Datsun OEM rubber is amazing - it is still in good condition on my 1974 620.
I bought 2 new firewall grommets from an online Nissan parts house, which became NLA not long afterwards.
It's maybe 2 years and they are cracking all around the edges.
The rubber they are made from is truly inferior. I don't know if they would last much longer if kept wet with ArmorAll.
They were expensive then and even more so now. And since now coming from the aftermarket, could they be even worse? Probably not possible. Who knows, maybe the aftermarket is better than the ones I got from the dealer.
Yes, I saw that 0.813 that you marked red - that was copied from zhome.com
I also found a massive table of what seemed to be all Datsun transmissions and it listed same ratios for all 620's and also some or all 720's too. That made no sense.
I'm going to edit the red, it should be 0.882, right? It would be nice to have all the ratios in one place.
NOTE: The change in the 5-speed ratios definitely coincide with the shallower 4.11 rear. However, it doesn't explain that the 4-speed has the deep 1st all the way thru 1979 - whereas the 77-78 5-speed had a higher 1st.
But hen in 79, the went to 4.11, kept the 4-spd low and lowered the 5-sped low to match.
Sounds like some indifference between the 2 lows with the L20B.
I could definitely pull the Big OD: there is a summit on Rte 30 just East of Ligonier that is a massive grade - usually you get stuck behind someone terrified of the grade and there is no hope of passing because most cars don't have the big HP to do that. But my L18 620 made the grade at 50 mph in 4th - although it was floored in a few sections maybe totaling a mile at most. So on the PA Turnpike, that 0.746 would be perfect, even with the taller 205/75r14's.
But I have been paying attention to the various really steep pullouts I have to make locally - I kinda like the low I have right now.
I'm undecided about tires: either tallest I can get if I have to drive in the snow, or the shortest for handling. If I go short, the Big OD would be OK. Tall, I'm just not so sure. I don't really plan to haul anything more than a 1/2 of chip stone maybe a couple more times in my lifetime and other than that, no big loads. I think I could deal with big loads if I had to with the Close Ratio trans. HaHa: if faced with an unexpected big haul job, maybe I could have some really short "hauling tires."
Actually on the tires: maybe have very tall All Season tires for snow and trips and run the low profiles other wise. Actually that might be a good solution.
But then the Simple Question: What is bugging me right now? Obviously High Rpm on the Interstate. So maybe that should get tahe concern.
Oh, but what about that BW T5? it's a 3.50 / 0.78 5-speed? That would be ideal
I guess another thing not to loose site of is heavier transmission waste more HP. So the Z-car trans are heavier since they can take more torque.
Maybe a L20B 5-speed is the best compromise. In fact, it would directly address the Interstate rpm. (And aren't they 55# and basically UPS-able?)
But much higher (numerically lower) 5th (.75 -v-.85)
I've got OS 205/75r14's which have a 10% speedometer error and have no issues whatsoever with the L18 pulling out in 1st. Pulling out in 2nd is too tall. The 3.062 is "1/3rd the distance to the goal" which might be an issue.
But the wide 5th would be TOTALLY AWESOME at 80 mph on the Interstate.
Has anyone put this transmission in an L18 or L16? Did you like it?
And are there any installation issues using a Z-car trans. I'm pretty sure my L18 is long tail housing 4-speed so it should bolt up to the block and the drive shaft should be correct.
Some people say there is an issue with the trans cross menter/mount?
And finally issues with the shifter location - someone told me to get a L20B 5-speed from a 620/720.
I sometimes forget, stick the nozzle in the neck and squeeze the lever all the way - then I sometimes get gas all over me.
The gas shoots out of the neck like I had the filler nozzle pointed out of the neck.
There is a big difference if I put the nozzle against the neck ID in different places and also with different nozzle angles - but I never remember which way works the best.
Is this common? because it is very frustrating.
I did put a new filler neck hose on it - a nice Gates universal with a 45* bend. It was a little oversize maybe 1/8"
Thinking about it, perhaps the clamp at the tank, is too far down the tank tube so that the hose is actually pulled away from the end of the tube - the step messes up the gas trying to slide down the ID into the neck....
... just thought of a way to check this: put another hose clamp at or just beyond the tank tube end and see if that solves the problem.
But then it's still a legitimate question if these trucks are prone to this projectile spillage during fillup?
Note: none of the venting tubes are connected correctly and the monkey's that worked on this truck (they couldn't afford apes) could have done all sorts of mischief on top of the tank.
TW is 420 but the sidewall feels like an inner tube and I can press my thumb over an inch into the tread. Not quite dirt track tires they fold up and stack on the car hauler.
They were 205/75r14 Douglas M&S on the WalMart closeout tire rack. Noticed them, not even looking to buy tires, and they were $28 each. So I got a set. Then I have this other set of 3 older Douglas and figured might as well get one more to use up the other set. So they still had 2 left. Manager walked buy and having just asked if they wheel and deal the pair, they mentioned it to the manager and he said $20 each for the last 2. So I bot them.
Crappy tires for a cheap price.
NOTE: I would much rather use a lower aspect ratio tire for handling, but I have the 4-spd and man it is brutal at 70mph even though with the 205's the speedo is about 10% slow. I should acquire a 5-spd for when I replace the clutch.
The alignment is spot on - I do it all with temps and can nail pressures too using that method. (After temp alignments, I'll never attempt to do a measured alignment unless for some autoX or track thing.)
But you know, I discounted the effect of the drive wheels. Yes you use the brakes here and there, but when you drive down the road, to maintain your speed, you are continuously applying torque to the drive axle. So it would make perfect sense that going down the highway, the rears should wear more. And frankly, 55/45 weight distribution for a half ton is very good for a 2wd 1/2 ton pickup - those big block Ford CobraJet Mustangs were that bad and maybe worse.
That is definitely true and what I've seen with the rear wheel drive cars I've owned, however I may be seeing the opposite in my pickup:
I've got some cheap 1-ply tires on the front and some nice snow tires on the rear that I want to replace with more of the cheap 1-plys. The snow tires look like they're not wearing whereas the fronts definitely are. Of course these are two different types of tires and so this proves nothing.
However, there are factors that contribute to front wear:
axle load: nose heavy (about 55/45)
braking: front brakes do most of the stopping
cornering: more axle load, more wear: nose heavy (this is two-fold since turn-in really wears tires)
I think the lower the engine HP, the lower the traction wear - an L20B would wear the rears more than an L16?
Have some different tread depth tires (6, 7, 7, and 11/32nds) to mount and trying to get it right the first time.
But I drive pretty hard in the corners on windy PA roads and since there is more weight on the front axle, I would expect more wear on the front. In fact, I'd expect to see more wear on the heavier loaded axle.
I know the passenger size rear wears more than the driver's side.
People say rear because that is the drive axle. While the L18 is not a lot of HP, 1st gear is pretty deep and does put some high load on the tires - so I'm sitting on the fence with this claim.