Should be able to use a standard flywheel and clutch set (ie manual trans like t5 behind a 2pc rms V8), with the hydraulic throw out bearing conversion... Who was it made the hydraulic TOB conversion, McCleod maybe?

 

Looks like Ram does make what im looking for. $1190 for the clutch disc, pressure plate, flywheel, and hydraulic t.o. bearing. Looking forward to it arriving!!

 

Hey all,

Sorry if this has already been talked about. I'm considering going with a tranny swap. I've been reading through the thread for about 45 mins and haven't found anything specific. Has anyone completed the hawks automatic to manual t56 swap kit? They say they provide everything needed to complete the swap but after reading a number of posts on this thread it appears that this may not be correct? I know they recommend getting new clutch, flywheel, master and slave cylinders, and they mention the need for a Ram clutch (think it was) for those with a 2 piece rear. Outside of that, I guess I am asking if that is indeed everything I need to make this work. For example, do I need a different drive shaft or will my current drive shaft from my 92 bolt right on to the t56? Someone also mention something about there being an issue with the speedo. This wasn't mentioned at all on the Hawks site. Is there going to be an issue with the speedo (I believe my 4L60 uses an electronic speedo). The last question is related to the ECM/Promm. Will I need to get a new Promm to complete the changeover or can I use the stock one that I currently have from my car?

Again, sorry about all the questions. Been considering this for a while and am trying to see exactly what I'm getting myself into as I have found that nothing ever seems to be as simple as advertised or as complete as they say.

Any assistance from anyone that has successfully completed the Hawks 93-97 auto to manual T56 swap would be greatly appreciated.

Thanks

 

There are several folks who did 700-R4 to T56 swaps. Look at how long this thread has been around. You may want to read it again and copy-paste notes into another doc. for reference.

The 85 T5 flywheel bolts to 100% of 305 and 350 engines 85-down . The 86-up T5 flywheel bolts to 100% of 86-up 305 and 350s. So does the 93-97 T56 flywheel but it is a unique depth to fit that trans./clutch. The aftermarket conversion flywheels to run an early engine with the 93-97 clutch are a reliable setup and no need to stick to Ram specifically.

The late third gen electric VSSs are 4004 pulse per mile. The 93-97 T56 is 11 or 17 pulse per driveline revolution. Obviously nowhere near the same and definitely needs conversion. All ECMs in third gens need a compatible VSS signal to best operate engine management and a manual tune is highly recommended. Again, there are posts on this.
​​​
Seriously make a doc or excel sheet with a list of what you know you need. It will help you think through it and reinforce What you read. Look at parts in a store if possible if that helps you make sense of how things will go together. There are still salvage cars out there with parts and new parts available.

 

Thanks for the info.

I started up an excel doc with a parts list etc a little while back but was just doing a bit more research before pulling the pin on the kit purchase.

I'll have to have a look around about the VSS signal difference (I didn't know that was a thing before today) and how to get that sorted as well as the manual ECM. I know that there are custom promm's that can be programmed, I just wasn't sure if it was something that I had to do right away or if it was something that I could do later, like when I eventually change out the engine.

I guess the other thing I have to find out is if the stock driveshaft from my 92 will bolt up to the T56, or will I have to buy a 4th gen shaft as it's about 5/8" longer than the 3rd gen shaft.

Thanks again for the help.

 

So my car was an auto and I swapped to a t5 and then a t56. Both swaps are pretty easy, they just require the right parts. I used a magnum f t56, a quick time bellhousing, American powertrains 82-92 t56 hydra release bearing system and a ram concept 10.5 dual disk clutch w a normal flywheel. All of this bolted together and has held up really well. I used a spohn x member/torque arm and a custom aluminum drive shaft.

you can get converters for the vss to calibrate your speedo.

I kind of feel like the hawks conversions kits are cool but expensive for what they are.

