funknut
Well-Known Member
Looking good, Hawk! I'd show you the pics from some of my welding projects but I destroyed all incriminating evidence.
The first "Hawk-Rod" resurrection, Roadkill style
- Thread starter HawkRod
- Start date
So I had a number of small electrical gremlins (including needing to plug the tack back in). As much as I wanted to do this the easy way, there was no other way than to dive right in:
I got the tack, brake lights and a few other issues fixed and then put it all back together. Yesterday I drove the car 115 miles up to my father-in-law's place. Here it is parked at their place:
At the shop today, I pulled my distributor and checked the timing curve. The first 10 degrees of mechanical advance comes in by about 2000 RPM, and then the last 3 degrees come in pretty slowly after that. Not ideal, but OK for now. BUT, I found out that my vacuum advance took a crap an is no longer functional. Crap!
Here is a picture of the distributor machine - I forgot to take a picture with my distributor on it, so you'll have to suffer with a GM product for the illustration!
Today, I drove it back in the rain. Based on the trip, some highlights:
Good:
Hawk
I got the tack, brake lights and a few other issues fixed and then put it all back together. Yesterday I drove the car 115 miles up to my father-in-law's place. Here it is parked at their place:
At the shop today, I pulled my distributor and checked the timing curve. The first 10 degrees of mechanical advance comes in by about 2000 RPM, and then the last 3 degrees come in pretty slowly after that. Not ideal, but OK for now. BUT, I found out that my vacuum advance took a crap an is no longer functional. Crap!
Here is a picture of the distributor machine - I forgot to take a picture with my distributor on it, so you'll have to suffer with a GM product for the illustration!
Today, I drove it back in the rain. Based on the trip, some highlights:
Good:
- Engine runs strong. It is not a race engine by any means, but it has plenty of torque and power and is silky smooth.
- The Gear Vendors overdrive works exactly as it should.
- My transmission shifts fine.
- The car, after the front end rebuild and alignment, drives straight and true and handles great. Really nice to drive even at 80 MPH.
- For many years I have had a harmonic vibration at about 65 MPH. It is annoying. Damn it, it is still there, and darn near the entire drive line is new.
I have confirmed that it occurs at 65 MPH regardless if the O/D is on or off, so that says it MUST be the driveshaft, rear axle (or maybe the overall drivetrain angles). I have to deal with this and fix it. It is extremely annoying. - My transmission leaks slightly at the front seal. Not enough to be terrible, but not little enough to not worry about it. I'll build another transmission this winter to replace it.
- I bought a 500 Cubic Inch big block (for my 70 Road Runner) that came with an engine and transmission. I threw that torque converter from that combo in my yellow 73. I looked recently and it is a 3000 RPM stall speed converter. It is too much for the street engine, so I need to throw in one that is a bit less aggressive. It is great for doing burnouts in the neighborhood, but not so good for cruising down the highway at 2500 RPM!
- My wipers broke, in the rain, on route 80 on the way home.
The clip that holds them on the motor keeps popping off. So, time to find proper pieces for this and fix them. - There are other smaller issues I need to fix that are still on the list, temperature control cable, A/C, etc. Time to start dealing with all that too.
Hawk
MoparJimT
Well-Known Member
Hey HawkRod, overall it still sounds like a good trip. The car looks Great!!. Winter is coming fast and I am still hopeful that I can get at least decent road trip in but we shall see. Cannot wait to see your car in person. I told Builderguy we need to meet up with you when you do your road trip. I am buying the Beer.
That would be great and a lot of fun. OK, you can buy first round, and then we'll have to argue about the next one!
Hopefully I can get some of the gremlins out of mine to ensure it is reliable. I just got back from visiting family in Los Angeles, so there has been no progress on my car in the last few days. I MIGHT take it to head down to skyline drive this weekend, but not sure the weather is looing good enough for that. Will check weather forecasts tomorrow and see how that looks.
At the moment, my 'Vette is on the lift with a leaky fuel pump, so I guess I'll rebuild that first and then throw the 73 back on the lift for other stuff. Always something to fix!
MoparJimT
Well-Known Member
Yep same here. Need to get the some gremlin resolved as well. SpeedO is jumping all over, tach as well. Heater fan does not turn on the fan. Stuff lime that. Looking forward to those brewski'sThat would be great and a lot of fun. OK, you can buy first round, and then we'll have to argue about the next one!
