RX7freak08

I heard that you do not have to have the rubber inserts in the corner seal. I heard all it does if for installing the rotor into the housing.

scrip7

iTrader: (6)

The rubber seal is used to minimize compression loss at the corner seal, but it isn't very effective. On high mileage engines they are often burnt to a crisp, and boosted engines tend to burn them up even faster. You could switch to solid corner seals, but on your n/a it would be pointless. You could save money and just replace the rubber inserts.

RX7freak08

Ummm so really just replace the inserts. What would it do if i didn't replace them.

RX7freak08

Ok does anyone have a opinion.

Noel Caraballo

iTrader: (2)

just change them their less than a dollar a piece

iceblue

There to cheep to not change so I replace them. They tendto harden but only on the tip the mid way and down tend to be still rubbery.

This hardly has much effect on such a small tight object but it is still a consideration.

The more rotationg mass you have the more chatter you have always. Using the OEM style you have less mass and using a fill component like rubber you have vibration dampiner. So even if they harden all the way or part way or never you still have a insert dampening the amount of harmonic vibrations from the corner seal. It tends to have no effects on the motor itself thought the corner seal does toutch the apex seal so I can only help but to wonder, if the seal vibrates against another metal object does it not inturn induce vibration and fetige to the apex seal directly? And that being so does not the apex seal vibration cause more internal wear and chatter? ;-)

scrip7

iTrader: (6)

Good questions Iceblue. I bet the rubber insert does little to dampen the natural "frequency" of the apex seal or end piece. The idea is for it to help reduce compression loss through the groove in the corner seal, and little else.

There are differing opinions on the cause of chatter. I have seen excess chatter marks on engines with high mileage, also on engines with low mileage on a rebuild but with apex seal-to-groove clearance that was beyond spec, and I have seen consistent chatter marks on engines that had used older 3-piece apex seals. I like to make sure that clearances are on the tighter side of specs during a rebuild, and if the customer's budget doesn't allow it, at least they are made aware of the long-term affects.

RETed

Some people will argue you don't need them.
On radical port jobs, these rubber insert tend to "spit out", so it might be a damage concern?

Thye are under $2 / each, so to replace all 12 of them isn't that much of an increase in cost.
I replace them in all the rebuilds I do.


-Ted

iceblue

That is a good point I forgot to add Ted thank you. On large port that compromise I use the solid corner seals.

Script7 - That is very true and no one was taking the point away. I think something to add is the reason threw the years that Mazda has continuously lowered the thickness of the apex seals is to do just this, diminish chatter as much as possible. Buy lessening the rotating mass they are able to reduce chatter.

scrip7

iTrader: (6)

I use solid corner seals on boosted engines and rubber inserts on N/As.

I agree with you about Mazda's approach. They also did away with the 3-piece seals, which actually had better gas sealing due to the "double wedge", but also caused rapid wear of the apex seal groove in the rotors, contributing to chatter.

RX7freak08

So what if I used solid ones will it be better.

rx7vadim

I have a question. They are designed to better compression, are they also there to keep carbon out? I cant use them in my build, i wonder if it will be ok for 10k miles, i worry about too much carbon build up.

scathcart

On racing engines, it is common to open the apex seal grooves up to the higher end of the clearance spec. While low rpm and cranking compression are reduced, the reward is increased gas pressure under the apex seal, which REDUCES chatter and increases chamber sealing at higher rpms.

RX7freak08

Oh thanks buddy.lol. but this thread is like 5 months old but thanks for the advice.

rx7vadim

ok, so 10k miles will be ok?
is this thread too old to bring back?

rx7vadim

Is the rubber(viton) plug also designed to keep carbon out? My port doesnt support them (only a tab) so they will fall out and damage things. Can i run without them? I would aprociate your advices.

rx7vadim

can you help your rotary comrad out?

Chaotic_FC

my personal advice is just go with the solid corner seals if you're afraid of them falling out.
my engine will have a bp, so it makes sense to me to have them.
however, i have no real knowledge of if it helps.

scathcart

It is fine to run without them. Solid corners will offer no advantage on an N/A engine.