I dont get why people continue to use the 93(ish) LT style setups. There's more modern stuff now and the LT stuff seems to be more limited as far as aftermarket support. To be honest, this comment is totally from a lack of knowledge of those systems. The LS stuff seems to have so many options as far as clutch style/release systems/gear ratios etc. and using the LS stuff behind a sbc is pretty easy.

 

The T-56 VSS, in a stock 93-97 T-56, is 17 pulses per rev (17000 per mile). The one in a T-5 or 700 is 4 pulses per rev or 4000 per mile. Not sure how the "4004" or "1001" or whatever still gets quoted, or how that's what the factory still says, even though that's NOT what they ACTUALLY make. A simple glance at a mechanical odometer will illustrate why: the first reduction gear in it is for 1/10s of a mile, which at 1000 revs per mile, requires a gear train that gives 100:1 reduction, which is exactly what you'll see (2 reductions of 10:1) when you LOOK AT it. There's NO POSSIBLE gear train that will give a 100.1:1 ratio. No such thing CAN EXIST since that would require gears with fractional teeth (like, 1/10 or 1/100 of a tooth somewhere). Either a mech or a gear-driven VSS is thus geared to give 1000 revs of the cable or VSS per mile, which means the speedo changes over from 0 miles to 1 mile on the 1001st rev, then counts up another mile every 1000 revs after that. I.e., it counts up miles at rev 1001, 2001, 3001, 4001, etc. ... 1000 revs per mile, NOT 1001 revs per mile or multiples of that which would be 1001, 2002, 3003, 4004, etc., since that's IMPOSSIBLE. I suppose that "first mile" count is where the confusion starts. Your particular VSS outputs 4 pulses per rev, meaning your odometer counts miles starting from birth at a pulse count of 4001, 8001, 12001, etc., 4000 per mile after the first one, NOT 4004, 8008, 12012, etc.

In any case, all you need is a digital divider box, to divide the 17 pulses per drive shaft rev down to 4. With that, all your stock stuff then gets what it's expecting; no "custom PROM" or any of that is needed. One output pulse for every 4 input ones 3 times, then an output for the next 5 inputs, then 3 more 4s and another 5, and so on.

The 3rd gen drive shaft fits a stock 93-97 T-56 just fine.

Can't comment on a "Hawks kit" specifically. I can only assume that they're tearing down 4th gen cars and selling the parts, maybe supplying a few goodies that are hard to gank out of a car or that likely need replacement anyway. In which case what they sell is the same as anybody else's stock 93-97 "kit", or if you just piece it together yourself like I did for my 83, or whatever. You don't need to worry about the "special" flywheel such as from Ram or Centerforce since a stock 93-97 one will fit your motor. The reason Hawks recommends getting a new one is because ... then you'll have a new one instead of a used one. It's not needed as far as fitment is concerned though, only for renewal. One part you'll definitely need however, is a crossmember, because the trans mount is about 5" or so farther rearward than a T-5 or 700 one. No way to make a stock one work except by welding something up to it, which turns out kinda weeeeenie, at best. In my car I ended up with a Spohn CM & TA. Of course in my car I had to use a "special" flywheel because I have the 85-back crank pattern, and I had to have a "custom" extension housing to hold a mech speedo "bullet", butt you won't need any of that.

I kinda agree about the 93-97 stuff. Makes sense why one would have used that back in the 90s and early 00s, before anything else was widely available, and 93-97s were still fairly new and low mileage and all that. In 2025, those things are getting ever rarer, and more beat to hell; not near as good a choice as it was when I bought my T-56, a 96 one, in about 98.

 

Just for clarity on my shaft comment, sofa is correct on the 93 trans using the stock shaft. The magnum f and LS t56s are longer and some use a different slip yoke so you may need a different shaft (likely) and minimally need a conversion u joint for a 1350 yoke. My experience was also w a ford 9in rear so there's that part of my equation and limited experience.

