Throwout bearing problem (T5 conversion)

Varilux

Well-known member
My car is 1/8 to 1/4" from being drive-able, so I hope someone here can help.

The problem is arising with a clutch change. The issue is when the pedal is depressed to disengage the clutch, the throwout bearing is extending just far enough past the end of the transmission's output shaft to cause the oil ring to catch (mechanic says it is literally just 1/8" to 1/4"). This causes the throwout bearing to momentarily hang up and then crash back when it finally releases.

By way of background info, I have a '65 inline 200 with the 8.5" "dogdish" flywheel and a T5 transmission. Everything was purchased through Modern Driveline years back, and I've never had this problem (and the clutch has been replaced before).

Here's the head-scratcher... I had the clutch replaced just a couple months ago with the same bearing, clutch plate, etc. The issue was the flywheel was at the end of its life. We tried turning it one more time and installed it. However, I was getting chattering (but the clutch was NOT hanging up like it is now).

So, I found another new/old dogdish flywheel that was in good shape and had the shop swap the new flywheel in- THIS is when the problem started. The pocket depth is a perfect 1", so that isn't the problem. The mechanic said he tried taking out the play in an effort to decrease the travel, but no go. By the time he adjusts it far enough so that the bearing doesn't catch on the end of the output shaft, the clutch will no longer disengage (in fact, if you push the pedal in too far you just get a nasty sound).

Any thoughts would be greatly appreciated. I called Modern Driveline, and they've never encountered this issue (and they correctly pointed out the parts they supplied with the clutch kit worked with the old flywheel- so there must be an "installation error"). The mechanic says this is one of the simplest installs he's done- but he cannot account for why the throwout bearing is traveling just far enough to hang on the end of the output shaft.

The mechanic and I thought perhaps a longer throwout bearing would work, and I see a simple solution in just having the adapter plate machined down 1/4" (but the mechanic says we'd need to make sure the output shaft won't then make contact with the flywheel). Really though, I'm just trying to figure out how we're having this issue when the only difference is the new flywheel.

If someone has an idea, please share it... I want to put her back on the road to enjoy this beautiful spring Dallas weather!
 
I trust your mechanic, and MDL. HAMBers and JalopyJournalers have discussed this at length.

See this. Becasue of new compnentry, you'll not be able to see the traces of wear. This is the root cuause, though, missalignment, and it won't be the clutch, the MDL plate, the work your mechanic has done....

CLUTCHALIGHNMENTISSUES.jpg


What I think has changed from Day One is that the bellhousing isn't where it should be on the Ford Blueprint. It may never have been, and that's caused run out issues. The first clutch burn out was most liely surfacing, but it could have been input shaft to crank spigot issues as well.


Unlike V8's, there is no proper alignment holes for the I6 clutch. Unless yu do this test below, you and your mechanic are just guessing. Educated, experienced guessing, but unless you've checked run out, its not going to be an eassy correction.

Often, just 1/8 washers or steel plates helps correct this kind of stuff, but you need to ensure no docking missaligment exists.

I think its another issue based on my experience. This is a Ford I6 issue, very common, and no one checks it, they just throw parts at it. My neighbour had an I6 Valiant Charger with the same issue. Had been line bored with 4" Chevy 327 pistons, 650 Double Pumper, and a 3 spped gearbox which just kept breaking, again and again and again. Not becasue the box couldn't handle it, but due to run out typical of Detriot style casting process shifts, which then go off course again after an engine build re postions the crank just a fraction.

The runout on the input shaft needs to be double checked if there is any multiple clutch failure.


The input shaft is effectively orbiting the crank with runout, becasue the bellhousing is not in the ideal postion.


There are corrective 1/2 dowels that allow you to correct the position of the bellhousing.


