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SBF to Modular Pattern Transmission Adapter |
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Rockatansky 
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Joined: 30-July-2010 Location: On The Road Status: Offline Points: 6398 |
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 Topic: SBF to Modular Pattern Transmission AdapterPosted: 19-August-2024 at 11:46AM |
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72 GT Ute
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peter.jenerette
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Joined: 08-February-2023 Location: Nevada, TX Status: Offline Points: 1054 |
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Posted: 20-August-2024 at 1:21AM |
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Nice find. Now to figure out where to find the pennies that i need to save for the next 3 years in order to revisit this swap.
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Pete Jenerette
1972 Gran Torino (H-Code - 4R70W) 2022 F250 XLT 7.3 2003 Thunderbird |
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72 RS 351
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Joined: 04-September-2014 Location: Knoxville TN Status: Offline Points: 3443 |
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Posted: 20-August-2024 at 3:57AM |
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That's a good find, that's the best adapter kit I have seen for adapting a SBF to a later modular V8 trans. It has a far better torque converter spacer than the other adapters made before. The first kind all have small stud extenders, a little spacer to go onto each torque converter stud, to extend it 1/2"(the main adapter thickness). I did not like those prior adapters, those stud extenders increase the shear forces on the TC studs, moving the force 1/2" out from the surface of the TC(the base surface where the stud is welded). I would not use those with anything but a mild power engine, and it's still not a good idea. This new adapter is much better, the thick TC spacer mounts separately to each stud, and each flexplate hole. That transmits the force far better, through the body of the adapter to each mounting point. I plan to skip the adapter for my SBF Explorer project. If you accept that using just five bolts is enough for your engine and application, you can cut off one bolt hole ear, thread two block holes, ad the rest is bolt on easy. I will be using the stock 6R80 torque converter, starter, and separator plate. That is a no cost method, leaving it with five bolts holding it together instead of six. I'm good with that, I don't expect to reach 600hp, just under that.
Edited by 72 RS 351 - 20-August-2024 at 4:09AM |
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Don
73 Ranchero "Sport 72 front end", floor shift/console, planning EFI 7000 rpm 351 stroker 73 Ranchero GT 351C-4V &4R70W for sale later. 92 Lincoln Mark VII SE GTC, OBDII 347/4R70W |
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Jaybee
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Joined: 28-July-2024 Location: Chesapeake, VA Status: Offline Points: 51 |
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Posted: 11-April-2025 at 4:22PM |
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I know this thread is a few months old, but I'm just now looking into this swap. While the pattern isn't the same as this, the early SBF used a 5 bolt bellhousing with the bottom bolt on the right side missing. This seems in principle like it might work just fine...and save a bunch of money on the swap in the process.
Edited by Jaybee - 12-April-2025 at 6:20AM |
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Cars are meant for driving
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72 RS 351
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Posted: 12-April-2025 at 5:06AM |
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Line up the trans against the SBF, and notice that three old block holes line up perfectly, and two others(the dowel holes) also match the modular trans. Use those five holes and find the proper bolt lengths, doing what is needed to the block holes. I described how to do it above very briefly. I don't know if anyone has made the swap without an expensive adapter. The 4R70W automatics are relatively low cost to find and build. The six and ten speeds are far more expensive, the core, building it, plus the controller. Doing it with the 4R70W is possible of course, but try to find the right SBF version and skip the odd method I discovered. If the 6R80 is your idea, research the high costs slowly, they can easily be $4k more than a 4R70W to swap.
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Don
73 Ranchero "Sport 72 front end", floor shift/console, planning EFI 7000 rpm 351 stroker 73 Ranchero GT 351C-4V &4R70W for sale later. 92 Lincoln Mark VII SE GTC, OBDII 347/4R70W |
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Jaybee
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Joined: 28-July-2024 Location: Chesapeake, VA Status: Offline Points: 51 |
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Posted: 13-April-2025 at 11:35PM |
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Looking into this a little deeper, there's an option no one anywhere seems to have considered. Older fords used 1/2", solid dowel pins. Modular engines use 16mm, hollow dowel pins. Using a hand reamer or step bit so the hole doesn't walk, expand the dowel pin holes to 16mm, then put cap screws or bolts through the center of the dowel pins. I don't know what the inside diameter of the dowel pins would be, but the trans bolts on SBF are only 7/16". The hollow dowel pins aren't that thick. a 1/2" bolt looks like it would fit.
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72 RS 351
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Posted: 14-April-2025 at 1:15AM |
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Good find, the online guess info suggested the dowel holes would be smaller than the size needed for the normal bolt size. Threading cast iron is not simple and easy, so getting that done right would be tricky. The engine I plan to try it with is the spare 302 coming out of my 92 Mark VII. It's a low mileage HO engine, so it is valuable to resell, but I want to use it as a test for doing the swap to a 6R80.
