My Thoughts on Driving the Biscayne with the 409

425/409ER

425/409ER

Well Known Member
I got to finally drive the car this weekend to get out to the BTT 50's car show here in MN. After all the work I have done this year, there were some good points and some bad ones. First the 409 runs pretty good but smokes (smells rich) on startup sometimes and runs fat at idle so I will need to try another carb on it soon. Second my nasty vibration that I have been fighting for the last few years is back. Replaced the hanger just this past week and it was fine for a few days then on Friday it started to get bad and was just like before, it sucks. Today I put the car on jack stands and took a close look at the driveshaft and found the front u-joint was loose (don't know how I missed that) and was ready to pop in a new one and my boy said "we should run it in gear and look at the driveshaft so it's straight", good idea I thought. So we start her up put it in gear, take a look and WOW, in the middle of the rear shaft you can see it moving up and down, great. My feeling is no amount of balance will fix a shaft that is like that as it's has been balanced twice already and I am surprised the shop did not catch this. No more car show on Sunday, I am now going to see if I can put the 1 piece Chevelle driveshaft in the car now. I will trim the e-brake brackets and what ever else I need to get rid of the hanger crap. Looks to be enough room to do this and most likely will need to cut the rear bottom plate of the frame and then drop the rear axle to get it in. This problem has been so frustrating as most of you guys know from experience.
 
61BUBBLE348

61BUBBLE348

Well Known Member
Supporting Member 11
That's a shame you have some issues, but to be fair this is all about dialing your build in, things like tail shaft are all about balance fit and correct angle tolerances, I did a single piece shaft back in 1981 on one of me X frames with a MKIV and T400, chased a faint vibration at 70mph for 6 months and finally fixed it with a single shaft, my current X frames have no issues with stock tail shafts, the 61 is quite low while the 64 is at stock ride height.
 
Mearl

Mearl

Well Known Member
Supporting Member 6
Not to hijack your thread, but yesterday I drove the 63 to town for our family reunion and I still have a vibration that turns to a roar at 50 mph. I'm still not sure I have the drive line timed right. Could someone post a picture of a correctly timed driveshaft set up?
 
Mearl

Mearl

Well Known Member
Supporting Member 6
I couldn't remember if they were lined up or 90° apart, I think I have something in between anyway. I didn't have it at ride height either, when I put it in. The car was on the 2 post lift. I'll try it again and have it on the 4 post. Thanks James!!
 
models916

models916

Well Known Member
Supporting Member 7
This is the cut for a one piece with a 700r4. Trans is longer and required less cut because it places the tailshaft further back in the frame. I had the driveshaft made to fit. Pretty sure it's 3.5". The curved piece is welded over the cut to restore strength and allow the shaft to drop low enough to clear the rear for removal.


DSCN0005.JPG 6 inch pipe.jpg pipe cut down.jpg
 
ragtp66

ragtp66

Well Known Member
Might want to look at this post I had similar questions http://www.chevytalk.org/fusionbb/showtopic.php?tid/325622/

This part sounds like it may be of some help. I picked up another 58 driveshaft today and this one like my original has the front half out of phase. Then searching the internet for something un related I stumbled across this article:http://www.superchevy.com/how-to/engines-drivet rain/sucp-0209-1958-chevy -driveshaft/

and this excerpt from it which pretty much explains the reason:

In some of these stock-configuration '58-64 big cars the yoke holding the front portion of the two-piece driveshaft was intended to be at 90 degrees to the front U-joint (at the transmission end). This controlled secondary couple loads. The rear half of the driveshaft then went on the required angle to properly connect with the differential. If your '58-64 big car has the stock rearend setup, and you are experiencing a severe vibration between 12 and 20 mph followed by a lesser one between 30 and 40 mph, it means that the yokes are in line rather than at 90 degrees. This will drastically shorten the life of the support.
 
425/409ER

425/409ER

Well Known Member
Here is what I found yesterday, as I went to pull the driveshaft I noticed it was hard to get out, then when I did get it the hanger was in two pieces. I thought that was odd the I realized what had happened. The shop the did my driveshaft years ago used the wrong yoke, it bottoms out in the trans then there is no movement when the shaft goes back and forth pushing the rubber out of the hanger. I found my Chevelle driveshaft is slightly shorter and this should work perfect. Out comes the cutoff wheel and plasma cutter if needed today, no more hangers for me.
 
La Hot Rods

La Hot Rods

Well Seasoned Member
Supporting Member 15
models916 said:
This is the cut for a one piece with a 700r4. Trans is longer and required less cut because it places the tailshaft further back in the frame. I had the driveshaft made to fit. Pretty sure it's 3.5". The curved piece is welded over the cut to restore strength and allow the shaft to drop low enough to clear the rear for removal.


View attachment 54202 View attachment 54203 View attachment 54204
Click to expand...
How far forward did you cut the rear of the frame?
 
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