A long time FE drag racer noted this. I've accidently quoted him amny times, then one day, he read some stuff, and realised it was HIS......
Rory428":32m30jfs said:
....On my cars, I use the offset dowel pins to get the housing "dialed in". To prevent the dowel pins from moving out of position, I hold them in position with small Allen headed set screws that thread into holes that I drilled and tapped into the block near the dowels. This way they can`t move if you need to remove the housing at some point. Also, if you were to do the welded washer deal, it would be good on that particular engine block, but may well not be within spec if a different block is used later on.
__________________
78 Fairmont 428CJ 4speed ET10.03@132.17mph
1985 Mustang 302 5speed 12.31@106.9mph


Its a little involved, but the first thing to do is check

http://www.hotrod.com/articles/ctrp-040 ... alignment/
If there is an off-center condition, select the offset dowel pins that are closest to your measurement. Lakewood makes them in 0.007-, 0.014-, and 0.021-inch sizes. (If the reading is 0.016, divide by 2 to get 0.008. The closest replacement dowel pin is 0.007 inch.) The first step to put them in is removing the bellhousing.


I'd use http://www.robbmcperformance.com/products/dowels.html as a supplier. Support your industries!
 
Thanks for the info! I'm printing this out for the mechanic.

Just for my own edification, how would misalignment of the bellhousing cause the throwout bearing to travel too far on the tranmission's input shaft? I'm not saying it wouldn't, I'm just trying to understand the reason.

Another suggestion I've received (on vintagemustang forum) is to go with a longer throwout bearing (Ram Clutch 498F, which is 2.25" long). This bearing is used for racing clutches.

I've spent the last hour or so searching (probably should have done that first), and apparently I wouldn't be the first person to need a longer throwout bearing with the setup I have. Also need to delicately ask if they may have installed the clutch disc backwards. Mostly, I see posts suggesting it is a problem with the amount of free play- but the mechanic says he has adjusted it all over the place looking for a position where the clutch disengages but doesn't hang up. He says the issue is in order to get the clutch to disengage the bearing HAS to travel just far enough to barely click over the end of the input shaft (the oiling depression is what is clicking over and catching).
 
It is becasue the standard thickness of the block separator plate is wrong from the blue printas well as the bellhousing spacer kit from MDL. 85 to 94 thou with an 89 thou average thou on the stock sep plate, and a few thou on the MDL plate, plus the T5 input shaft won't actually be 7.18".

So the input shaft won't be were it was when Ford designed the 2.77 trans and bellhousing. MDL can't control that, they will just have a 1" adaptor depth, and it'll be 1.005 or 0.995, 1"/-10 thou. But it might not be the ideal. I'm just saying, production changes are legion in mass production. If Ak Miller could say the average wall thickness of cast iron at a Ford six plant in 1970 was 189 thou, how did he get that figure?


Because some white coaat Poindexter Lab Technician measured a snap shot of every engine casting, and thats what they got....


(I'm an ex Laboratory Materials testing technician...)


I've seen 63 thou plates and all kinds of variances. That will change the docking postion of the input shaft. And the Z bar will also vary, but not much.

V, You might be right about the TOB. I've done so many 3 and 4 speed swaps, and automatic swaps, and the only problem I had was my 1984 auto Ford Falcon. Same production tollerances issue ruining starter after starter, and the problem was the flexplate to block position variance. Runout. They (Dunedin City Ford) installed 3 flexplates before it got fixed. I'll bet the did some other changes to bring things into alignment. My 250 six had been line bored, and I'm sure that was the root cause. The engine was always rougher than other engines, yet it had a low duration cam. The engine shook a lot more thn other 250 sixes at idle.

Doing the same thing over and over again expecting a diffeent result.

insanity.jpg



And that is production tollerances. Because it really is different each time. Ask the makers of the Chevy Vega engine block.

My technical support was an ex Ford service technician from my home town. He said "The throwout bearing is the means of stopping the binding between the clutch plate and input shaft, its just a grazing ray. The problem happens when things don't orbit properly, and they gall. He talked about the witness marks, and how Ford use the service technicain as the process control.


He said "you ALWAYS use a dummy shaft to load a Ford clutch, as they suffer from production tollerances. Everything suffers from production variances".

