trans slip yoke problem?


Staff member
" hey grumpy, I recently swapped from a TH350 to a 200r4 and I had to get a new transmission slip yoke because the old u-joint damaged the original slip yoke when it failed, now I purchase a used slip yoke that looked decent, at a salvage yard, but it won,t slide into the new transmission more than about 2" is this normal on a 200r4?"



Ok, first step is obviously to clean the parts up and carefully inspect the splines on both the transmission out-put shaft and the slip yoke, count the splines and look at them with a brite light, use a caliper to measure carefully. most slip yokes will slide in at least 3" so inspect your drive shaft splines on your slip yoke for crud or bent splines, since it slips in 2" chances are good the splines are either twisted or full of crud keeping it from slipping deeper


measure carefully and do your research CAREFULLY, and yes there are conversion u-joints where one side is lets say a different width,or bearing diam. or both so a drive shaft with say 1310 size u-joint can be used with a yoke that fits 1330 size u-joints or the bearings are a different diameter from the other perpendicular bearing set ... ion&mc=PRE

remember its common for some transmissions to have a master spline which mandates the slip yoke can only slide in indexed in one location to insure it goes in exactly the same way, its also fairly common for the splines to get twisted or filled with crud, so cleaning and careful inspection before assembly is mandatory.
be sure to grease the splines and be sure the rear seal is correct for the application.
slip yokes come in several diameters lengths, spline counts ETC.



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I thought this diagram above covered yoke length requirements fairly well, obviously you might require a different length drive shaft or the yoke you use might need to be cut a bit shorter in some applications , but remember the yoke needs to move in and out freely without binding and the u-joint should be fairly close to the rear of the transmission as excessive extra yoke length provides leverage that can cause damage if a u-joint fails


you obviously must know the spline count and shaft diameter, but these are fairly standard, the yoke length is not, you simply slide the yoke into the trans tail till it bottoms outdraw a line on the spined yokes outer surface,then back it out 1" and draw a new line,remove the yoke,there should ideally be about 3" or a bit more from the second line to the end of the yoke, insuring good spline contact , there should be less than 2" from the first mark drawn to the u-joint saddle, in an ideal world, but obviously your drive shaft u-joint spacing length comes into play here!
OK, if you don,t have a spline yoke to fit the trans yet ,just slide a strait stiff soda straw in between the spline shaft and the inner trans tail, measure the depth it will slide in and you can use that depth measurement, lets say it slides in 4.7", if so you want a spline yoke at least 3.5- 4"contacting the splines with 1" of possible movement without contact,or bottoming out in the trans, so about 5.5" would be ideal,so you could get 3.7" of spline engaged and 1.8" before the u-joint,would in theory contact the trans tail shaft, (yes it bottoms out in the trans before that could happen), lets say your choices are 3.5" and 7.5" 3.5" is too short
you would buy the 7.5" and have a machine shop cut it to the ideal length AFTER you measure the drive shaft length and spline engagement
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Staff member

viewtopic.php?f=63&t=1348&p=2954&hilit=ballance#p2954 ... ion-1.html ... =End+Yokes ... uctId=2719 ... index.html ... /overview/ ... index.html ... ange+Yokes ... pe=UJoints ... goryID=128 ... nsive.html ... index.html ... sion+Yokes ... toview=sku ... 5&x=22&y=9 ... to_03.html

Randy_W posted these links ... index.html ... onSwap.htm


grumpy! I removed my u-joints on the drive shaft to replace them, now I don,t remember which end had the slip yoke on it ?

