while i had a fail with nitrile at 2.5 mm
you must factor in the plate was already heavily corroded there and i was running 1.3 bar cap and i did get the engine up there to around 250 F before it went

the nitrile was infact intact ( and was fine in all other grooves ) and the plate had failed
there was evidence of squeezed extrusion indicating 2.5mm is perhaps just a little too large for groove in plate
( but,, going by that fact some aftermarket peoples provide them this big that 2.5 is possibly fine in groove in housing engines )

another thing to note is that when made,, nitrile is very easy to extrude with precision
viton on the other hand apparently is not
and so as explained to me by a professional that sells this stuff all day
a 2.4mm viton extrusion has a more significant factor +/- for oversize and under-size along the same 100 M roll

i would think if you used the 2.55mm,, ( which is already tight at 2.5mm )
then you run risk of getting some potentially being 2.60 mm and more

and the risk then may be compounded by having been used in lapped plates with a now lesser groove


if you think your coolant grooves are still in good nick,, and are good castings from factory
then by all means give them a go

if you have other variables such as plate machining , 1.1 bar or more cap , or less than perfect meat left beside the groove
than i would err to 2.4mm and no more

Good rationale, Bumpstart. I like it. 2.4mm it is.

Brian,

Are you sure about that? I had always thought that RA was just reselling the mcmaster ones?

pat

They're a different o-ring, Clint. Well, at least up to about 4 1/2 yrs ago when I was purchasing their kit they were using a different o-ring. It was slightly skinnier than the o-ring on McMaster (the inner TES one).

wow, this thread has evolved and seems to be providing even more wonderful information than it started with. this is a rarity, a true gem .... :)

Ordered 20 feet of 2.4mm Viton and 30 feet of 2.0mm Buna-N today. Should be enough for two engines. Under $45 and we were placing an order with McMaster-Carr anyway.

I have been using the 18-gauge (.091") Belden electrical wire with middling success. When the temperatures get cold, they don't seal combustion gases, and then burn. Going to try this stuff now.

Last month I ordered 15ft of #2542t21 for the inners. This is squared Viton and not round. I had previously been using the round cord #9464k537. I'm hoping for more contact surface area like the stockers. The 20b is going back together next week since my final stage experiment mods are done. :) I'll be pulling it apart again in about a month so well see how well this holds up.

I'm curious to see how that goes, t-von.

By the way, you're not very far from me. Going to have to come out there and check out your car sometime!

B

Found o-rings for the LIM (rotor housings), front cover slot for both S4 and S5, and front crank bolt.

Confirmed Bumpstart, the 15.8mm x 20.6mm x 2.4mm thick viton o-ring worked for the tubular dowel pins. Tested on a Renesis motor yesterday. Also works for the oil filter stands.

B

I read threw ausrotary and this thread at least 4x. Im still lost haha. Hopefully someone makes a part number list & were to buy for us retards. Im going to read it again because i need to buy new Oil Control "O' Rings

Mcmaster-Carr.com

Inner oil control o-ring #9464K125 "5 per pack" This will do one engine leaving you with 1 extra.
Outer oil control o-ring #9464K116 "2 per pack". Buy two of these to get 4 total.


Be very carefull putting these in as they are a BITCH. Use the thick edges of your feeler gauge to work them in with lots of lube.

If those are the same as the Atkins spec O-rings, they went into the holders very easily.

Getting the holders into the rotors, however, took a fair bit of patience. Trick seemed to be plenty of assembly lube along with doing everything possible to put the holder in completely flat. If part of it goes in first and allows it to go cockeyed, it won't go in.

