Shifting Suggestions

[Wayne Elliott IV]

Hello, my Dad has put a lot of work into restoring our 49 Mack but we have had a lot of difficulty learning to drive the thing. We both can drive our stick shift ford and I got my CDL getting towards two years ago now. I have driven a few bigger manual trucks at work without causing any accidents but this transmission is completely unsynchronized. The thing is unpredictable and keeps us humble but we haven't gotten much enjoyment or use out of it for this reason mainly. I am familiar with double clutching and matching rpm with road speed but like I said this truck is difficult. Also I've heard these old trucks may have something called a clutch brake, and that this could wear out. The transmission may not be original and has a 5 speed stick with a second stick closer to the passenger side next to the too far to reach in an emergency brake. The original stick had a two or three way splitter on the stick that is now nonfunctional, and the second stick isn't a split rear end either I believe it goes to the transmission itself. If I get back home I'll try to find the numbers off the truck but for now I'm stuck at school. Any advice will be appreciated because its sorely needed.

[mrsmackpaul]

mate the clutch brake only works when the clutch pedal is all the way down to the floor so what this means is for driving and changing up and down gears DO NOT PUSH THE PEDAL ALL THE WAY TO FLOOR as no matter how well you try to match speeds the input shaft will stop spinning and grind every time the only time you will use the clutch brake is when you are stopped and what it does is stop the input shaft from spinning so that the shaft speeds in the box are matched ie both are stopped spinning other wise you have to sit and wait and wait and wait oh yeah and wait some more and if its a Mack Maxitorque better lite a smoke as those shafts weigh so much you will have wait a long time for those shafts to stop spinning and if the gears arent lined up you let the pedal back out to have another go at getting the shafts lined up again

So as you can see the clutch brake is only used to stop the input shaft from spinning when you are starting off

Another thing if you are coasting up to a stop and push the clutch pedal down to the floor and the truck is in gear the whole truck will be trying its hardest to tear the clutch brake out so you need to keep the pedal a inch or two off the floor when in use unless you are trying to start off stick with it and it will get much easier real quick once you under stand the way its meant to work also might pay to adjust the clutch to make sure there is enough clearance for the clutch brake to work correctly

hope some of this might help

Paul

[Wayne Elliott IV]

Thanks Paul I had hear that vaguely before but that makes it a lot more clear. I'm worried the clutch brake in ours might have been long worn out before we got it and we haven't done it any favors. The truck might also have an issue involving the carburetor that requires the hand throttle to be on slightly to keep it running, which means the rpm's don't drop very well. I've also heard that driving without a trailer is harder in the first place. I'm also confused as to the pattern of the gears...it isn't set up to split each gear with the second stick unless you're willing to drive from the center of the truck with an arm through the wheel. We've still wondered if that is how it's done though. I need to look up the numbers on the transmission to figure out what it actually is.

[blackdog2]

You only gain 3+4 miles per gear so it take practice patience and a little game of twister.

[41chevy]

. The truck might also have an issue involving the carburetor that requires the hand throttle to be on slightly to keep it running, which means the rpm's don't drop very well.

Your truck came from the factory with a 63-AW series Zenith Carburetor. Make sure the carburetor it tight to the manifold with no air leaks on the base gasket and the choke plate fully opens. If that's okay, than set the base idle on the carburetor to keep it running. Than turn the mixture screw(s) SLOWLY in or out to set the mixture. The RPM will raise and lower, turn the mixture screw(s) to get the maximum rpm 's. Than reset the base idle screw to 550 to 600 rpm. Paul

[1958 F.W.D.]

Check out youtube for some good videos on operating two-stick trannies.

[doubleclutchinweasel]

Lots of possibilities with 2-stick transmissions. Some are better. Some are easier.

Several ways to drive them effectively without a lot of "split-shifting", too.

I could split-shift the Quadruplex fairly successfully back in the day. But, it was sometimes okay to simply do your upshift on whichever box needed it first, then do the corresponding downshift on the other one. One guy saw me do that once and told me he had never seen anyone "triple-clutch" a truck before! I thought that was as good a description as any!

[fauthpk]

Sounds like the float might have a pin hole in it causing fuel to fill the bowl, which in turn will cause it to flood requiring you to raise rpm. if thats the case you will never be able to shift at right rpm which for me is 1200-1500. one of the greatest pleasures of owning an antique vehicle is being abe to go through the gears. also- make sure the tranny is full of gear oil.

zenith carbs the number is on the top. ebay is a great spot to find replacement bowls..

