3ac Flywheel Dimensions

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Pleco815
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Posts: 5
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My tercel:: 1986 4wd

3ac Flywheel Dimensions

Post by Pleco815 » Mon Apr 30, 2018 6:05 pm

hello I'm new to the forum. I'm planning on doing a 4age swap into my 86 tercel 4wd. I bought a new 3ac flywheel online to have modified to fit the 4age. (bought a new one so i could still drive the tercel around while doing some of the preliminary swap stuff.) when comparing the two flywheels however it seems that the 3ac I ordered is actually bigger OD than the 4age flywheel. 3ac = 10 and 7/16" or 265mm 4age (bigport)=10" or 254mm. I am not an expert so any help is appreciated. I'm just wondering if I bought the wrong flywheel.

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Petros
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Posts: 11104
Joined: Sun Jan 28, 2007 6:31 pm
My tercel:: '84 Tercel4wd w/extensive mods
Location: Arlington WA USA

Re: 3ac Flywheel Dimensions

Post by Petros » Tue May 01, 2018 1:58 am

I can tell you in a few days, my flywheel is in the machine shop getting resurfaced.

I have converted two flywheels, 1) modfied a Tercel3ac flywheel to fit on the 4age, and also 2) modfied a 4age flywheel to fit in Tercel.

1) required you to have the 4 of the six holes welded up (to do it properly the flywheel has to be heated to a dull red glow or weld will fail), than it has to be machined to match the eight bolt 4age crank shaft. you will use the same ring gear and clutch as the stock engine. the stock 3ac flywheel should also be lightened, it is too heavy at 19 lbs, if you can get it down to 14lbs or less that would be good. It will also have to be reblanced.

2) requires you to remove the 4age ring gear, recut the ring gear seat to fit the smaller dia 3ac ring gear. this I think is much simpler and less costly. It also allows you to use the larger 4age clutch, the stock 4age flywheel is lighter than the 3ac flywheel already, but it could also loose some weight. you may have to clearance the bell housing a little if the larger clutch is at risk of making contact with the bell housing.
'87 Tercel 4wd SR5 (current engine swap project)
'84 Tercel 4wd (daily driver, with on going mods)
'92 Mazda MPV 4wd (wife's daily driver)
'85 Tercel 4wd DLX auto(daughter's daily driver)
'01 Honda Civic (other daughter's daily driver)

Pleco815
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Posts: 5
Joined: Sun Apr 29, 2018 9:03 pm
My tercel:: 1986 4wd

Re: 3ac Flywheel Dimensions

Post by Pleco815 » Wed May 02, 2018 7:39 pm


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Petros
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Posts: 11104
Joined: Sun Jan 28, 2007 6:31 pm
My tercel:: '84 Tercel4wd w/extensive mods
Location: Arlington WA USA

Re: 3ac Flywheel Dimensions

Post by Petros » Wed May 02, 2018 11:32 pm

looks like my 3ac flywheel is about 9-7/8" in dia, with the six bolt center (250 mm dia). You have got the wrong flywheel, but it will bolt up though likely the ring gear is too big and will not line up. that may be off of the later '87 and newer Tercel, same bolt pattern but different transmission, different engine installation.

attached is a picture of mine, took the pic at night with a flash light, so not sure if you can see much, but you can see it is smaller than the one in your picture.
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'87 Tercel 4wd SR5 (current engine swap project)
'84 Tercel 4wd (daily driver, with on going mods)
'92 Mazda MPV 4wd (wife's daily driver)
'85 Tercel 4wd DLX auto(daughter's daily driver)
'01 Honda Civic (other daughter's daily driver)

User avatar
Petros
Highest Ranking Member
Posts: 11104
Joined: Sun Jan 28, 2007 6:31 pm
My tercel:: '84 Tercel4wd w/extensive mods
Location: Arlington WA USA

Re: 3ac Flywheel Dimensions

Post by Petros » Wed May 02, 2018 11:38 pm

actually now that I look at your picture again, it is not even the same hub. just by eye ball you can see the bolt circle dia is too large. completely incorrect flywheel for a 3ac.

send it back, and find a used one out of a wrecking yard for just the ring gear (or see if you can find the the ring gear for a first or second generation Tercel with the 3ac engine). than take your existing 4age flywheel to a machine shop and have them remove the 4age ring gear (there are youtube videos on how to do that), and have them cut the ring gear seat to fit the tercel ring gear.

you will be better off keeping the larger clutch that comes on the 4age, everything else will line up fine.
'87 Tercel 4wd SR5 (current engine swap project)
'84 Tercel 4wd (daily driver, with on going mods)
'92 Mazda MPV 4wd (wife's daily driver)
'85 Tercel 4wd DLX auto(daughter's daily driver)
'01 Honda Civic (other daughter's daily driver)

Pleco815
Newbie
Posts: 5
Joined: Sun Apr 29, 2018 9:03 pm
My tercel:: 1986 4wd

Re: 3ac Flywheel Dimensions

Post by Pleco815 » Thu May 03, 2018 9:21 pm

Thanks Petros

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