Shutting car off while in gear
 

I can't ratchet up to neutral through the finish line. Is it safe to shut car off while in third gear through the traps? Will that stop the pump and lose lubrication in the trans? I want to check all the plugs after a run.

Re: Shutting car off while in gear
 

Bobby,

I do not know the solid answer but to me, it seems like a potential problem. I have visions of the pump pressure slowly bleeding off and causing what ever clutch pack is engaged to slip. A one time deal might be OK ??

In my opinion, I think your plug reading would be acceptable to just stop as quickly as practical and switch engine off as you near a stop.

Re: Shutting car off while in gear
 

Bobby, would be best I think to contact whom ever built your trans and run it by them first.

Re: Shutting car off while in gear
 

Bobby,

Congratulations for making it to the final at Atco last weekend. Great driving, and a close race.

Don't know what you have for a shifter, but the quarter stick shifts very easy from 3rd to neutral in a C4 with a reverse pattern. Pull back the lever and push right up. I had one for years before going to a PPP pneumatic shifter in my super stocker.

Another solution would be to call Joel's for a valve body with an electric neutral. I've heard mixed reviews about them, but I think that they make the only clean neutral valve body for a C4. I'm probably going to go that route too, since shifting back from 3rd with the PPP leaves something to be desired. You're almost waiting for that moment when it gets hung up in the pattern, and you don't reach neutral.

Good luck.

Re: Shutting car off while in gear
 

Clean "N" valve body will be the best and safest investment you can make
Call Joels he will set you up 248- 446-6024

Re: Shutting car off while in gear
 

Wouldn't it just be safer to switch to a forward pattern valve body?

Re: Shutting car off while in gear
 

Might be off base but would it work to use a wide band o2 and record somehow it's readings over the 1/4 mile. Even w a go pro videoing it

Re: Shutting car off while in gear
 

We have one of Joel's electric neutral setups and it works great. In fact I probably use it more than I should. Return road etc.

Re: Shutting car off while in gear
 

I asked the same question to someone I consider an expert and his opinion is that the neutral on a forward shift is a natural neutral but not a "clean neutral. Something about the path of the fluid in a natural neutral is totally different from a "clean neutral". He has both types of valve bodies and still recommends the clean neutral for shifting on the top end. I bought the clean neutral one for myself. Even though I had to purchase a new shifter also. Oh the PPP is now my shifter of choice.

Re: Shutting car off while in gear
 

Thanks, I didn't realize this. I guess I better ask my transmission guy some questions.

Re: Shutting car off while in gear
 

I've run it by my dad a few times.. he doesn't seem to think it's a great idea lol, so I ran it by you guys instead!

I use the B&M Hammer which is a ratchet shifter so I can only go one gear at a time which makes up to neutral impossible. It's not a huge deal I do run an o2 sensor in the collector that records the entire run and that has helped tremendously in tuning but my next objective is to get each individual plug reading the same which is a great perk of EFI.

Re: Shutting car off while in gear
 

For what it is worth ATI doesn't recommend it at all - even with a Clean N. Once for a plug reading, okay that is cool. But the guys that do it ever pass are just reducing the life of the unit. In the pits, on the track, doesn't matter. When the engine is stopped, the transmission pump is not moving any fluid to lube the gearset that still being spun by the driveshaft.

Re: Shutting car off while in gear
 

I've been told in a TH400 clicking it into neutral causes the driveshaft becoming the driver and the way it multiples will cause one of the drums to spin to 20000 rpm+ and it can go boom.

Re: Shutting car off while in gear
 

Could somebody explain what "clean neutral" means. I have a reasonable understanding of automatic transmissions and have heard this term many times but never an explanation. Thank you, Louis Jeffery

Re: Shutting car off while in gear
 

Clean neutral valve bodies dump the forward clutch and keep the direct clutch applied so all the gear train rotates at the same speed. The engine has to be kept running (idling) to keep the direct clutch applied.

Jim Mantle V/SA 6632

Re: Shutting car off while in gear
 

I've put many runs on both a Coan XLT-350 and a Pro-flite with clean neutrals shutting off above 10,000 RPM. Never had an issue with either, tear down at end of season shows no signs of unusual wear. I have noticed it seems to take longer for the T-350 to "let go" of the engine not sure why but never caused a problem.

Re: Shutting car off while in gear
 

The reason it takes so long to dump the clutch at high rpm is due to the fluid in the clutch drum. As the drum spins the fluid is centrifically forced to the OD of the drum and effectively creates a higher pressure on the clutch piston. The feed for the clutch is closer to the centerline of the piston. When you want to dump the clutch, a valve opens and exhausts this feed channel, the problem is that the spinning drum keeps high pressure at the OD of the piston, and limits how much oil can be moved to the centerline of the piston. Most pistons or drums have a small check ball that is machined close to the OD of the drum. When the clutch pressure drops to a designed value the check ball comes off its seat and exhausts the clutch oil. At high rpm the clutch centrifical oil pressure may be too high to unseat the check ball and basically keeps the clutch on. Some tranny builders know this and drill a small hole (constant bleed) near this check ball, That is a "fix" to try and get the clutch off quickly, and is unaffected by rpm.