I have a 99 F150 SC with a 9.75 ls rear. It has about 87,000 on it. It has had some leakage around the differential for a while now. When I changed the oil today, I notice it was actually dripping. Before it just made the differential housing look wet. I have changed the fluid and seal before and it was the same thing with the wet housing. I think it is the pionion seal. It is definitely coming from where the driveshaft connects. I have never done a pinion seal. Is this tough? WHere can I find better directions than the chilton manual? Thanks.

D

 

The best instructions would be found in a factory repair manual. There are places online that sell them for about $75. They are a great investment, they will tell you how to test and replace every single part of your truck.

As far as the pinion seal goes, it's not too bad a job but you will definitly need an air impact gun for the pinion nut.

-Jon

 

Does this sounds like a pinion seal? I want to make sure I have thought this through. Is this something that needs done right away? I know about t he factory repair manuals. Are the ones on cd the same thing? Chilton talks about having a seal press and some other things that I don't have. Like checking the resistance with a in-lbs torque wrench. I guess I don't understand why you would need to do this.

 

dnale;
The pinion seal can only be replaced by removing the yoke from the end of the pinion. The yoke is the part which the driveshaft u-joint connects to. The reason that your Chilton manual tells you that you need to check the pinion rotating resistance with an inch pound torque wrench is that the nut which holds the yoke on also preloads the pinion bearings and crush ring. If the rotating resistance is not set correctly, you could quickly damage the pinion bearings and cause other damage. The only way to properly check pinion rotating resistance is with the carrier removed from the differential. So...., although this at first sounds like a small and simple job, I wouldn't tackle it yourself unless you are prepared to do it right by removing the differential carrier. You may be better off to talk to your Ford service rep about this one. I would also be wary of a shop which said they could do it without removing the differential carrier. Some people have written posts stating that they have replaced the pinion seal and simply torqued the pinion nut back to specification without checking rotating resistance, but at least one of those people did report some whining and a bearing failure and I personally wouldn't want to drive around worrying that my differential may suffer damage because I had an improper bearing preload. Good luck with your repair but remember that some extra money spent now could save you a lot in repair bills later. GlennMc.

 

Glenn,
I know it sound silly, but what kind of shop would do this work, aside from a ford dealer? Can I nurse it along a coulpe of more months by makin sure there is enough fluid in the differential? (Just bought a house and can't really afford more big bills.)

Does anyone have any idea of what it could cost to get it replaced?

D

 

dnale
I'm sure you could wait a couple of months if you are diligent about maintaining a proper level in the differential. Waiting will also give you time to figure out the best repair method. Here's a trick to do while you wait;

1) Take your truck to Ford for an estimate on repair time and cost.
2) Have the service rep explain the work that needs to be done. He will probably explain that the job is so expensive because they have to dismantle the diff, install a new seal and crush ring and then re-assemble the diff.
3) Using the Ford quote as a guide, talk to reputable garages in your area that have been recommended by friends. If they say that they will replace the seal without disassembling the diff, make sure that they understand that they could end up with improper preload on the pinion bearings. They may have another method to insure proper preload and should be able to explain this to you. If they give you the old "you don't know what you are talking about" look, then it's porbably them that don't know what they are talking about. I would not let them touch the diff.
4) Pick a service garage. Based on what you have learned, you should be able pick either Ford or a private garage that you feel will do the work properly and guarantee the result.

The trick to this whole project is to learn as much as you can about the job yourself and this will help you find the right person for the job. Good Luck, GlennMc.

 

Another ? is about the seal. Is it really the seal that would need replaced? What else needs replaced at the same time (or since I was in there....)? The seal looks to be about $10 at fordpartsonline. Toss in a couple of quarts of 75-140 some ls friction modifier.... I am still hoping someone would have an idea about the cost.
Also, if I'm in elbow deep in the diffential, should I opt for 4.10 gears? If I already have the 3.73 ls what else would I need there?

I need to make this truck last a little longer, I still have years to pay on it....

 

dnale;
There are not many parts to replace when you do the seal. There probably is no cover gasket other that a bead of silicone. The manual probably recommends a new crush ring and pinion nut. The pinion nut has an interference thread that won't work as well if you re-use it. It is cheap insurance to replace it. Your major expense will be the fluid. If you can get prices on these parts online, you should easily get a total cost for the job.

Why do you want to replace gears now? Do you tow?, Is your truck underpowered? If not, I would leave them alone. Gears will cost at least another $200 to $300 for parts and the cost of installation as well. I replaced my gears last year by myself but got lots of negative feedback from some people on this site that this is not a DIY project. To that I say, If you can, do, If you can't, don't. But don't let others make up your mind for you. Good luck, GlennMc.

 

Glenn,
The truck isn't neccessarily underpowered, but hey, who couldn't use a stronger faster truck? I hope to put some 33's on when my current set of tires wear out. Not that the 3.73's won't be ok. I changed the fluid in the differential last summer. It was more of a mess than difficult. The only oil I could find was the Amzoil 75/140 for $12.50 a quart. Also last summer I put the add-a-leaf's on the rear. I've heard some people say you need the change the angle then of the rear. I didn't notice the difference all that much. I had a friend help and he is much sharper than I, and he thought it would be ok. Could this have been a contributor? (Of course it was already leaking slightly then at arounsd 60 k.) I am usually not afraid of taking on projects with my truck, but I usually need it to be a weekend project cause I have to use it again on mondays. Thanks for all of your help.

