Drop Rear Bar Size on Boss with 285 Square?

[ShifterX]

Yep the first set are the ones, plug and play, they were used in PWC.

Look THIS IS VERYIMPORTANT, I personally know of at least 2 Boss 302s that had under 2K miles on them that were recently purchased and ran on the track, BOTH blew the engines which, if I'm not .mistaken were related to valve spring issues. The problem is that these cars have been parked for over 10 years. Depending on where the engine landed when it was last run, some of those valve springs have been in the compressed .mode for over a decade. I would absolutely replace those valve springs before buzzing an engine at the track.

Would this be an issue for all coyotes or just the boss?

 

[blacksheep-1]

Would this be an issue for all coyotes or just the boss?

Well, in PWC, with the Boss 302R, we were allowed to change the rods, valve springs, and go .020 on the cylinders, eventually they allowed better oil pump gears, that's the way those engines came. Any semi competition engines over ..say 50 hours which was the overall life span of those engines before overhaul, I would think need to be replaced.

 

[ScoobtotheNoog]

Well, in PWC, with the Boss 302R, we were allowed to change the rods, valve springs, and go .020 on the cylinders, eventually they allowed better oil pump gears, that's the way those engines came. Any semi competition engines over ..say 50 hours which was the overall life span of those engines before overhaul, I would think need to be replaced.

No offense meant, but I'm not sure that information actually answered the question he posed, based on your statement to me.

 

[ShifterX]

My 2 cents worth... My Boss "feels" better with a small 18mm rear bar, but at the track, its much faster without. For a mainly street car I would probably run the rear with small bar. Running without is pretty much all about corner exit when racing.

What Black sheep said. These cars NEED camber/caster.

Thoughts on rear sway bar size when using the factory trac-loc? I will be saddled with this diff for at least another season so I need to make it work. I am pretty happy with the balance now on the stock 24mm rear bar. The diff is freshly rebuilt and tight. But...adding power with steering angle on slower exits provokes inside wheel spin. I may have to work on my driving by over rotating early in the corner to unwind the steering on exit. But back to the sway bar, thinking this out, no sway bar should help the inside spin, right? Or should I not bother using the sway bar to mask the poor diff action?

 

[Mad Hatter]

Thoughts on rear sway bar size when using the factory trac-loc? I will be saddled with this diff for at least another season so I need to make it work. I am pretty happy with the balance now on the stock 24mm rear bar. The diff is freshly rebuilt and tight. But...adding power with steering angle on slower exits provokes inside wheel spin. I may have to work on my driving by over rotating early in the corner to unwind the steering on exit. But back to the sway bar, thinking this out, no sway bar should help the inside spin, right? Or should I not bother using the sway bar to mask the poor diff action?

Its easy to take off the bar and give it a try. BUT!! the car will behave differently. Be prepared for corner entry understeer, so trail braking is critical to rotate the rear. The up side, and the point of the exercise, is corner exit where you can get very big gains.

Getting on the power sooner is really helpful. I have seen Cayman GT4 cars disappear in the mirror due to running a no bar setup.

 

[Dave_W]

Would this be an issue for all coyotes or just the boss?

I think there are two main variables at play here. One, the Boss has a higher redline / rev limiter than the GT, so when pushing hard on track it will stress the valvetrain more. Two, and by far the more important, is that there is very little chance of finding a 12-year-old GT with under 5K on the odometer, and an engine that has not turned over for years at a time. The issue stems from valvesprings that have been in the fully compressed position for a very long time.

If you're concerned about tracking an older car with very low mileage, valvespring replacement could be considered a preventive maintenance step.

If you're storing your car for long periods, I'd recommend to keep it on an intelligent trickle charger and crank the engine every month or two. A trick with some modern EFI engines (including Mustangs) is to apply & maintain wide-open throttle while cranking to trigger "flooded mode" in the PCM, which disables the fuel injectors. This lets you build oil pressure and flow in an engine that's not been run lately without the added stress of combustion pressures. It also avoids "washing" the cylinder walls with fuel.

 

[blacksheep-1]

No offense meant, but I'm not sure that information actually answered the question he posed, based on your statement to me.

Point I was trying to make is that those car had those recognized weak points from day 1. It may have gotten better with some of the new engines, ( except maybe the GT350 flat plane crank) but things like valve spring have a limited life at 7500rpm
.