I am rebuilding an NRH3 5 speed tranny for the first time. I have the countershaft reassembled with synchrotech carbon Synchros. There is one brass synchro in the package that is identified as the reverse synchro for the main shaft. Which synchro position do I use this synchro for? I've read through the diy transmission threads but still unclear where this "reverse synchro" sits on the main shaft in relation to the other Synchros that I'm supposed to replace with the other carbon Synchros included in the rebuild kit.

 

They are pulling your leg. There is no synchro ring for reverse as it is unsynchronized.

Reverse is an idler gear and the gear teeth cut into the 1/2 synchro sleeve.

Only 5 synchro rings unless you have double or triple cones on 1 and 2 but I don't think that transmission had this feature.

 

Yeah, that was my understanding, it's the straight cut gear. If that's the case where should I use the brass synchro on the main shaft? The rest are carbon. I'll take some pics to show what I'm referencing, appreciate the help.

 

Here is the response from synchrotech and a shot of the mainshaft along with new synchros. You'll notice that one of the Synchros is brass while the rest are carbon. Per the response from Synchrotech I'm assuming I should be placing it in the top most spot for a synchro that's near the top of the shaft. Still not sure why they are referring to it as "reverse synchro".

 

It has nothing to do with the gear tooth type... the synchro and lock ring keep the transmission in Reverse when you select it. It is called the blocking ring by Honda. Call it what you want... it looks like a synchro. It is found at the top of the mainshaft... opposite the 5th gear synchro Basically, your 5/R shift fork/selector actuates the slider... choosing either 5th gear or reverse. There are no dog teeth for reverse.

 

Thanks, I think I figured it out and have it put back together. Do you know if that synchro and snap ring are the same size as the others? Reason I ask is that the snap ring seemed to fit more loosely than on the other synchros.

 

Some Honda transmissions use a reverse synchro and some do not. The NRH3 reverse synchro (blocking ring) is #8 in the diagram located at the top of the main shaft. It applies pressure to the reverse stopper cone as the 5/R slider moves to the upward reverse position while the reverse idler gear engages with the outer straight teeth on the 1-2 slider and main shaft.
NRH3 3/4/5/R synchro springs are the same size.

 

Ohhhhh learned something new today.

 

Me too, thank you everyone for the help. Much appreciated! Have the main shaft back together, ordered the correct shims for the countershaft, installing the final drive gear on a new mfactory race pack 1 lsd then should be able to button it all up.

 

What do you call the reverse idler #5 in the diagram and the teeth it engages on the main shaft just to the left of #1, and the teeth on the counter shaft?

 

That's what I was referring to so curious to know the answer as well.

 

Straight cut gears. No dogs on any of the gears in that transmission. Dogs are the 3-6 teeth on the face of a gear that lock onto the neighboring gear or hub.

Look up dog face gears.

Reverse has straight cut gears and the idler has the face of those gear teeth beveled like a synchro to help alignment when selecting reverse.

 

I would call it the "reverse spur gear"... the factory calls it the "reverse idle gear". When you shift into reverse, the 5/R shift fork is moved toward the top of the main shaft and this forces the 5/R slider to engage the reverse synchro and locking ring. At the same time, this movement of the 5/R shift fork also simultaneously contacts the reverse switch AND the reverse shift holder and lock cam, which rotates the reverse idle/spur gear into position between the machined teeth on the main shaft and the corresponding teeth on the 1/2 slider at the bottom of the counter shaft... finally engaging reverse. Yes, the reverse gear teeth are essentially a straight cut design.

 

Common misconception referring to straight cut reverse gears as dog engagement I suppose.

 

Gear teeth. Dog teeth are the small teeth on synchronized gears that the selector sleeve interacts with.

 

It is a 'synchro' (which are also called called synchronizer blocking rings) that acts as a brake pad that stops the mainshaft from rotating, so that the reverse idler gear can be moved, where it becomes in contact with the mainshaft and countershaft 1-2 synchronizer sleeve.