Projects 1939 Chevy Master 85 235 and T5 - crossmembers and floors

Hi all,

I am deep into a build that I didn't want to do, but want the outcome

39 Chevy Master 85 sedan...I have a 1959 Chevy and am changing to a 1990 S10 NWC with a T5 5-speed transmission. I want to keep the 235 for the coolness vibe, and the 5-speed will be very cool. I have a 1955 Chevy truck rear end I plan to put to use.

What is crazy is that the trans and motor combined are over 5' long:


I will post a separate thread about my progress with the motor, but it is a regasket with a Delta Cams regrind, with mostly stock components.

The car with the old motor in it...broken piston ring, older 235.


Now, the issue is that the T5 is significantly larger than the old stock 3-speed. I had to cut the original transmission crossmember to fit the transmission and motor. I cut the floor a bit to clear the shifter, but now the tail shaft is hitting a floor support. However, I think the motor needs to be raised up in the rear by another inch or so. Here is the motor and trans in after cutting the crossmember. I installed the original front motor mounts to align, but will be using Davis Speed side mounts (just roughed in for now):


The rear-most part of the transmission tailshaft is hitting the floor, and in particular, the floor support:


So, before I cut more, I was curious if anyone has tackled something like this on a 37-39 car. If so, does this all feel about right, and does that part of the floor need to be cut out and the tunnel raised to accommodate? One issue that makes me think yes is that the rear of the motor is too low, even with the tailshaft interference. The rear part of the oil pan is hitting a mid-section crossmember, but the front of the motor seems to be in the correct position with the old mounts. I can't raise the rear without cutting the floor.

So, any thoughts from anyone would be welcome!!!

I did shore up the original trans crossmember and will be adding a new crossmember for the T5, which will be 4 to 5 inches further back...but can't do this until I settle in on the overall trans height.

Thanks in advance...I have searched the interwebs and nothing. Thanks, Jeff

 

Great post. and cool car!! I am doing this with my 38. So I am following this! What did you do with your emergency brake handle and mounting underneath the floorboards? Did all that have to come out with the mount modification? It looks like you have a straight axle in it. correct? Is the new motor a 55-57?

 

You should consider using the side mounts on the block. Or a bellhousing with mounts. You need some side to side support, not just mounted at the original front plate and trans mount. I have the same combination in my model A couple. You'll like it.

 

Hi I cut the old transmission crossmember mount including the parking brake brackets. The PB S is won’t be doable with the T5. I figure I will run a Lokar or other set up once I settle things in. I then bought some 1/2 x 2” c-channel to replace what I cut out. 1/2 x 2-1/4 would fit better, I had to grind some of the channel. For a newbie to modifying, cutting was daunting. Here are some pics. First one shows the cut out section. The second two show the c-channel bolted in.


Also, the motor was a good running 59 I picked up. The car had a 54 235 with a bad cylinder. I could find main bearings and searched for a long while. If they popped up they were the wrong size or were snatched up fast. I had the cam from the 54 resound to a mild RV level. I got free 60 235 but it was trash, so I had the 848 head redone. Finding a decent 235 or 261 has been tough here in Utah. People think they are gold lol.

I am still using the original 216 bell housing and flywheel. The T5 adapter is from Hotrod Works and fit perfectly.


I will keep posting progress here. I have not found any real info on this swap for 37-39 cars, so you and I can help with that. Hoping someone here has some insights before I cut mor floor

 

Hi, I am with you. I am using Davis Speed side mounts. I put the stock ones in as locators. Here is a pic of the DS mounts mocked up. This is how it sits now. I might also put the bell housing mounts back in. The brackets have to be there for clutch and accelerator springs anyway.

 

Do you think cutting part of the floor brace away and boxing it in will allow the trans to raise up enough to get closer to level? And what degree down angle is it at now? 3-4 degrees down wont hurt a thing, and if you can get close you shouldn't have any problems, and no issues with clearance.
I'm a bit puzzled by your oil pan hitting anything? I don't know what crossmember would be there that is close to the pan? I put a V8 and automatic trans in my '39 Chev coupe and didn't need to do anything to the floor or firewall, and no crossmember anywhere near the oil pan.

 

I think this describes hotrodding in a nutshell. Put what you want where you want it (or where it needs to be), remove all impediments along the way, replace the structure relating to those impediments in a manner that works with the new intent, paint and enjoy.

 

Hi, I spent a fair amount of time looking through your build thread! I could see your set up went in without a lot of drama..you also shared some info with me on crossmember cutting and building, which has been really helpful.

Mine has a crossmember between the oil pan and flywheel. It is a bolt in, so I wonder if it was removed from your car before you bought it? Here are some pics of mine:


The mount is bolted in, so would be really easy to remove. the old bellhousing mounts attach to it. I wonder if since I am doing the side mounts from Davis Speed, if I can skip the bellhousing mounts and just remove that crossmember. Then I could drop the rear tail shaft slightly. Right now, the motor shows 1 degree tilt to the back, but that is with the trans tailhousing right up against the floor support.

 

I would remove that cross member between the bell housing and oil pan. Replace the cross member, if it fits, back to where the T-5 Tranny mount is. Do what you need to make the T-5 sit on that cross member with an original rubber transmission mount. You might also be able to shave some of the upper area of the tailshaft where it seems to be hitting the floor cross member. Putting a T-5 under my 52 took some accommodations to the original tailshaft as well as the original transmission cross member. Also, you need a degree of downward tip at the rear of the engine. Maybe getting the right angle downward might just allow the tailshaft to no longer hit the floor cross member?

 

thanks @52HardTop . If I can remove the cross-member in my last pics, I can drop the trans a few degrees and I think it will clear the floor OK. Should I be concerned with losing that cross-member? I am adding in the side motor mounts per one of the pics above. My only thoughts are rigidity...but I am really tempted to just unbolt and keep moving! Thanks for any advice.