Swap info, links, and part numbers are listed in another post below! Go about a dozen posts down and you should find a master list of everything needed to do the swap
(END EDIT)
Hey guys. I'm gearing up to do a 4t60 swap in an '86 GT auto and I was just wanting to make sure I had everything I needed. I have read several build threads so I think I'm good to go but I just wanted to be sure.
-transmission (from an '89 Bonneville, Free ) -new stock Fiero mounts (cradle to trans mounts, Rock Auto, ~$5 each) -trans mount from FA: http://www.fieroaddiction.c...th=19&products_id=15 -Governor Cap (getting from a member here) -Axles: NAPA, p/n 95-9178 and 95-9208 -Adjustable modulator (rockauto, $15)
Now for questions.
1. The pigtail for the TCC is the round style on the Bonnie trans. I can just splice the wiring from the square TH125 mount, correct?
2. The Bonnie trans is geared 2.84. The TH125 is geared 3.33 (I assume). I only have the governor gear from the TH125 so how far will this throw my speedometer off? Will larger tires get the speedo closer to being accurate (I have a near-new set of P215/65R15 from a LeSabre)? Can I just solder a resistor in the wiring for the speedo to get it back to being accurate?
If so, should I go ahead and buy the 67-69 Dodge Dart 273 V8 engine mount (~$5, RockAuto) to get everything properly aligned in the engine bay or is that only an issue with the 4 cylinder?
Picture of mount:
[This message has been edited by Alibi (edited 03-07-2009).]
You can use the 4T60 mounts, redriill the mount holes and adapt them to the Fiero cradle. FIeroAddiction has the measurements on his website or I can look them up for you. The 4T60 is the four speed cousin of the TH 125H.
------------------ " THE BLACK PARALYZER" -87GT 3800SC Series III engine, 3.4" Pulley, N* TB, LS1 MAF, Flotech Exhaust Autolite 104's Custom CAI 4T65eHD w. custom axles, HP Tuners VCM Suite. "THE WILDCAT" 87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H " ON THE LOOSE WITHOUT THE JUICE "
1. You can splice the new connector on but some people have had a problem with the engine wanting to die possibly because of the Normally closed 3rd and 4th gear switches verses the normally open 3rd gear switch on the th125. I would say using this 55 psi switch this is the easiest and least headache way to go: https://www.fiero.nl/forum/A...090219-2-087546.html
2. The final gear assembly and governor gear is not related. The governor gear is based on tire/rim sizes. As long as you keep the same tire/rim size during the conversion the same gear will be fine even though your going to a final gear.
3. Most people dont seem to have issues with the motor being tilted.
For the most part, I'm very familiar with the 4T60 as its the same transmission thats been in my last half-dozen cars or so. However, when it comes to modding it I've never messed with it before.
For the mounts, I went ahead and got them from FieroAddiction as, the more I think about it, I want this to be as plug-and-play as possible. I decided to go ahead and buy the Dart mount just in case I do need it and if I don't I'm only out $5 (I love RockAuto ).
Thanks for the clarification on the governor gear. So will there be any issues with the speedometer since I'll be using a 2.84 transmission instead of the factory 3.33 (or 3.03, whichever it is)? Using my larger tires would throw the speedo calibration off about 4% according to the miata.net tire size calculator and thats a bit more than I'd rather have.
I did not know about that pressure switch though... I'll have to look into it as having a functional TCC is very nice in my other 4T60 cars. Is there an online source for a correct switch or is this going to a trans-shop only item?
Once I get my mounts in from FA I'm going to clean up my Bonnie trans and start bolting everything up so that I will have less work to do when I get the Fiero.
Is this the correct switch that I should go with or was it just a random example of what to look for? One of the other posters in the original thread was using a 55 PSI switch that was engaging the TCC as about 55 MPH. On my Buicks, the TCC engages at about 47 MPH so I would think that the lower pressure of the 52 PSI switch would be more accurate.
Am I barking up the right tree with my thinking thus far?
