PhilAndrews

Exhaust was getting noisy on acceleration, tick tick tick. This afternoon I pulled the manifolds off. Yup, there's the problem. Made some new gaskets and reassembled it all. Waiting on the rtv to cure. Phil

The dew on the car has gone all strange. Voodoo witchcraft. First drive shows ride quality has been reinstalled in the vehicle, so that's good. Gearbox changes well, lending more credence to the theory that what counts for summer temperatures in Detroit is fine for a single weight hydraulic oil, but average ambient temperature here requires a heavier oil. Phil

Problem fixed, cause remedied and car back on the ground with new shocks. Phil

Found the fault. These shocks are slightly more stubby than the previous ones (1/8" or so) and don't clear the top mount correctly. Ordered a new set. Car currently OOS with a case of Low To The Ground. Phil

Oops. The beautiful road surfaces around here did a number on the top mount of one of my new rear shocks. Further inspection tomorrow up underneath, hopefully the top mount didn't break on the car. Phil

Yeah. Got one of the vents open and a heater inside to try get it dried out. It is moist. Phil

Just got back and noticed the car window has been down overnight. It's been raining since 4pm yesterday...

Needs a valve job but it runs pretty well. Phil

Yup. Followed the manual procedure. Tipping it sideways lets the valves fall out under their own weight. The smaller ones need a gentle flick of the wrist for the same to happen so those are all good. Phil

Well, that'll be the acid test for sure. It'll be spoiled by the fact I need to set my valve lash...

I said get it completely stripped down, cleaned out. I'm glad I remember how it all goes together... The bores are perfect, so that's a good thing. Hopefully this one has another 100,000 miles in it. Modern oil should help prevent it wearing so badly also. Got it all back together and ready to go. Phil

Dismantling of the valve block shows it is indeed not NOS. It is, however a factory reman so all the wear items are new. Fire was employed to allow gentle removal of all moving parts. It's cleaned up nicely, time to reassemble it after dinner. Phil

Soaking down now, so we'll see

I jave a can of Berryman Chem Dip. Thinking of giving it a bath in that, though I was also going to see if heating it up a bit would free it up enough to get the pistons to slide out to be cleaned (probably in gasoline). Phil

Oooh. Brand new old stock valve block. Gummed up solid with 70 year old storage oil, so that's next on the plan, trying to figure how to free it up. Phil

Well, the D51 has a lot of clever things going on, most of which are "improvement" upon beefing up the clutch packs to cope with the additional torque from bigger engines. A good portion is connected to the throttle valve control, which is why that is important to be adjusted correctly - difficult without the correct tool, which they fail to give dimensions for. Handy. But, at idle, the TV (throttle valve) is closed, which means that the overall pressure is low (40-50psi), the front pump creating said pressure and the reduction caused by the uppermost shuttle in the pressure regulator having no pressure behind it from the TV. The non-return ball seals shut and prevents line pressure being lost via the rear pump, which isn't moving if the vehicle isn't. Placing the selector in Dr should cause pressure via the 1-2 valve, which will be in the 1 position. That engages both planetary gearsets into reduction by clamping the bands down. Gently applying the throttle (enough to get to about 8 mph, 2nd gear) will leave the line pressure low and result in a very gentle shift from 1 to 2. By the time you've pressed in the throttle enough to get to 11-12 mph the line pressure is brought up by TV behind the regulator slug and a more positive engagement occurs for 3rd, and then 4th. Neither should be jarring but if the shift to 3 (and particularly 4) drop briefly to neutral during shifts the TV position is wrong and needs to be adjusted. The light-throttle low pressure is inadequate to get the box to shift 3 and 4 correctly. The TV pressure also pushes against each shift valve, assisting the springs which determine shift point. Light throttle means the governor pressure simply overcomes the spring; the TV pressure also regulates the compensator pressure (that boosts the pressure to the servos and at light throttle causes the shifts to engage gently, heavy throttle it clamps down hard for a positive, no slip change under heavy acceleration). The governor pressure has two outputs. Primarily, the small governor slug modulates the pressure to push against the shift springs directly in relationship to the speed of the vehicle; the other output opens up from nothing to full at about 7 mph or so and that is fed to the reverse blocking mechanism, which physically prevents reverse accidentally being engaged above that speed. Reverse also has a hack fix; the original incarnation simply had a latching pawl that engaged into the reverse planetary. However, the vehicle had to be at a full halt before it could be engaged otherwise it would grind horribly before engaging with a bang. The pawl was retained but a metal cone clutch was employed in addition, which meant it could slip and engage while the vehicle is moving. Pressure on a piston prevents the pawl from engaging with the engine running. Switched off, it will engage reverse if selected; with no pressure the large spring on the second servo engages 3rd gear reduction. The two ratios working against each other effectively lock the transmission solid, and provide a parking brake. The cone clutch doesn't work very well, so second line pressure hack engages when R is selected; the middle slug in the regulator recieves pressure behind it and that forces the regulator shut until about 120psi is achieved. This clamps it tightly enough not to slip on a sharp uphill incline, for instance. There's a few other niknaks in the valve block but they only work to provide the effects described above. Common fault I have found is that reverse blocking doesn't work because the passages that feed the piston get choked up with friction material debris as they have no flow through. Doing about 10 mph, in Lo you should be able to pull the shift lever toward you and gently ease down toward R. If you can get to the between point where the box finds neutral, your reverse lockout system is likely blocked. You shouldn't be able to move the shift lever past being fully engaged in Lo. If you find that your shift is harsh 3-2-1 (particularly 2-1) or it shifts 3-1-2-1, the TV slugs are getting stuck and need cleaning, also a symptom of using hydraulic oil that's too thin for a worn hydraulic system (Dexron, Mercon etc). Shifting 1-3-4 with a difficult 4th (occasionally getting 2 to engage after snapping the throttle shut, ditto 4th, with 3rd freewheeling at about 30mph off throttle and not shifting to 4th) is symptomatic of the 1-2 TV slug being worn and I've not found a 100% fix for that yet. Phil

Well, this one was broken and I figured I couldn't make it much worse! Definitely a learning experience. The manual does explain relatively well, but the nuances of operation are not well described and that's what's thrown me off track a good number of times. I should write a theory of operation for it... Phil

The clock was losing time decided being adjusted, so time for a service. On the bench, pinions oiled and then set the hairspring balance. Yup, that's easiest set up with an oscilloscope. Nice and even pulses, meaning the balance wheel is running evenly each side from rest. Keeping time on the bench, checked for problems. Running well. All back together and in the dash again. Tick tick tick. Phil

Car came in useful for taxi service tonight. It carries the largest volume of passengers of all our vehicles. Loaded six up, we drove on into the sunset.

Just snagged a new old stock valve block for the transmission. That'll mean I can see about getting a sleeve machined for the current block and see if that fixes the issues also, as a viable spare. Phil

5 element "ice blue" ba9s LED bulbs. I'm not sure if they're available in 6V.

A week of driving in 40° and 80° weather has shown there is scope for improvement. Hot, particularly with heat soak after sitting switched off after being driven, it'll hang up. I think what might work will be to put the end block into the oven and get it nice and warm, put some blue on it and see where it makes witness marks upon moving the hydraulic pieces. Phil

Wish I still had a shop! But, if you need help I can certainly become the peanut gallery, for sure. Phil

Significant improvement. Under very light throttle at low speed it can sometimes still get hung up but under regular acceleration it changes well. So far. Phil