Synchro Preference

[TStinson]

I've noticed some vendors swear by the NVG composite-faced synchronizers for the NV4500, while others will only use all-brass synchronizers.



Anyone care to expound on what the difference is & why?

 

[kentdiesel]

Hello,

All I can do is share my experience after having used both types of synchro ring.

My truck came with the composite synchros and shifted pretty good. Nothing was wrong with the NV4500 but I decided to install a fully spined mainshaft. I also installed new bearings and solid brass synchro rings since it was apart.

It required alittle more effort to shift for the first 3000 miles. Then after about 3000 miles it shifts smoother and easier than the composite rings did.

If I ever have to change synchros in a NV4500 again I would use the solid brass rings.

If you use the solid brass synchro rings I recommend changing the oil after about 5000 miles because after the new brass synchros "break in" the trans oil has alot of fine brass particles in it. After the first oil change the oil has stayed clean. The Eaton/ Fuller trans filter kit that Geno's Garage sells is a good addition.

Hope this helps,

Kent

 

[DTroy]

Thanks for the info.

I wanted to put all brass in when I did my rebuild, but I had never heard from anyone that had done the swap.

Now that I know that they work well in our trannys, I will go that route next time. transmission lube changes will be a whole lot cheaper!

 

[Woodenhead]

I've been told part of the reason the NV5600 doesn't shift as well as the 4500 is because the 5600 uses brass synchros and the 4500 uses composite.

 

[TStinson]

Go Figure!!

So far I am getting the same consistant responses to my question.



One likes brass due to experience showing it shifts smoother.

One wants to go w/brass so cheaper lube may be used.

One has heard brass doesn't shift as smooth as composite.



Consistant, but getting us nowhere.

 

[DTroy]

I spoke to an automotive tech about this last night. He stated that the NV and Borg Warner went with the carbon fiber because of the transmission size. The rotating mass is a lot greater, and the fiber has a higher coefficient of friction. It grabs the gears better, matches speeds quicker, and provides a smoother shift more consistently.



Personally, I don't have any data on this to prove/disapprove anything. It does make sense though.



One more to ponder. . the reason they line the bands in an automatic transmission is to provide more grabbing power.



Hope this helps.

 

[JAlford]

I rebuilt my NV4500 last winter after 5th gear wiggled off. Went with all new bearings, brass syncros, fully splined mainshaft, and SBC clutch. The trans has 18,000miles now, and still shifts noticibly stiffer than before the brass syncros. Still using the proper Castrol fluid. Shift is more similar to the 6spd. My original syncros had NO wear on them, at 94,000 miles. If I had it to redo, would definately stay with the fiber stock syncros.

My . 02 worth.

Jeff

 

[DTroy]

Okay, a vote for the brass and a vote against. Has anybody else tried the all brass?