My 1997 F-150 with 86,000 miles, offroad package, 8.8 rearend, 3.55, and L/S has been making a clunk noise when driving over rough ground a slow speeds. So I just jacked it up (both rear wheels off the ground) and grabbed the tire and pulled/pushed in and out. I am getting about .030 end play from both axles by pushing in and then pulling out with a dial indicator against the wheel. When I do this I also get the clunk obviously. I know a little play is normal but am I getting to much and if so what is allowing it? Thanks in advance for any input.

 

I don't know the end play specs, but excessive endplay in a limited slip 8.8 is usually caused by worn limited slip clutches. Axle shaft endplay is determined by the distance the shaft can move between the side gear and differential cross pin. As the clutches wear, the clutch packs obviously gets thinner and the side gears have more side to side movement which gives you axle shaft end play. The other downside to this is that the side gears don't mesh as tightly with the spiders as they should which creates slop in the differential and wears the side and spider gears more quickly. Like I said, I don't have the specs for end play but .030 doesn't seem that bad. When I put clutches in my 8.8 it had well over 1/8" of end play, probably closer to 1/4". Needless to say, the clutches were SHOT!

 

Thanks RayD. This thing really makes a loud clunk when driving slow over a bump or whatever. So far no seals are leaking, I thought maybe the bearings might be going bad. About all I've ever done with a rear axle is change the fluid and change out a few pinion seals so not real confident messing with the posi, or ring and pinion. I'll keep and eye on this see if it gets worse. Thanks again.

 

it seems to be a normal habit on trucks. my 8.8 does it and always has since i got it. i can walk up to the bed of most any truck i have access to and shake the bed and receive that clunk noise that drives me nuts.

 

I did a lot of research on this once and found that you can't find an end-play spec anywhere (at lest for the GM axles I was researching). The bottom line from engineers and experts was that it wasn't hyper critical (except maybe to your sanity if the noise was driving you nuts). I did however, discover that there were different thicknesses of c-clips available for the axle I was working on, so I used them to tune out the noise. The axle I was working on had something like 0.095" end play. It was not a plate-type limited slip, so the clearance would stay more or less constant. IIRC, I shimmed it cold to about 0.020" (that was a WAG, but I wanted to leave some room to allow for thermal expansion). At that level it didn't clunk. I'm surprised that yours clunks very much at 0.030", especially considering how much better the disc brakes would hold the axle in place (over the drum style I was using). Wouldn't have guessed it would at that small clearance. Anyway, I don't know if assorted thickness c-clips are available for Ford axles, but you could check.

 

you could make shims that fit between the carrier and c-clips?

 

It's a 97 and has drums on the rear so maybe thats part of the issue. I heard this noise before but it just seems louder than it used to be. Trucks getting older so I hear a lot of things I didn't used to and I know my ears are not getting any better...(my wife will verify that). Just trying to stay on top of anything before it costs big money. Anyway thanks again for the input. Take care.

 

The in and out movement of the axle is normal. You are taking up the space between the axle and cross pin. All c-clip Ford axles will do the same thing. I don't suspect that is your particular problem.

 

I agree with bigbronc, that this probably isn't your particular problem. However, I once spun the passenger carrier bearing on my 8.8. I don't know how long it was going on, but it wore enough of the side of the carrier away that the axle could move far enough inwards that the c-clip fell off. I was mudding when that happened, and I was lucky enough to just need to spider/side gears and a carrier. I'm not sure if .03" is acceptable (although it sounds alright to me) but I am sure that it couldn't hurt to have somebody check it out.

 

I'm sure you could, but it's better to shim the clutch packs. LS rebuild kits come with shims in different thickness to properly set up the new clutches. All you're doing with the shims is setting axle shaft end play and side/spider gear mesh though. In my opinion, the proper mesh between the side and spider gears is more important than end play on the axle shafts.

 

meh all i know is i pulled my rear carrier out and stuffed in a detroit (after popping a powertraxx unit with a stock 4.6)

 

Yeah, a replacement carrier diff is the best solution. For whatever reason my 8.8 likes to eat clutches so I'm keeping my eyes open for a deal on a tru-trac or something similar.

 

just dont overlook the full automatic locker they offer. i run it in the back of my truck and absolutely love it. it dont chirp like people are afraid of.

 

My 04 clunks pretty bad on low speed bumps and turns. Is there an easy way to shim it? Has anybody found a spec on the allowable end play (I'm thinking mine might have enough that the extended warranty should cover it)? My truck sounds like a piece of junk when driving around parking lots and stuff.

 

Axle endplay specs are exactly 0.030". That is what you get with a C-clip axle assy. If you go over a bump with one axle before the other, a noticeable "clunk" is normal due to axle tolerances.