Frame to output shaft dimension for 4R70W install

[GPatrick]

I am in the middle of a C6 to 4R70W conversion on my 1970 F250 LWB two wheel drive mated to an FE 390. I failed to get a dimension from the bottom of the frame rails to the centerline of the output flange on the C6 before I removed it. I have an empty 4R70W case that I am using for the mock-up and need to set the position of the output centerline to figure out how much tunnel work I will need to do to clear the housing. Once I have the clearance I need I will modify the rear crossmember for the transmission mount. This has the two-piece driveshaft. If anyone has a chance to crawl under their truck I'd sure appreciate a quick measurement.

I am starting with a u-pick 4R70W from a 2003 Lincoln Town Car for the initial build and have it mounted to a Bendtsen’s adapter. The adapter moves the transmission back about 1.5" and I have the long output shaft version of the 4R70W. In total, the output of the transmission is about 4 inches longer than the flange output version of the C6. It is a little tight against the frame mounted gas tank but really no closer than the C6 setup. When I get closer to the final install I plan to take a lot of pictures and post the process.

A few quick notes - I initially planned on using a Qucktime bellhousing. After receiving it I found out that it can only support a 10" torque converter from Performance Automatic with a 3000 plus RPM stall. Starting price for the T/C was north of $800. For the truck, I need to use a late model full size low stall truck converter that easily fits inside the original 4R70W case. Holley/Quicktime had no mention of the T/C limitation in their literature and they did take it back. PA also advertises that they have a FE to 4R70W bell but it appears that it is just the Quicktime unit.

The Bendtsen’s adapter is pricey but includes everything including a new starter. I had to do a small modification for the mod motor case but other than that the quality is quite good and the dimensions are spot on. I'll never reach enough miles to break even on this project but it is a hobby/restoration and sometimes you do things because you want to do them.

Gary

[cdnwillyg]

Hey Gary on mine it measures 5-3/4" to the center on the flange closest to the tranny to bottom of the frame rails using a 4' level. The frame does curve in that area a little. I hope that helps.
Willy

[GPatrick]

Thanks. I'll start with that dimension and use a little math to figure out where I need to be 4 inches further back. I decided to cut and temporarily shorten the front section of the driveshaft to check driveline angles as well before I set the final position for the rear mount.

I saw a post in my searches suggesting that there is a heavy duty center/carrier bearing that should be used with a splined transmission yoke. Is there such a thing? I have checked with a few experienced people locally and they think that I will be fine with the standard carrier that I have. Anyone here heard of a heavy duty bearing?

[basketcase0302]

Always wanted to do this to BC #16, and I would love to see your tach before and after. I replaced the carrier bearing on the one ton 3510 series driveline on BC #16 via my local driveshaft shop at the time.
I wouldn't rule out a Timken part but source it carefully as even they started subbing out manufacturing to Japan and China a few years ago.

https://www.summitracing.com/search/pro ... t-bearings