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Discussion Starter · #1 ·
Not sure what forum to ask this question in. I cant find my transmission to engine bolts for my 4R70W. Looking on line, I see bolt sets but they say for manual transmission. I believe the bolts are 10MM 1.5 about 2 3/8 long. Does anyone know if the ones listed for manual transmission will work or have a source for those specific to the Automatic?
 

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Can't answer the question directly, Herb but the answer is easy to get.

Use a dial caliper to measure the depth of the bolt hole in the block, add the thickness of the flange of the bell housing. That dimension will get you to the top surface of the bell housing.

Now you need three more dimensions added to the stack height you have so far. The first is the thickness of the washer and the second is the height of the nut. You can get both from McMaster Carr. The image below is from McMaster for a 10mm x 1.25 nut.
175689


Pick the washer you want to use and download the corresponding print for it.

Find the nut you want to use from their listings and download the print for it. the final thing you need to add is the additional length of the stud above the top of the nut. Plan on two threads. If your fastener is a M10 x 1.5. then 1.5mm is the thread pitch and you need two of those above the top of the nut or an additional 3mm. Now you have your minimum required stud length. You can go longer but you can't go shorter.

When you go looking for studs you will find grade 5 SAE spec equivalent fasteners usually. If you look for metric set screws in the same thread and the length you require you will get fasteners that are a minimum of grade 8 and typically higher.

At that point you are done — other than assembly. BTW studs (high strength set screws) are the best way to assemble the transmission to the block, especially if the block is aluminum.


Ed
 

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Discussion Starter · #3 ·
Thanks Ed! I found what I needed on their site. If any one is wondering, the flange on the transmission is 35MM at all bolts. The depth of five of the holes are 32MM deep and go all the way through (ordered 60MM long bolts). Two at the top are max 12 MM deep so i ordered 45 MM bolts. Now, as long as I don't loose these....
 
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Herb,

If you are using bolts instead of studs you want to try to get within 3 to 4mm (0.120" to 0.160") of the bottom of the bolt hole. If you use studs go right to the bottom. If it is an iron block bolts are fine. If it is an aluminum block I encourage you to use studs.


Ed
 
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