Time for an update. We took a vacation to see our kids at the end of June so the car sat until we got back. Now it was time to do the 4.10 axle thing.
I had bought a spool from a member here so I got another 489 case and a new set of 4.10 gears and had it set up by a local axle shop. When I pulled the axles, I was happy to confirm the car has the bigger 35-spline Moser axles. Those things are a lot bigger diameter than my memory is of stock axles! So in went the new 3rd member.
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I also lashed the valves and worked to seal up a pesky LH valve cover leak. Even with those big cushy Moroso blue gaskets and the fabbed covers, the LH cover is determined to make a mess of things. This time, I THINK I found a pinhole in a weld and put some RTV on it. But just to be safe, I also put RTV around the whole lower edge of the cyl head/valve cover joint surface. Time will tell!
Now let's get to the track and try this new rearend out. Nope, Mother Nature refused to cooperate and gave us rain for 2 weekends straight and then every track in a 2 hour radius had some special event the next weekend! Bikes, donks, you name it...no place to race. So this past weekend, it looked like it may rain on Sunday so we decided to take the car to a TnT on Saturday. I need practice and need to try a few things so off we went. We got there almost 3 hours after they opened but were able to get 5 runs in, basically limited only by the time to let the car cool a bit between runs. DA was 3780 - it was 90 degrees.
Something to note...the TC stall speed was unaffected by the 4.10 axle ratio compared to the 4.56 that was removed. Flash stall remains right around 5000 rpm. Burnouts are better as the wheel speed is obviously faster with the 4.10. The car dead hooked every pass with the rear CalTracs doing their job. Maybe the new rear shocks helped too? Not really as this car has hooked well since i got it. The car has quite good rear lift/body separation you can see here.
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The front end gets light but no more daylight under the tire like with the 4.56. As for performance, well, no comment on the first 2 runs other than driver error. Runs 3-5 were spent playing with shift points. In this air, each run kept improving and the last run was an 11.52/113.5 mph. That compares to its previous best with the 4.56 of 11.31/115.3 on a day with a DA of roughly 1950 (67 degree day). If I would have made another pass, I believe it would have knocked out an 11.4x so all in all, pretty happy with how it performed.
The one thing that did not change was the 1/8th mile ET is quite quicker than the 1/4 mile ET. Meaning with its 7.25 1/8 mile time, the online 1/4 mile ET estimates would put it in the 11.30's. Not much different than last year's 7.11 1/8 mile went 11.31 but the online numbers would predict 11.1x's. More to come on that. Maybe the Super Victor intake is not ideal for an engine shifted at 6300? I have an Airgap for it if I feel inclined to make the swap one day.
Because we were late getting there, I still have not done any jetting in the 850DP. It has 83/82 jets...completely backwards from what it should have but I'm changing one thing at a time and this has not yet been done. I would think something like a 79/84 might be better but changes will have to wait for the next track day.
Pic below just for fun. The track has a guy that does the water box and pulls you in and he clearly loves his job. Points at you to see if you're ready, pulls you in and stops you at the water exit, big arm wavings to start the burnout, and a big hop and pointing down track for the finish. For him, every car has John Force driving and he makes for a good time! You can see him motioning below to hold/keep the burnout going. Wish everyone had the exuberance for their job like he does!!
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