More Frame Questions

[nam vet]

I got the frame/transmission mounts swapped from the diesel frame over to the gas motor frame. Everything seems to be in the correct position now for the diesel motor that is in the gas frame,  but when I try to line up the holes in the trans mount to go thru the rubber mounts I need a pry bar to get one side lined up,but then the other side doesn't line up. The truck that originally had a gas motor in it{now converted to diesel}was a double frame truck. It looks like the double frame goes inside the original frame. The double frame is 1/8 thick x2 sides makes everything 1/4in narrower than a stock frame. Does anyone know if there are special trans mounts for a double frame to compensate for this 1/4in difference? I am thinking thats my alignment problem,I might have the wrong mounts. Thanks for the help.

[doubleclutchinweasel]

On a lot of the single-frame stuff, there is just a spacer to take up the space where the inner frame rail would have been.  I saw this in several spots on mine.

[Vladislav]

I didn't work with B-models but noted such a fact on a R-model. Ok, R and RD. Transmission mounts looked pretty similar, I'm even sure the casting was the same. But those off a RD were milled off more over the mounting surface to compensate the thickness of the frame inner rail. My R-model has a single frame and its original tranny mounts had that "excessive meat". So I couldn't use RD mounts or would need to add spicers as DCW mentioned above.

Also I got a trouble using a rear crossmember off a single axle R-model to be installed into a double frame, also R-model. Just couldn't fit it in since it was wider. At the same time some spots utilize spacers, that's true. For example a bracket for a torque rod attaches to the frame rail with a spacer. Looks like you don't need it if use that same rod and the bracket with a double frame. I talk regarding a R-model again, to be clear.

[Vladislav]

P. S.

Inner rails are 1/4" thick, each one. Same thick as the main rails in many cases. 1/8" is too thin for that application.

[mattb73lt]

I've seen cast spacers and washer stacks underneath transmission and motor mounts on trucks I've parted out. If the alignment is good the bolts should go right through the mounts and bolt up, you shouldn't have to force them and they shouldn't have any preload on them. Pictures of what you're dealing with would be really helpful to help us see what's going on to help you? 

[nam vet]

Thanks for everybody's help. My tech skills are not that great but I will try and post a few pictures in the next day or two Thanks again

[mattb73lt]

There are variations to what Mack did. Most frame and transmission mounts were cast. Gas and diesel mounts are different as we discussed. Just for general info, there is a difference in single and double clutch arrangements, too. Double disc clutch’s require a 1” deeper bell housing on the transmission side, moving the transmission back 1”. Mack used an offset welded mount made out of 1/2” plate. They’re roughly made and not cast. My B73 has these. If you look at these pictures you can see the off set. Most mounts bolt directly to the frames and transmissions.

[doubleclutchinweasel]

Even your transmission is gorgeous, Matt!  Triplex or Quadruplex?

[terry]

5 hours ago, doubleclutchinweasel said:

Even your transmission is gorgeous, Matt!  Triplex or Quadruplex?

Looks like a triplex to me.    terry

[mattb73lt]

Triplex. TRTL-720 to be exact. Double overdrive, double disc clutch and a clutch brake.

[nam vet]

Yikes Matt, I was going to try and post pictures of my problem with my trans mounts but after seeing your trans pictures I am embarrassed to post any pictures. My truck sat deep in damp weeds and exposed to salt air for almost 5 years. I have the market cornered on rust. You do some really nice work. Congratulations.

[mattb73lt]

No worries, post away. That transmission and frame was a dirty mess when I found it. 350K + miles and left in a field. It wasn’t a magic wand that made it look like that.

[h67st]

I like the mouse poison block on your shop cart! SOP when you have a barn, old truck, old car, anything like that.

[Mark T]

On 7/18/2023 at 12:04 PM, doubleclutchinweasel said:

Even your transmission is gorgeous, Matt!  Triplex or Quadruplex?

EZ there DCW...... you're lusting for a tranny

[Geoff Weeks]

23 hours ago, mattb73lt said:

Triplex. TRTL-720 to be exact. Double overdrive, double disc clutch and a clutch brake.

Does it use a Push type double disk? I thought I saw a "nose type" front bearing retainer and no upper cross shafting.

[mattb73lt]

9 minutes ago, Geoff Weeks said:

Does it use a Push type double disk? I thought I saw a "nose type" front bearing retainer and no upper cross shafting.

Push type. I hadn’t put the cross shaft and fork in yet when I took that.

[mattb73lt]

BTW, I’m not trying to hijack nam vet’s thread, just trying to give him some visuals to help with the issue. TY.

[nam vet]

 

Its been interesting but I think I have my problem figured out. Over the past few months I have posted questions about engine length,engine placement and trans mounts. I figured out my problem was gas engine tranny mounts on a diesel engine which pushed the the whole deal forward about 2 1\2 in. After putting the correct mounts on the tranny and pushing the whole combination back into the factory position I still couldnt get the tranny to sit in the correct position. After a few days off to clear my head I started with a fresh outlook. After much investigation,the pictures show what I found. My truck is a 57 B with the emergency brake drum on the driveshaft. The linkage for the e brake setup was sitting on the air tank, holding the trans up just enough so nothing would line up correctly. Moved the air tank back and everything fell into place and the leaning motor straightened up better. Thanks to everybody for all your help and I am sure there will be many more questions.

[mrsmackpaul]

Very good result there

Some times a moment's break to stop and think is all we need, good find

 

Paul