[mrsmackpaul]

one more thing I was thinking is if you are going to twin stick it only shift one stick at a time until you work it out a bit other wise if you stuff it up its all to easy to end up with trans stuck in neutral as the interconnecting shaft in the box can stop spinning and then the only way to get moving is to stop and start again

I always find the less I rush the easier it is so slow right down with the actions on the stick as a truck is heavy it will have heaps of momentum to keep it moving but the first thing is work out what the transmission is and then you can work out how shift it

Paul

[gearhead204]

find a quiet nearly abandoned level road to practice on, then increase the training practice once you master flat lander stuff, as said before you must get the engine running proper before the rest will function as designed. enjoy the father and son time together and......... don't tell mom all the new words that you found in your vocabulary!

[Swishy]

Twin sikn a Quadbox n grab n one stik thru the steer n wheel twaz all the go many years ago

Eye might B a rusty now but they say tiz like ride n a bike ...U nevr 4 get

LOL

A 1949 model may Have cum out wiff D Duplex box 5x2

cya

[mrsmackpaul]

Swishy I wonder if they do the same with a arm thru the wheel when the wheel is on the wrong side ?

Paul

[Swishy]

Mrs

Gudday M8

if Mr law man saw U swapp n cogz wiff one arm thru steerzman wheel probly B a hang n offence

LOL

[xdudebrahx]

If you have the TRXL107, you're in for a treat. I love driving mine. Floats like a dream and you never need the clutch except for starting off.

[Wayne Elliott IV]

Thanks for all the help ya'll I'll hopefully have some pictures and numbers after I head home this weekend.

[Wayne Elliott IV]

A (belated) big thanks for the carburetor suggestions and transmission information, everyone.  I've been distracted and lazy in getting back and reading stuff here.  I posted a couple pictures of the truck in the discussion about it's value (which has yet to be established...somewhere between scrap and priced of a restored truck as that is it's condition).  We are probably going back into the carburetor come May when I finish up school and I'll be sure to post the numbers and put the truck in the registry then etc.  The hole in the float suggestions is something we'll have to look at as that and maybe timing issues would be the main reasons I can think of why rpm's wouldn't drop quickly like they should (I don't know much, please float any and all ideas and corrections).

I read over the transmission advertisements and I noticed something the didn't quite fit:

This truck has a stick with a disabled air splitter on it that I assume corresponds to whatever transmission is down there, but the shift patterns on the cab roof (which match the shifter) look like the TRL078 *with reverse on the main stick.  Again it would seem that the second mechanical stick just replaced the air splitter function, but this second stick is just a hi-low with no reverse.  Dad claims that second stick connects directly to the transmission and not to any sort of added "Brownie box", I'll have to take a closer look but it's been a while since I looked under the truck.  It's titled as a 49 at least, makes me wonder about Swishy's duplex suggestion for that year.

In any case since the engine is a swapped in rebuild and the transmission setup isn't original, I need to get the numbers when I get home.

 

[j_martell]

The fact that the motor and tranny may not (are not?) original may be a HUGE part of the problem.....if they don't match, of course they won't work......

[Wayne Elliott IV]

j_

That is something to think about, it's a Mack flathead gas (Continental?) motor with a number that didn't match the original when trying to get the title worked out.  So that type of motor should be what the truck originally came with, hopefully same size.  For now I'm hoping the transmission is original (stick pattern matches the roof diagram) with a stick doing what the air splitter was originally supposed to.  If not then maybe this transmission and motor weren't supposed to be together.  If the truck was sent to Mack for the "refurb" then hopefully they are compatible, if it was done by the family we may have something botched together indeed.

Really wish I could go out in the yard and look at the truck, gotta wait until I get home but I'm excited to figure out what is actually under there.

- Wayne

[ekennedy21]

A Mack gas is made by Mack not continental. I wonder if the truck has or had at some point a 1 speed axle and that is what the air shifter on the stick is related to?

[j hancock]

29 minutes ago, ekennedy21 said:

A Mack gas is made by Mack not continental.

That is incorrect.  Continental made plenty of Mack flat head gasoline engines.

[ekennedy21]

really? I was under the impression they were made by mack and they also sourced engines from chrysler.

 

[41chevy]

7 minutes ago, ekennedy21 said:

really? I was under the impression they were made by mack and they also sourced engines from chrysler.

 

Chrysler 354 Hemi was used in a few  B-85F seriesl Fire Trucks and the RB series 413 was used in a few R-400 series 

[mowerman]

gotta chance to see one up close around 25 years ago,,,,oakland california mack dealer,,,had in there working on it R400 hadda chrysler V8...pretty cool...bob

[ekennedy21]

I saw a b-30 or B-42 (can't quite remember which) that had a Chrysler in it and the owner claimed it to be original. Any truth to that?

[wingman]

A tid bit  about the clutch brake, they only came on twin disk pull type, not single disk push type. The clutch brake is only used to make it easier to get in gear at a dead stop. Never push the clutch all the way to the floor while your moving along through the gears as you will prematurely wear it out. Most trucks built prior to and including the B-models (except with Cummins engine) had single disk clutches.

Edited April 18, 2016 by wingman
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