[This message has been edited by Alibi (edited 03-01-2009).]
Are you using larger tire setup then what came from the factory on your car? If you are your speedo has been off this whole time. Either way your speedo will show exactly what it shows right now no matter what final drive you use. (2.84,3.03,3.33,3.73..ect)
I don't actually have the car yet so as of now its got stock tires but they've seen better days from sitting. I just happen to have an extra set of rims with good tires for one of my Buicks that I could re-use the somewhat larger tires from on the Fiero. As of now it looks like I'd be better off to just buy new correct-sized tires.
The car is up in KC at the FieroFarm. Its got a bad motor but hes got a known good block that I'm going to swap over parts with new gaskets to get it going again over spring break. The condition of the trans is somewhat unknown and I figured I might as well do a swap while I have the cradle dropped and while I have an extra 4T60 laying around.
It says its "less than 50 PSI" but that may be too little. I'm leaning towards the 52 PSI switch though as long as I know the threads are right.
Edit to fix link...
Edit 2: The more I think about it the more the 52 PSI switch sounds right. It is threaded for another GM trans in the governor area and this is where I need one on the 4T60. I think I'm going to go ahead and order it as I'm down to about 2 weeks for gathering parts.
[This message has been edited by Alibi (edited 03-02-2009).]
I'm buying axles and an oil pump this afternoon from NAPA. I assume its probably a long shot to expect local parts stores to carry pressure switches? Any other parts for the trans I should get while I'm at it?
I installed a 52psi pressure switch in the pressure port for the governor on my 4.3/4T60 swap. With the 3.33 ratio, the TCC locks up at 42 mph once in 3rd gear (I have one of the early 4T60's with the NO 3rd gear switch - just like the 125C).
If you are going to pull the side cover, then you can swap out the NC switches and install the NO ones to run the TCC just like the 125C. There were a couple years of the 4T60 that were setup like this:
[This message has been edited by fieroguru (edited 03-02-2009).]
I installed a 52psi pressure switch in the pressure port for the governor on my 4.3/4T60 swap. With the 3.33 ratio, the TCC locks up at 42 mph once in 3rd gear (I have one of the early 4T60's with the NO 3rd gear switch - just like the 125C).
If you are going to pull the side cover, then you can swap out the NC switches and install the NO ones to run the TCC just like the 125C. There were a couple years of the 4T60 that were setup like this: [IMG]http://i152.photobucket.com/albums/s162/fieroguru/86440T4.jpg
I don't have a problem with pulling the side cover but if I can get the same effect by just installing a pressure switch then I think I'll go that route. I'd rather install a bit of wire than buy the proper side pan gaskets and switches as it would cost more.
I think I'm going to go with the 54 PSI switch. My 4T60 should have the 3rd gear switch since its a later version so I think it will lock between 50 and 55 which is close enough to the original lock-up for my Buick with the 4T60 (about 47-48 mph).
I lied and I actually didn't get the axles today... my chem lab ran later than I expected and I was hungry so I went home instead. I'm going to get the axles, oil pump, and axle seals from NAPA tomorrow.
I'm going to go ahead and order the 54 PSI switch tonight. Once I get my mounts in from FA I'm going to separate the trans from the Bonnie motor, clean it up, and then prep it for just dropping in the Fiero.
Thanks for all the help so far! I'm going to post back after I start getting parts in and my trans prepped for anyone else who may need the info in the future.
Edit: Ok, and I bought the pressure switch. $17 with shipping so not too horrible. So far here are my expenses:
$0 (Bonneville 4T60 trans) $150 (FieroAddiction mounts) $17 (54 PSI pressure switch) $18 (Rubber transmission mounts, Rock Auto) $140 (axles, NAPA Estimate at this point since I don't have them) $15 (axle seals, NAPA, also an estimate as of now)
So I'm probably looking at about $400 when I'm done. Hopefully I won't have any trouble and the swap will pay for itself in a few months from all the gas I'll be saving
[This message has been edited by Alibi (edited 03-02-2009).]
