[mikemustang289]

I Took the runout on the scattershield and starting at .000 the greatest difference 180 degrees apart was .014 divided by 2 equals .007 misalignment.

According to this sight .005 should be max

My confusion lies in the fact that the 4 bolts which hold the transmission to the bell are not a ZERO tolerance fit to the transmission. Meaning, if I were to take one of the 4 trans bolts and insert it into the trans mounting hole, there will be side to side play, not a lot but at least .002 of a gap.

If I were to leave the bell this way, wouldn't the trans align itself during install and the space between the bolt and trans makeup for any misalingment?

It doesn't make sense to me because these parts are not a zero tolerance fit. The trans has some room to move around when it is bolted to the bell. As long as the clutch is lined up with the alignment tool, and the trans slides in flush against the bell, and the bolts line up, the input shaft should be centered correct?

 

[mikemustang289]

Well, I guess I answered my own question to a degree. I measured the opening hole in the bell and the diameter of the input shaft bearing retainter which fits inside the hole of the bell.

There is pretty much a zero interference between these two parts. The input shaft retainer fits snug against the inner diameter of the bell hole.

So why not open up the bell hole slightly to allow the trans to slide in and thus align itself perfectly? We are only talking a few thousands of an inch here, I can easily open the hole up slightly with sand paper to allow some play between the input shaft bearing retainer and bellhousing, then slide the trans in by hand, (not forcing) till it mates up flush, and bolt it in. Anyone see a problem with that? It would be much easier this way than dealing with dowel pins. I can't see problem gaining .002 the way I'm talking to get it in tolerance.

<font size=-1>[ This Message was edited by: mikemustang289 on 4/24/06 10:20am ]</font>

 

[n2omike]

The front bearing retainer of the transmission (the thing the throwout bearing slides on) is supposed to be what centers the transmission in the bellhousing. It is supposed to be a tight, interference fit in the bellhousing hole. The bolts are just there to hold it on tight.

[edit]
Oh, I just read your self-reply. I guess you figured it out.

About using the clutch tool to center the trans... Those aren't precise enought to do that.

Good Luck!

_________________
66 mustang
302 4-speed 289 heads, 10.63 @ 129.3
http://www.mustangworks.com/cgi-bin/moi-display.cgi?220

<font size=-1>[ This Message was edited by: n2omike on 4/24/06 10:58am ]</font>

 

[mikemustang289]

yeah, but would what I am suggesting work? I mean, if I open the whole up I can effectively shift the trans slightly in the opposite direction toward the centerline? We're only taling a few thousandths, seems like it would be a lot easier than dealing with the hassle of the special dowel pins. I can shim the bearing retainer to the side while I bolt the trans down to the bell, pull the shim out and I'm done.

Has anyone ever bothered to check the runout on a fatory bellhousing? I never hear people doing this, do factory tolerances fall within spec? It doesn't seem like it to me otherwise lakewood would build these bells within spec and you wouldn't have to even check.

and who's to say that the input shaft falls exactly in the center of the trans? I'm sure there were tolerances to where the machined holes in the case were cut.

 

[BLstangin]

No, do not open up the hole, it will be able to walk around then, even with the bolts tight, and the input shaft is centered on the shaft, it's all machined on a center. Get the bellhousing RIGHT!!!!

 

[n2omike]

Yes, do NOT open up the hole.

Offset dowels are not a big deal. You just put them in, and clock them both to the same orientation... the orientation that best corrects the alignment. They even have a screwdriver slot to do this with. They even come in different offsets for different degrees of misalignment.

Good Luck!

 

[mikemustang289]

Ok, I will get the dowels. but what about factory bellhousings? Do they typically fall within spec?

 

[gjz30075]

I found my factory bellhousing at .017" runout and the shop manual calls for .014 for a toploader. Since I was putting in a T5, I got .014 dowels and that got me to within .005.

 

[Sonny]

Hot rod did a article on this and a stock bell was near perfect in comparsion to aftermarket parts.