Crazy craftsmanship. Truly a work of art.

Any more info on the Muffler silencers? Been thinking of doing something similar for my Magnaflows. Block off/restrict one of the outlets. I have quad tips.

Jeremy

The muffler silencers make a huge difference when running without turbo. They restrict power for sure, but a simple way to temporary reduce the exhaust sound.

I have modified the exhaust on the passenger side and added a larger wastegate there.


Previous 50 mm wastegate location.

https://cimg7.ibsrv.net/gimg/www.cor...cd24d70656.jpg

Exhaust header before modofication.

https://cimg1.ibsrv.net/gimg/www.cor...709d3ee6e3.jpg

Testing out location for new large 60 mm wastegate.

https://cimg3.ibsrv.net/gimg/www.cor...e51860dc71.jpg

https://cimg4.ibsrv.net/gimg/www.cor...745b77fd71.jpg

Header modification

https://cimg6.ibsrv.net/gimg/www.cor...fc5d5bab52.jpg

Finished header

https://cimg8.ibsrv.net/gimg/www.cor...54ddde9aa7.jpg

https://cimg7.ibsrv.net/gimg/www.cor...7f0662e238.jpg

Downpipe modification

https://cimg8.ibsrv.net/gimg/www.cor...2655003169.jpg

https://cimg9.ibsrv.net/gimg/www.cor...a7b50a8b4b.jpg

Finished!

https://cimg0.ibsrv.net/gimg/www.cor...90c8f2f2f2.jpg

I put the Corvette on the dyno roller in late august.

Without boost control ( Wastegate spring only ) I got about 6 psi boost and it made almost 600 hp to the wheels. This was in third gear ( 1:1 ).
#935 run in the graph.

At about 11 psi boost and 720 hp the load cell maxed out so I had to use fourth gear to continue. I lost about 50 hp when switching to fourth.

On the last runwith about 21 psi boost, #944, injector duty was over 95% and boost control duty was even higher. With bigger injectors and a 4-port boost control valve I could have pushed the numbers up a bit more. The orange line is exhaust pressure before the turbo and that is affecting engine breathing at this point.

If I could have made all runs in third the #944 run should have been at least 50 hp higher compared to the #935 run.

https://cimg6.ibsrv.net/gimg/www.cor...0dcf6c7706.png

realy nice numbers :thumbs::thumbs::thumbs:

One more year ...

Bought some new tires, Hoosier DR2, 295/50-16 and that really maxed out the available space.

https://cimg3.ibsrv.net/gimg/www.cor...4a6d0c3f89.jpg


Stock 255/50-16 tires on front wheels

https://cimg5.ibsrv.net/gimg/www.cor...921f0f2fa1.jpg


I went to a local 1/8 mile "test and tune" event a few days ago.
This is my third and best time slip.
1.54 sec 60".
6.34 sec 1/8 mile ET.
186 km/h 1/8 trap speed. ( 115 MPH )

https://cimg6.ibsrv.net/gimg/www.cor...c7ece44d9b.jpg

And a log from the ECU.
It has a built i G-meter and peak value was about 1.5 G.
It was down to 1.0 when shifting to second.
At the end it was about 0.5 G.

On the yellow RPM it seems like it is shifting uo three times but the second one is when I lock the tourqe converter in the middle of second gear.

https://cimg7.ibsrv.net/gimg/www.cor...81f4a76bca.jpg

On that pass with 1.54 sec 60" I launched @ 3200 RPM with 60 kPa boost ( 9 psi ).

A few weeks later at another track I launched @ 3500 RPM with 90 kPa boost ( 13 psi ).

https://cimg5.ibsrv.net/gimg/www.cor...6c38e116df.jpg
https://cimg6.ibsrv.net/gimg/www.cor...5477267a47.jpg

Good kill, looks like you found the next weakest link. Did your exhaust get destroyed as well? Time to upgraded driveshaft to a composite and some billet bits.
https://www.qa1.net/driveshafts

Curious on how the rear end internals look like?

Are you using "Rcklessdriver" method for controlling the rear under launch w/the extended suspension stops? No big deal about the joint, but it's a bummer it beat the shaft end so badly.

That is some solid 60' time! :thumbs:

Looks like the joint body itself just failed.... Things just break sometimes.

I will also say that in my experience, the Spicer joints with the round body are a bit stronger than that type with the cross shaped body. I broke a couple of those cross types and with no warning... they just broke an ear off the body and the needles/caps were still 100% fine. Once I switched to the Spicer round body type joints I never broke one again.... I could crush the needles in the caps, but we were able to catch that damage before they 100% self destructed.

When you replace the U Joints buy these:

https://www.dennysdriveshaft.com/p46...1350_seri.html

I also ran the Van Steel billet caps on the inner and outer stub shafts to replace the sheet metal straps.... I did manage to stretch out a few of those factory Spicer sheet metal straps.

http://www.vansteel.com/index.cfm?fu...p=1906&ID=2385

Will

I bought the Dana 44 with the batwing installed it back in 2001 and I have never had them apart. It is a 3.45:1.
Before that I had upgraded the u-joints to non drilled type, but not the superior Spicer round body.

I am not sure what broke first, joint body, strap or strap bolt. I am just happy that it was the outer one and that the half-shaft stayed in place in the spindle. I have already repaired using used stock parts and rear end internals seems to be ok.

The suspension stops have been replaced by longer ones, but I think that they are softer too, I am not sure how much they compress. I have also raised the rear about one inch to make more room for the 295/50-16 tires.

DennysDriveshaft does not ship to Sweden but there are other options. When I installed the 4L80E I bought a custom driveshaft from Strange Engineering and that came with the good Spicer jounts. I could get some custom chromoly halfshafts from there. They are heavier but I can live with that.