 

Hey Guys, It seems as though I have scoured the internet regarding my swap and the issues I've been having. I'm hoping someone has a gentle ear to listen (read).

I have a 1989 IROC-Z. It was more or less a stock car with a mild cam and a 700R4 stock trans with a shift kit and no other modifications. Was one of those "survivor" type hardly modified cars that was stored for 15 years and hardly driven.

After owning it for 3 or so years, I was set on finally doing a T56 swap. Its my toy/weekend car and wanted to enjoy driving it while taking the kiddos out for ice cream, or the wife on date night. The auto with the shift kit was simply frustrating and delivered a kick in the A$$ every time it shifted 1-2 and 2-3 so it became a nuisance more than a joy. This year as I was about to get the car on the road from storage, I came across a steal of a deal on a 1994 Camaro Z28 6spd car that had a toast motor. So I bit the bullet and bought it as a donor for my 6spd swap.

I pulled the drive shaft, transmission, pedal assembly, clutch, PP, Flywheel and all necessary parts for the swap and retained the car until the swap was basically done just to ensure I didn't need anything else.

I marked the flywheel/clutch setup before removing it from the 4th gen, and installed everything the way it came out of the 4th gen I used the 4th gen pedals, 4th gen drive shaft (i liked the idea of the anti-vibe ring on the yoke) and fully assembled my car. I had the tail housing mod done to allow for the cable drive speedo to work and bought a BMR trans crossmember that also isolated the torque arm mount.

After going for my first drive (very low speeds) everything seemed great, I started to reassemble the interior and went for my first real maiden voyage home and once i got into highway speeds the car shook/vibrated rather aggressively. The whole body of the car, not the steering wheel or the rear end like a tire imbalance, the whole darn car.

So of course, brought it back to my shop and have been puzzled since. I had it up to speed on my hoist and found the drivers rear axle was bent causing the rear wheel to wobble 1/4". ok, replaced the axle, no more wheel wobble. confirmed balance on wheels and everything.

sitting idling there's a vibration between 2500-3000rpm. I tried my OEM drive shaft, no luck. I tried having the flywheel surface re-machined still no luck, I then measured the driveline setup to find out that the BMR crossmember sat REALLY low compared to the OEM auto setup, exactly one inch in height difference from the tunnel to the center of the output shaft. I cut the BMR mount, jacked the tranny up to the same height as the auto modified the bracket and re-welded it together. I did the same for the torque arm mount, checked the height from where it sat with the auto and made it the same. So basically what I've done is replicated the driveline positions of the Automatic into my manual setup to keep OEM driveline angles. To be clear, I had none of these vibrations before swapping.

Originally my T56 did not have dowel pins on its faceplate to mate with the bell housing, I bought new. still no fix. Is it possible that the flywheel/PP are not clocked properly? I have seen the Yellow paint mark on the PP but I do not have a corresponding one on the flywheel. Which is why I marked the components before I removed them from the 4th gen. Its 100% possible that the previous owner installed it wrong, I know the transmission was removed before I bought it as he mentioned installing a new clutch. The vibration seems to appear in that 2500-3000rpm range and sitting idling it gets a little better at 3500, but is still very present. when driving its certainly more apparent as its under load 60-70kmh (35-45mph) in 3rd gear and its in that rpm range and its intolerable.

Please tell me that there's something I'm missing. I have probably pulled and installed this transmission 10 times looking for any indication of what is going on. I have also recently discovered that the clutch kit that was installed looks to be factory or aftermarket factory, and there are 3 dowel pins (spring pins, split pins, call them as you wish) that go through the "fingers" of the PP, are missing. and from what I've understood and observed, these dowel pins prevent the "finger" plate from rotating. Which is fair, but even if the dowel pins were installed, there is a fair bit of room for that "finger" plate to move. Would this have anything to do with my vibration?

