So heres the story. I did a transmission swap in my FC a couple years ago. I went from an automatic to a S4 TII trans setup using the parts from a '87 TII. I installed a new clutch, ACT prolite flywheel and the rest was straight from the donor. The TII had like 150k miles on it and the car was hammered. The transplant was a success and I ran the car on the track the following week. As far as numbers go the car launched like a bat out of hell with a 1.92 0-60 feet time but only trapped at 76 mph! Only 3 mph faster than when it ran a sorry 20 seconds with the auto trans. I was like what the ****? Then I started to hear a whirring noise when the clutch pedal was depressed (throw out bearing obviously seeing as how I used the old one) then the syncro in 2nd went out completely and whenever I push the car past 5k rpm it feels like its struggling and the shifter vibrates like crazy.

Now the 5th and 6 ports are functioning fine, when the car is not in gear it revs with no hesitation, and it builds plenty of low end and mid range power. So my question is would a worn out transmission seriously decrease power? 1st pulls like a bat out of hell. 2nd pulls good but I notice a decrease after 3rd gear at high rpm. The trans isn't leaking and is filled with royal purple gear oil (75w-90) The engine checks out fine but runs a little rich. Blows a little blue smoke but only while in gear. Any thoughts? I have a good S4 TII trans waiting but I'm debating on just swapping into a N/A trans (easier to push?) I probably answered my own questions but I'd like to hear thoughts on the subject.

 

dont mean to thread jack, but what is needed exactly to complete a successful tranny swap from auto to manual? Is it a fairly easy swap, is there any cutting or special modifiying that needs to be done? Or does it just bolt right up to the motor and you punch a hole throgh the firewall for the clutch pedal? also price range, and in the end is it worth it?

thanks, matt

 

Search, you are hyjacking his thread.


BC

 

It sounds like the clutch disc is slipping.
The clutch (disc) is either defective or misinstalled.
I would tear everything down and inspect the clutch disc, pressure plate, and flywheel surface to see anything amiss.


-Ted

 

A fubar'd pilot bearing would also mess up shifting at high rpm's. I put one in wrong one time and I couldn't shift over 3000rpms.... Needless to say, I was dissapointed. Pulled it out, re-installed a new one, and it worked perfectly.

 

Clutch is fine. It grips fine and every other gear than 2nd shifts fine. The pilot bearing was brand new also. I can shift at redline but from 1st to second it chomp the hell out of the transmission. I was just seeing if the transmission itself was worn out maybe and causing the engine to struggle.


That- The swap wasn't easy by any means. The only modification you need to make is the crossmember brackets. The transmission crossmembers don't match up. Everything else bolts right up. It took me 10 hours without any hang ups (had a pro help me out with questions) in a shop with air tools. Your best bet is to buy a whole car for cheap and use it for the swap. But its the best upgrade by far for an auto FC.

 

Redline shifting 1st -> 2nd is always going to hurt.
The ratios are too wide, so it always crunches.
I'd recommend to stop doing that.


-Ted

 

how do you know your auxilary ports are fine? How did you test them? What are your other mods on this car? I've thought my auxilary ports were fine when in fact they weren't. It took a dyno sheet to prove that to me. You need to get on the dyno for a baseline pull. The reason 1st gear feels like it pulls hard is that it has a short gear ratio along with the 4.10 final drive... the butt dyno is a liar.

I think your car is just slow as ***** for a competely non-drivetrain related issue.

 

i seriously doubt it is the transmission, plenty of guys running up in the 500WHP range on stock T2 trannies and they can just take the abuse so i really doubt you could fubar it unless it was ran low on oil.

to me it sounds like the engine is the cause of the lack of power in the upper gears, in lower gears the requirements are completely different than high loads in higher gears so any real issues would show in higher gears.

pull codes, make sure all the tune up items are covered(spark plugs, wires, set the TPS, set the timing, etc..) and be sure the fuel system is in good order as well as the 5th and 6th port system. lastly inspect the catalytic converters, when they begin to fail you will notice the power dropping off in higher RPMs at higher loads.

 

yeah if you've got good compression than a clogged cat could be killin ya

 

Ok. There is no cats. The car is straight piped. Also the car has 3.90 rear end. Not a 4.10. Remember it was an automatic prior. Which might have something to do with it but not likely. The engine is strong and running 100%. I thought the aux ports might not be working but they are. I had the car checked out by a pro. Not some dick at jiffy lube.

