Jump to content

Recommended Posts

Sorry

Right side

4KB 5122A

LFC

4 24 66

Left side rear

Part no 281KB531

Thanks

Share this post


Link to post
Share on other sites

Hi Day;

I'm looking for a number such as TRQ7220 or just Q7220 or something along those lines.

The 4 24 66 I believe means the transmission case was either cast, (if raised), or manufactured, (if stamped) on that date. Either way it appears to be a replacement transmission.

Share this post


Link to post
Share on other sites

I'll try again tomorrow.  Where should I expect to see these numbers?

Thanks

Share this post


Link to post
Share on other sites

Should be on the left side of the main case. About centered. The numbers will be hand stamped; not cast into the case.

Share this post


Link to post
Share on other sites

Many thanks.  Tranny is pretty clean, and does not appear to leak much.  I'll scrub it up and find them.

Share this post


Link to post
Share on other sites
Posted (edited)

What size are the tires? Look to be 11X24 from the photos earlier. 

Edited by Rob

Share this post


Link to post
Share on other sites
1 hour ago, Rob said:

Should be on the left side of the main case. About centered. The numbers will be hand stamped; not cast into the case.

Should be right behind the fill plug.    terry:MackLogo:

Share this post


Link to post
Share on other sites

Many thanks for the suggestions, guys, otherwise I wouldn't have found the numbers.

They are:

TR 7220
3K610
11KBA3648
AP51

Share this post


Link to post
Share on other sites

You are missing a "Q" after the "TR" which denotes a quadraplex transmission. You don't have a "Brownie" behind a five speed do you? The "TR" only is a five speed. The 11KBA number is a Mack number. The others I don't know without research as it's been a long time for me.

Sounds as if you have the transmission I originally thought being a TRQ-7220 which is all cast iron case and double overdriven. I'll look later for a top overdriven ratio. Still need to know the size of the tires too.

Share this post


Link to post
Share on other sites

Rob:

What I have I believe is called a "married box", which is to say that the main and auxiliary are bolted together as an integral unit w/o a driveshaft between them.  Both the main and auxiliary have Mack labels, and are clearly meant to be a unit.

Should I look again for the Q?  It's very possible I missed it; these stampings were faint at the best.

Thanks

Share this post


Link to post
Share on other sites

I would say your rear end ratio is either 8.15 or 9.02's if you have 11:00 tires.

Share this post


Link to post
Share on other sites
23 minutes ago, dayradebaugh said:

Rob:

What I have I believe is called a "married box", which is to say that the main and auxiliary are bolted together as an integral unit w/o a driveshaft between them.  Both the main and auxiliary have Mack labels, and are clearly meant to be a unit.

Should I look again for the Q?  It's very possible I missed it; these stampings were faint at the best.

Thanks

I'm sure the "Q" is there. Those stampings can be faint but if you know it's a quadraplex that is probably good enough. The shifting legend plate in the cab will denote and 18 speed transmission as there are two sets of gears that almost overlap so of no practical use.

Share this post


Link to post
Share on other sites
10 minutes ago, BOB DINGSDALE said:

I would say your rear end ratio is either 8.15 or 9.02's if you have 11:00 tires.

The ratio I listed earlier are the only ones offered originally. I don't see 902:1 listed in the series differentials these are.

Share this post


Link to post
Share on other sites

It's raining out here, as usual.  Can't mow, and nothing else to do, so tomorrow I'll go out and 

1. check tire size
2. take a pic of shifting legend, which I believe I transplanted from old cab before repaint.  (Got rid of that putrid green color they put in the interior of these trucks originally.)
3. look again for the elusive 'Q'.  It's dark as the inside of a cow under there.
4. take a pic of the whole tranny

i really appreciate the advice and help.  I'm particularly interested in whether this tranny is original.   Don't know a whole lot about this truck, other than the fact that I got it with a bum engine, no bed, and had to reconstruct it from scratch.  

I will say, after all the work I've put into this truck, that Macks are not disposable  commodities--at least the B models, which is all I know.  Everything on this truck was well built, and, if broken,  is very fixable.  I can't say that about most of the stuff I deal with anymore.

Best Regards,

Day Radebaugh

Share this post


Link to post
Share on other sites
10 minutes ago, dayradebaugh said:

It's raining out here, as usual.  Can't mow, and nothing else to do, so tomorrow I'll go out and 

1. check tire size
2. take a pic of shifting legend, which I believe I transplanted from old cab before repaint.  (Got rid of that putrid green color they put in the interior of these trucks originally.)
3. look again for the elusive 'Q'.  It's dark as the inside of a cow under there.
4. take a pic of the whole tranny

i really appreciate the advice and help.  I'm particularly interested in whether this tranny is original.   Don't know a whole lot about this truck, other than the fact that I got it with a bum engine, no bed, and had to reconstruct it from scratch.  

I will say, after all the work I've put into this truck, that Macks are not disposable  commodities--at least the B models, which is all I know.  Everything on this truck was well built, and, if broken,  is very fixable.  I can't say that about most of the stuff I deal with anymore.

Best Regards,

Day Radebaugh

If that green were not original I would not like it either. However that being said I do like it for that aspect only. Don't really need to measure the tire size, just relay the size imprinted on the sidewall. Pretty certain you have either 11X24, or 10X22 given the "look" of them from the photos. Most likely being the 24" series given the heavy specifications of the truck.

The older truck were made to be repaired and supported as such. They weren't such a throw away item as much is today.

