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Discussion Starter · #1 ·
Hi, I am in the process of calculating the proper hydraulic throwout bearing length for my manual transmission install. It requires you to know the distance from the bellhousing mating face with the transmission, to the tip of the pressure plate fingers. I am doing this by taking my bellhousing length, and subtracting my pressure plate installed height, flywheel thickness, and the dimension from the engine block to the crankshaft mating surface with the flywheel. Does anyone have this dimension handy? SBC 350, 2pc rear main seal.

Bellhousing with block plate: 7.068"
Pressure Plate: 2.100"
Flywheel: 0.964"
Block to Crankshaft: ??

Thanks very much!
Steven
 

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I would contact tech line from Summit Racing Tech Help
1-330-630-0240

9 am to 9 pm EST Monday through Friday, for help with parts installation or application. Please have all relevant vehicle information ready when you call.


Gilbert A. Soto
The Colony,Texas 75056
 

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Discussion Starter · #3 ·
Thank you Gilbert, they didn't have an answer for me though.

This picture may describe what I mean a little better. If anyone has an engine assembly and some calipers handy, it would be much appreciated:



Thanks again,
Steven
 

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Kind of off topic but I'm curious...I might be missing something as I am used to looking at pre-90's manual transmission stuff, but what is that pilot bearing intended for?? It is incorrect for any GM trans prior to '91 as it is in the wrong place in the crank. The correct pilot bearing fits in the smaller bore just behind the current bearing in your pics.

Is this some kind of later model swap like T-56 or NV3500 or a swap to a different brand (Ford, Chrysler, other??). Just curious.

The dimension you are looking for is .675-.680" from block rear face to flywheel mounting flange on the crankshaft (measured off my '74 400 block and Scat crankshaft, actual was .678").

Just a heads-up...Make sure you measure the flywheel thickness from the crank mounting flange to the clutch face, and not the total flywheel thickness at the outside edge. The mounting flange is sometimes inset from the back face of the flywheel.
 

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Discussion Starter · #5 ·
Thank you very much Eric. That helps a lot.

The pilot bearing location showing in the picture is indeed unconventional. This is an adapter bearing and bearing position when using a TKO transmission with a ford length input shaft, which is ~0.675" longer than the GM version. I have an adapter Lakewood bellhousing to take up this longer length...but it has caused me several problems inlcuding the hydraulic throwout bearing setup.

Here's a link to the bearing:
http://www.summitracing.com/parts/LAK-15975/
 

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Thanks, that's why I was curious about the pilot bearing. Wouldn't it just have been easier to machine up an adapter plate to go between the trans and a standard spec Chevy bellhousing to make up for the longer length Ford input?? Or are there bearing collar/spline location issues?? I am considering going this route to use a 5.0 Stang T-5 behind an SBC but haven't gotten any farther than just the idea.
 

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Discussion Starter · #7 · (Edited)
I am not sure what Lakewood's thought process was behind this adapter bearing. I have their 15030 bellhousing, which is longer than a standard SBC one as I mentioned. Perhaps they thought that the clutch disc splined hub would interfere with the collar before you could get full release of the clutch, so they elected to move the transmission further back with the bellhousing and then compsenate with a bearing that is further back.

The bellhousing retainer diameter is 4.850" on a ford, compared with 4.680" (if i recall) of a chevy, so that is different. Also, the throwout bearing to use is a Ford 1.430" ID diameter like N1714, instead of chevy's N1716.

Quicktime also makes an adapter bellhousing, RM6064, but I don't know if they take the same approach with the pilot bearing.

If I could go back in time, I would simply swap the TKO input shaft with a chevy, then I could use a standard bellhousing...and my clutch fork wouldn't hit the firewall because it would be closer to the engine...then I wouldn't have to spend more money on a hydraulic clutch setup.
 
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