Just picked my truck up this morning from the trans shop. While I was away for a week I had the trans rebuilt and a SBC Con-O installed. Trans is much quieter. There's still gear rattle at low RPM, but the scary growl under load in 4th is gone. It shifts a little notchy with the new synchros, but once I get a couple thousand miles on it I'll drain the 5w-30 synthetic and put in Redline MTL.

The new clutch is nice! I'd say pedal effort is about 2/3 of the stock clutch, and engagement is a lot smoother. I can't say for sure that it'll hold for a couple weeks, SBC says it needs to be broken in with 200 miles of city driving. I got on it a little bit too hard in 4th on the way home (testing for noise ) and it slipped. I hope I won't regret not plunking down the $$$ for the 13" clutch.

Anybody who put a Con-O in notice more vibration at idle? Mine seems a little shakier than normal and I'm thinking it might be due to the lighter clutch assembly. The lighter rotating weight ought to help out on the dyno, that cast-iron clutch cover sure is heavy!

 

I didn't experience any noticeble vibration when I installed my SBC Con-O. My Con-o slipped a couple of times at first, but has held the power without complaint after it broke- in.

 

Hey Wanna, congrats on the new tranny/clutch! I built my getrag in January after getting the truck---I think they're just noisy units. I have new syncros and bearings. Even went with new reverse-idler thrust washers for good measure. Still, she rumbles pretty good if you load her down low in 3rd and 4th. Sounds like the thing is gonna come right apart I setup my bearing preload six times to be sure I was within spec and I dafinitely am...just the nature of the beast, I guess. It was kinda dissapointing after all that $$ and effort on my part to still have it be noisy....oh well, come on nv5600, come to papa! The good news is I've been thrashing it for 6000 miles now and the syncros have loosened up and it's still in one piece! I'm running about 6 quarts of mobile 5-30 full synthetic---what's the deal with this Redline? Better than the mobile?
greg

 

Calvin- Your truck and mine are pretty close in mods, if the Con-O is holding yours it ought to hold mine once I get ii broke in. I just gotta behave for 2 weeks.

Greg- The Redline MTL is supposed to help the synchros grab better for better shifting. I put it in when I first got the truck (it had gear lube in it ) and it made a big difference, especially when cold. I'm breaking the trans in on 5w-30 on the advice of the builder. He said to run the 5w-30 until it stops being really notchy, then change fluid. He didn't want to waste that nice oil on break-in.

Yeah, I was expecting gear rattle so I wasn't surprised. Above 1500 RPM it's quiet. Nature of the beast. I'm just glad it doesn't sound like it's gonna blow in 4th.

 

you lucky dog. can't wait to get mine together. i chompin' at the bit.

 

I have the the 13 1.25" CON O version with a new flywheel and NV4500. No noticable vibration or chatter. However, before the Con O I tried the Rally and there was definately a chatter.

 

What's an SBC?

 

South Bend Clutch, I believe. They're the folks to go to when you need a good clutch from what I hear.
g

 

Found the vibration. The trans shop put the clamp that holds the downpipe to the bellhousing on wrong so it was resting on the frame. 5 minutes with a 9/16" wrench cleared that up.

 

DOHT! Glad it was that easy! Remember that feeling

 

Hey - GREAT to hear you're back on the road. Hope it was a nice week off.
Just wanted to say "THANKS" again for all the info.

I have wiring problems w/cold start and trans. BUT, I can get it handled now, thanks to your help.

BY THE WAY, I happened to take my truck back to where I had the transmission and transfer case done. They are telling me that my transmission and transfer case levers/rods are acting normally.

I happened to install a "LUK" PRO GOLD clutch in mine.

Am just curious to throw this out to the group:

After 200 miles since installation, I picked up the vibration in the transfer case shift lever again and now I have the transmission gear selector shaft throbbing in first gear when I have it against the governor. The shop is telling me that I have other problems. Most likely mounts.
Also getting the clutch chatter taking off in second and sometimes now in first.

Down pipe to bellhousing? ............................. ( EXHAUST) ?

REDLINE MLT (?)

Company that rebuilt the trans. & transfer case said to just use what was specified in the owners manual. That's what I've done. (ONLY) synthetic 5W-30 (Mobil) He mentioned that you need the specific oil for the synchros. (?) This can't be that new age. (?)

Sorry ................. wife says 'Dinners ready'

 

My SB is slipping but that's because I'm running about 450 hp through a 350 hp clutch. It only slips when I get down on it which I seldom do.

 

Hey Joel .... could you please define "seldom" ?

 

Thanks for the kind words.

I dunno on the throbbing. The chatter is very possibly loose mounts.

Not sure what your question is re. exhaust and bellhousing?

5W-30 synthetic certainly won't hurt the Getrag, but I like the Redline MTL better. MTL is a synthetic oil that is similar to 5W-30 in viscosity, but has friction modifiers that help the synchros grab better for quicker/smoother shifts. The MTL is formulated for transmissions that use 5W-30 or ATF, they have a thicker version called MT-90 that's for transmissions that take gear lube (NV4500 for example). The Getrag does not tolerate thick oils well because it is such a tight transmission. It is set up with preload on the beaings instead of clearance, this means that you need a thin oil for good lubrication. I was very happy with the MTL, I noticed a definite improvement in shifting, especially when the trans was cold. I'll be changing back to it after the break in period. The trans guy told me to run the 5W-30 he put in until I felt the synchros "loosen up". It feels pretty good to me now, 3rd still hitches from time to time, I'll probably put in the MTL in another week or so.

 

Dave-
Again, thanks for the info. It's time to drop my oil now and looks like I'll see if I can get
some of the MTL for mine.

Mark