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I did the T56 conversion to my '84 T/A in the fall of '17. I used a (verified non-magnetic) brass pilot bushing, a Quicktime bellhousing, the aluminum Ram conversion flywheel, an O'Reilly's stock replacement clutch, and a used T56. I took care to align the bellhousing for both parallel and concentricity, and got it within .002 and .008 TIR, respectively.
The car had a nasty clutch chatter in reverse and would pop out of third every once in a blue moon, so I pulled the trans and sent it off to be rebuilt. The pilot bushing was wallowed out pretty bad, so I replaced it with a brand new one and confirmed the BH alignment. The tip of the input shaft was a bit rough and there was quite a bit of play, so I chalked those up to being the issues.
I reinstalled the fresh T56 and went on a 6k mile road trip in 2018. The car developed a pretty violent clutch chatter, but I drove it the rest of the year. Everything else seemed fine, no noises or popouts.
I just recently pulled it again. The pilot bushing was again shot, but everything else checks out. I did measure .003 on the parallel reading for bellhousing alignment this time, and was able to make adjustments and get the measurements down to .001 parallel and .002 concentricity. I checked the flywheel for runout; it is under .005. The bellhousing seems to have .002 clearance around the dowel pins, though I highly doubt that it could move once bolted down and torqued anyway.
I'm getting a max of .015 TIR on the input shaft tip, but the reading is inconsistent. I'm not sure that the indicator is very secure, or that wear on the tip or movement in the input shaft bearings aren't to blame. Still, while not negligible, I cant imagine that being the issue.
Only other suspicions are that the input shaft isn't deep enough into the pilot, the pilot is being damaged when inserting the trans, or that the clutch may have some massive balance or chatter issue on its own, if that could somehow cause damage to the bushing.
I ordered an extended brass pilot bushing from Jody's transmission, and also spoke with the builder, who recommended using the new larger style roller bearing from the LS engines that sits in the larger crank bore and turning the input tip down enough to fit. I trust the builder, but I'm a little apprehensive about doing that, especially if it could somehow destroy the input shaft, crank, or thrust bearings if something goes wrong.
At the end of my wits. About to dump the whole damn thing and go T5, or buy an LS1 car and swap the whole dang drivetrain over, lol.
Last edited by midnightfirews6; 06-11-2019 at 01:35 PM.
Aaaand the other concern. When I had the front plate off, I inspected everything I could see for wear. Noticed some grooves that just barely catch a fingernail on the bearing races and towards the outer edges of the rollers themselves. Wasn't sure if that's typical (or at least harmless) or a big red flag. The builder said that he'd run it, but I'm always open to second opinions. Would like to go a year or several without being on my back and going through all of this again.
I don't know that much about trans' but did you measure end play on the input shaft in addition to run out? and did you measure side-to-side play? How about clearance on the splines to the clutch disc?
A lighter flywheel is a mistake if you want smooth engagement. While it's apart, go iron. Al. might sell well, anyhow.
Seek out a brake and clutch exchange place. See if they can machine your used flywheel, your new slightly heavier flywheel, and re-line the disc. New flywheels and PP surfaces can be concave or convex, and not flat. Give yourself the best starting point possible.
Lateral movement at the pilot end of the maindrive (input) is not relevant when the trans. is out of the vehicle. Preload at the transmission bearings is relevant. Period.
I like the idea of the bigger bearing. It's more robust than the old bronze style third gens originally had, or the roller. But that's not the only reason clutches chatter, so don't consider that a fix and case closed.
Above all else, I hope you're running a 1993 box w/ at least 2.97 first with an LG4 / 3.23. A shorter (3.73) gear would help w/ clutch chatter. And if you do have a 1993 box, 5th / 6th can be changed to GTO 5th / 6th ratios if you want, to match a 3.73 rear. However, 0.63 and 3.73 works really well across southern IN, and that's all I have to say about that.
You didn't have transmission noise with those bearings did you? Troubleshoot the clutch, rather than the "everything while I'm in there." Your bushing wasn't going to live long w/ thousands of miles of chatter.
