Dad's Dodge

[regan wilson]

That turned out really nice.

[Russell Ashley]

That turned out great, you and your "crew" should be very proud.

[makman1297]

Thanks guys.

I think I found my vibration problem. The tail shaft sits at 5 degree down, the driveshaft is 4 degree down and the rear diff is 5 degree down.

Both ends match, but the problem is the rear pinion is higher than the drive shaft and everything I read says that will cause problems.

I ordered 2.5 degree axle shims to fix the rear and then I will see if I can shim the transmission up 2 degree.

I figured that since I used dodge engine mounts and tranny mounts that I would not have a drive line issue, but I also swapped in a 904 instead of the 727 which is shorter and I replaced the rear springs. All of these accounted for the angle issues.

[mongocanfly]

Love that family pic...truck turned out real nice..!!

Rear 5deg down?..wow..yeah it needs to match the angle of the trans...but opposite..
Trans down...rear up...with equal numbers
The 2.5 axle shims still wont get your diff to a positive angle...it will still be down 2.5deg...
Without moving the trans..say if you left it at 5deg down..then the rear would need to be 5deg up..
Trans -5deg...rear +5deg....when setting up I usually shoot for these angles to be 3deg
You said you replaced the rear springs..could there be a issue there?
Shimming up the trans wont be a issue...
I went back and looked at your spring pics but nothing really stood out...

[67C10Step]

I fought a similar issue on my son's Toyota Tacoma for a while. Toyota flunked drive line 101 because his truck is completely stock and the trans tail shaft was 2 degrees down but the input on the differential was 4.5 degrees up. Got some 2.5 degree shims and it took out 99% of the vibration. Still has just a bit but nothing compared to before.

By the way, I like everything about this truck and build. Love the back glass treatment and color choice.

[makman1297]

67C10Step, thank you.

Miss understanding, so the rear diff is 5 degree up from level. I said down because I was using the down angle for the pinions calculators, all three angles are down from front to rear. The front and rear are both 5 degree, however the pinion is pointed higher than the driveshaft.

I also noticed I have an issue in the leaf springs too, the pass side is about 3/4 higher for some reason. I think the springs are not matched. I will take some more measurements from level to verify, but I can already tell they were not put together the same, the overload is backwards from one side to another.

Perhaps the springs are throwing off my angle.

I told my wife this is the drivability phase where I get to spend money fixing the things that don't work right . At the end of the day I want to cruise with no vibrations.

[makman1297]

I did some tinkering on her today. I put it up on jack stands and leveled it under the front part of the box where the frame is flat. I then pulled the tires so the suspension was able to hand all the way down.

I took several measurements front left and right side to my 8 foot level on the floor. I found about a 1/2 frame discrepancy from side to side. I remembered that I bolted all of the cross members in and loosened up the two rear ones and adjusted the from with a jack. I was able to get it within 1/8 of an inch (until I haul something I guess).

I also made some adjustments to the shackle brackets because they didn't match by about a 1/4 inch. I was able to get them to match as well.

I pulled the leaf springs out since my 3 degree shims came in and measured them, one was about 1/8 taller when unloaded. I also found that the overload was installed backwards on one of the packs. I installed the taller pack on the drivers side. re torqued everything and measured again, pass side is 3/4 taller then the dr side, what the heck!

I figure that maybe the gas tank is on the dr side of the frame and 30 gallons of fuel is about 200lbs. I think I am going to get heavier springs anyways as these ones are better then the original but are pretty soft. I put in 1700 lb ones and I ordered 2500 ones, I will put the higher side on the drivers side to compensate for fuel and driver, lol.

I also installed the 3 degree shims. After torqueing everything down my pinion measured 1 degree nose up (originally measured about 5). I was able to put about 3/4" of shims under the tranny, which measure at 3 degrees tail down (was originally 5 down). Dive shaft is still about 4 degrees down from front to back. I was able to do a short road test and got it up to 70 mph for a few feet, I did not notice any vibrations this time I will road test tomorrow since I have duty anyways.

Not sure the best angles for this stuff as the info on the internet is all about racing, but I gather leaf springs need a little more angle to compensate for all the movement the rear end makes up and down plus torqueing.