D

 

Listen to what Glenn is telling you it sounds like he knows what he is talking about. However, I would also replace the pinion bearings, It doesn't take much more labor and only a couple of parts. I work for a dealer and make pinion seal repairs all the time. I always replace the crush sleave it is impossible to get the preload (glenn discussed) correct without replacing the sleave. If you take your truck to someone who justs wants to slap a seal in it chances are highly likely in the near future you'll be spending lots of money replacing all the bearings and maybe more.

 

ok, so this sounds more and more like something I could/should do myself. Hopefully this time the weather will cooperate. I am still a little unsure about the parts. I looked online at fordpartsonline and the only thing I saw was the pinion seal. The pinion bearings had like 6 different peices from a cup to shim or something. I don't know where the pinion nut is or where the crush ring could be found (for pricing.) Thanks again for all of the help.

 

Please help me understand-----My truck started leaking at the pinion seal. Dealer replaced the seal and crush collar. It started leaking again, 2nd. time they also replaced the yoke and 1,500 mi. later no leak and all sounds good. Could I have trouble later because they didn't remove the carrier, Lots of members here had seals replaced and no trouble (without carrier removal)

 

The crush sleave goes between the two pinion bearings, you shouldn't ever really need to replace the pinion shim unless you change the housing or the ring and pinion. I don't know your mechanical skills so I can't advise you if you should do it or not. To replace the pinion seal and do it properly requires above average mechanica skills I hope this helps

 

Bubbadewsky, Yes you can replace the seal without replacing the crush sleave. I have worked for a Ford dealer since 1984 and I wouldn't think of replacing the seal without replacing the crush sleave on my own truck. Your right the companion flange is a often overlooked cause of a pinion seal leak, make sure that you inspect the flange for a groove on the seal surface.

 

Many times I have witnessed "do it yourselfers" do more harm to their diff. or transmission. If you cannot afford to have this done, please reconsider before doing it yourself.

Some of the tooling to repair a diff.: micrometer, dial indicator (preferably one with a magnetic base), impact gun and some sockets, hammer & a bronze or copper drift.

To replace both pinion cups and cones, You first must remove the rear diff. cover & drain the lube. Mark the respective diff. caps (so you get them back on the same side that they came off of--diff. center section is machined and caps are not interchangeable or future failure will occur). Next, remove the diff. ring gear carrier assy. (this may need to be pryed-out with two prybars), do not let carrier assy. fall on the ground--you may chip ring gear, make a mess or it could fall on you and cause bodily harm.

Driveshaft will need to be unhooked and pinion nut removed. Use a suitable brass or copper drift--strike drift with hammer & blast pinion out the rear of carrier (You will probably need someone to catch pinion when you are driving it out of the housing--to prevent damage to pinion). Crush sleeve should be on shoulder of pinion (remove it with your fingers). Next, remove inner pinion cone (you may have to take it to a machine shop or local shop that has a press or puller to remove it). Have new inner pinion cone installed (be sure shim under old cone is re-installed before installing the new inner cone).

Remove old seal & old outer pinion brg. (cone). Install new outer cup & install new inner cup (be sure they are seated in the housing--or future failure will occur). Install new crush sleeve on shank of pinion before inserting pinion in housing again (you will probably need someone inserting pinion from inside of housing, while you are in front of housing installing new outer cone) Use a suitable driver (or flat punch to drive new outer cone on pinion).

Most importantly (this is where most people mess-up): use an impact with old nut to starting drawing down (tightning) the old pinion nut to the yoke. CAUTION. As You slowly draw the pinion nut tighter, take notice frequently that you still have in & out play on the pinion yoke. When you have no in and out play on the pinion and there is almost no drag (when you spin the yoke), You are very close to preload. If you have access to a Ford shop manual--you need to find out how many pounds of resistance you need on the pinion pre-load (I do this by feel, you should not do this by feel). This is done with a small hanging type scale (like the one you would weigh a prized fish that you caught at the lake or river). If You overtighten the yoke--dis-assemble the pinion, start over with a new crush sleeve or future failure will occur.

After initial pinion preload is set: reinstall diff. carrier assembly (start with same side spacer's & shims on their respective side that they came off of or future failure will ocur). You may need a diff. side bearing shim kit to obtain the correct backlash & diff. side brg. preload, or future failure will occur. Diff. side shims are in different thicknesses (this is where you need the micrometer).

Be sure that diff.side spacers & cups are firmly seated into the housing (if not, you may break one on the main diff. caps--then you will need another complete axle housing). Be sure that diff. carrier is not super tight (when installing) or super loose--or future failure will occur. Your objective here is to obtain a diff. side (slight preload if you are using used side cones) and at the same time you will use the different size spacers (or shims) to obtain the necessary backlash (distance between the R/P to work correctly--otherwise, it will burn itself up, whine howl, or shuck its teeth). Backlash should be approx. .008" to .012". Backlash is measured with the dial indicator.

Once backlash is set, and caps are torqued the final time, remove pinion nut and yoke. Install the new seal. Again, tighten the "New" pinion nut down, being Very, Very, careful not to overtighten the pinion bearing, or future failure will occur.

Re-install driveshaft, silicone rear cover back on and start the axle lube fill procedure. Add friction modifier to the lube if you have L/S. Fill axle with lube, jack-up one side, wait about four minutes, bring axle housing back to level, then refill & jack-up other side, then check lube level. If axle tubes are completely cleaned, when diff. was dis-assembled--you need to make sure You get enough lube back into complete axle housing assembly or You may burn-up an axle brg.

I wish you the best of luck, should you choose to do this job yourself. Did You notice how many times I stated "or future failure will occur"? If you are like most truck owners, You don't want any future failures. gearmanx17