Heavy duty transmission jack

[Frank S]

Many years ago when I regularly worked on heavy equipment and trucks I owned a heavy duty transmission jack the other day a friend called me to ask if I could put a clutch and rear main seal in his Mack. I told him sure why not. So he said he would be passing through in a couple of weeks after I hung up the phone I remembered that I don't have a jack any more. No problem I'll Hire my neighbor who lives about a mile away to bring his over. Big problem his is busted he needs to have it repaired. I offered to rebuild the ram for him but he had already taken it to a shop where they have ordered the parts not sure when they will be in or when he will get his jack back. So I decided to just build one.
After looking around I pulled a couple of 4x4 1/4" sq tubes out of my usable scrap pile dug out 4 heavy duty casters 2 rigid and 2 swivel from my storage van then found an 8 ton engine hoist jack. Hauled a piece of 1/2" plate steel out of my scrap pile and 8 lengths of 1" pipe that at one time was a sprinkler system A few feet of 3/4" 1018 cold roll rod for the pivots shafts and a lenght of 1/14" chromed cylinder rod for the pivots and a few set collars that I made up previously and I was all set I had a heavy duty transmission jack the only thing left to do was cut drill and weld all of this together







After welding the 1 " pipes together to make the link arms I needed a weld jig to make sure the ends were parallel and matching lengths
so I already had 1 hole in the 1" thick table I used my mag drill to drill another turning the table into a welding fixture or jig

I mig welded the ends on by welding about an inch inside of the pipes filling with weld

After all the ends were welded on the link arms and cooled I reamed the bores using my #7 tap handle on the tang of the MT#3 shank of a 3/4"

Pre-assembled everything before welding

Just tacked together

Now a fully functional transmission jack

I used KBS rust blast to remove the surface rust and provide a pre paint primer surface

KBS rust blast leaves a zinc coating that can either be brushed off or left in place Since I was out of etching primer I opted to just rub off and loose residue and leave the rest to serve as a primer

Painted with KBS rust seal machinery gray

[rossbotics]

Looks like it will work to me


Doug

[suther51]

Looks good! Could have used one a few months ago helping my cousin pull the trany out of his 1989(?) Kenworth. Thank goodness his "boss" let him use an oldy but goody jack to reinstall. He took a school of hard knocks crash course in rebuilding it. A previous owner had engaged the pto with every thing spinning and took 2 teeth off the pto gear. They slept in the bottom of the housing till my cousin engaged the pto blower to work the motor up to temp after changing the coolant. Oil must have slung the teeth into the main trany housing where they happly raised havoc on his next run. Some of the gears were unrecognizable as gears, no teeth left at all. Talk about buyer beware.
Eric

[Frank S]

Here is a picture that of a jack like the one I used to have
It was an OTC 2000 cap Jack which was a good jack but it had things about it that I found more or less useless for a jack of its size.

the adjustable tilt to the table was next to impossible to change positions on once the weight was on it also the table plate was too small for the larger 15 & 18sp transmissions of the time it did have a lower collapsed height than the one I built by 1 1/2". BIG DEAL I'm not crawling under a truck that is on the ground anyway I have a pair of 20 ton aluminum ramps 8 ft long by 20 inches wide that I will use to back the tandems up on to a pad of 8x8 blocks then I'll use my 15 ton air jack to lift the steer axle up till the oil pan on the engine is level and set that on a pair of my heavy duty jack stands and blocks under the steer tires as well
My jack will go down to 8 1/4" and raise to 38" the parallel link bars are 10" apart to give it tone more stability than any factory jack made plus they are wider and thicker in stature having a full 1 3/4" long pivot where as a factory jack is only 3/4" on little 1/2 by 2" bars By welding 2 pipes together this gives them more resistance to twist or side sway. Also I used a long ram 8 ton engine hoist jack this puts the lifting force applied directly to the plate which allows for a better lift transition angle over those of factory design which are really little more than elongated floor jacks
here is a picture of the cad drawing of the jack I built the 4 adjusting bolts will be added once I have a look at the bottom of his transmission then a lock down strap will be added as well to secure the transmission to the jack plate

[suther51]

The otc jack looks the same as the one my cousin borrowed. It had been widened in the front and as you say the tilt mechanism was useless, thread striped, and broken to boot. Like the idea of your way to adjust the attitude of the trany with adjusting bolts. Thanks for the post.
Eric

[Frank S]

Eric I also have a 600 lb transmission jack it is so old I have no idea the make it has the standard adjusting screws to tilt the table left or right and up or down front to rear Other than the problems with adjusting angularity its plate was also small and wasn't very suitable for using when removing the flat bottomed automatic transmissions from cars additionally it was thin the bolt on adapter perches would bend the plate when trying to lift the weight of a 300 lb 5 sp pickup transmission I skimmed off everything from its top plate and welded on a 12 x 12 by 3/8 plate that seamed to work fine but as I have said about my larger OTC the link bar pivots were too close together. I have found in building other parallelogram equipment the stability is more than squared by the distance the links are spaced apart in both width, length. and thickness of the pivot points By using an 8 ton ram on my jack it can easily lift a calculated weight of about 4000 lbs

[DIYer]

Thanks Frank S! We've added your Heavy Duty Transmission Jack to our Transmission category,
as well as to your builder page: Frank S's Homemade Tools. Your receipt:

Heavy Duty Transmission Jack by Frank S

tags: transmission, jack

[Frank S]

Finally put the jack to work
The truck came in that I built the transmission jack for.
the first thing I did set up my ramps to back the truck on.
A lot of guys pulling transmissions out of trucks will just raise the front end so they can have some room to work This is problematic as the engine and transmissions are mounted at a down slope angle if the front is higher than the rear the angle increases When pulling a transmission that weighs over 1000 lbs or any transmission for that matter the closer to having the engine and transmission parallel to the floor the better this makes for ease of removal and reassembly. since the jack only has to roll and not be adjusted for height as you are doing the job

It helps to have a lot of heavy duty large wood blocks

I have more if needed LOL

Back the truck up the ramps

Secure in place

Font is 10" off the ground and the rear is 18" the work floor under the truck is 2 4x8 sheets of 3/4 treated plywood

Transmission out on the jack. It works like a charm was able to raise the transmission and the rear of the engine with it to lift above the rear mounts and add a support under the engine to hold it in place was probably having to lift at least 4000 lbs


Due to there being a PTO mounted on the bottom of the transmission adjusting bolts were out of the question So I used my next favorite way of supporting things. Solid oak blocks then the transmission was strapped to the jack so it couldn't move

[Frank S]

My mechanic neighbor stopped by for coffee this morning and to ask me if I was going to need his transmission jack because he hsd gotten his repaired.
We walked out to look under the Mack. Then he said if that jack ever comes up missing you will know where it is. He said he paid $1500.00 for his and it wasn't a 10th of what mine is.

[suther51]

Coments like that make one feel good, till the jack comes up missing. Lol. Looks great, bett there are many more applications than transmissions.
Eric