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Rotor Placement?

Old 12-16-2018, 03:41 PM
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Rotor Placement?

When rebuilding, is it possible to place the rotors upside down? That is to say should the front rotor go in with the apex to the top or should it go in with the apex to the bottom. It goes without saying that the rear rotor goes in opposite to the front. It's my second rebuild and having starting issues. Getting fuel and spark so wondering if it is possible I built it wrong. It could be the starter speed, which seems slow to me. Compression is about 34 on all lobes. Yes, I tested with a conventional compression tester. No gots the bucks for the proper one and that is the comp I had on the first rebuild. Note: Do yourself a favor and replace all hoses when you rebuild. Sucks that a 20 dollar hose costs a rebuild.
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Old 12-16-2018, 04:43 PM
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They really only assemble one way, but the orientation could be anything. There isn't really an "up". Maybe I'm missing something?
But there are plenty of other things that could have been done poorly. Out of spec housings, incorrect seal clearances, loose apex slots... what's the history of the big parts in the motor?
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Old 12-16-2018, 05:09 PM
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rotors only fit in one way really as stated. im assuming its an S1? have you done the starter upgrade? ie. replace with an 06 and above starter?
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Old 12-16-2018, 06:17 PM
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Have not done the starter upgrade. That is my next step as the starter is OEM and not an 06+ model (04). Is there a way to assure one purchases an 06+ model starter?
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Old 12-16-2018, 07:24 PM
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yea, count the teeth, if you go to a parts house ask how many teeth are on the 04 and how many are on the 06. i cant remember the numbers but it should be more. when they order it or if they have it just count the teeth. even if it doesnt fix the issue your gonna want it anyway. i thought i had a blown engine cus it wouldnt start when warm, but the oem starter just didnt have the oomf to spin the compression up
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Old 12-17-2018, 05:32 AM
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Old 12-17-2018, 06:57 AM
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If you're looking for the best starter for a 6MT, just specify a 2009 or newer car.
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Old 12-17-2018, 12:14 PM
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Thanks folks. I have found a number of sources with a 13 tooth, 2.7kW starter. Dealer is asking 400.... prolly not going to happen. Bosch is 150. More like it.
Would add that the form factor seems to be different on like 2009 and up. Different mounting points. Yes, they are MT models. AT is a whole nother thing.
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Old 12-17-2018, 12:41 PM
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All 6MT starters will mount to all 6MT models.
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Old 12-17-2018, 05:10 PM
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How old is your battery? If its more than a few years old I would go exchange it at Walmart for $50. 34 psi is way to low to be able to start the motor. Less than 80 psi and its pretty damn difficult.....
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Old 12-17-2018, 06:15 PM
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Starter ordered. I used a helper battery to assure that was not the issue. Just not spinning fast. Slower than my old van or CV. May take it in for a proper comp test after I get it going. I don't have access to a proper rotary comp tester.
Anyone have experience with the 1-piece apex seals for a Renesis? If/when I go in her again would like to use those. The 2-piece thing just looks dodgy. Is Atkins the best parts supplier or are there other recommendations?
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Old 12-17-2018, 06:28 PM
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OEM is the best parts supplier. 2 piece may look dodgy, but once it's in the engine it's not going anywhere.

Also the apex seals are the least of your concerns when facing a rebuild. Unless you know what you're doing, it's faster/cheaper/easier to get an engine already rebuilt by a pro or Mazda.
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Old 12-18-2018, 05:31 AM
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Originally Posted by rockfish View Post
Starter ordered. I used a helper battery to assure that was not the issue. Just not spinning fast. Slower than my old van or CV. May take it in for a proper comp test after I get it going. I don't have access to a proper rotary comp tester.
Anyone have experience with the 1-piece apex seals for a Renesis? If/when I go in her again would like to use those. The 2-piece thing just looks dodgy. Is Atkins the best parts supplier or are there other recommendations?
I have always used a regular compression tester and it has provided me with good enough information. Take a spark plug out of each rotor housing and while you are testing the front rotor for total compression, listen to the back rotor for 3 even pulses. Then vice versa. If you can get 80+ psi on at least one rotor, you probably can make it start with enough patience. Even if you can get it to start for a few minutes, your compression will likely climb enough to make it start again and so on. I have started a fresh rebuild and kept my foot on the pedal with RPMs at 3-4k for a few minutes and compression have jumped 10-20 psi. From my experience 90% of the break-in will be done in the first 30-60 minutes of run time.

One-piece seals are for full bridgeport motors where they can't have the corner piece fall into the port. Two piece seals are what you need, they make the best compression at startup. I don't see any reason why Atkins wouldn't work on a stock motor. I would not run them on a boosted one. Just super glue the 2-piece seal together prior to installing. I have done all of mine that way and its never been an issue.

I also run my car on an chinabay starter I paid less than $100 for, and the car starts up fine and fast. No need to pay $400 for a starter on any car.

Last edited by strokercharged95gt; 12-18-2018 at 05:35 AM.
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