I'm happy to answer any questions as promptly as possible. As silly as it sounds, so far the only thing I haven't done is run the car with JUST the flywheel attached, no clutch, PP, trans etc. I work on the car when my dad's available to help (he's a mechanic), but even he is stumped with this one. I know he's doing his best to try and save me money so we aren't simply buying new parts and throwing it at the car to expect a result, but If a new clutch/flywheel is what I need, so be it. I just don't want to be wasteful with money as todays economy is about as stable as cooked noodles.

Any help or insight is appreciated in ways I cannot express. Also, I'd be happy to Uber anyone a case of beer that provides a solution.

cheers,
Pete.

 

So, it does the vibration while not moving and in neutral as you rev up to 2500-3500? Does it do the same w the chutch engaged and disengaged?
did you retune the ecm or use a manual chip!

 

Yes the vibration/shake happens both while moving and not moving, its just A LOT more pronounced when driving. clutch engaged/disengaged doesn't matter.

I did not retune the ECM or put a manual chip in. I remember reading that the auto chip is fine but some guys mentioned that the only thing that changes is the idle speed/force due to the torque converter. but after doing my swap, the idle sits around 5-600 rpm. I will say that the car at idle is more "shakey" than the auto. My guess is that's because the torque converter somewhat dampens things like a cushion, whereas the manual is now a solid mechanical link.

 

Flywheel and engine balance not cooperating?

 

This is possible. but to "check" that what I did was compare the original flex plate and the flywheel.

My original flex plate has a welded weight on it. its the way I removed it from the car. I checked various mfr's websites for flex plates and they all had the same looking welded weight on it. Ok cool. I then put it on my wheel balancer as it has some pretty free-rolling bearings. I used wheel weights and found that 4oz seemed to balance the flex plate weight. ok cool. I took the manual flywheel and also mounted it on the same balancer and attached the exact same 4oz wheel weights to it directly across from the "heavy" side of the flywheel, and voila, it also balanced.

So based on my findings here, I would think that the flywheel should be compatible both in fitment and balance. maybe I'm crazy, but wouldn't that ring true?

 

So it's either a flywheel/balance issue or tuning/vacuum issue. I'm pretty sure the LT engines are balanced like a standard 350 but I'm not positive on that. I'd start w checking plugs/wires making sure you didn't knock something off while you were doing the swap. I know this sounds dumb but we've all been there. There are people on here who know more about the tuning of these cars and swaps. Same goes for flywheels. I'd also think about issues w injectors. You said it sat for a while. If the injectors are gummed up it can cause stuff like this.

 

spark plugs and wires are new, maybe 3000km old. The guy I bought it from did a bit of a refresh before I bought it. It was in 100% running condition. I also replaced the complete distributor, cap, rotor and ignition module to ensure the ignition system is 100% complete. Injectors were also replaced and the plenum gaskets done too, all leading to the flywheel/clutch imbalance.

again, none of this vibration was present in the auto setup and I had driven it for 3 years of summer cruises.

 

I had a similar vibration issue. found an engine shop that was able to spin my flywheel on a balanced rotating assembly and confirmed that it was out of balance. They were not equipped to balance the flywheel though. That flywheel had no balance weights nor any sign of material removed.

the second new one I bought had no balance marks either, returned it without installing and the third one (I think a LUK stock replacement) had some weights, installed it and no more vibration.

 

Silly question, but is the flywheel clocked correctly on the crankshaft?

 

lol, somewhat silly, but worth asking as I didn’t mention it. Yes the flywheel dowel pin is located in the right hole and all 6 bolt holes line up accordingly.

 

From what I’ve read, our flywheels/flex plates have an intentional weight attached to them to balance the rotating assembly. Maybe I’m wrong but I’ve read many many things about this almost to the point of confusion.

the flywheel I have definitely has a weight on it on the inside (motor side) and almost 180deg from it there are 4 large drill bit marks that were made, I can only assume to fine tune the exact balance it required to be in spec.

so far everything points to the clutch/flywheel/PP I just don’t want to blow $1200-1500 (everything in Canada is expensive) on a new setup to find out nothing changed and I wasted the money by buying parts and throwing at it.

