Hi all, I've got a TH125 out of a non-Fiero application that I'm about to rebuild--or, well, I was about to disassemble and rebuild--and I hoped that someone might have a quick-and-dirty answer. The transmission in particular drove just fine, but wouldn't hold in park. Also the shift lever seems to bind and not allow anything in the range below D--I get P-R-N-D, but no 1 or 2. The kicker is that it will only drive in first gear; if you let up on the pedal, it will coast, not lock as it would do if you had it shifted into 1. Upon pulling the trans out and dropping the pan, the fluid appears to be in near-immaculate condition, but I found what appears to be the parking pawl broken into 4 shards in the bottom of the pan. My question is two-fold: One, can you get a replacement parking-pawl (short of getting another trans and tearing it down just for that), and two, does the shift oddity sound like the pawl may have torn something up on the way out, a bent linkage in the transmission, or valve-body related? Thanks in advance!
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07:21 PM
PFF
System Bot
Dennis LaGrua Member
Posts: 15761 From: Hillsborough, NJ U.S.A. Registered: May 2000
A TH-125H rebuild is too complex to cover in an online post so just buy a rebuild video and it will take you through the process step by step. The rebuild videos can often be found on eBay for around $25.00. I have rebuilt TH-125's and they are not that difficult to do
------------------ 87GT - 3800SC Series III engine, 3.4" Pulley Flotech Exhaust Autolite 104's 4T65eHD 87GT - 3.4L Turbocharged engine, modified TH125H " I'M ON THE LOOSE WITHOUT THE JUICE "
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10:50 PM
3057 Member
Posts: 49 From: Columbia, SC USA Registered: Feb 2008
I figure that; I've got a rebuild manual, and I've gone over the procedure enough times that I'm comfortable with it. The parking pawl issue is just something I've never heard addressed as far as replacement goes, and the shift lever binding up is odd as well. I was wanting to see if there were any yeah-duh things I was missing before I pulled it apart and found out for sure.
A TH-125H rebuild is too complex to cover in an online post so just buy a rebuild video and it will take you through the process step by step. The rebuild videos can often be found on eBay for around $25.00. I have rebuilt TH-125's and they are not that difficult to do
Don't you need special tools? The FSM says you do.
Ed
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04:56 AM
AlongForTheRide Member
Posts: 27 From: Charlotte, NC, USA Registered: Nov 2005
Even better, why don't you make the 1.5 hour (each way) drive and buy a 1988, 80k mile TH125 for $50 OBO? It shifted great before I removed it at the end of last year for an L67 swap.
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10:51 AM
3057 Member
Posts: 49 From: Columbia, SC USA Registered: Feb 2008
Don't you need special tools? The FSM says you do.
Ed
No but it depeds on how well you can adapt and jury rig ordinary auto tool,
------------------ 87GT - 3800SC Series III engine, 3.4" Pulley Flotech Exhaust Autolite 104's 4T65eHD 87GT - 3.4L Turbocharged engine, modified TH125H " I'M ON THE LOOSE WITHOUT THE JUICE "
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05:14 PM
82-T/A [At Work] Member
Posts: 25009 From: Florida USA Registered: Aug 2002
Hi all, I've got a TH125 out of a non-Fiero application that I'm about to rebuild--or, well, I was about to disassemble and rebuild--and I hoped that someone might have a quick-and-dirty answer. The transmission in particular drove just fine, but wouldn't hold in park. Also the shift lever seems to bind and not allow anything in the range below D--I get P-R-N-D, but no 1 or 2. The kicker is that it will only drive in first gear; if you let up on the pedal, it will coast, not lock as it would do if you had it shifted into 1. Upon pulling the trans out and dropping the pan, the fluid appears to be in near-immaculate condition, but I found what appears to be the parking pawl broken into 4 shards in the bottom of the pan. My question is two-fold: One, can you get a replacement parking-pawl (short of getting another trans and tearing it down just for that), and two, does the shift oddity sound like the pawl may have torn something up on the way out, a bent linkage in the transmission, or valve-body related? Thanks in advance!
Hey, not to ruin your fun, but you should take this opportunity to upgrade to a 4 speed automatic. The Th-125 is considered bullet proof (most of the time), but the 4T60 is a great all around transmission. It shifts firmer in stock form than a stock Th-125 does, you can get it with the same final drive, and it has the 4th gear for better highway cruising.
The swap is really quite easy. It requires new axles, but other than that, there's not much else you have to do. I'm seriously considering this in my Fiero. I've got most of the stuff I need to convert it to a manual, but I think for now, I'm just putting a 4-speed auto in it.
I'm strongly considering it; there are enough late 80s/early 90s Cadillacs around the pick-a-part yards here, but if I can get a 3-speed for cheap I'll likely stick with it for simplicity's sake.
