Hello to all, I hope all is well. Well I been working on 54 Bel Air since August of 2011. The car came with a Chevrolet 350 and a 700r4 transmission bolted up to Chevelle rear end. Other than that Ive done everything myself. After finally getting the car road worthy and what not, I had to iron out little things here and there. We all know how that goes. As for the history of the car, the motor is bone stock later 350. And I was told that the transmission has a shift kit installed. But I really dont know, I can tell you that it shifts quick and hard into second gear, which it took getting use to driving without barking second gear. And the rest of the gears seem to shift normal. I can say that Im pretty mechanically inclined and I could hold my own. But as for transmissions, I can take them out, install them and do the basic adjustments and thats really about it. <?xml:namespace prefix = o ns = "urn:schemas-microsoft-comfficeffice" /><o></o> So here is the issue that Ive been chasing for a while. When the car gets to highway cruising speeds, the transmission starts to chatter, shudder or whatever you may call it. I notice that the chatter will go away as soon as I give it gas and as soon as I let go off the gas. It seems like it happens when youre just floating your foot on the accelerator. <o></o> So now I come before the gods asking for your help or inputs. This is what I have done so far.<o></o> -Replaced both U-joints-<o></o> - Had the driveshaft shorten to the correct length and balanced-<o></o> -Checked engine mounts, transmission mounts, flywheel bolts to make sure that they were secured-<o></o> Thanks for you all of your support.<o></o> Henry<o></o> <o> </o>
Have you verified pinion angle ? If the front and rear ujoints arecoperating St different angles during cruise I believevthat could cause the condition you are describing. RAY
So many possibilities, everything that is rotating can be the culprit, starting with the crank and ending up at the rear axles. Since you cure it by loading and unloading the strain (speed up and slow down) that sort of tells me something might be loose. I would start with the convertor to flexplate bolts. They work loose and can cause a chatter or rattling sound. Then get under the car and turn the driveshaft back and forth by hand, looking for any slop, either internally on the transmission or in the driveline. You could have a worn transmission yoke or yoke bushing too. The output shaft of the trans and/or the inside of the yoke might be sloppy too. Don
Ray-I have checked the pinion angles numerious times. And they check out fine. Don- I have checked the driveshaft, and its appears to in good shape no slop. It's tight. I'm kinda thinking that it may be transmission internals. I'll keeping checking the cheaper stuff first. Before I think about doing transmission repairs. Thanks Henry
does the driveshaft move up and down in the tranny? i had a car do that and it needed the bushing in the tail shaft.
2 words.... Friction Modifier.... Welcome to todays super lubricants....Too much lube is sometimes a bad thing... If you research this topic, it might fix your issue. That is as long as everything else is OK. Good luck
Sounds like pinion angle problems. How is torque converter controled, internal with no electric power to trans? As in lock up when trans shifts to 4th? What ever it's unlikely it's converter clutch related, not impossible just unlikely.
I'm thinking it's the torque convertor lockup. In particular the input shaft seal for the torque clutch (this ain't the big seal, it's the O-ring). I had a 90 1/2 ton that would chatter under a bit of a load. If I put the brakes on slightly (electrical disconnect of torque convertor) or stepped on the gas a bit or let off it would go away. The easiest way to tell if it's a lock up problem, is to just disconnect the electrical connector on the trans and drive it and see if it's gone away.
I had this exact same issue, although with a Ford 351W/C4 combo. Turns out I forgot to put the index plate back in when swapping in a new trans. The same chatter you mention in the same driving conditions. That index plate is .060" or about 1/16th". Just enough for the bolts holding the bellhousing to the trans to rub and even put a slight groove in the convertor. Lots of good advice on what to check, but I'd bet somebody was in a hurry when they put the drivetrain in there.
Thanks for the responses to all.So here are some updates. I got the car in the air as close as I can to ride height.Here are some of the things I found. Transmission serial (4YP187BT) From what I can see, it's a 84 with mechanical speedo, and one white electrical connector on the driverside that is connected but has no wire. So from what I have came across,it's not electronically control.And it seems to go into overdrive without any issues. As for the tailshaft yoke, there is very little movement up and down and side to side.Not to sure how much play there should be. Now for the interesting find and something that I over looked.And keep in mind the car sits low and I always had a had time getting the correct pinion angle.Rear end has 3 inch blocks and 2 leaf springs taken out on each side.And it appears that the transmission is sitting 0 degress and the pinion up at 4 degrees.And I know that this is wrong. Unfortunately because how the cross member sits, I can't drop the transmission any lower. But I can bring it up a bit. Also it seems like the rear end pinion may sit a tad bit higher than transmission tailshaft yoke. So what I was thinking of doing, is bringing the transmission up 3 degrees and bring down the rear end 3 degrees. And see what happens. What do you all think? Thanks again Henry
You got the TV cable adjusted correctly? If this is wrong your transmission will shift weird! I see nothing about this in your original thread.
D2, to best of my knowledge the cable is adjusted correctly. From articles that I have read and videos that I have watched. Henry
Sounds like it could be pinion angle based on your description but check the run out of the drive shaft as well, particularly if it has been shortened or modified. That was the cure on my wifes 50 Chevy for a vibration acting just like yours. It was 0.050 out.
that's good. How is the TCC being applied? Computer? If the TCC is intermittent then you will probably feel the engagements, but chatter sounds like something else. Just a thought.
Good morning, Well here are some updates. After modifying the trans mount and exhaust pipes. I was able to adjust the pinoin angles. I was able to get the transmission down to 4 degrees. And I left the rear end where it was at. It appears the chatter is gone now. I'll keep driving it and see if anything changes. I want to thank you all for your support and ideas. Thank Henry
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