I don't know that much about trans' but did you measure end play on the input shaft in addition to run out? and did you measure side-to-side play? How about clearance on the splines to the clutch disc?
End play- 0.000, the builder said that he shims all of his builds to 0 with good results.
0.020 side to side, pulling both directions as hard as possible.
Splines- 0.004 indicated runout when pushing up on the splined portion of the hub alone, 0.018 when pushing up on the edge of the hub and moving the whole disk. I repeated this with a brand new Valeo disk, which measured the exact same. The hub on the new Valeo does seem tighter and it seems to have less free rotation on the splines, but that could just be normal wear and I'm not sure of an easy way to measure that.
A lighter flywheel is a mistake if you want smooth engagement. While it's apart, go iron. Al. might sell well, anyhow.
Seek out a brake and clutch exchange place. See if they can machine your used flywheel, your new slightly heavier flywheel, and re-line the disc. New flywheels and PP surfaces can be concave or convex, and not flat. Give yourself the best starting point possible.
Lateral movement at the pilot end of the maindrive (input) is not relevant when the trans. is out of the vehicle. Preload at the transmission bearings is relevant. Period.
I like the idea of the bigger bearing. It's more robust than the old bronze style third gens originally had, or the roller. But that's not the only reason clutches chatter, so don't consider that a fix and case closed.
Above all else, I hope you're running a 1993 box w/ at least 2.97 first with an LG4 / 3.23. A shorter (3.73) gear would help w/ clutch chatter. And if you do have a 1993 box, 5th / 6th can be changed to GTO 5th / 6th ratios if you want, to match a 3.73 rear. However, 0.63 and 3.73 works really well across southern IN, and that's all I have to say about that.
You didn't have transmission noise with those bearings did you? Troubleshoot the clutch, rather than the "everything while I'm in there." Your bushing wasn't going to live long w/ thousands of miles of chatter.
I went with the Al flywheel since the conversion flywheels are so large. IIRC, the Ram unit was around the weight of a stock L69 flywheel, ~18 lbs, whereas the steel Centerforce chunk was listed as 30. Figured the lighter weight would let the LG4 spin up a little quicker and get the car out of corners faster. The flatness aspect did cross my mind, might pull it off and check it on the coordinate measuring machine at work and go from there. Now that I think about it, the clutch and flywheel are the common denominators throughout this whole ordeal...
I'm running a 1997 box. The ratios definitely aren't ideal from stoplight to stoplight, but they work much better than the old 700R4 did on the road course and back roads. I know what you mean with the southern Indiana comment, it is wonderful idling right past everybody on the interstate and rural highways in 6th Once the car's finally sorted, the plan is to build something a little hotter than the LG4, and reassess the rear gear situation then.
Nope, no noise. I just like to overthink everything haha.
I've been there with my old fox body mustangs. Getting under the car, removing, replacing, measuring, repeat. it is VERY frustrating. What I usually found was that I was missing something obvious and would blow right past it into these fine, complex measurements that most drivers ignore and end up with a setup that is just fine.
I just did a quick search on clutch chatter, it seems to these guys that you may simply have a defective part...
Hate to resurrect a dead thread, but hate threads that don't have a conclusion more.
Follow up: In 2019, I ended up sending the transmission back to the builder, who replaced the bearings in the photos and rechecked everything. Ordered a new Valeo clutch and extended pilot bushing and put it all back together. Last year (2020) I dropped the transmission to seal up a leak from the tailshaft, and once again the pilot bushing was wallowed out. I checked flywheel runout, as well as bellhousing parallel and concentricity... all well within spec. Only thing I can possibly think of is that the lip of the Quicktime Bellhousing occasionally scraping on speed bumps and entrances might've caused enough flex to throw the input shaft alignment off. I ground the bottom flange of the bellhousing down, installed a new Hooker Blackheart crossmember that tucked the transmission up much better than the flexy Hawk's piece, installed a new non magnetic extended pilot bushing, and sent it. Hopefully it stops eating pilot bushings, but we'll see.
06-11-2019, 01:06 PM