I will get the Van Steel billet caps.

I have an idea to use my old Dana 36 batwing and an adapter plate. I would extend it to the sides and also weld loops to it in case the inner joints would fail.

I have seen pictures where the pinion broke off from the differential housing. From what I read that happend when shifting to second on a manual ( unloading and loading ). Has it ever happened on an automatic?

Outer stub axels seems to break and also the spider gears. What are my options?

You could put an o-ring, rubber band, or some type of clip/clamp on your shock rod. Launch the car and see how far up the shock rod, the shock body pushes the device. Poor man's telemetry. :)

I never broke the pinion off the D44 housing with my automatic car..... I did break one with my 6spd car - Like you said it happened on the gear change.

The outer stub shafts are pretty strong on the pre-89 cars.... they are about 1.5" shorter than the 89-96 C4's with the wider suspension track. I only ever broke 1 outer stub in the years I ran my 84 on IRS.... and it had hundreds of sub 1.30 60fts before it let go. I just replaced both with stock stub shafts I bought off eBay and ran it for another year.... that stuff is still getting down 3yrs later in Rons (AKA - 89L98TPI) car running 1.40 60fts on radials with no problems. He's made hundreds of passes on it.

Summers Brothers will cut off the factory stub shaft then broach the left over yoke and press in a bigger 31 spline stub shaft. You also have to send them the wheel bearings so they can bore them for the bigger shaft....

https://www.summersbrothersracing.com/

Not much you can do about the spider gears, except keep the Posi clutches tight, so it can't slip one tire and overspeed the Posi spider gears doing a one wheel burn outs.... that is really how people kill the stock Trac Loks. Clutches get loose and they go doing huge burnouts with only 1 tire spinning.... pretty soon - BOOM!

Get a 36mm socket and a TQ wrench, jack one side of the car up and check how much break away TQ the Posi Clutches have...... Keep a log of your Posi clutch break away TQ. When it gets less than 75lbs breakaway TQ, shim or replace the clutch plates. Only use the Spicer PN 707018X clutch plate kits.

Take some time to read thru this D44HD Trac Lok build I documented for a customer of mine.... I put in a lot of effort to document it for the C4 Corvette guys. I have pics of a damaged D44HD Trac Lok Posi, pics of disassembly and what potential problems to look out for. Reassembly, with all the specs as well as how to set the the D44s up for racing.

http://www.corvetteforum.guru/modules/newbb/viewtopic.php?topic_id=17573&menumode=2

You can replace the Trac Lok with a "Detroit Tru Trac" gear driven Posi diff but they have their own problems. You can also machine a regular D44 spool to fit the D44HD IRS.... it's a bit of work to the spool on a lathe and a mill, fabricating a center support to go in the spool, and then some grinding on the inner stub shafts for retention bolts. I used a modified spool in my IRS for many years. Ron has it under his car now.

Will

Thanks! Some good pointers there.

I never had any problems with one wheelers. I will check the break away TQ. Good info on that rebuild!
The Corvette is a street car so I would rather keep the differential than install a spool.

It is good to hear that the stock IRS can handle that much after an automatic transmission.

Current action plan:
* Check the break away TQ and condition of differential.
* Adapter plate with half shaft loops for Dana 36 batwing.
* Van Steel billet caps.
* Stronger half shaft with the good Spicer u-joints.

I am also thinking about my custom built driveshaft. The 4L80E yoke uses a 1350 joint and the rear is a stock 1310. Both are the good Spicer type.
Do I have to worry about the rear 1310 joint? From my resaerch it seems like a 1350 yoke from a Dana 60 would fit the Dana 44HD. It would require modifications on the C-beam for clearaence.

I dont think you have anything to worry about with the 1310 in the drive shaft. Upgrading to all 1350s would be good insurance but I am not sure if it will clear the rear of the C beam or not. I never had any trouble out of the 1310s in my C4s drive shafts, so I never bothered to upgrade.
Will

The 1350 Dana 60 yoke does fit, and the 1350 clears the C-beam without any modifications. Mark Williams Billet Dana 60 Yoke. https://www.markwilliams.com/39014.html

On mine the 1310 yoke was almost touching so I did some minor grinding on the c-beam. That yoke also has the simple straps that I don't like any more.

https://cimg6.ibsrv.net/gimg/www.cor...1059049ed4.jpg

I finally made some measurements. I had the Corvette on the lift with transmission in park. I made a simple tool to put over the wheel studs and used a torque meter that store peak values.

https://cimg5.ibsrv.net/gimg/www.cor...51fe217e48.jpg
https://cimg4.ibsrv.net/gimg/www.cor...cba981ef66.jpg
https://cimg6.ibsrv.net/gimg/www.cor...3f9ad1a9a9.jpg
https://cimg7.ibsrv.net/gimg/www.cor...78bff251ac.jpg

Breakaway TQ was 304 Nm ( 224 lbs ft ) in one direction and 308 Nm ( 227 lbs ft ) in the other direction.
I don't see that having both wheels in the air and locking with park in the transmission would measure differently than jacking up one side like you suggested.

Still, that is tripple your minimum value.

I tried with the 36mm socket first but I started torquing the nut instead so that is why I made that tool.

Edit:
After thinking some more I probably get double breakaway TQ by locking diveshaft compared to locking other wheel.
Slip angle on friction discs will be doubled as the other wheel is turning the other direction compared to standing still.
I will meaure again to make sure.

I can not believe Ive been watching this thread since `2007. Awesome.

:cheers:

First part of this thread starts in 2005
https://www.corvetteforum.com/forums...o-by-joby.html

I bought the Corvette back in 1998.