https://www.rx7club.com/3rd-generation-specific-1993-2002-16/viton-oil-control-o-rings-733565/

I was wondering if any of you guys would have any input on this. It's more general rotary than FD specific.

Thanks.

 

Help me understand your thought process......the oem ones work very well, and have zero issues that I'm aware of. What is the advantage of deviating from them?

 

For one, the OEM ones flatten out after a while. I've heard builders say this and have seen it myself. The viton ones have always looked like new when i pulled them back out.

They are also inexpensive compared to the mazda o-rings. Even from atkins rotary they are less than 1/2 of what I would pay with my mazdamotorsports membership.

From my supplier, the military-spec o-rings are 1/7th the retail price of mazda o-rings.

As far as OEM not having issues, there seem to be plenty of people that have oil control and smoking problems from the reading I've done on here.

I've already used the viton ones from atkins in my FC for 25k problem free miles, so I've already deviated from the mazda o-rings.

I could always go back and buy the mazda ones, though I'm pretty confident a MIL-spec o-ring is going to be even sturdier than the atkins ones...

Now, I'm not trying to be stubborn. If doing this is poor judgement, I'd like to know. However, it seems to me that these are as good or better than the ones I already use with confidence.

 

I ordered the atkins viton anyways.... I don't want to take a chance on this motor. I just want to drive that thing...

I'll keep the ones I bought and use them on a project in the furture, though.

 

I personally bought used viton rings (not sure from where) off ebay for like $10.00. for my 91 vert. All my other rebuilds I have used McMaster-Carr versions. 18k later my engine doesn't smoke at all. I love these viton rings and I especially love investing in re-usable cheap parts. Some people just don't understand, when your always experimenting and re-opening engines all the time, it's really nice to have products like this available. The only down side is they are a bitch to install.


Oh yea, I also use the reusable tephlon coolant inner seals.

 

Thanks for the info guys, food for thought

 

Thanks for posting! I knew someone had tried this. I don't have too much trouble installing them. You just need a really rigid, smooth, flat object. I actually use a view port from a scrapped GC Mass Spectrometer so I can watch the rings slip in.

So, which mcmaster part numbers did you use?

The ones I got are:

1201T876 (dash 244) and 1201T828 (dash 158). MIL spec.

 

I'm surprised you've never tried/heard of these. Must be a cheap *** FC guy thing. haha

 

Viton inner #9464k125 1 pack of 5
Viton outer #9464k116 1 pack of 2

 

Damn, if those work well, then the MIL-spec ones should be bullet proof.

The MIL-spec are rated for their tensile strength, temperature handling, and higher than normal resistance to compression set.

I may just try these in the FD...

 

Thanks t-von, i just ordered mine up.

 

Just remember guys, installation of these are a bitch when brand new. Lube them up and use a spare oil control ring to press them in. Use the thickest blade of your feeler gauge to work it in as you press down. That portion of the feeler gauge wont cut the ring. Get one side started and just work your way around. Once in make sure the ring has good movement and rebound. It will be a tight tight fit.

 

I compared the mcmaster o-rings to my atkins ones and the 244 (inner o-ring) does not match the thickness of the atkins ones. It is thicker than the atkins o-rings. The atkins o-ring must be some size in between the 1 and 2 series o-rings.

The 158 is a perfect match, though.

I'll be using the atkins rings until I find the proper size for the inner rings. It's no wonder you have a hard time getting those in.

 

Interesting how articles written by the now deceased Rob from rotaryshack always STRONGLY recommended against using viton oil control rings due to them failing prematurely. I dunno it's hard to know who to believe with critical parts such as oil control rings but personally I would run OEM mazda parts.

 

why did he recommend against them?

 

About half way down the first page here.

https://www.rx7club.com/showthread.p...lding+thoughts

"Viton is a great material for many applications. We use it, in various grades, for water seals (tested for 7 years in multiple engines before we sold them to the public), rear stationary gear o-ring, dowel o-rings, oil filter pedistal o-rings, etc. BUT, in our experience Viton DOES NOT LAST as an oil control o-ring. I mention this because certain companies sell Viton oil control o-rings and we have seen many premature failures (20K or less). The stock oil control o-rings are a very expensive flourinated rubber, but they last 100K miles or more. This is not something to cut corners on! The aftermarket ones exist simply because the profit margin is so high.

Viton is one of those materials with a hyped reputation on the internet. While the reputation is deserved in many applications, it is rediculous to think it is superior in ALL applications. In this case, it's similar to Titanium and Carbon Fiber. Don't get hung up on the name; consider the application and weigh the costs and benefits."

 

They are the only engine builders I have heard of having problems with these things.

This is one of those statements that sounds good on paper, but makes little sense. Viton is also an expensive flouro-elastomer (flourinated rubber).

I've never seen pictures to back up these claims. I've experienced no problems with 25k and several years on my own atkins viton rings. I've talked to reputable builders who use EXCLUSIVELY atkins viton oil control o-rings.

It seems likely that these claims originated because some people used the wrong size, material, or grade o-rings.

 

Robert from Rotaryshack isnt deceased....is he??? When did this happen???

 

Holy crap must have been drunk that night, didn't mean Robert (Roberts the man BTW!, he's still alive and kicking). I meant Blake Qualley from Pineapple racing.

Sorry for the mix up, one too many beers I guess...

 

edit

 

The problem with the atkins and McMaster Carr viton rings is the tight fit: it does not allow the oil control rings to move very easily, hence the tough installation. In high-rpm engines, the insanely tight fit can have the rings sticking, causing engine smoke.

The problems that arise are not related at all to the material, viton works very well for this application. The problem is that they using a SAE sized o-ring to replace a metric o-ring. The Atkins and McMaster Carr rings are not the same size as stock, they are slightly larger.

Dave Gibson at FC3s.org had viton metric rings sourced/manufactured in the correct size years ago, but they were $35 each IIRC, and no one wanted to pay for them.

The stock oil rings function very well if you manitain frequent oil changes and don't overheat the engines.

 

Thanks for the informative post scathcart, makes perfect sense

I recently installed a set of customer-provided atkins oil control o-rings in a motor and the experience sucked.....tight is right! I cut the **** out of both my thumbs, they did *not* want to install, and I used a considerable amount of force. That dude has a lot of my blood inside his motor

I'll stick with stock, thanks.

 

When I used to use them, I installed them (obviously with plenty of assembly lube), by placing the rotors on a hydraulic press and then setting a sheet of clear lexan on top and pressing them into place, one at a time. This reduced any localized stress to the metal carrier rings by applying even load to the entire circumference. It also saves your thumbs. The rotor grooves are chamfered to allow the rings to slide in, so using a feeler gauge to shoe-horn the rings as mentioned above in place was unnecessary.

Subsequent removal of the rings at the end of season showed the rings fully pressed into their grooves, rather than allowing for free movement as they were designed for.

I haven't had any problem with the stock rings when proper maintenance is used, and they fit and function correctly. Until the aftermarket again offers a metric-sized viton ring, I can't see myself ever risking using the existing viton rings again.

 

I thought I was the only one...I've cut my fingers every single time. Cant help it!

I went with RA btw...no miles on it yet just 2 heat cycles, no smoke.

 

Man, you guys just need to use something to press it in with! ****, the first time I did it was on my FC and I used some left over synthetic wood flooring. Anything smooth and rigid...