I also found some original advertising from 1981, pretty cool as I have never seen most of the options that they offered.

[makman1297]

My new leaf springs came in today and I think I will get them in and check the pinion angle again.

I also downloaded a vibration app for my I phone, you put in the details and drive. It is showing a level 1 tire speed vibration and a prop shaft level 1 vibration.

I think I found the cause of most of the driveline vibrations, in addition to the angles I found the mount is shifted.

I decided to make a better spacer that was stronger then my test one. I found the tractor supply trailer shackle kits are almost perfect flat stock with the holes being almost correct. I had to grind them slightly with my die grinder to open the holes up about 1/8. They went right on and were the correct height that I needed.

During the installation I noticed the tranny mount looked a little off, I measured and sure enough it was holding the trans about 1/4" to the pass side of the truck. I loosened up the engine bolts and pried the rear over. So far it has stayed pretty close to center of frame.

I also noticed that the yoke was holding the u-joint slightly off center. I removed the yoke and put a new joint in. I has to file the side that was off slightly to get it to center again. I think I was slightly bent when assembled.

When I was done it was pretty close to center of frame measuring from u joint to frame lip on both the passenger and drivers side.

I have only put a few miles on, but it feels better already.

I also had to pull the speedometer out again, it would go to 65 and then jump to 85 and hang out there until you slowed way down. I took it apart and swapped around some parts with another one. Finally I think I have a winner. I had the same problem with my 80s Chevy truck speedos. I think it took me 3 to get one to work.

[mongocanfly]

nice...did you get the weberauto nvh?

[makman1297]

Mongo,

I downloaded Shimmy Diagnoser. It was about $18 and it seems to work alright for that price.

I also worked on fine tuning the carb, it seems I have an off idle stumble when cold and it pretty much clears up once warm. I didn't realize holly has so many changeable parts and I ordered a larger accelerator discharge nozzle.

[mongocanfly]

I havnt seen shimmy diag...ill have to check it out..ive been looking at the weber nvh but never could get it to download..and its a lot more $$$

[makman1297]

Mango, for the price I cannot complain.

I continued to work the drivability issues. I replaced the insulation gasket for the carburetor as it seemed to be leaking already (edelbrock). This caused me to re tune my idle circuit as I had to turn up the idle from the vacuum leak. This lead to the leaning out of idle screws, which prompted an off idle stumble. I also noticed my vacuum seemed low at 15".

I decided to try what many other mopar people have stated and set the timing to 10 degree BTDC. This increased my vacuum to 17" and helped with the stumble. I decided to go with a larger accelerator pump and installed a #35. I will need to drive it some more but this seems better.

I also decided to tackle my tire vibration a little differently. I got a static balancer to check the tires and rear drums. The rear tires were balanced fine, but when I checked the drums they were both 2.5 oz out of balance. I have read that people have had problems with old cars and modern drums not being balanced properly so that's why I checked them. I attached some wheel weights to see if it makes and difference.

I also decided to try some liquid tire balancer, if this works as advertised, once static balance is achieved I should never need to rebalance the tires. I have only done the rear tires, but a 6 mile test drive was significantly better. I no longer have the out of round tire feeling as I am braking.

[makman1297]

Liquid tire balancer I think was too much, perhaps half of what it stated for stock tires. I rebalance the tires and seem to have gotten rid of most of the vibrations.

I replaced the input seal on the gear box again, as it started leaking already. This time I unthreaded the cap and also replaced the O-ring inside.

I noticed some growling sounds from the rear end and the pinion didn't feel that great when I had the drive shaft off. I decided to replace all the bearings in the rear axle, pinion, carrier, and wheel.

I found lots of pitting on the pinion bearings. It seems to be smooth now, but have not driven it very far yet. Old ring and pinion looked spot on and backlash was easy to get.

I also decided to try an under dash AC system and it should be here by Friday. I have never done any AC and this should be interesting to try and install. I need to figure out how to mount a compressor with all of the V-belts.

I also got tied of spilling my coffee so I made a drink holder, lol.