bgiere

There was a thread that discussed these some time ago. I am wondering if anyone has used them and what their opinions are....

http://www.longacreracing.com/catalo...id=579&catid=9

mrbill_fl

I HAVE NOT used these, but spoke to someone who ran them.

IIRC, He liked them, except when there was a full course black flag.

I think the idea was you set them to say, 40psi, cold, and they would bleed off air as the tire got hot. but in a 10-15 min black or red flag the tires cooled and psi went to say 35, then they would have hard time getting back up to temp and pressure... so it was a disadvantage on the restart...

so depends on the likelyhood of a 'black flag all'

(he did stop running them, in SCCA IT)

Janni

This is a timely thread- I was just looking at these over the weekend.

My thoughts are this - based on the above caveat....

I'd probably start my pressures just a touch higher than normal (2-3 PSI) and still work them up instead of starting them at the max and allowing the bleeding off to start right away. But - would that make any difference? Once ou bleed the eccess pressure off - you bleed it off. Hmmmm....

Perhaps this is worthy of a call to Longacre to see how they recommend using them - as a "max PSI safety net", or as a way to start your pressures close to the max and start hard from the beginning of a race. Or - does it make any darn difference?????

Any other experiences????

bgiere

Janni, I was thinking the same thing...I think I'll give Longacre a call in the AM...I see there is a whole kit you can buy to set them up.

Janni

I am also wondering if this wold be legal in the group we run with - as it's a "spec" series and would thins be a mod, or is this just a better way to manage tire pressures?

We've determined that missing the tire pressure set up is much better if we miss HIGH instead of low - since hubby seems to be much more comfortable driving a loose car than one that feels dull. But - since he's a "drive with the throttle" kind of guy, he wreaks havoc on the rear tire pressures.

Looks like Longacre will be a little busy in the AM. There also seems to be several type - and some that are "quick change" or some that you can add air through, etc. I also want to know if we could use the existing valve stem hole - otherwise - drilling the rim half on the BBS's could be a pretty costly experiment. Sigh.

Oh - and one other thing - I have seen some others (not sure of the source) that says they go up to 41 PSI instead of 38. I think I'd prefer the max up around 39/40 myself..... but - if the Longacres are easier to use - I'd deal with it.

I'll keep you all posted - and Brant, please do the same, OK?

bgiere

will do!

JackOlsen

Years ago I bought a set of these. I read through the manual, and now I can't understand their appeal to anyone for anything other than maybe street driving. You have to calibrate and run a test on all four valves whenever you want to change pressures, right? So that's at least one session lost to getting uniform pressures all around -- maybe two. I guess that's fine if you have one maximum tire pressure that you want for all of your tires on all tracks and under all circumstances. But I run different pressures on different tracks, and I run different pressures in the rain versus dry, and in different ambient temps -- and I've been known to throw on a new set of tires at the track that maybe aren't the same brand/model I had on there previously. I also tweak the car's handling with F/R pressures.

All of this would become a huge pain in the butt with these bleeders, unless I'm reading the literature wrong. Isn't it easier just to check the tire pressures after each session?

daigo

Misconceptions
There are a few misconceptions about these valves on this thread. I have used these in the past and they’ve worked incredibly well. The only PIA is that they must be absolutely clean. Easy to do, but you can’t neglect.
The comment about Black flags is confusing and maybe I don’t understand the point. The purpose of the valves to run your tires at the pressures you optimally run at full temperature. In other words if one is currently running 39lbs of pressure when their tires are up to temp, then you would set your valves to 39lbs cold. As your tires heat up, they will bleed off pressure to keep the pressure at 39lbs. There is no difference in the amount of pressure loss during a black/red flag whether you’re at 39lbs hot with the valve or without. The benefit is the first couple of laps. There is no question your tires are suffering greater wear and tear as it rolls on it’s sidewalls until the temps come up. In the spec series I was running in I had a huge advantage during the first couple of laps.\
Hope this helps

mitch236

In my opinion, this is just another part to fail. Why is it needed in the first place? If you have a good handle on pressures, and you should, you won't need this valve.

bgiere

Does a hole get drilled in the rim or do you use the valve stem hole?

Gary R.

While I agree with your logic Mitch I think Daigo explained the benefit well. Along with being able to start out with the correct pressure you also don't have to worry about ambient temperature variations and knowing what your tires do at each different track. At Watkins Glen I start at 31R 30F and if it's around 80 degrees I get to my ideal 38/37 after a lap or two. At LRP I put an extra 1.5LB into my right front to start. At Summit my first day my left rear gained 11.5LB after a few laps (went to 42.5) and I felt it (all others were close). Would be nice (if they work consistantly) to have the right pressures at all times!

Just MHO...

mrbill_fl

HONESTLY, I'm not sure I understood that drivers comments on the black flag either. but thats what he said.... and he did stop running them. so I didn't look into it futher.

he also said if they got dirt in them they could stick..

kurt M

The full kit comes with a pressure setting tool that you use to set, test and reset as needed anytime before you install them on the rim. The part that controls the pressure bleed off is removable without loosing tire pressure so you can test and change easily. Jack Olson’s thoughts on setting pressures and loosing track time is not true. You can, in fact, set the max pressure before you ever hit the track so in fact it is quite the opp. Running Hoos and want 40 psi max? Set the device to 40 psi, put 40 psi in the tire and go. No need to add and remove between runs until you get it right and worry about over expansion damage. You can install in the existing stem hole or drill new on opp side of rim.
The device only limits the max pressure. If you tires get cold and the pressure drops during a long yellow or black flag they will drop and come up the same as if you did not have the system installed to start with.

The only real problem or issue you need to address is keeping them clean so they don't leak.

daigo

Thats exactly right. I've never met anyone who knows how much to adjust cold pressures as the ambient air temps change through out the day, or from day to day, and achieve the same hot pressure. Then there's the concern of where the tires are sitting before the pressures are checked. There are so many factors. With reliefs you have optimum tire pressures period. They must be clean though. It's a great job for my wife and kid...lol.

bgiere

By "clean" do you mean the insides of the tires? or the outer valves? I guess i need to see these up close to get an understanding.