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View Full Version : how close to spec limitations on runout is safe?



formula
06-26-2005, 08:49 PM
I checked the runout on my bellhousing, and it showed right at .005 from center vertically... my dial indicator isn't precise past .001 but both of the vertical measurements shied towards the safe side of .005 (total vert runout), so it is within spec but just barely.

am i ok?

GMJim
06-27-2005, 04:58 AM
Formula
.005" IS the maximum tolerance so I think you will be fine but not knowing for sure if your dial indicator is accurate is a little concerning. A sheet of bond paper is .0025" thick so if you think dial indicator is not correct, get another one. Also, what tranny are you using?
Jim

formula
06-27-2005, 09:24 PM
i'm sure it's accurate, there are just no markings smaller than .001 so i can't figure out an exact value beyond three decimal places.

i'm running a tko-500.

andrewb70
06-28-2005, 03:51 AM
Keep in mind that when you are measuring from center you have to divide by 2 to get your run out. So your reading of .005 at the vertical position indicates .0025 runout. That is more than accaptable. As I recall the generally accapted spec is .007".

Andrew

GMJim
06-28-2005, 03:22 PM
Andrew
What transmission are you using? If it's a Muncie you can get away with a lot more runout than todays transmissions like the TKO. Tremec requires a maximum .005" run out and any installation I have done has been within that spec so I can't tell you how long you will run trouble free if you don't stay within that spec. If you are using a Tremec or other tranny that requires tight tolerances like the Tremec and can't get your stock bellhousing aligned, consider a McLeod bell housing/scatter shield. They are manufactured to be within spec right out of the box on the stock straight dowels. No muss no fuss just bolt it on. If you are using a Muncie your tolerances are much wider. I haven't seen a published spec but I feel you could get away with .010" or so without any ill effects. I wouldn't use a pilot bearing with this much runout. I would use a pilot bushing.

formula
06-29-2005, 07:58 AM
yeah the actual measurements are something like a little less than .0075 and a little more than .0025, not quite .003. So i'm right on the line but on the comfy side of it.

Don't the muncie input shafts actually flex a little? I heard that that makes them 1) less prone to a misalignment and 2) a lot easier to install

JodysTransmissions
07-15-2005, 03:25 AM
The concentric tolerance for run-out is +/- .005", this actually means a total of .010" of misalignment is acceptable. The parallel tolerance is +/- .001", this is a total of .002". This is industry standard for any transmission installation. But remember, the closer you can dial the bellhousing in, the better. We actually only allow for half these tolerances when we dial a customers bellhousing.

If you use the off-set dowel pins, it is also OK to use only one off-set with a stock dowel pin. Or, maybe two different sizes of the available .007", .014", or .021". Yes, don't be affraid to mix and match them together.

Take your time, measure 2 or 3 times to confirm the same repeat readings.

Regards, Jody