I have a 92 Ford tri axle dump truck with a Fuller 8LL. The truck is relatively new to me, I have had it a couple years, maybe 7 or 8 thousand miles. The trans has shifted fine. Today while driving in top gear I had my hand on the shifter, and it started moving, as though it was going "farther into gear". It is as though a stop fell out. The hear itself feels and shifts fine, but the stick just doesn't stop when the heat is engaged. If you don't push the stick past where it should go it just kind of stays there. I took the top plate off with the stick, and everything appears ok. The detent springs are in place and intact. I can slide the shift forks back and forth. What really has me is that there doesn't appear to be a way for the shifter to over travel. The forks slide back and forth and stop at the case. They physically can't travel further. I have another identical transmission sitting in the shop and everything appears the same, visually anyway. Just wondering if anybody has seen an issue like this before or maybe somebody understands how the trans works and would know what could cause it.
Could a snap ring come off and cause this. Truck Shop will know sounds similar to a problem a buddy of mine was having that I discussed with him.
A broken snap ring seems plausible, I just don't know where. The big coil spring that holds the stick into the "cone" or top housing seems ok. When I watch the top as I shift it doesn't seem to allow the shift lever to lift up any more than the other gears. The gasket between the shift lever housing and the top of the transmission is torn above where the lever would push the fork, consistent with over traveling, but when I slide the forks back and forth with my fingers they all seem the same.
What is the model of the transmission? There are a few 8LL transmissions.
I am not sure, I can try to find a data plate later. It is a "U" pattern shift, and it is behind a 3406C set at 425hp.
Was having similar issue with a later unit in a 2015 Western Star, Best thing to remember is DO NOT Use the shifter as a Hand Rest. Was bad years ago on 1110s, 9513s, just leaving hand on shifter allows a slight pressure on the fork to shift slider, causes wear that will eventually cause jumping out of gear.
The U pattern should mean its an overdrive transmission. There could be a thrust washer problem with the front main shaft but there are usually other problems like jumping out of gear and staying in a gear with shifter in neutral.
Two thoughts, first, it is not jumping out of gear. The actual gear feels and works normally. If I don't push the stick to hard it will stay where it normally should sit. Second, I don't know about the overdrive bit, it doesn't feel any different in the gearing with other 8lls with H patterns. I really don't know.
With shift tower off inspect isolator bushing between stub lever and shift lever. Next slide dust boot up on stub lever and try to rotate stub. the stub lever can wear enough on the locating pin it can cause extra fore and aft movement of the shift lever. The other problem is the stub lever tang that fits into the shift blocks in shift bar housing. if rounded and tower worn enough it can cause shifter to slip out of shift blocks. Page 44 in PDF below gives exploded view of shift tower. There are three styles, low, med and high models which is the tower height. Start there first. If shifter moves on throttle on off that's main shaft movement/usually rear main shaft support bearing. https://www.eaton.com/ecm/groups/pu...anger/documents/content/rr_rtlo-20918b-t2.pdf
It is all fairly worn in the shift tower area. I have driven plenty of different trucks, but only really worked on this one (mine) so far, so I don't really have a lot to compare to. The other trans I have is out of a worn out junker I parted to get the current truck running. I can get a replacement shift tower assembly with the stub lever, so I will probably go that route. Is there any measurement spec to differentiate between the different tower heights? Mine looks like the high, but pictures I am finding of parts are not conclusive, and I don't really trust pictures online.
There should be a part number stamped in the tower. S-1677 low, S-1967 med, S-1579 high.
Thank you Sir
Truck Shop, you nailed it. Boy, it doesn't take much wear on the levers to actually allow them to fall a few inches.
It's been awhile, but I thought I would update this thread. Back in the summer I didn't really have time to do more work on the truck than necessary, but when I had it apart came to the conclusion that TS was most likely correct, and it wasn't going to tear things up to run it. I just had to be careful not to push the shifter too far. I just got the truck back on the road after doing a lot of work on it over the winter. I replaced the shift tower and the stub lever; this fixed the issue. Thanks Truck Shop ....
Thanks for the update.
Were the early 8LLs the U pattern, and then they went to the H ? I remember D&N's first 2 425 cats having the U, and every 8LL after that was the H
IIRC the early were U, but with Eaton designs are generational. When it comes to manual boxes Eaton had a tendency of running with a design for five years, It kept them from constant updates. The two biggest changes was the higher tooth count then changing to tapered bearings in the rear section to make the series of High Torque transmissions starting in 1992. Most all pattern changes is done in the shift bar housing/top cover.
Example-RTLO18913A below is a overdrive box, pictured is the front section. The gears on the main shaft in order R-Low-1st-2nd-4th-and direct is the input gear all the way on the right-3rd it's connected to the input shaft. This trans still has a H pattern which is controlled in the shift bar housing.
