1975 RS685LT

[terry]

5 minutes ago, Maxidyne said:

The Fuller is an inferior transmission, stick with Mack. Besides, the Fuller will need different mounts and driveshaft. Unless the components are worn out, stick with stock and change as little as possible. Changing to a different ratio in the Rockwell rears may make sense though, not so much to get more speed but to get the cruising RPMs down which will really help your cruising MPG. IIRC, they offered 3.90, 3.70, and 3.55 ratios in that R170 rear end.

I would agree just a rear change would be easier, if he can find a desired ratio, but a fuller trans would be fine on a hobby truck.    terry

[Maxidyne]

If he can find a whole assembly with the desired ratio that's the easiest swap, a lot of big carriers used R170s with 3.70 gears. Another option staying within the Mack family would be the 5 speed plus overdrive version of the 1000 series Maxitorque, though that would require a shorter driveshaft.

[david wild]

Well I watched the bad mouthing of the fuller trans and have to chime in, Our Mack 18 speeds are the most problematic trans we have run other than early Allisons, and the new Allisons still heat up on the job site and stop , and I might add at the worst times. you can buy a new Fuller 18 from LKQ for a little over 6k fixing the rear half of a Mack 18 with new clutch costs us 6k, I'd rather have the easy shifting, less HP drag and replace the trans every 4 years than maintain the Mack, in fact all Mack failures are being replaced with fuller trans. we change trans oil twice a year, get all updates done and have Mack make sure they are right, the fuller we change the oil and run the crap out of them, the Mack does have better gears for reverse but with a AT1202 aux we use fixes that. Mack trans are great for truck shows but we are tired of the excuses from Mack about the problems and the noise they make. But then maybe we are not loading them heavy enough and that's the problem, but I do not believe that,  We run up to 500k with a single truck and after that we use a pusher, if lots of hills we add another pull on the front just for the hills. We have had not one failure with the Fuller 18, we have had 2 Mack 18 failures in the last 2 trucks.   

[Maxidyne]

We're talking about 40 to 50 year old transmissions, not the current models. It's hard to beat Eaton for value per dollar, and as you and many have noted here Mack drivetrain quality and reliability have declined since the Volvo takeover. If I were buying a Mack today I'd probably spec an Eaton transmission.

[Quickfarms]

If he can find a whole assembly with the desired ratio that's the easiest swap, a lot of big carriers used R170s with 3.70 gears. Another option staying within the Mack family would be the 5 speed plus overdrive version of the 1000 series Maxitorque, though that would require a shorter driveshaft.

The 2070 is the 5 speed overdrive with two low gears

Is there a difference between the 1000 and 2000 series transmissions

[Maxidyne]

IIRC a 2070 has a .60 overdrive top gear, definitely would cut your cruising RPM down!

[kscarbel2]

Given you have a 675, I would change the ratio in your R170 from 4.33 to 4.11.

[Maxidyne]

Mack initially allowed ratios as low as 3.90 on 20/22.5 tires until UPS persuaded them to offer 3.70.

[Quickfarms]

Mack initially allowed ratios as low as 3.90 on 20/22.5 tires until UPS persuaded them to offer 3.70.

Any idea how much weight ups was hauling with 3.70?

Were they on std. height 20/22.5's?

What engine and trans combo where they using?

[Maxidyne]

Was back in the late 60s, so standard height 20/22.5 tires.In most cases weight was around 40-50k pounds, but UPS tractors sometimes pulled Turnpike doubles and triples that got up to 70k pounds or more. Engines were the 237 horsepower Maxidynes and transmission was the wide ratio 5 speed Maxitorque, though initially they used a Spicer wet clutch but they were later retrofitted with a conventional dry clutch.

[Quickfarms]

The shifter on my 5 speed trans is real sloppy.

I have looked in the manuals but can't seem to find and information on the actual shift tower.

Is there a bushing that wears out?

What should I check when I remove the shift tower?

[j hancock]

No bushing that I remember.  Things may be just tired from lots of shifting.  In the tower there is a large spring which pushes up on the stick.  The tip of the stick that goes into the trans. is rectangular in shape with slight radius where it fits into the shifting rails of the trans.

