datzenmike Posted March 29, 2015 Report Share Posted March 29, 2015 Have 720 2wd 5 speed but need it to fit an L series engine. The solution is to simply swap the L series bolt pattern front case onto the Z series 5 speed. It should be about a dozen 12mm bolts, snap ring pliers and a dab of sealer. Should be... Pulled it out of storage and using a spare clutch disc I spun the gears over in first gear and 3.3 turns in for one turn out IDs this as a mid ratio 5 speed. I was afraid it might be a wide ratio with 3.592 turns. Magnetic oil bung clean. Remove cover plate bolts and ...give the clutch arm pivot a smack to dislodge it. Cover off. This seals in the oil around the mainshaft input and the countershaft bearings. Bearings look ok but be sure to recover (and save) the thrust washer or select fit shim on the counter bearing... Next remove the snap ring and save it. The snap ring fits on a groove in the mainshaft bearing and must be removed in order to separate the case from the adapter plate. Ready to remove the front case. Just hammer forward on the front and case begins to separate from the back.... Quote Link to comment
datzenmike Posted March 29, 2015 Author Report Share Posted March 29, 2015 The bearings sink out of sight as the case slides forward and off And now I notice a glitch in the plan. I got this 720 5 speed in trade and assumed it a common older one with the smaller 56mm counter bearing. The 56mm bearing was used on all '72 and up 4 speeds and '77 and up 5 speeds. Very common. This transmission must be an '85 (or '86) when they were replaced with a larger stronger 62mm bearing. The problem is that all L series cases will have the smaller hole and this bearing won't fit! This is the L series case I plan to use. This is the Z series case that has the larger bearing. If there were time I would have the case milled out to accept the better larger bearing so the only thing to do is buy a smaller 56mm bearing take the 62mm one off and swap it on. 62mm bearing off. Will get new one ASAP and continue this when assembling. Quote Link to comment
ggzilla Posted March 30, 2015 Report Share Posted March 30, 2015 Excellent. So use GM orange RTV sealer? Quote Link to comment
datzenmike Posted March 30, 2015 Author Report Share Posted March 30, 2015 Wa ha ha ha ... sure if this was a GM transmission. Quote Link to comment
ggzilla Posted March 30, 2015 Report Share Posted March 30, 2015 So Nissan gray RTV sealer. Quote Link to comment
datzenmike Posted March 30, 2015 Author Report Share Posted March 30, 2015 Yeah. Or Hondabond which is probably a rose by another name. Quote Link to comment
Dime Dave Posted March 30, 2015 Report Share Posted March 30, 2015 Don't you need to open up one of the shift rod holes in the L Bell? Or is that only in going from a KA Type "C" trans to L? Quote Link to comment
flatcat19 Posted March 30, 2015 Report Share Posted March 30, 2015 Where's the L case and the 56mm bearing from that trans? Why wait? Quote Link to comment
ggzilla Posted March 30, 2015 Report Share Posted March 30, 2015 From 71B to 71C is more complicated. From 71B L-series to 71B Z-series is just the from case swap. Quote Link to comment
Stoffregen Motorsports Posted March 30, 2015 Report Share Posted March 30, 2015 Yeah. Or Hondabond which is probably a rose by another name. Yamabond, Kawibond... It's Threebond 1211. It can be found at most motorcycle shops. That stuff is excellent, but expensive. We ran a motor on the dyno once for about 15 minutes before I realized there were no bolts holding the intake on, only Threebond. It was a race motor with no gasket. I usually use high temp grey RTV or black "Right Stuff". Quote Link to comment
datzenmike Posted March 30, 2015 Author Report Share Posted March 30, 2015 Don't you need to open up one of the shift rod holes in the L Bell? Or is that only in going from a KA Type "C" trans to L? Only the 71C and the very late 71B has the larger 16mm 1st/2nd shift rod. I have an '85 CA18ET 5 speed and it is almost a 71C inside. Gears are wider, synchros are way different, 62mm counter bearing and larger 16mm shift rod. The vast majority of 71B are 15mm rods. Pretty sure this 5 speed has the smaller 15 mm rods but it's simple enough to drill the hole out. Where's the L case and the 56mm bearing from that trans? Why wait? This is because the front case I've had probably for 15 years. It was in my '78 620 when the trans started jumping out of gear and I scrapped it. It's been sitting there just waiting for today. Quote Link to comment
flatcat19 Posted March 30, 2015 Report Share Posted March 30, 2015 This is because the front case I've had probably for 15 years. It was in my '78 620 when the trans started jumping out of gear and I scrapped it. It's been sitting there just waiting for today. But it could be done this way, right? Quote Link to comment
datzenmike Posted March 30, 2015 Author Report Share Posted March 30, 2015 Absolutely, yes you could just swap the bearings. A new one is advised as this is one of the weak points on any 71B transmission.. Quote Link to comment
ggzilla Posted March 30, 2015 Report Share Posted March 30, 2015 CA20ET? from 200SX Turbo? I didn't realize there were 71B transmissions so beefy. Quote Link to comment
datzenmike Posted March 30, 2015 Author Report Share Posted March 30, 2015 It was a CA18ET. They were only 135 horse. As I said the gears are wider and it has the 71C type synchros, larger shift rod and massive shift forks and the larger 62mm counter bearing. It's 'almost' a 71C Here it is... Quote Link to comment
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