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'81 Chevy C30 dually, NV4500 swap woes.

2549 Views 11 Replies 4 Participants Last post by  Richard/SIA
'81 Chevy C30 dually, SBC 350 to NV4500 swap woes.
Hoping this may be informative for anyone else considering an NV4500 swap.

Since I had to pull the engine anyway for a rebuild I thought this would be the best time to upgrade to an overdrive transmission.
Found an early NV4500 with "Granny low" at a decent price and bought it.
Seems that was the last smooth transaction.
Had to exchange the first Advance Adapters (AA) kit as it was wrong for my transmission.
Not too big a deal as Summit Racing had the correct part in stock, just an exchange.
Also had to buy the kit for using the original mechanical clutch linkage. Still no big deal.
Thanks to CCP Virus the whole project got delayed several months.
Finally got my engine back from the machine shop and assembled, test ran it on my stand.

Now finally trying to bolt everything up for putting into the truck, and the real problems begin.
Being a heavy truck it has always had a 12" clutch.
At the very bottom of the page AA says to use an 11" clutch with their kit. :(
This was not made clear when I bought the kit from Summit.
I contacted AA tech support and was told this is due to their making the Bell Housing "Compact" so that the kit would work in Toyota Land Bruisers and Jeeps.
But they also stated that "Some 12 do fit", "some will fit after a little grinding".
"Put it together and see if it turns".
My feeling is that real trucks should not have to use an undersize clutch for the kit to work.

Today I finally got to bolt the trans and bell to my engine. Pro-Tip, the NV4500 is really very heavy!

At 65 YOA I'm past crawling around on the ground with a flashlight trying to determine if parts are clearing.
So tomorrow I get to try to hoist the whole assembly onto a steel table that I think will bear the weight.

I was not able to turn the engine over from the crank nut so expect to find a clearance issue.
The clutch cover I have is fairly low profile so I hope to be able to make it fit.
It's been on the shelf too long to exchange for an 11" version.

With the kit assembled I found one more issue, the clutch TO arm bottoms at the rear of the opening before the TO bearing can depress the clutch.
This is the TO bearing and arm supplied by AA.
That pretty much guarantees that I will have to change either the pressure plate, TO Bearing, or both.
No way I make my planned trip to pick up cars and and an engine next weekend. :mad:
I'm already overdue and the sellers are getting impatient.

I have to get the engine and trans back into the truck before I may make measurements to determine how much to have my forward driveshaft shortened. Measuring both trans I believe it will be 6" but the shop doing the driveshaft insist I measure with the engine/trans in place.

Just to be sure, but I believe the 11" and 12" clutches will fit the same 168 tooth flywheel, correct?
If I must go to an 11" clutch what would be recommended for long life?
Please remember, freight and towing use, not racing.
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The Joys of changing major components off from stock .
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