Danny, my next door neighbour with the Charger, replaced TO bearing after TO bearing. I wondered why that would happen. Its something that
 
Are you using a three finger pressure plate or a diaphragm? When I changed my set up from a small bell 2.77 to a large bell 3.03 & subsequently T5, I went with a diaphragm plate. The Z bar through was too long on the rod from the Z bar to the clutch fork resulting in over extension of the plate fingers. I ended up adding a new pivot point (on the Z bar) for the rod that goes from the Z bar to the fork. Just a though that you might me over extending the linkage...
 
Still using a 3 finger pressure plate. The new plate has slightly more aggressive springs (according to MD). I've ordered a throwout bearing that is about 0.75" longer than the stock, which I'm hoping will resolve the issue. When they pull the trans again, they are going to check the dimensions of the new flywheel and pressure plate against the old parts to see if there's a difference somewhere that has caused this issue.
 
Just a wrap up, the longer throw-out bearing (Ram Clutches 498F) did the trick. It is about .75" longer than the stock bearing, and it allows the bearing to fully disengage the clutch without hanging up on the end of the shaft. Additionally, it still allows the proper amount of freeplay to be dialed in. With the "new" flywheel and clutch in place, shifts are better than ever.

Thanks for the advice!
 
"each piece adds to the whole"
thnx 2 U both.
 
Well done...you and your mechanic were 100% correct. Sorry for any mis-information.

Actually, the information you provided was very educational (to both me and the mechanic :^)! Although I don't enjoy mechanical problems (be nice if things just always worked as they should), I do enjoy learning about areas I do not understand, and this clutch issue has greatly improved my knowledge of how the clutch mechanism works. Thanks for taking the time to share it- the page is now printed out and hanging on my "tech sheet wall" (next to the torque specifications for the head :^).

Speaking of which, every once in a while I am just "taken by surprise" when working on a project. For example, when I swapped out my rear axle, it finally dawned on me that the whole assembly (i.e., the entire mechanism that puts the power of the engine to the ground) is held on by the spring shackles. It just never occurred that it's just a few bolts holding everything on the car back there. Likewise, when I look at that relatively tiny clutch disc, it's amazing to think all the torque of the engine is passing through that thing on its way to the transmission...

(Knocking on wood)- I drove the car around a bit last night, and it is just driving better than it ever has. I fixed the stall on stop problem by figuring out the float was set incorrectly, I finally seem to have the linkages just right with my 3x1, the clutch and brakes are performing perfectly, and I've even got the tune dialed in enough to get the idle down to 600rpm (even with the A/C on). Life- for the moment- is GOOD! (Just in time, the first car show of the year is this Saturday.)
 
Congratulations on the fix! Which show are you going to this weekend? Is it the cars and coffee in Plano?
 
One of our favorite shows to attend is called Christian Classic Cruisers, in North Richland Hills (it's held at the Birdsville HS football stadium). They have monthly shows from March to October and usually get 200-400 cars. All the entry fees are saved up through the year to purchase Christmas presents for disadvantaged children, and they put on a fun show- plus there's a Whataburger right next to the parking lot (as soon as we get the car wiped down, we head over for a burger :^)! I've only taken home a few plaques, but it's fun to check out all the cars- they get quite a variety.

A few years back, I attended a car show near Mansfield. It was put on by a restoration shop (they had something like 7 different buildings- pretty extensive looking operation).
 
Let me know when you head that way next time. I would enjoy putting a face with a forum name and checking out your tri power setup and the rest of the car.
 
Will do! The 2017 car show season got off to a pretty good start. The weather was absolutely perfect, and they had 196 cars come out. We usually do not win in our class at this show ('65-67 modified), because there's a Shelby Cobra club that usually shows up with 7 or so gorgeous kit cars that sweep up the plaques. Somehow, we managed to squeak in tonight, and as usual my son ran up to grab the goods. The only hiccup of the night came when my friend's '69 GTO broke down on the way home (electrical), but we managed to get the Goat back home safely.

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:beer: Beautiful detailing work on your Mustang and congrats on winning (y) :nod:
 
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