As mentioned earlier the transmission is probably a replacement from what I suspect is a date coding. Nothing to really be concerned with as parts wear out and a heavy truck wearing it's transmission out is normal. It could be from another truck, or a rebuilder unit from an independent shop. Regardless if nothing wrong, nothing to be concerned with.

When I was a pup there were still a few of the B series earning their keep by working. I worked on a few but the R series had long replaced the B series by then. The book I'm looking through for your information was given to me by a Mack dealership mechanic in St. Louis when I was probably 12 years old and I've always used and cherished it as it contains information you'll not easily find elsewhere on the series. 

Share this post


Link to post
Share on other sites

Rob:

Further details:

1. Tire size 1100-24
2. Pic of shifting legend.  It reads "14-speed quadraplex transmission with main direct in 4th speed"

0606191113b.jpg.323786735ab38c35f9664755d24ef2db.jpg

3. Found what must be the Q, so it reads TRQ 7220
4. Pic of transmission:

0606191120a.thumb.jpg.3f4056318fe399389b85f3fdf717c4a8.jpg

Thanks for your help.

I grew up in Detroit, and watched with fascination the building of the Interstate system.  Particularly intrigued by the "Michigans" which were hauling rock and gravel.  Mostly Autocars then.  My Dad worked at Detroit Diesel, and so did I for awhile.  He was a salesman for Detroit Diesel, and they were experimenting (this was the '50's) with repowering a variety of trucks with Jimmy's.  He would drive home the latest project they were working on.  Still love the sound of a high-revving Jimmy 2-cycle.

Share this post


Link to post
Share on other sites

Being a double OD, you lose a few more gears then a Single OD transmission has.  You don't split 5th, since it is OD, thus it is only a 14 spd   Once you get to 4th OD, the last shift is moving the main box to 5th which completes the double OD.

Share this post


Link to post
Share on other sites

Yes, that's exactly my understanding of how it should go.  That is, when I get to 4th Direct (which I think you're calling double-OD) I then shift up by going immediately to 5th Direct.

Don't completely understand the nomenclature on the tranny.  I take it that a) the first OD is what is term HI-Split; b) the 2nd OD would then be what is called Direct.  Is this correct?

I should have 5x4=20 speeds.  How do I end up with 14?  I see that I lose 3 in 5th main by not being able to run 5th in LO-LO, LO-SPLIT or HI-SPLIT, so I'm down to 17.   I must lose another 3 speeds somewhere.  Could it be that I can't use the full auxiliary range in 1st main?

Anyway, plenty of gears for what I need, and thanks for the education.

Share this post


Link to post
Share on other sites

Correction:

When I get to 4th HI-SPLIT (which I guess you're calling double-OD) then I go directly to 5th HI-SPLIT.  So Direct must be OD, and HI-SPLIT must be double-OD?

Thanks again.

Share this post


Link to post
Share on other sites

Don't get all 20 because of ratio overlap or redundancy which is noted by the asterisk.

Here is a chart with the ratios so you can see what you have. 

Mack Quad Ratios.jpg

Share this post


Link to post
Share on other sites

Each box has its own overdrive, when you start off in 1st in the main and first in the aux, shift the four in the aux. put the main in second and put the aux.in low split, then direct and then hi split, when splitting the main box you do not use lo-lo in the aux. do this to 4th in the main and the aux. is in hi split. your last shift is fourth in the main and hi split in the aux  to fifth in the main. sounds confusing but just takes some practice.     terry:MackLogo:

Share this post


Link to post
Share on other sites
Posted (edited)

Clear as mud LOL!!

In a std single OD transmission, once in 4th/HI, you go to 5th/LO.  Once in 5th/direct you are direct drive.  Then the overdrive is when you shift the compound to OD.

In your transmission, 4th/direct is direct drive.  Then 4th/OD is the "first" overdrive.  The last shift is 5th in the main box, which basically doubles the overdrive ratio.

Edited by Freightrain

Share this post


Link to post
Share on other sites

Many thanks for this information.  I believe I get it now:

1. I lose LO-LO across 3, 4 and 5 in the main.  Minus 3 gears, down to 17.
2. 5 LO is useless, since you've been there already with 4 DIRECT.   Down to 16
3. 5 DIRECT redundant to 4 HI.  Down to 15
4. 2 LO-LO gone as well, so down to 14 effective gears.

Conclusion:

1. Forget about LO-LO unless loaded;
2. Unloaded , option 1: 2(LO/DIRECT/HI), 3(LO/DIRECT/HI), 4(LO/DIRECT/HI), then 5 HI--unnecessary, if unloaded
                                     2:2(DIRECT/HI), 3(DIRECT/HI), 4(DIRECT/HI), then 5 HI--also unnecessary, if unloaded
                                     3:1 (HI), 2(HI), 3(HI), 4(HI), then 5 HI--perfectly OK
                                     4. Better yet: 1 (HI), 2(LO/DIRECT/HI), 3 (HI), 4 (HI), then 5 (HI)--a little easier getting going

Opinions?

Share this post


Link to post
Share on other sites
Posted (edited)

I would not worry about starting anywhere near 1st gear.   You've got plenty of gear in the back, as that 13:1 first gear, plus 8.x in the back is 104:1 to the tires.   

With my added Spicer box behind my triplex in LO-LO, my lowest gear is 100:1 to the tires.   Believe me, you don't need that to get moving.  I only use that for slow truck races LOL!!


Figure about 3rd gear for getting moving.  Might even get 4th LO??

Edited by Freightrain

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


×
×
  • Create New...