The tower spring could be weak making it seem sloppy?  If the tip of the stick is badly worn you could get a better used stick.  Hopefully the slot in the shifter rails are not badly worn, that will require a bit of work to change out.

Remove the cap screws and pull the stick.  See what you have got going on.

[Quickfarms]

I know it's been a year but this project has been on the back burner

 

The ford F800 is almost finished so I have decided to get to work on this

 

It seems to me that the manual steering box, with partially working garrison assist, takes more turns lock to lock than the power boxes on my F800. Am I right or is this just me?

 

Does anyone have a parts breakdown for the 5 speed direct shifter tower? There is a lot of up down play in the shifter.

 

 

 

[j hancock]

1 hour ago, Quickfarms said:

It seems to me that the manual steering box, with partially working garrison assist, takes more turns lock to lock than the power boxes on my F800. Am I right or is this just me?

Does anyone have a parts breakdown for the 5 speed direct shifter tower? There is a lot of up down play in the shifter.

A manual box with assist will have a different ratio than a power box usually.  That will account for your difference in lock to lock.

I don't have a parts breakdown but there isn't much in the tower.  When you remove the tower, I believe you will find a worn out or broken spring.

[Quickfarms]

How is the spring held in there?

[Freightrain]

I just rebuilt(tightened up) the towers in my triplex.  Not much to them, just unbolt it and lift it up.  The handle mounts on a pin, which is likely really worn.  I welded the ball on the end of the shift arm to tighten the slop between gears.  I measured the slot in the shift rail and carefully ground it to fit.  Not perfect, but better.

[Freightrain]

9 minutes ago, Quickfarms said:

How is the spring held in there?

It wont pop out removing tower.  I took pictures of mine.  They are simple to understand once you remove tower.

Edited December 15, 2019 by Freightrain

[j hancock]

11 minutes ago, Quickfarms said:

How is the spring held in there?

 I want to say mine was like a cast nub in the tower that captured the spring.  I didn't have to mess with the spring which is why I don't really remember.  It was a couple years since it was off.

It is straight forward.  Take it off and see what you have.

[JoeH]

My Eaton 8LL has an oring with that metal disc that goes on the spring. Oring deteriorated and fell out, allowing the shifter tip to pop out of the rails. 

[mowerman]

missed this R model post some how.....cool rig....the single drive rigs,,,always interest me....nice neat look....also like the ford.....bob

[Quickfarms]

I pulled the shifter and the spring has popped out of its retainer



The sides of the bottom of the shifter have what appear to be grinding marks but not much if any material is warn away

The corners of the tip of the shifter are warn at 45 degree angles, should I weld them up?



Here is the inside of the trans



Also there are two welds on the shifter arm



Suggestions

[Freightrain]

I think those tapers are suppose to be there?  It doesn't look worn but on the two edge(you can see the polished points).   I welded those tips to tighten them up when in gear.  It took some fine tuning to make it shift properly, but works fine.  Not as much slop in handle when in a gear.

The spring just kinda screws up into the cup.  You see the tabs, that is what the large diameter of the spring sits on.  Might take a few tries(like mine) but you should be able to roll it back up in there.

Edited December 16, 2019 by Freightrain

[j hancock]

The shifter tip has a little wear but isn't horrible.  The tip shouldn't be square cut.  I might look for another to get rid of the welds on the shaft just to have something nice.  It may dress out OK with some grinder and flap wheel work?  Little bit too much bubble gum in the lower weld....

Try to  "flatten" out the spring retaining tabs to look more like the ones in Larry's tower.  It will sure hold the spring better if they are flat.  Are all three tabs there?

[Quickfarms]

All three tabs are there

With the pin being welded in place it's not going to come apart without some grinding, I was thinking about leaving it welded in there.

Tomorrow I was going to clean up the welds, hopefully the welder v them before welding, and wire wheel the whole shifter and give it a coat of paint

I was thinking about making a tool out of a harbor Freight screwdriver to help with getting the spring back in

The tower did have some funny paint markings on it like the salvage yards use. I wonder what P30 means

[Freightrain]

I ground the weld and removed/replaced the center pin.  They a quick tack to hold new pin in.  Not a big deal.

I think i used needle nose vise grips to screw the spring back in.  Just have to watch getting the last turn in and seated.  Took a few tries.  Did mine last winter.