I have seen other clutch setups and I’m curious to know if any one of them would solve this issue. I’ve also heard of guys buying replacement clutch/flywheels and having a vibration right out of the box.

 

If you can put it in gear, with the clutch pedal pushed in (clutch released) and increase rpm to the vibration point and it still vibrates, that eliminates the clutch disk itself as the culprit. If it's an original GM flywheel, I don't see how it could be out of balance enough to be the cause.

I'm leaning heavily towards a faulty pressure plate. I run a basic Zoom brand clutch kit in my '86 and it's buttery smooth.

I bought a more aggressive "M-Pact" clutch kit from Rock Auto for my '79 with LT1 style T56 swapped in, but I have not run it yet. It was very cheap. Hopefully soon I will find out if it sucks or not.

 

The flywheel may not be GM original, it’s just what came off the 1994 Z28 donor car and I know the clutch kit was replaced. The flywheel looks as new as the rest of the clutch, no rust inside against the engine side anywhere.

I believe the friction disc was stamped valeo, but the rest of it doesn’t have a brand stamped on either pressure plate nor flywheel.

There is a yellow paint mark on the pressure plate that looks to indicate something, clocking maybe? But there are no corresponding marks on the flywheel.

are there any markings to look out for?

 

I've run into balance issues with aftermarket stock replacement flywheels before, but I don't remember ever replacing a flywheel on an LT1 T56 car.

 

I think I’m going to do this:

1) run the engine with only the flywheel on, no PP or clutch. Assess the vibration (unless it’s gone).

2) run the engine with the clutch and PP installed, maybe trying it in multiple locations starting 180deg from where I originally put it. Either it’s going to get better or worse or do nothing.

3) if all else fails, I plan to drive the car again, get it to the speed/rpm where the “shake” and push the clutch in and let the rpm’s drop to idle while rolling. Either the vibration stays or it doesn’t.

in situation 3, if the vibration goes away, the issue will be in the flywheel/clutch. If the vibration stays. It’s a driveshaft/pinion angle issue.

is my theory correct?

 

I'd start w just the flywheel/disc pressure plate combo and see what that gets you. This way you know the disc is centered. Then loose the whole clutch and see what the effect is. You're gonna pull it all out again either way, may as well just get it figured out and fixed asap while it's still good driving weather!

 

well I’ve got nothing installed currently I’ve pulled the setup out and put it back in about 10 times. It’s bare engine and crank, no flywheel. And it’s up on the hoist. I’ll hopefully get a chance tomorrow to try to do these tests. see what I come back with

 

well, I guess start w the flywheel! You'll know soon enough.

 

A thing to watch for, is the transmission contacting the body, in the tunnel. In which case, all the vibrations that exist, get transmitted directly to you.

There's a place that many T-56/3rd gen combos do that. Can't recall where it is. Seems like it's more toward the front somewhere. Check carefully.

 

this was a thought I had as well, but I can almost get my hands through everything around it and I’ve got a set of mitts. Even the rubber bump stop at the top rear in front of the shifter is in place and I’ve got a finger gap (1/2-5/8”) and there’s not enough movement in th drivetrain for that to happen, otherwise there’s more issues to look for.

here goes some testing…

 

My t56 (magnum f) was touching the metal fuel lines that run across the trans tunnel. There was one bolt head on top of the trans that hit one of the lines. I put a new fuel system and that is a non issue at this point but the trans is close in a few spots. Curious what you find w the flywheels.

 

After testing here’s what I’ve found:

1) flywheel alone: smooth revs all the way up to 3500rpm (didn’t go beyond that as I didn’t feel necessary)

2) flywheel and clutch: almost perfectly smooth, 1900rpm very very minor vibration, but nothing to worry about.

