AMC Eagle Den Forum

The Mighty 258 => The Engine => Topic started by: AMCLOVER258 on February 10, 2015, 07:31:50 PM

Title: Fly Wheel
Post by: AMCLOVER258 on February 10, 2015, 07:31:50 PM
Ok guys, I've gone through 3 starters in the last 9 months so i am now pointing the finger at my flywheel... My question is will a 80's jeep 258 flywheel bolt to my 258??
Title: Re: Fly Wheel
Post by: carnuck on February 11, 2015, 08:27:15 PM
Yes, BUT what year is your Eagle? Around '86-87 they changed the flexplate offset and went with a Jeep XJ starter. The AW4 flexplate won't work. 999 plate from a CJ with Mopar auto will work but they are rare. PIONEER Part # FRA108  or Napa Balkamp BK 6005007

Too bad you didn't need one for a TH400. I have a brand new one.
Title: Re: Fly Wheel
Post by: vangremlin on February 11, 2015, 11:26:39 PM
Quote from: AMCLOVER258 on February 10, 2015, 07:31:50 PM
Ok guys, I've gone through 3 starters in the last 9 months so i am now pointing the finger at my flywheel... My question is will a 80's jeep 258 flywheel bolt to my 258??

I was going through starters also. Ended up having the flex plate replaced and they also adjusted the starter position. That worked for about 10 months until the telltale grinding noise started coming back. I ended up installing a high torque starter off ebay.   The car seems to start much better now, and is much quieter when it starts.
Title: Re: Fly Wheel
Post by: AMCLOVER258 on February 13, 2015, 02:26:18 AM
Luckily '83. Is the auto th400 a direct bolt? I'm going to be rebuilding the engine soon and the tranny is slipping pretty bad and I figure it's probably cheaper to get a used "newer" tranny than to rebuild the old 998
Title: Re: Fly Wheel
Post by: eaglefreek on February 13, 2015, 10:16:59 AM
Just to clarify, you in your first post  you asked about a flywheel. If you have an automatic, you have a flexplate. I personally wouldn't install a TH400 or 727. They take more power to operate than the 998 and the 258 is already a little under powered.
Title: Re: Fly Wheel
Post by: AMCLOVER258 on February 13, 2015, 02:09:49 PM
Good advice! I will take that into account.  and yes you are correct flex plate...  :-[
Title: Re: Fly Wheel
Post by: carnuck on February 15, 2015, 03:10:39 PM
TH400 doesn't direct fit and AW4 is easier to put in by far than a TH400 (physically). The flexplates are different for each trans but 9XX (904, 998, 999, etc) and 727 interchange until '87 when they changed the ring gear offset (10mm or 3/8") closer to the motor and went with the XJ starter. Another possible starter fix would be to find a '72 -80 IH Scout starter for 6 cyl auto. It's a Delco Chevy style starter that is way better than the Ford ones. Speaking of the Ford ones, most cheap rebuilds come with an actual Ford starter drive which is too short to mesh correctly with the AMC ring gear long term.

I haven't checked fit yet but Napa starter number 246-0674 "should" bolt right up. They use the same flexplate.

Correct length AMC starter drive
(http://i6.photobucket.com/albums/y209/carnuck/tech/photo-20.jpg)


Sorry for rambling (even for a Rambler man) I blame it on the cold meds!
Title: Re: Fly Wheel
Post by: carnuck on February 15, 2015, 03:18:43 PM
PS: When I put the 727 in my Eagle, I went one gear ratio lower in the axles (3.08) but I wouldn't put one in an Eagle wagon with 2.37s! 2.72 was okay with the 727 till I went to the 235/75/15s. A lockup trans would be better for economy if you drop a ratio too. My wagon is slightly sluggish off the line still, but that's carburation and not lack of power (I still need to do work to get past 17 mpg) Later I will do an AW4 swap with NP242 tcase. EFI will go in at the same time. The AW4 has the least drag of any auto trans that's easy to bolt in.