I just bought a 1988 Ford F-150 with a 5.0 and 127,000 miles on it. Now there is a clunk you can hear and feel when i left off the gas. Truck has all new u-joints and a new rear driveshaft. What could be causeing this problem i ran out of ideas. Thanks

Todd

 

Motor mounts/trans mounts ???

 

[updated:LAST EDITED ON 04-Jan-03 AT 10:00 PM (EST)]Don't laugh, but are your rear lug nuts tight? I had the problem once, I replace slightly worn U-joints and still had the noise. For some reason, I looked at the rear wheels, and found the lug nuts were loose on one wheel, causing the clunk.

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'94 E-150 Conversion Van 4.9 / C-6 -- '89 Mustang LX 5.0

 

i agree with motor and tranny mounts
they are rubber and the split
common problem

 

Check your rearend 8.8 rears are weak spyder gears are made from recyled soup cans. Put truck in gear or park. park off switch off. Get under truck if it is high or get down where you can see rear ujoint have someone rock truck back an foe see how much slack is in rear If its like most 8.8s with high miles it will be shot. Next if it seems to have slack pull off rear cover let someone rock truck and watch spyder gears see if they are slack if so replace them.

 

It could be your u-joints (yeah, I know you said they're new). Park on a REALLY flat spot, set the e-brake, put the t-case/trans in Neutral, get under the driveshaft, and see where the looseness is.

 

>Check your rearend 8.8 rears are weak spyder gears are made
>from recyled soup cans. Put truck in gear or park. park off
>switch off. Get under truck if it is high or get down where
>you can see rear ujoint have someone rock truck back an foe
>see how much slack is in rear If its like most 8.8s with
>high miles it will be shot. Next if it seems to have slack
>pull off rear cover let someone rock truck and watch spyder
>gears see if they are slack if so replace them.

I agree, that's the first thing I thought of when I read the post. My '86 (209,000 w/ 8.8 inch) has this problem currently. How big of a job is replacement? I don't know how much longer it'll keep going the way it is.

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1995 F-150 Supercab XLT 155" 4x4 M5OD 302
1986 F-150 4x4 NP435 300

 

When my 8.8" got noisy, it was from wear on the big pinion shaft thru the middle - not on the gears themselves. I collect parts like that in junkyards, so I don't know how much it costs new. DON'T reuse the little lock bolt, though...

 

I went through my 93 8.8 after the carrier ripped itself apart one night. Make sure if you don't pull the rearend out of the truck that it is suspended so you don't preload the bearings. It is time consuming to rebuild and set up right have a good shim set and a dial indicator/mag base and a micrometer. I put one of those rear covers on I think it was called a "girdle". It is an alloy cover with jacking studs to set tension on the bearing caps, I was told by a diff shop that under load they move. Not good for gears to misalign under load.

 

I'm not sure what was in the '88, but if it's like my '87 it has a 2 piece driveshaft. If it has a two piece driveshaft, you can try greasing it (there's a grease gun fitting) and see if that helps.

 

Assuming you in fact do have new u-joints, it could be the pinion bearings in the rear axle. My pinion seal went south and I had a guy put in a new pinion seal and pinion bearings. I thought I had a brand new truck when I got it back.

 

[updated:LAST EDITED ON 01-13-03 AT 06:01 AM (EST)]if you change the spyder gears is there any more you have to do to set them up as far as shimming them or anything? how do I check the through pin. just looking at it can you tell if it or the housing is worn. and one last thing where can you buy the spyder gear is it a dealer item.
did you get the problem solved todder?


Ben