/pub...IR#>/smile.gif ..

lol, i might order some bearings.... you're beating mazdausa by like $26 each

11 bucks? Woah.. that's cheaper than Mazdaspeed USA sponsorship deal.



They want like $37

No doubt! Hook this cracka up https://www.nopistons.com/forums/pub...IR#>/smile.gif

Something I noticed yesterday when I had a close look at a high power shaft, the main bearing oil feeds are offset 3mm towards the ends of the shaft. Since the RX8 stat gears are dimensionally the same as earlier items the only explanation is the stat gears are offset in the RX8 irons.



Because of this I used an FC shaft instead.



Does anyone have some RX8 irons they can compare to earlier ones?

I thought it was RPM, not cylinder pressure, that hosed the stationary gears. The tooth loads rise at an almost exponential rate with engine speed, far more than mere cylinder pressure.

It is Rpm and the mass of the rotor, what made you think it was cylinder pressure?

It was the mention of turbocharging. Series 4 rotors are not the heaviest ones ever used by Mazda, the 3mm seal 13B rotors are much heavier.

That is true, but I just made that comparison due to people saying that the s4 gears are somehow inferior to the s5 gears since everyone seems to be in the mood of throwing away s4's for s5 or rx-8.... Just for trivia, anyone know what the lightest 13b rotor weight is?.. https://www.nopistons.com/forums/pub...#>/biggrin.gif

without considering compression ratios my guess is (from lightest to heaviest)



1.) rx8

2.) S5 NA

3.) FD rotors / 13BRE rotors

4.) S5 TII rotors

5.) S4 NA

6.) 13B GSL-SE 3 mm

7.) S4 TII

I never bothered to weigh them, but #2-4 supposedly are the same weight, as are 5 and 7. So it's 1, 2-4, 5&7, 6.



http://www.mazdatrix.com/faq/rotorwgt.htm

There is one missing from that list , and its the lightest..

10A??

the 74-85 13b rotors are the heavy ones, 12+ lbs each. s4 is like 10

12a from 74-82 is like 10lbs

83-85 is like 9.6 or so, about the same as the s5 13b



i dont know about the pre-73 12a's, ive got some rotors, but they are like the 74-85 13b rotors, useless

Its an 80mm rotor(13b) rotor as well..

can you explain this enough to give me a mental picture? even better, do you have any pictures of either the FD or the FE shafts? I'd just like to see what is staggered and also, the benefit/reasoning behind it.



Thanks.

probably one of those post-'96 special model REW engines that never came here. am i close? https://www.nopistons.com/forums/pub...IR#>/smile.gif

Nope.hehe..

OK I will give it up...

13b/20b mazda sports kit rotor.. 4000 g, 9.4 compression, 3mm groove for carbons. Produced during the 90's and floating around Japan in the odd used parts store, usually without the required counterweights. This was the rotor produced for the mazda sport kit PP engine that was availabe to the public in 309 ps for 13b and 450ps for 20b forms. The rotors were also available seperately.

zry1-11-b10a listing says "rotor gear secured with snap ring, light weight rotor for 13b engines, 3750gm" then as a footnote it says "using 20b lightweight rotors in the 13b engine requires 13b rotor bearing (zry1-11-b21) and rebalancing the whole rotating assembly"



nla here, dealer cost is 1693.05 each

https://www.nopistons.com/forums/pub...IR#>/blush.gif bargain.....Wonder why the weight difference, unless they shed another 250 g from when my book was printed? I just found another set of rotors that are odd ,7.5:1 and 8.3:1..

you guys are downright scary ... but i like it.

dunno, mine's the 97 mazda comp catalog, or hell maybe theres 2 different ones?



7.5 should be like the bonneville/757? rotors. thats the 81-86 bridgeport twin turbo engine, 520hp@1bar and 8500rpms, 2xht20 turbos. not sure what apex seals they ran, but it doesnt seem like it was all that reliable....

I just bought $600 in bearings, hook it up MaxT LOL



I could use some of those 7.5:1 rotors too !!!