78 b210 rear end

[bob3d]

My 4 speed is jerky at all speeds. I replaced driveshaft and clutch with no change. My Dad never would downshift and I wonder if the H150 diff could be worn. It does not make noise. 110,000 miles. New carb, struts and shocks. Any ideas? Thanks.

[datzenmike]

Clutches, driveshafts, transmissions, differentials or axles do not cause jerkiness.  Interruption of smooth engine power delivery does.

 

For example if the ignition wire is loose and the engine turns off and on randomly it will jerk as the power jumps on and off. If your fuel filter is part plugged the engine will stumble from not getting gas when it needs it.

[bob3d]

I have cleaned the gas tank and lines, filter replaced and fuel pump.Pressure is good. Idles and revs perfect. New plugs and wires. Head professionally rebuilt. I did notice low power and replaced the distributor sometime ago. Could the reluctor adjustment cause this or something else with the dist? Apparently my carb was ok but I replaced it with a rebuild which didn't help. Have not changed the electronic ignition yet but have a new one. Have removed most emissions stuff and disconnected the transmission 'high' switch . I appreciate your vast knowledge on these subjects.  Diff yoke rotates about 1/4 inch but doesn't wiggle at all.Thanks.

[datzenmike]

Well define 'jerky'. It may seem fine when stopped but when riving under load (slowing or accelerating) the engine torques over to each side on the engine mounts. Maybe a mount is broken? Transmission mount? loose wiring?

 

Does this happen while cruising along at a steady speed?

while lightly accelerating?

while heavy accelerating?

while slowing down with foot off the gas?

 

BTW there is almost never a reason to down shift when slowing or braking. It just wears the engine bearings and clutch out.

[bob3d]

The mounts look good but I have new ones if needed. No loose wiring. Distributor same as original, D4F5 , 70 MM ID. Happens under all conditions of driving. Its not real bad but its such a nice car I just cant accept that its not perfect. Yes it does it while coasting too. There is a very slight whining in the rear end. Should I tighten the yoke nut a little and risk the crush sleeve? It is not loose. Crush sleeves are hare to find. This is a family owned car since new so I know its history. My Dad was in the habit of driving in high gear st slow speeds so the car would shake like crazy. Maybe crush washer affected? I'm grasping at straws now. Thanks.

[datzenmike]

Leave it alone.

 

Inspect the U joints with the car in neutral. Driveshaft should turn only. There should be no side to side or up/down movement at the joints.

[bob3d]

Replaced driveshaft with new. Old one was good. U joints not replaceable so had to get them with a new driveshaft while I could still find one so I could have a spare for future use.  The old diff oil looked as good as the new with nothing on the magnetic plug. 

[mhub91]

Hi Bob, Welcome to Ratsun.

 

Did you replace / resurface the flywheel when the clutch job was performed?

[datzenmike]

 Jerky as in vibration or like turning the ignition on and off??

[bob3d]

Since I had a shop do the clutch ,I don't know if the flywheel was resurfaced but since they only work on Datsun and Nissan , I assume they would do it right. I've done a lot of clutch jobs where the flywheel just needed to be deglazed.  I took another look at the timing and it was jumping back and forth at least 5 degrees. I changed the rotor and it was steady. When I got the car it wasn't jerky But one of the first things I did was replace the distributor and the car sat in my garage for 5 years.I replaced everything I could to prepare for future unavailability of parts. Nothing was actually bad. Maybe the rotor was the problem. The new one was a little different. I will take it for a drive to see what happens.

[datzenmike]

Put the old distributor back in and see. I suspect a loose wire or connection.

[bob3d]

Checked the connections and they are good.  Timing mark steady now. Went for a drive and its really not bad for a 40 year old car.  Tried both distributors. I will continue to monitor the situation. Thanks.