Ok, went to NAPA today and the left axle would have to be shipped in from Kansas City and the other axle wasn't currently available. He said I could still get it but they would have to ship it direct from their suppliers which would probably add about $10 to ship it via UPS. Not a horrible deal but while he was looking up parts those were the axles that were cross referenced for the '89 Pontiac 6000. I've seen some different numbers for those axles but now I know the difference must be with the different auto parts stores.
So... on the axles I think I'm going to order them from RockAuto (making this my 3rd lump of parts from them in the last couple weeks). I did go ahead and buy the oil pump from NAPA as it is a high volume unit and the pick up screen/tube is included for $124. Thats better than everywhere else I could find online so I'll do my business with them.
I put together a list for the FieroStore and will be calling them tomorrow with part numbers to order the last parts I (hopefully) should need. All that is left for now is to clean up the transmission and take it to a local shop to have the axle and TC seals replaced.
Its time to bring all this information together in one post. I'm going to start a build thread pretty soon too so I'll be linking to this information again. So far this is my master parts source list for the swap.
*Links to important sites/threads that I used for information*
Rubber mounts can be had from http://www.RockAuto.com for $5-6 each. Parts stores rip you off as they normally charge around $30. You might as well buy the correct axles while you are there (A1 Cardone brand) and save yourself some time and money on shipping.
Note: At this point I'm not sure which pressure is better suited for getting the TCC to lock up at about 50 MPH.
*Sources for 4T60 Governor Cover*
PM PFF member "BrewCheese" -- he keeps an eye out for them and is very easy to deal with and is fair on his prices. Its really the easiest way to go as these caps are a bit hard to come by.
My pressure switch came in today, I ordered a bunch of stuff from the FieroStore and I ordered axles from RockAuto since they were charging only $5 core vs. NAPA's $40-something. Considering I don't have any axles to turn back in, I'm just going to eat the core.
Currently I'm just waiting on parts to come in from RA, TFS, and FieroAddiction (mounts) and I'll be set
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03:49 AM
Mar 7th, 2009
jsketcham Member
Posts: 434 From: Meadville, Pa, USA Registered: Jan 2009
i'm considering doing this swap soon also, are the axles the same as the ones you would use on a th-125? you said you didnt have any axles to return so i'm just trying to figure out what all costs would be involved. mine has good axles and cv joints, I jsut dont like a 3 speed auto.
i'm considering doing this swap soon also, are the axles the same as the ones you would use on a th-125? you said you didnt have any axles to return so i'm just trying to figure out what all costs would be involved. mine has good axles and cv joints, I jsut dont like a 3 speed auto.
No, you can't use the TH125 axles, you have to buy different axles. The 4T60 transmission is a different length between the hubs then the TH125 transmission.
The axles needed for a 4t60e swap are different then the ones needed for the 4t60 swap. Neither one reuse the TH125 axles. The 4t60 swap uses the axles from a 84-89 Pontiac 6000, Buick Century, Olds Cierra, or Chevrolet Celebrity with a 4 speed automatic with .785 diameter threads (light duty brakes).
I'm trying to get everything into one thread so that it might end up in the construction zone
As its already been said, you can't re-use the old axles. In my post with the information that I've pulled together read all the threads and articles I linked to and you should be able to see what needs to be done to do the swap. Basically, you have to drop the cradle, pull the old trans, modify the mounts, put the new trans/axles in, rewire the TCC plug, swap governor caps (if your particular trans has the wrong style... most of them do), and add a vacuum line to the modulator. After that just button everything up and you're done.
For the axles I found that RockAuto is the best place to buy them because they have the lowest core charges. You could turn in the TH 125 axles for core (I guess) but in my case I'm leaving them with my TH125 after I pull it as a spare so I'm eating the core charge. If you buy the axles for the '89 Pontiac 6000 w/ 2.8 motor then you'll end up buying the correct axles for the swap. I just bought mine a couple days ago from RA and it ended up being $153 shipped for the both of them.