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Don
73 Ranchero "Sport 72 front end", floor shift/console, planning EFI 7000 rpm 351 stroker 73 Ranchero GT 351C-4V &4R70W for sale later. 92 Lincoln Mark VII SE GTC, OBDII 347/4R70W |
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Jaybee
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Joined: 28-July-2024 Location: Chesapeake, VA Status: Offline Points: 51 |
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Posted: 14-April-2025 at 1:58PM |
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If my information is right, the SBF bellhousing bolts are 7/16", while Modular bellhousing bolts are 10mm. Looks like a bolt that big or maybe even 1/2" should go through the stock dowel pins, since 16mm is 5/8". Plenty of clamping load. Accu-Fab makes dowel pins that are threaded on the inside. They're made to be easier to pull without distorting, but should allow the biggest bolts...but they're about 10x the cost at $32/pair. I figure putting a bolt running backward through the dowel pin to give purchase on the block ear. If the hole is too close to the side of the block a grinder could make a flat or a capscrew with a little smaller head ought to work.
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72 RS 351
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Posted: 15-April-2025 at 1:07AM |
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The bell housing bolts should be virtually the same diameter, 7/16" and 10mm are very close in size. The 1/2" and 13mm are virtually identical, note any sockets of those sizes. I'd suggest the failure rate of threading a hole in cast iron is fairly high for an amateur person, and an expert would not succeed every time either. I'll probably practice on a couple of old cheap value 302 engines before I try my good engine. If I think I can do it right, I'll give it a go. But I'm still possibly a year away, not knowing what house or garage space I'll have. BTW, I also just learned of two more differences of the SBF and modular engines. The adapter kits don't mention these, so several people had to discover it in trying to install those adapter kits. The torque convertor studs are located in metric dimensions, while the SBF uses SAE, thus the stud locations don't match the flexplate holes in a SBF plate, those people had to enlarge the holes to make the studs go in. Then they found out that the torque convertor snout is slightly different than the SBF versions. That part I'm not worried much about, they had to use an adapter from the kit placed onto the TC, and that didn't fit properly. So some of that may be the kit part being made poorly. I don't know how important it is for the TC to lock into the back of the crank, that will need to be figured out. Hopefully that isn't very important, and just needs to clear. I figured it should be possible to buy a flexplate with the different TC stud pattern, with the other SBF dimensions. It would just mean buying a nicer one(SFI) made specifically for the application.
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Don
73 Ranchero "Sport 72 front end", floor shift/console, planning EFI 7000 rpm 351 stroker 73 Ranchero GT 351C-4V &4R70W for sale later. 92 Lincoln Mark VII SE GTC, OBDII 347/4R70W |
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Jaybee
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Posted: 15-April-2025 at 1:58PM |
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That's interesting information. I don't think you have to thread the cast iron. Drill out the 10mm bolt holes in the bellhousing to 7/16", which is 11.11mm. The dowel pin holes on the block would be increased to 16mm, which is the size of the modular dowel pins, but they aren't threaded. I'd probably use a reamer rather than a drill for the dowel pins. It produces a more accurate hole for at the points that are most important for precision. Single hand reamers are available at reasonable cost online.
I'm afraid I don't know it all about the torque converter snout or mounts. I was wondering about it, but I was hoping it wouldn't be a problem since the kits use a spacer behind the stock flex plate, near as I could tell. Sounds like the right combination is;
The torque converter snout of the modular matches the 1.375" diameter of the most common sbf size, but that doesn't mean much if the converter bottoms out against the crankshaft. That would need to be checked. There's a 1.850" pilot out there as well, but I think it's uncommon. Edited by Jaybee - 15-April-2025 at 3:11PM |
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72 RS 351
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Posted: 16-April-2025 at 2:49AM |
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That $1400ish adapter kit I think also includes a small adapter for the snout of the TC, for it to reach the back of crank. I wasn't paying a lot of attention to that part of the thread I found, the main author was a user name something like "nevrstuk" on a 4x4 forum. He was the one who discovered that the other kits that used 1/2" spacers, cause cracking of the flex plate with enough power. He first found the dimension difference, and had to wallow out the four holes. He mentioned other people, and their solutions. I didn't find that thread until this past week. When I first saw those 1/2" stud spacers, that's when I damned those and decided I'd never do that. I knew that spacing the studs that way would create massive forces on the flexplate. One solution was to have 1/2" steel welded to the torque convertor, which would work, but then it's not a bolt on TC(it's custom). The 6R80 is notably bigger in the dimensions of the case, mainly the top part and the width there. Fitting those to an older car might require extra clearancing of the trans tunnel. There's a lot of little details to work out with such swaps. It would be smart to learn them all before beginning, the costs overall will be high.
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Don
73 Ranchero "Sport 72 front end", floor shift/console, planning EFI 7000 rpm 351 stroker 73 Ranchero GT 351C-4V &4R70W for sale later. 92 Lincoln Mark VII SE GTC, OBDII 347/4R70W |
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