3) flywheel and clutch rotated 180deg from original position: same as original position. I would assume rotating in any of the other 6 bolt holes wouldn’t make any difference either. I know… assuming…

4) on the road after testing, same result crazy violent shake at 100kmh (60mph)


after speaking with a buddy of my dads, this guy is apparently a driveline specialist. He said confidently, it’s my pinion angle.

He’s confident enough that he’s willing to measure the whole drivetrain angle setup and confirm his suspicion.

If his measuring points to this, an adjustable torque arm bar will be in order, and I’ll adjust accordingly.

ill keep everyone posted as soon as I have more to say.

 

Should be VERY eeeeeeeezzzzzy to identify as engine/FW/clutch vs drive-shaft-related. All you have to do is get it into the situation where it's doing it, and see putting it in a different gear, or no gear at all, changes it.

 

the shake still happened during shifts and different gears. Which leads me to the pinion angle.

As it turns out, I did some very rough measurements of angles. My engine/trans sits back somewhere between 2.5-3 degrees, close enough to 3degrees that my small digital level would basically round up to 3 if I breathed on it. And for some magical reason 3degrees is the magical number.

after the car sits down on all 4 wheels my diff is basically perfectly level at 0degrees.

I will be making my own adjustable torque arm to adjust the rear pinion angle. Aiming for roughly 3degrees up.

and if by some miracle this fixes my vibration issue, I’ll kiss the guy who suggested it.

 

Well everyone, thank you for all the help and suggestions.

As it turns out, an adjustable torque arm fixed everything…

I guess 3 degrees is enough to cause a “whipping” driveshaft at the pinion.

So for anyone that has drivetrain issues, check your angles. A lesson well learned and unfortunately taught the hard way, but I don’t mind.

So here’s basically what I’ve done and learned:

3 degrees of slope towards the back is what you want your engine and transmission to do.

your differential (pinion) needs to be parallel to this or at most be 0.5 degrees less, so maybe pointing up at 2.5degrees so that under load the differential/pinion can load upward to 3 degrees. If you have a poly bushing up front, closer to 3degrees works fine as it is rigid enough to hold the torque arm in place.

The adjustable torque arm adjustment has to be done with the vehicle ON ITS OWN WEIGHT. So sitting down on its wheels.

another thing to note:

if your car is lowered, that’s fine. Use a straight edge on the front crank to get an angle of the engine/trans. all of these angles are RELATIVE. So if you’re running a tall rake setup with big fat radials in the rear, doesn’t matter, measure the angle of the engine trans with one of those digital angle finders.

AS LONG AS YOUR PINION IS PARALLEL or up to half a degree LESS than the engine, you’re fine.

an adjustable torque arm is not a “want” item when it comes to this swap, it’s absolutely necessary on anything but a stock car.

as for driveshaft angle, this matters if you have a large discrepancy between output shaft and differential centre lines. Shimming the transmission may be necessary.

Through all of this what I did was this:

After having the issue I ripped everything out, installed the auto trans and crossmember as it was stock. Measured the height from the top of the tunnel to the centreline of the output shaft. Took all that apart. Reinstalled the t56 bellhousing and transmission and BMR crossmember (TCC016), and found that the t56 sat at a VERY aggressive angle to the back, so I measured the height of the output shaft and compared with the stock Auto setup, sure enough, it was exactly 1” different (lower). So instead of shimming the transmission mount, I cut up the crossmember and raised it 1” to accommodate for this. It does 2 things for us 3rd gen guys, 1) gets the output shaft in the right location (compared to stock) and 2) GROUND CLEARANCE! I then also compared the location of the torque arm location to the output shaft of the automatic, again, in stock form. So I located the front torque arm mount (adjustable on my crossmember) to where it matched the OEM setup, which coincidentally is the highest set of holes. After that, it basically puts the t56, the engine/trans angle and torque arm all back to OEM spec. The rest was the adjustable torque arm fixing the pinion angle. Job done.

hope this helps someone in their future build.

 

That's what I ended up buying.