I've always understood that stick forward in high gear always means it's an overdrive. Direct always is back no matter what and they just change the ratios for the other gears.
The OD ones have an O in the model number and the goofy shift pattern. The OD ones with the normal shift pattern have an X in the model number. If I have my facts right.
I kind of doubt mine is OD, it really isn't a road runner. I should get under it and scrape around and try to find the tag.
Straight gate box without a DIR/OD Rear Section and splitter control will not be OD if High is full Rt and Back.
Top gear is right and forward. So my curiosity was peaked enough to walk down to the shop in the rain and see what I could find without going under the truck; (This is not a go under the truck sort of day, been under that filthy thing all week) The sticker on the visor with the shift instructions says "Roadranger RTO 11708LL - 147088LL"
Overdrive in High
If it has a O or X in the prefix it's overdrive, RT is a direct box. The photo I posted is a overdrive box with 3rd to the dash and 4th back. That is achieved in the Shift Bar housing. The RT 14615 direct box had a standard shift pattern the overdrive was to the dash, all that being done in the shift bar housing. Yes the ratios do make a difference. Shift bar housings cannot be swapped from one to another.
What is meant by "direct box"?
1:1 in High Gear, Input rotation to Output. Direct Drive at that point.
In this ratio chart you will find the percentages of splitter gain. It lists RT direct, RTO overdrive, RTOO double over drive and those have a final of .62. Plus those were the only double overdrives after the 14613 no more were offered. Plus there IS no such thing as a double overdrive 15spd, direct and single over only. The top ratio for any overdrive 15 was .78. Double overdrive 15spd is a myth. Eaton Fuller 13 Speed Transmission Ratios - Global Transmission Supply Eaton Fuller 13 speed transmission ratios. Find the ratios for your fuller transmissions. Includes transmission gear ratio, weights, length & PTO speed. www.globaltransmissionsupply.com
Ratios for a 15 spd, notice there is no double overdrive. Eaton Fuller 15 Speed Transmission Gear Ratios Eaton Fuller 15 speed transmissions ratios. Includes transmission gear ratio, weights, length & PTO speed. Find the ratios for your fuller transmission. www.globaltransmissionsupply.com
I laugh my *** off with the posts on FB truck pages about all the up against the DASH double overdrive posts. It's total trucker BS, never was such a thing. It was the final drive ratio of 3.70 or 3.55 combined with a overdrive 15 that gave the appearance it was a double over. Because back in those days a standard highway final drive ratio was 4.11 or 3.90. To get fuel mileage trucks were spec'ed with higher final ratio and a overdrive 15 to drop the rpm. Our Cascadias with a DT12 transmission coupled with 3.05 final ratio coupled with a DD15 power plant that put's out 1500 Ft Lbs torque at 980 rpm and climbs to 1850 at 1600 will run down the road at 1200 rpm at 65 mph. Going back some years lets say 1984 using a 359 Pete spec'd this way. 3.70 final ratio with a 15spd overdrive coupled to a 400 B model Cat cruising at 60 mph would have been turning 1500 rpm. fact.
I remember a 15 with a deep reduction on the dash. Almost a ten speed with a deep reduction. I don't remember, was it the 15 over with the U pattern. 8LLs, 9 speed, ten speed, super tens, 13 direct, 13 over, 15 direct, 15 over, 18s. A lot of time if I can't find the sticker, I go by the color of the splitter button, or the lack of a splitter, or if it's older and has the pull up knob or the flat round selector, and then figure it out while driving. And don't forget the 2 stick combos. I thought PRND23 was hard. Kept trying to put it in R for racing.
In order to be a proper Super Trucker doing 110mph in your long nose Pete across Wyoming you need that double over ....
A 15 is nothing more than a 10 with a back section, deep reduction was for getting around on/off road. A highway truck with high final ratio and a 15 spd over, normally with a experienced driver would use the deep side for backing up. Early trucks it was located on the dash then moved to where the splitter button is on shifter control knob.
I drove a GMC that had a 15 with the switch for deep reduction on the dash. It didnt have a OD and the speedometer didnt work . I think it would do 50 mph. It would pull anything about any were. I moved several loads that the load weighed 100.000.
?
Damn K100C I had with the Driptroit had the Toggle Shift for the Deep Reduction that NOT EVER got used. Another waste of money. Will have to have the MHC boys pull up my Chassis number, find out what ratio Eatons are in it. Never did find a Tin Tag anywhere and original Tape Tags on door jamb are about fully washed out. 1650 at 72-74+/-mph in OD on the 15.
That would have been about right for 3.90 IIRC.
Thanks
That mythical 15 double overdrive ...
Error on Truck Trans, mine is 18 spd but shift as 13 just have splitable low side!! 3:90 would explain how is easy to start off in third or third OD.