L20B into 510, keeping it AUTOMATIC.

[5casey1dimer0]

Hey all. I dug around some, and want to confirm I have the correct info.

 

What I have: '72 510, floor shift automatic l16 engine.

 

Going in: L20B engine from 1980 720 P/U. Currently mated to a 4 speed manual.

 

What I wish to do: mate my 3 speed auto, to the L20B with correct flex plate and torque converter set up.

 

Theory In my head that I'm hoping you can either verify, or tell me where I'm wrong so I don't pull apart a perfectly good running car and have it sit for weeks while I'm trying to get facts straight:

 

I SHOULD have a JATCO 3N71B transmission (post 71 car, floor shift)

 

The L16 uses a 5 bolt Flex plate that will not work on the L20B.

 

But the 3N71B torque converter should bolt to a 6 bolt L20B flex plate.

 

There for I need a flex plate and the two 6 bolt spacers (pilot-converter plate, and crank to converter plate) off ANY? Auto L20B???

 

My L20B+sourced L20B flex plate and 2 plate/spacers+ my L16 torque converter+my L16 JATCO 3N71B = success?

 

Thank you so much in advance!

[Tristin]

Correct.

 

You can can actually use any L-series 3N71b 6-bolt spacers and flexplate; the Z-cars have them  as well. 

[datzenmike]

My L20B+sourced L20B flex plate and 2 plate/spacers+ my L16 torque converter+my L16 JATCO 3N71B = success?

 

Thank you so much in advance!

.

Plus an extra bolt. Preferably an L16 automatic one.

[5casey1dimer0]

Thanks Tristan and Mike.

[Stitebunny]

I would like to do this also.  Is it possible with the Borg Warner column shift trans?

Do you guys have pictures of the 6 bolt spacers?

Can't quite picture it.

[Tristin]

I would like to do this also.  Is it possible with the Borg Warner column shift trans?

Do you guys have pictures of the 6 bolt spacers?

Can't quite picture it.

 

Not a direct bolt-on with the BW trans... I just recently figured that out for myself. 

 

 

 

Here is what the spacers look like, but the 6-bolt ones just have an extra hole:

 

[Stitebunny]

Nice thanks!

 

Have you come up with an answer to make it work or still working on something? 

Or gave up?!

[Tristin]

Nice thanks!

 

Have you come up with an answer to make it work or still working on something? 

Or gave up?!

 

Ill let you know when I get it running. Its not some elegant solution, but so far it seems to be holding. 

[tr8er]

I have an L20b with a Borg Warner 3speed auto column shift. I just pulled it all out and I'm ditching the auto for a 5 speed. All I needed when I put the l20b in was the 6hole flex plate and one spacer plate I believe. The torque converter bolted right to it, and the crank bolted right up. I'll take some shots tonight of what I pulled.

[Stitebunny]

Sounds great guys!  Thanks for the info Tristin, let me know how it works out.

 

Would love to see the pictures tr8er.  Interested in selling the parts?

 

Chris

[Tristin]

I have an L20b with a Borg Warner 3speed auto column shift. I just pulled it all out and I'm ditching the auto for a 5 speed. All I needed when I put the l20b in was the 6hole flex plate and one spacer plate I believe. The torque converter bolted right to it, and the crank bolted right up. I'll take some shots tonight of what I pulled.

 

Are you sure it was a BW? We just tried to do this same exact thing a few days ago and the flexplate spacing is different than the torque convertor spacing. 

[tr8er]

Slightly? I recall my flex plate holes looked reamed/ovaled. Wish I had a pic at work... I actually had a bolt start to back out and cause vibration. Use a torque wrench! I bought the flex plate from some shop near Freemont. For all I know, it could have been some custom deal. Pics will reveal all.

[tr8er]

But yes, twas a bw

[Tristin]

Slightly? I recall my flex plate holes looked reamed/ovaled. Wish I had a pic at work... I actually had a bolt start to back out and cause vibration. Use a torque wrench! I bought the flex plate from some shop near Freemont. For all I know, it could have been some custom deal. Pics will reveal all.

 

That would make sense if they were reamed/ovaled. The pattern was off, but not by some giant amount. We actually talked about doing that, but at the time it was easier to just drill new holes. 

[Stitebunny]

That was kind of my thought.  You could weld the holes up and have a machine shop drill new ones.  Or probably get it "close enough" with a drill press to make it work.

[tr8er]

Just grab some self tappers from lowes.  

[MikeRL411]

But yes, twas a bw

 

British Lechtworth or American Muncie Indiana?  Don't remember the transition date for the 510 series.  Main difference aside from the country of origin is cable or vacuum downshift.

[DanielC]

I do not know if this will be an issue or not.

I recall from automotive classes years ago that an automatic transmission used engine vacuum to modulate pressure in side the transmission, and how harsh it shifts.  The shifts get firmer the closer you are to WOT, move higher in the RPM range, and the clutches inside the transmission actually have more hydraulic pressure on them, to reduce them slipping, and reduce wear. 

 

The problem is a L-20-B makes more torque than a L-16, lower in the RPM range.  So the transmission thinks it has less torque applied to it, than it actually has, and this could wear out the clutches faster

[tr8er]

So it appears I have the highly coveted, extremely rare factory B 8 hole flexplate.  Here is a picture.  

Looks like the PO just drilled new holes at 45deg. of.  Thus the weight is still balanced, and the holes line up.  I think welding the existing holes would be a bad idea.  The heat could warp the plate.  It's kinda thin metal.  

[Tristin]

Yep so it looks like mine. 

[tr8er]

Triston, does yours go round, round, round yet?  haven't seen the minty thread in a bit.

[Tristin]

Triston, does yours go round, round, round yet?  haven't seen the minty thread in a bit.

 

No. When I did the swap we used a newer version of the BW trans which had a bit of a different plug setup... we "think" Im having issues with the neutral safety switch. Im headed down tomorrow to hash out the last of it. Everything is installed and ready to go. Just have cranking with no actual starting. 

[izzo]

bypass it... 

[Tristin]

bypass it... 

 

Thats the current plan. Just hoping that thats it. Everything else seems to be fine. 

[datzenmike]

So it appears I have the highly coveted, extremely rare factory B 8 hole flexplate.  Here is a picture.  

Looks like the PO just drilled new holes at 45deg. of.  Thus the weight is still balanced, and the holes line up.  I think welding the existing holes would be a bad idea.  The heat could warp the plate.  It's kinda thin metal.

The new holes don't have to be exactly 45 degrees to retain balance but better at least away from the old ones some. The new holes don't have to be perfect either. The torque converter is aligned to the crank, thus keeping it in balance, by the spacer plate on the crank, not the flex plate holes. The flex plate holes just secure the torque converter.