Duplex top case covers

[SuperB]

Hello everyone. I'm trying to figure if there was more than one style top cover used on the duplex 10-speed transmissions, and I was hoping someone could help. I just removed the older model duplex from my truck. I think it's a late 50's and it's a TRD-72. I have the correct year and type transmission for my truck all ready to be put in, and ran into a problem. This transmission is a 1965 TRDL-722 aluminum 10-speed. The issue is that the hand brake mounting is different between the two. In trying to figure it out, it looks like my 1965 transmission actually has the triplex style top cover even though the transmission's part number is right for my '65 B61. Its has the provisions for attaching the small triplex shifter box/housing on the driver's side. I guess that doesn't necessarily mean this cover is wrong for my truck, but it would require a different hand brake mounting bracket than what the TRD hand brake has.  

Any help in figuring this out would be really appreciated, I don't have any info on this in any of my books or manuals, and I can't find any pics online either. Thanks in advance 

[Geoff Weeks]

I would think anything by 1965 would have spring brakes? The requirement came in in the very late 50's IIRC

Edit: I am having trouble finding a statute that spells out exactly when "self applied" e brakes were required, so I may be wrong. I have always seen auto applied spring brakes on stuff newer than the 50's.

Edited Tuesday at 02:12 PM by Geoff Weeks

[SuperB]

According to the build sheet for my '65 truck, it came with a handbrake arrangement. Also, the transmission I'm putting in had the brake drum assembly on it when I bought it. That's all I have to go on though, unfortunately. I don't have any parts diagrams for my particular truck/transmission.

[Geoff Weeks]

I stand corrected.

It is like the "no recaps on steer" on trucks, everybody says it, but that isn't what the law says. I thought spring brakes were a requirement on stuff newer than early 60's late 50's.

Tru-Stop disk driveshaft brakes would meet the stopping requirements (I was told) but lacked the self-applied function, so they faded away from use.

[h67st]

I have TRD-67 and TRD-720 transmissions in mine, I may have a spare brake mount if you can post a photo of what your transmission looks like (where the brake mounts).

[SuperB]

Thanks for the replies.

The greasy thing is the early TRD-72 duplex that I have the handbrake from. It attaches with the 4 backed-out bolts.

The 3rd picture is the TRDL-722 duplex. It's the exact transmission the truck originally came with, but I don't understand the difference in the case covers. This cover looks like a TRT triplex cover without the small compound shifter box installed. I think the handbrake on a triplex would attach to the side of that shifter box, but i'm not 100% positive

[h67st]

Well, I can't help there...my trucks are H67 and they have a completely different mount than that. Is that the handle mounting? My handle mounts on the cab floor.

[mechohaulic]

1 hour ago, h67st said:

Well, I can't help there...my trucks are H67 and they have a completely different mount than that. Is that the handle mounting? My handle mounts on the cab floor.

the cab overs will be totally different . hand brake mechanism  goes up/down inside with tilting the cab, with cable going to hand brake drum assembly on transmission. the B which assuming is the truck being repaired will have the handle set up bolted to interior floor ;;; linkage connecting to transmission.

[Freightrain]

Ok, that bottom picture is a top that could be used with a Triplex.  The two horizontal holes in the front corner are for the shifter mount.

Remember, a duplex has the compound on the RIGHT side of the main.  Tri and Quad are on left side.  A duplex would not need those two holes.  So maybe the "early" lid was not universal fit.

Yes, your brake handle would need shimmed up about an 1/8" to clear the two lumps for the cross bolts.  I am not sure where they mount a brake on a trip/quad?  

 

[SuperB]

I agree with what you said there Larry. I kind of think Mack just finally decided at some point to use the same case covers for all transmissions, duplex, triplex and quad, since it would work for all 3. They probably just revised the brake mounting bracket for when the cover was used on a duplex.

I'm pretty sure those two bolt bosses on the side of the compound shifter housing in your picture is how the handbrake is mounted on the triplex and quad. The rear bolt boss even sticks out further to create the correct mechanism angle that my original one has when it's bolted on.

I feel confident now that I can go ahead and install the transmission knowing this case cover is the right one and won't have to come back off. Hopefully I'll be able to find the right brake mount for this transmission, and just make my old one work for now.

Thanks guys 

[steve s.]

I have a hand brake setup that I removed from a Quadruplex. I think it may be what you are looking for, but I will have to find where it is in my cluttered garage. I will get back to you. 

[mechohaulic]

2 hours ago, Freightrain said:

Ok, that bottom picture is a top that could be used with a Triplex.  The two horizontal holes in the front corner are for the shifter mount.

Remember, a duplex has the compound on the RIGHT side of the main.  Tri and Quad are on left side.  A duplex would not need those two holes.  So maybe the "early" lid was not universal fit.

Yes, your brake handle would need shimmed up about an 1/8" to clear the two lumps for the cross bolts.  I am not sure where they mount a brake on a trip/quad?  

 

another BMT bit of info I never paid attention to ::: duplex right side /tri & quad left. thanks . must be late =have to type with one hand (left) right hand going through shift patterns LOL !! like transmission holder  and clean shop