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rx8 auto starter on rx7 fd auto flexplate

Old 12-28-18, 07:22 AM
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rx8 auto starter on rx7 fd auto flexplate

sorry for a re post but i added to the wrong gen before

hi guys need some info please ignore the gearbox and engines im only intrested in flexplate with ring gear and starters (will make sence!)

im doing a project using a rx7 fd automatic flexplate as a dona ring gear for a starting system on a stationary engine I have to use auto due to the way i need the starter to sit and due to the lightness of the flexplate (before you ask no has no torque converter fitted but yes I have put a thick support plate in its place to strength)

my question I need to put a starter to this which is fine a rx7 auto starter is perfect due to its bolt on design with idle gear. but will an rx8 2kw 20 tooth work on a rx7 fd flexplate as the rx7 fd auto starter is a 18tooth starter.

if I have to ill do the rx7 starter motor upgrade but putting a rx8 starter on would save me some extra as i wouldn't need to but 2 starter motors.
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Old 12-28-18, 07:49 AM
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FD auto starter is 2kw
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Old 12-28-18, 08:42 AM
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Originally Posted by Banzai-Racing View Post
FD auto starter is 2kw
sweet.

do you know if a manual one will fit the auto flexplate?

given that both flywheel and flexplate both have 125 teeth the auto starter gives me better positioning on the ring gear as its got a free spinning idle gear I beleive? (someone to confirm) but the manual starter is pos easyer to mount as.

Last edited by billybobbooth; 12-28-18 at 09:57 AM.
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Old 12-28-18, 09:45 AM
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Auto mounts to the side of the engine, manual mounts through the trans bell housing
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Old 12-28-18, 10:00 AM
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Originally Posted by Banzai-Racing View Post
Auto mounts to the side of the engine, manual mounts through the trans bell housing
this make 0 diffrence to my application, as its not getting conected to any sort of gearbox only thing will be a mount made to hold the starter motor, i may find that no one has tried to put an auto flexplate with a manual starter or vise versa
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Old 12-28-18, 10:11 AM
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Maybe if you explain what you are trying to do in more detail, I could actually help you. The auto flex plate and manual flywheel are the same diameter, if you are making a custom bracket to mount the starter and need it to be behind the engine, go right ahead. If you already have an auto rear iron and an auto starter, just mount the starter to the side of the engine like Mazda did, if you have the available real estate.
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Old 12-28-18, 10:23 AM
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Diameter and tooth count is the same. Flex plate sits further away from the rear plate, which does not matter since you are making a custom mounting bracket. I have done something similar in a hover craft engine we built.


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Old 12-28-18, 10:23 AM
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Old 12-28-18, 10:24 AM
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Old 12-28-18, 10:48 AM
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One other thing I can tell you is that the RX8 auto flex plate has a one inch removable spacer under the flex plate between it and the CW, pushing it further away from the rear iron.


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Old 12-28-18, 11:53 AM
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Originally Posted by Banzai-Racing View Post
this helps this is Vertually what I'm doing! just take off the drive to the big belt.

I did say at top im trying to put a starter system onto a stationary engine but i cant put a normal manual fly on due to weight. ive got a pully that spaces the rx flywheel away from the engine by 3 inches so clearance isn't an issue but i have to mount the starter on the opposite side to the engine same as this pic. (if this pic is a auto flexplate with manual starter motor then ill be ok as i know either will work depending on ease of mounting)

the starter is the key as it must be fitted opposite side to the engine. mounted upside down to fit to the bottom of the fly but an rx flexplate is a direct bolt onto my custom pully by chance so make that easy. it's a question of which starter I use but if both will fit it gives me more choice. but my engine must turn clockwise if you stood at the engine furthers from the flywheel looking towards the flywheel.

hope this makes and helps
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Old 12-28-18, 12:04 PM
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It is not a case of them both working. If the starter needs to be mounted like the hovercraft above you need a manual starter. An FD or RX8 auto starter spins in the opposite direction since it is mounted on the side of the engine pointing toward the rear of the vehicle, a manual starter points toward the front.

Above is actually a LW aluminum flywheel with the friction surface removed, irrelevant to what you are trying to achieve since the function is the same as a flex plate.

Last edited by Banzai-Racing; 12-28-18 at 12:19 PM.
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Old 12-28-18, 05:33 PM
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Originally Posted by Banzai-Racing View Post
It is not a case of them both working. If the starter needs to be mounted like the hovercraft above you need a manual starter. An FD or RX8 auto starter spins in the opposite direction since it is mounted on the side of the engine pointing toward the rear of the vehicle, a manual starter points toward the front.

Above is actually a LW aluminum flywheel with the friction surface removed, irrelevant to what you are trying to achieve since the function is the same as a flex plate.
ah yes now you have corrected me, for some reason don't know how i had worked out the auto to spin the correct way as well reason being as most starters that sit that way round are clockwise starters and rx starters are ccw (counter clockwise) including the auto which is diffrent to most. also due to the fact I was looking at ford transit starters and flywheels till I found the adapter fitted an rx flywheel.

yes so am I correct in thinking a manual starter will fit an auto flexplate? and does it matter if the starter has a half cover over the starter gear or if the gear is completely exposed? I can find both that I can buy cheaply with 14 teeth to get the mounting correct before I buy a more longer lasting one

Last edited by billybobbooth; 12-28-18 at 06:20 PM.
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