Air Throttle/730 Air Line Lengths

gus · October 05, 2011, 06:28:51 PM

I understand from other posts that the lines from the rear throttle air line "T" to the trans and governor should be the same length?

Mine are 18" and 10'!! So, before I buy 10' of line I just want to make sure this is correct.

Hopefully this will eliminate some of the strange operation of my 730.

Thanks

Eagle Andy · October 05, 2011, 08:17:40 PM

Yup Gus that's right , When i did mine from where I teed off both lines are the same lenth. mine works great

gus · October 05, 2011, 09:49:10 PM

Andy,

Thanks, what did you do with all that extra line, coil it?

Cary and Don · October 06, 2011, 09:38:53 AM

If the line's "T" is in the engine compartment, just move the "T" up the line and add the leftover to the short line. Napa also sells the line by the foot.

Don and Cary
1973 05 Eagle
GM 4107
Neoplan AN 340

gus · October 07, 2011, 02:33:42 PM

Don,

Just what I did after thinking it over and realizing your method was the simple way to do it!!

Haven't driven it yet but am curious to see if anything changes.

Eagle Andy · October 07, 2011, 09:01:16 PM

sorry Gus for not getting back to you sooner. But yes what Don said. I think mine were about 32 inches each from the Tee in the engine compartment. I was up in the north country for a few days.

06 Bill · October 08, 2011, 10:55:47 AM

Gus ! About 6-7 yrs ago a roadside air line repair dictated about 6" tee to servo & 4' tee to tranny never saw one
iota of difference in shifting etc. 25K miles ago, still that way no prob. 06 Bill

Paso One · October 08, 2011, 01:56:47 PM

FWIW The Fishbowl's that come stock with the V730 have the "T" in the same spot behind the air throttle and a 8 ft line (approx) going to the transmission. Short line to air throttle

I looked at three buses all have the same set-up soooooo it can't make that much of a difference if GM did it that way.

luvrbus · October 08, 2011, 03:08:52 PM

I thought the Fishbowl's came with VH9 Allison,the 740 in real buses (kidding guys) lol won't shift right with a Williams air and modulator if the lines are not the same length I don't think it would be important in transit bus with the low gearing

good luck

gus · October 08, 2011, 06:08:02 PM

Well, I really don't expect any change now that I have read the new posts.

After all that hard, dirty work too!!

Now that I'm on the subject, there are actually two lines to the 730. One is the 3/8" OD I just changed which is in the air throttle system. The other one appears to be 5/16" or 1/4" going into the trans about 6" aft of the larger one. It comes out of a reducer in the end of a larger air line which is obviously one of the original air lines which is attached at the top of the compartment to what appears to be a pressure regulator (Not the one on the air comp). What is this line?

luvrbus · October 08, 2011, 06:27:26 PM

Gus I have a 4905 here for repairs that regulator and line on it goes to a air bag on the transmission then to Stone/Bennett shifter and both lines are the same length from the tee going to the modulator and throttle on it the tee is at the bulkhead fwiw

good luck

Paso One · October 10, 2011, 08:04:54 AM

Quote from: luvrbus on October 08, 2011, 03:08:52 PM
I thought the Fishbowl's came with VH9 Allison,the 740 in real buses (kidding guys) lol won't shift right with a Williams air and modulator if the lines are not the same length I don't think it would be important in transit bus with the low gearing

good luck

Ha ha transit buses still shift

more times in a day that most highway buses

I didn't notice anyone suggestioning a 3/8ths line from the Williams air throttle to the back "T"

That was a on going suggestion awhile ago

Gus I appreciate you pioneering this as I am still able to equalize my hose lengths if it does make a difference

I chose to use the williams throttle and the stone bennett shifter along with my 4:10 rear axle gears just minor variations from stock ( LOL )

luvrbus · October 10, 2011, 08:32:49 AM

Paso, they don't shift much all the broke ones I been around 1st,2nd gear or the single stage converter was bad lol, I always thought if you could install a 3 stage converter in one the shifting would be a lot better and smoother

good luck

gus · October 10, 2011, 06:42:07 PM

Now I'm really confused? Is this air bag internal or external to the trans? I haven't closely inspected the small line connection but it appears to go directly into the SB shifter or trans. What is the function of the air bag?

I didn't realize until I got into the 3/8" line change that the smaller line even went to the trans. There are so many wires there almost the same size as the small air line it was hard to tell!

That small line is completely separate from the air throttle/mod line, it is reduced from the regulator line which appears to be about 1/2"?

There is no bulkhead T because it was originally a 4 sp. The air supply is the line from the foot throttle cyl to the T I just installed, then split to the mod and gov cyl.