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08:25 AM
jsketcham Member
Posts: 434 From: Meadville, Pa, USA Registered: Jan 2009
excellent.. ty for the tip on the axles. I have 1 other stupid question , but since i dont know tha answer its kinda important to me.. if i'm trolling through a salvage yard looking for one of these trannies ( our salvage yard people are always like go find one and we will pullit out. ) how can i tell which model it is? is there a tag on it someplace that says 4t60 or 4t60e? or will i just look for a pontiac 6000 with a 2.8 in it and know it is the right one?
the 4t60 will always have a vacuum tophat modulator on the front side of the transmission under the tcc plug. The 4t60e ususally says 4t60e on the pan and will not have the tophat. The 4t60 will also have a TV cable like the 3t40
[This message has been edited by Dodgerunner (edited 03-07-2009).]
GM used a 4T60 in quite a few cars so I don't know of a complete list. However, if you go to a junk yard you should be able to ask the folks that work there to help you look for one with preferably low miles. As mentioned, the non-e trans will have the vacuum modulator AND the TV kickdown cable. The E version doesn't have the kickdown.
As for figuring out what the final drive of the trans is, GM uses a code tag on the back of the trans. I have never been able to find a complete list that breaks down this tag for the 4T60 but I have an incomplete list over on one of my other forums. Personally, I'm just going to live with the 2.84 trans that I have and lose the extra bit of acceleration from the Fiero trans with the higher final drive ratio.
Ive been keeping an eye on this thread, as this might be one of my near future projects! It would be really nice to have a list of the different vehicles that have the 4t60, and possibly the different gear ratios - as a "take-along" for the junkyard scavengers (me included).
Thanks to everyone who has been giving the great info!
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07:59 AM
jsketcham Member
Posts: 434 From: Meadville, Pa, USA Registered: Jan 2009
Also the easiest way to tell between the th125 and the 4t60 is the side cover. The 4t60 side cover is the whole side of transmission, the th125 side cover is about half the size of the 4t60.
The 4T60 was a very, very common transmission. Like I said above, if you want to ID one bring along someone that works at the junkyard and they should be able to help you. I don't know of a complete list but off the top of my head:
86-91 Buick LeSabre, Park Avenue Late 80's Buick Century 86-91 Oldsmobile 88 and 98 and Touring Sedan Late 80's Olds Cutlass 87-91 Pontiac Bonneville Buick Reatta (PLEASE tell me these don't end up in junkyards on a regular basis... they're super rare)
As for telling what their gear ratios are you have two options. First, you can find their RPO tag and look for certain codes (tag is located either on the spare tire cover or on the inside of the trunk lid on many GM cars). Off the top of my head GX3 is for cars with 3.33 final ratios and F79 is for cars with 2.97 gear ratios. However, there is no garuntee that the transmision has been removed and replaced at some point in the cars life so your best bet is to ID the trans by its tag.
Edit: 2.84 gearing was generally the lowest that GM went and therefore it is generally referred to as "granny gearing" as sportier cars had the higher ratios (like the LeSabre T Type, Bonneville SSE, Olds Touring Sedan, etc). 2.84 cars are by far the most common so finding one isn't too hard. The 2.84 will have relatively slow acceleration but that will help with your fuel economy and help you keep from getting too much attention from police
Edit 2: Here is a picture of the donor drivetrain for my various projects. The motor is going into an '88 LeSabre T Type that has a nasty rod knock and the trans is going into my '86 Fiero. The source car was an '89 Pontiac Bonnevile that originally had a 2.97 transmission according to its RPO tag but had at one point been swapped out for a 2.84 after verifying the differing code off the trans.
[This message has been edited by Alibi (edited 03-08-2009).]
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05:59 PM
Jan 3rd, 2010
Genopsyde Member
Posts: 774 From: Willoughby, Ohio USA Registered: Dec 2007
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