The issue isn't the engine. I hear a whirring noise when the clutch pedal is depressed. The transmission vibrates like its going to explode when I rev past 5k rpm.

 

check all the mounts and if everything is tight r u shure the tranny is the one that vibrates/?

 

If you have no cats, how are your aux actuators working... unless it's an S5?

Did your pro check comression quality?

Do you have a clutch interlock switch wired up? After my manual swap I put one in and it caused issues when I pushed in the clutch (mainly maintaining constant idle, but it could have other effects), so I wired it so I could start the car whenever.

 

I looked in your profile and it says you have a 1989 GXL. Did you use the flywheel from the '87? If so this may be your problem as the 89-92 cars had different front and rear counterweights from the 86-88 cars. The rear counter weight is part of the flywheel. if using a trans from a 87 TII you have to use the flywheel and clutch parts from an 89-91 TII. If not the engine would no longer be balanced properly. I don't know what would happen exactly but I imagine it would vibrate like crazy. If you used an 89-91 flywheel you can disregard this post.

 

well you can believe me or not but i still say it is the engine.

why? because i have a '87 T2 with a BEAT TO HELL original T2 tranny with 191k on it that whines in every gear but it still pulls through gears just fine. like i said, the tranny is pretty much bulletproof unless it has been run low on oil and it would howl like a mothereffer in every gear except 4th if the bearings are all shot.

if you really want to go through the transmission or replace it with another then go for it, not my place to say where the problem lies exactly without seeing it myself. every tech makes mistakes and will not be able to pinpoint an issue without some time to dig.

the T2 unit will slow your 1/4 mile times than it would have done with the n/a unit, also the 3.90 gears are hurting your 1/4 mile times also but this sounds a bit harsher than i would expect.

maybe you have a brake caliper hanging up? who knows, we can only speculate.

 

I was told it was pocket bearing (?) when I went to my friend about it. Compression on the engine was 105-105-105 on both rotors (not bad for a 17 year old engine with 150k on it) the car hauled *** at high rpm with the auto trans then it changed up after I swapped. Yes its a S5 with the proper counter wieght and flywheel.

Now the transmission was leaking at one time and I filled it up and last I checked it was full. What might also be a factor is the differences in vacuum lines and throttle delay nonsense that the engines equipped with automatics come with. Which no one knows a damn thing about. If I were to get an air/fuel ratio gauge would I be able to find out if there is an inconsistency due to the change? Because it doesn't make any sense. The car blows puffs of smoke randomly at WOT and considering it has an aluminum flywheel it produces an exceptional amount of low end power. Its high end power that I'm lacking. I have a feeling a new trans will improve but not solve the issue.

 

You should rename this thread "3.90 Diff hurting performance?". Because, thats what it is.... 3.9 is a HUGE difference between 4.10 or the GTUs 4.30

 

I've heard that before. Maybe i should consider dumping it for a 4.30 rear end.

 

Everybody should.... they are just hard to find.... would be easier to re-gear a TII rear end.

 

Actually I don't think it would. TII's only came with a 4.1 rear end in the U.S. as far as I know. So you won't find one in the junkyard or a car thats being parted out. There's a slim chance you might find one from a GTUs that someone is parting out but due to the raraity of the car not likely. Mazdatrix,Racing Beat and Rotary Performance all sell 4.3 gear sets for both the N/A and TII cars so re-gearing would be the same as far as replacing the gears inside the pumpkin. I wouldn't bother with 4.3 gears in your rear end as I don't think any auto's had LSD. I'd either find a N/A pumpkin that has LSD and put it in or get a TII pumpkin, halfshafts and necessary items to put it in. Either way it's a 4.1 and LSD and you could go to a 4.3 in either at a later date. I don't know how a 3.9 rear would cause vibration at upper RPMs. If it was the rear it would be speed dependant not RPM dependant as the rear end doesn't know what speed the engine is turning. I 'd verify it isn't something else before I started switching rear ends unless you already have the parts just laying around.

 

Dak: He doesn't have an auto....it WAS an auto... hence the 3.9's... and finding a TII rear end would DEFINATELY be easier than finding a GTUS rear end.

As far as the vibes..... thats a different issue all together. Probably motor mounts or counterweight/flywheel issues.

Gawd.

 

I know he doesn't have an auto now. What I meant was since the car was originally an auto before he put the TII gearbox in, he wouldn't have had LSD from the factory.

 

Ahh.. yeah. no.. he wouldn't.