Made me wish for a tool like the rear main seal tool for I'd like to say Gen III V8s or maybe Series II 3800s. The rear main seal came with a lightly cone shaped piece of plastic, you put that over the end of the crank, pushed the seal on over it, then pulled the cone out. getst he seal on with zero chance of tearing.

the trick with the outside control ring ( the inner i use fits no issue ) is to have everything free of carbon and use some diesel for lube
block o wood over the top and 3 or 4 even blows around the circumference
( do the oil control first before assembling the corners and the side seals )

double check there has been no pinch ( which will be visible )

having an extra in the packet here would be very desirable,, these have cost me a couple during installs
- also a couple of chromes ( and thats why you make the effort to get all the carbon out of the rotor track )

So for the american Coolent seals. Anyone know the part # and were to buy them? The glue that is being used?

I can't believe this thread is still going!

Refresh my memory BDC - you reported coolant issues and people gave you grief for it.

http://www.creavey.com/materials.html
sells custom viton, FEP teflon, PFA teflon (500F) orings. I haven't ordered recently.
You could order lengths to a thousandth of an inch. Wide variety of thicknesses.
No crap STRETCHING REQUIRED!!!
Approximately correct oring sizes were on file for 13B engines at Creavey. Ask!

Several different correct oring lengths were published by different folks. I was so annoyed I went out to the shop one night to confirm that slightly different lengths were required for the different (casting) generations of housings I had on hand.

RA and McMasterCarr selections were larger diameter, likely leading to hydro lock and opening up a gap to exhaust gas exposure, lost coolant and ultimately leading to oring failure.
Creavey specified a nominal crush. RA and McMaster seals were too big by that spec.
I have seen several engines with failed orings as a result, although many have also been fine.

I have pics, sizes and comments as to generation fitment somewhere. They were way cheaper than OEM and properly selected they fit and are reusable...
Or ignore all this and search for LynnH's uber cheapest oring replacements...
~7

Well these new square viton seem to be the ticket. Just broke down the engine again and they are perfect. They sealed really well also. I just ordered 18 more feet to use for the outer seals in my 20b as the stockers just keep expanding when you remove them. This viton could possibly be a long term cheaper re-usable solution. :)

Part #2542t21 .093" is what I'm using for both but, I think I could use #2542t22 .125" for the inners. I should have ordered a sample length but forgot.

Good stuff, T-Von.

I forgot to add my tension bolt solution to the thread

You can find the below o-rings at Lowe's in the plumbing section for very cheap. Like $2.00 a box of 10. #6 for 13b and #7 for the 4 larger 20b style bolts. All you need to do is take your old tension bolt seals and cut away the old rubber which now turns it into a washer. Slide the washer on and then you slide on the new o-ring. It's that simple and I guarantee you it wont leak. I've stacked my engine 4 times over the last year with the same rubber o-rings in place. This is something you can NOT do with the stock tension bolt seals. ;) Just make sure you dab a little oil on the o-ring when torquing the tension bolts.



#6 is 7/16" OD 1/16 wall thickness All 12a-13b-Renesis engines:
#7 is 1/2" OD 1/'16 wall thickness 20b large dowels:

https://www.rx7club.com/attachment.p...0&d=1305836297
https://www.rx7club.com/attachment.p...1&d=1305836297

Great stuff! Let me add to this, T-Von. Just found equivalent on McMaster-Carr's website.

Part #'s 5267T22 and 9464K16.

5/16" ID, 7/16" OD, 1/16" thick.

Brown and black Viton respectively, $8.44/100 and $6.32/100 respectively.

B

Anyone know rear stationary gear o-ring size?

^ I never worry about that o-ring because I never remove my gear when taking off the rear plate.

I'm going to port my engine irons so I think it would need to be taken out.

I wish I knew. I can't find anything that'll work for it. It's the one piece left I don't have.

UPDATE:

DO NOT USE #2542T21 for the OUTER coolant seals. I just tried to seal my engine and heard a pop. Broke the engine down and I have a broken outer coolant seal wall. This Viton is the same size as stock but due to it's harder durometer, they compress out a little too much and wont allow the block to seal properly. They are completely fine for the inners because of the wider walls but NOT FOR THE OUTER SEALS. I'll repair the wall and go back to recutting the stock outers until I figure something else out. ;) Also I will NOT be ordering #2542t22 .125" for the inners.