Hopefully I can get some of the gremlins out of mine to ensure it is reliable. I just got back from visiting family in Los Angeles, so there has been no progress on my car in the last few days. I MIGHT take it to head down to skyline drive this weekend, but not sure the weather is looing good enough for that. Will check weather forecasts tomorrow and see how that looks.
At the moment, my 'Vette is on the lift with a leaky fuel pump, so I guess I'll rebuild that first and then throw the 73 back on the lift for other stuff. Always something to fix!
So I have been on the move quite a bit and haven't had much time for the cars. I fixed a small issue with the center console door on the 73. OK, great, but not highly important, for sure!
The below is my main gripe at the moment, and damn it, I am determined to figure this one out!
Things the vibration is NOT caused by (or very unlikely to be caused by):
Today I tried swapping wheel and tires with my 70. Road Runner. Here she is wearing the temporary shoes:
Result? Vibration still there.
I measured my drivetrain angles. My understanding (for a street car, not a drag racing car) is engine/transmission should be between 0.5*-3.0* down and pinion angle should be 0.5*-3.0* up. Ideally the engine/transmission should be parallel to the pinion angle, but at least within 1.0*.
I have a manual angle finder:
Since the wheels need to have the full weight of the car on them, I had a lot of trouble measuring the angles. This manual gauge needle moved easily and I also couldn't get my eye in line to read it well. However, based on those readings it looked like my engine/transmission was 3.5* down, and my pinion was 1.5* up.
I tried shimming up the back of my transmission (at the tranny mount) with some shims that are about .110" thick. Result? Still there, but I swear it is a bit better.
I just received a digital angle gauge and will now use that to try and get some better measurements. In the mean time, if anyone has any ideas I am all ears!
The below is my main gripe at the moment, and damn it, I am determined to figure this one out!
For many years I have had a harmonic vibration at about 65 MPH. It is annoying. Damn it, it is still there, and darn near the entire drive line is new.
Things the vibration is NOT caused by (or very unlikely to be caused by):
- I have a brand new engine. Even the block is different. There is NOTHING the same engine wise from when the car ran a few years ago.
- I have previously swapped out the transmission to another 727. The only element I wasn't able to swap out at that time was the tailshaft, since I needed the slap-stik mounting bosses and the other transmission tailshaft didn't have them.
- Post the transmission swap, I installed a Gear Vendors overdrive. This replaced the transmission tailshaft with the GV unit.
- I am currently running a different torque converter than before.
- I have previously had my driveshaft rebalanced and U joints replaced. Recently, I had it shortened and rebalanced to accommodate the GV unit.
Today I tried swapping wheel and tires with my 70. Road Runner. Here she is wearing the temporary shoes:
Result? Vibration still there.
I measured my drivetrain angles. My understanding (for a street car, not a drag racing car) is engine/transmission should be between 0.5*-3.0* down and pinion angle should be 0.5*-3.0* up. Ideally the engine/transmission should be parallel to the pinion angle, but at least within 1.0*.
I have a manual angle finder:
Since the wheels need to have the full weight of the car on them, I had a lot of trouble measuring the angles. This manual gauge needle moved easily and I also couldn't get my eye in line to read it well. However, based on those readings it looked like my engine/transmission was 3.5* down, and my pinion was 1.5* up.
I tried shimming up the back of my transmission (at the tranny mount) with some shims that are about .110" thick. Result? Still there, but I swear it is a bit better.
I just received a digital angle gauge and will now use that to try and get some better measurements. In the mean time, if anyone has any ideas I am all ears!
Drive down the road and maintain speed where the vibration is the most severe. Shift vehicle into neutral. Is vibration same, less or worse? I do this sort of thing as part of my day job.
Thanks for the advice - I will take all I can get!
Honestly, it has been a long time since I did the test going into neutral. If memory serves, the vibration was still there but with less intensity.
However, since there has been a long time since I did the test AND my memory may not be correct, I will try that again and report back.
OK, I put the old wheels and tires back on, and took it for a drive again. Short answer to your question is "less".
Some observations:
- Since I have the Gear Vendors Overdrive, I turned that on and off. The location of the vibration stayed the same, i.e. in the 65-70 MPH range, regardless if the O/D was engaged or disengaged.