in almost every case Ive seen the longer tapper goes to the trans



Staff member
1967Firebird.jpg ... 32879.html

measure carefully and do your research CAREFULLY,and stop and think things thru ! don,t feel compelled or obligated to use only the components you have and you darn sure will find that having a few tools like a decent shop hydraulic press makes working on u-joints and axle bearings far easier, a press will easily pay for itself in reduced machine shop labor costs in very short order, in fact Ive had a single job replacing u-joints in a corvette with the cost of a new press and the u-joints combined cost less than a dealership quoted me for the job of replacing all 6 u-joints in my corvette! making the press purchase a total no-brainer!
I spent several hours yesterday at a friends garage trying to locate and diagnose a "transmission problem" that proved to be a cracked axle and loose pinion gear in a 10 bolt chevy/g.m. pontiac differential in a 1967 fire-bird, the owner had spent a good deal more time and money on that rear differential than I would have ever considered doing, because it was the original cars differential, and he had purchased a bunch of UPGRADES trying to strengthen the differential rather than just pitching it in the closest scrap heap where it belonged, in his particular application, and replacing it with one of several far stronger lesson I learned long ago was that you need to step back and think things thru rather than just assuming that working with what the original car came equipped with is your only option, and that throwing a few buckets of cash into upgraded aftermarket components, will solve most problems!
you can,t make a silk purse from a pigs ear!
theres zero question that a different, rear differential like a ford 9"
dana 60, or older pontiac 9.3" or chevy 12 bolt differential
built with quality aftermarket parts, would result in a rear differential ,that was 200%-600% stronger than the original 10 bolt Pontiac fire bird rear differential, that came installed in the car and with that optional advantage available of upgrading to larger rear disc brakes, rather than the original pathetic drum brakes, and while your at the up grades you may as well get better springs and install quality traction bars etc.


cal-track bars normally cost about $350, but you can, measure and fabricate decent cal trac bars if you have a welder and some basic machine shop skills, and understand the basic concepts involved


I have to point out that the u-joints with internal grease fittings tend to be demonstrably weaker and that most guys who install them , rarely if ever take the effort to grease them, most of the performance u-joints are the non-grease-able permanently lubed designs
RELATED THREADS AND INFO, and yes I'm only too well aware that many guys will skip reading sub links, but, its your choice!
a few hours doing research could save you hundreds of dollars and several days of work, and in some cases prevent extensive damage


viewtopic.php?f=46&t=4067&p=10823&hilit=pontiac+firebird#p10823 ... s/s60.html











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The Grumpy Grease Monkey mechanical engineer.
Staff member

related info

now one of the lesser known causes of u-joint failure , is the result of missing or high electrical resistance engine electrical grounds,
you should always ground the engine and transmission to the chassis ground in at least two places.
its not all that uncommon for a badly grounded engine to need the u-joints , radiators , pilot bearings and starters replaced on a much higher frequency,
simply because electricity will take the path of least resistance, to flow and if the engines rubber transmission and motor mounts,
and rubber exhaust system hangers make the drive shaft a partial path for the engines electrical ground, that current can and will eventually cause damage to the u-joints.

If the cables, grounds and terminals work as designed, current flow is not a problem. When cranking the vehicle, we turn the key and electricity flows from the battery to the starter motor, through a solenoid. We need the solenoid, because the key switch cannot conduct the high amperage needed to operate the starter. The solenoid acts like a heavy-duty relay. It allows the light-duty key switch to control the high-amperage starter motor.

After flowing through the starter, the current returns to the battery through the engine block. They connect the engine to the electrical system with a heavy cable, attached to the negative battery terminal. This completes the circuit. The starter uses 275 amps to turn and the same current returns to the battery. Current flow on both cables equals 275 amps. The current returning to the battery equals that leaving it.
Problems occur when corrosion and loose connections cause high resistance. The ground cable may only be able to flow 250 amps. If the starter pulls 275 amps, twenty-five amps will find another path to the negative terminal. This is known as transient current flow; electricity taking a path, other than that designed, to return to the battery. The end result can be considerable damage to seemingly unrelated components.
Transmission and suspension components are not designed to flow electricity. As the current flows through them, metal can be transferred from on part to another. This is similar to the electroplating process. In time the parts are destroyed and there may be a major failure.

Keeping all battery terminals clean, tight and with proper connections can help prevent transient current flow.

ost folks have never heard of a transient current flow. Transient current flow can cause thousands in damage to a vehicles. Normally there are very few outward signs until it is too late. Fortunately it can also be detected and prevented, with a few simple steps.

When there is an electrical load in our vehicle, current flows from the battery to the load. A positive current leaves the battery and travels through wires to the accessory. The same amount of current must also return to negative side through a ground. The ground may be provided by a wire or sometimes the vehicle body. The body is electrically attached to the negative terminal.

The current flow leaving and returning to the battery has to be equal




Battery terminal corrosion is a symptom of another problem
A few symptoms of transient current flow

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