- The vibration seems worst when under power at 65-70 MPH, for example, like accelerating slightly or going up a hill.
- The vibration is still there, but less severe if I shift it into neutral while driving 65-70 MPH
- It seems the vibration is less severe after I shimmed the transmission.
). This to get then two angles closer to parallel.As always, I appreciate any and all input. I want this vibration DONE!
How close are you to pittsburgh? I have a pico scope with the NVH pack that we could use to pinpoint it. I get out close to the border for work and might be able to swing by
I'm just shy of 5 hours away from Pittsburg.
Here's a suggestion: I finish trying to measure (and perhaps adjust) my transmission and pinion angle and see where that gets me. I am encouraged by the fact that I have now seen a change based on the shims I put in the transmission.
If that fails (which just about every thing I have tried so far has), then I would gladly and gratefully accept your offer. Obviously, I would work around a time that is most convenient for you and meet you wherever needed. Much appreciated sir!!!
Happy to help when I can. That tool is amazing at finding vibrations and noises like this.
Hawk, since the vibration is worse under power, when the rear axle is under load and trying to rotate upwards, then I am thinking you need to add some shims to create more of a downward angle at rest. Probably doesn't require much. I used to run 4 degree shims in the cuda, so that the driveline angles lined up under hard acceleration.
Thanks!
That makes sense. I am still going to try and measure my driveline angles and see what type of numbers I get. To me, the biggest encouragement is that it actually changed when I shimmed the transmission, so my hope is by adding the right shims in the right locations, it will finally be resolved. Now to just find the magic formula!
So I measured my drivetrain angles with the new digital gauge. I think the important point here is that while my car was in the garage, it was not necessarily leveled. My garage as a slight downslope (as I believe most do), so the key here are the relative differences.
- Engine/Transmission: 3.1* down
- Driveshaft: 1.1* Down
- Rear: 1.3* Up.
I was over at a friends the other night.
He swears this is the best stuff, after all Mopar knows rust better than anyone.
You don't need much which is good because it's pricey.
You need to shim the rear you can't just twist and tighten.
He swears this is the best stuff, after all Mopar knows rust better than anyone.
You don't need much which is good because it's pricey.
You need to shim the rear you can't just twist and tighten.
Does the 73 have the rubber isolated mounts on the spring? If so you may have to change them for solid ones in order to use the shims.
rumblefish360
Well-Known Member
My ‘79 Magnum has the ISO mounted suspension. I was out a tiny bit on the angles. I “RoadKilled” it by using thick washers under the between the spring and the rear.
Not a recommend path to take but it worked for the driver it is.
Thanks Don. I'll look up the rust penetrant oils. Much more rust repair to come!
I know I may need shims for the rear, but sometimes you may have just a degree or so of play when it is loose. I was hoping I may be able to squeeze just a tad bit of adjustment out of it...
Yes, it does have the rubber mounted springs. I think, as rumblefish360 states, it is called the ISO suspension. It has been so long since it has been apart that I am not sure how I would shim it. I'll look up some drawings tomorrow and see what that tells me.
I am NOT above RoadKilling it! I would certainly be up for using some washers if it could help prove what I need. If it works, then I'll gladly make or buy some appropriate shims.
So I did some more testing. First, I bought four new U bolts and broke/fought the old ones off. Here is old and new.
The rear looks like this with the U bolts off and the shock plate lowered:
Jacking up the rear mounts, you can see they are flat with a big hole in the center.
So first I stuck a shim in the rear of the pad to force the pinion down. The shim in the rear dropped the pinion by 1.7 degrees.
End result? I felt like the harmonic was more pronounced at speed.
So I reversed it. I took the shims out of the rear and put them in the front. This would then raise the pinion, and it ended up raising the pinion 1.0 degrees. End result? I felt like the at speed harmonic was about the same as no shims in the rear, but a new vibration was there when I accelerated harder.
So now I am going to remove all shims from the rear. I will still leave the back of the transmission shimmed as I felt this reduced the harmonic a little bit.
So there 'aint much else. Next step will be to check the bearings, and maybe the differential. If that still fails to find an issue, I may have to put my tail between my legs, admit defeat, and hope @Nxcoupe takes pity on my sorry arse and offers to meet me near Pittsburgh or wherever the heck he wants me to go. At this point, I am pretty dumbfounded...
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