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Hmmm... so opposite of how mine is, eh? thanks, Rick. Can anyone else chime in and break the tie?
Driveline thump/cunk when stopping/starting
- Thread starter schum4
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Hey Nakman
My wifes 91 is with me at work tonight so I looked under it, I believe it is all stock.
The rear drive shaft has the splines twards the Transfer case and the front Driveline has the splines facing the pinion. Dont know if this is factory but I believe I am the first to do anything to this truck and I don't have vibration issues.
S
My wifes 91 is with me at work tonight so I looked under it, I believe it is all stock.
The rear drive shaft has the splines twards the Transfer case and the front Driveline has the splines facing the pinion. Dont know if this is factory but I believe I am the first to do anything to this truck and I don't have vibration issues.
S
The FSM shows the front splines at the diff. I did have the truck re-geared so the mechanic might have gotten the shaft in backwards.
As I understand it, the driveshaft orientation does not matter, that from Tom Woods. He recommended however that the splines, which is where the movement takes place, be located at the t-case. This is to keep it up and protected from rocks and such.
Front slip yoke at the diff.
alia176
SILVER Star
***update***
I separated the slip yoke and gave it a closer look. There was grease in the splines, however, there was tons of old grease at the end of the yoke. After everythign was cleaned out, fresh grease was applied directly to the splines.
Afterwards, I noticed that the "thump" is still there but moved to a different time!!! Now, the thump occurs immediately as I take off from a stop. Before, the thump would occur about 1.5 sec after taking off from a dead stop. I wonder if thicker grease would do a better job here?
Just a FYI.
I separated the slip yoke and gave it a closer look. There was grease in the splines, however, there was tons of old grease at the end of the yoke. After everythign was cleaned out, fresh grease was applied directly to the splines.
Afterwards, I noticed that the "thump" is still there but moved to a different time!!! Now, the thump occurs immediately as I take off from a stop. Before, the thump would occur about 1.5 sec after taking off from a dead stop. I wonder if thicker grease would do a better job here?
Just a FYI.
I don't think it matters what direction the splines face on the driveshaft, I've had my rear shaft in both ways (no way to make that not sound dirty 
). On '99 Cruisers (and probably '98 to present) the factory puts the rear shaft in with the splined part near the rear diff, not up by the t/c, rather odd I thought (and wrong) but after seeing two bone-stock ones that had never been touched have it that way, I guess that's the way Toyota did it on those.
). On '99 Cruisers (and probably '98 to present) the factory puts the rear shaft in with the splined part near the rear diff, not up by the t/c, rather odd I thought (and wrong) but after seeing two bone-stock ones that had never been touched have it that way, I guess that's the way Toyota did it on those.
fj55-100
SILVER Star
This is a age old concern that is now giting ugly . Fact - the noise/thump is caused by the splines on the slip sticking, when the shaft was made the tool left small scallops on the surface some seen some not ,and under load and braking causes it to bind, then when you GO it unloads and thumps--- the 120s are so bad that they have redesigned the shaft as a countermeasure to fix it ---- they changed the pitch of the teeth and have polished out all the rough spots .
as a short tearm fix we were instructed to remove the shaft and use valve lapping compound on the splines and work the slip in and out for a loooong time to try to polish out the high spots, then thourghley clean the slip and reassemble it using a HIGH pressure lube . So far it has worked well enough to hold off the shaft replacement untill it is off backorder,
I have experemented with the new slip by putting one in my 55 , its soa so it to thumped from time to time,, and after 6 months so far it has not returned--
I have a 120 as well it has not returned there either----
All the shafts that i have worked on i have put the date and repair (new or lap ) engraved on the shaft to do some long tearm studys for TMC ,
So we shall see in the future how they hold up
Hope the info helps............................
as a short tearm fix we were instructed to remove the shaft and use valve lapping compound on the splines and work the slip in and out for a loooong time to try to polish out the high spots, then thourghley clean the slip and reassemble it using a HIGH pressure lube . So far it has worked well enough to hold off the shaft replacement untill it is off backorder,
I have experemented with the new slip by putting one in my 55 , its soa so it to thumped from time to time,, and after 6 months so far it has not returned--
I have a 120 as well it has not returned there either----
All the shafts that i have worked on i have put the date and repair (new or lap ) engraved on the shaft to do some long tearm studys for TMC ,
So we shall see in the future how they hold up
Hope the info helps............................
Hi all.
This has been a great read, I have only had the cluck for a few weeks, I do need to replace the rear U-joint, I will also give the splines a going through.
Thanks for the info.
This has been a great read, I have only had the cluck for a few weeks, I do need to replace the rear U-joint, I will also give the splines a going through.
Thanks for the info.
fj55-100 said:
Nice info. FJ55-100. I just removed, cleaned and regreased my rear driveshaft a couple of weekends ago.. still got the clunk. I did notice some imperfections (pits or notches) on some of the corner edges of the yoke spline teeth.
To clarify what you did to fix it (so far)..., are you saying you replaced the yokes with a new improved version that doesn't have the imperfection in the spline teeth? What do you think are some of the long term problems this could create...eventual replacement of the driveshaft and yoke, or possible side affects to the T-case?
Thanks,
Rookie2
semlin
curmudgeon
I am assuming that while working the slip in and out of the yoke for a loooong time you were instructed to think of baseball or does Mr. T advocate the brick wall approach?
fj55-100
SILVER Star
Rookie- the shaft itself on the 120s after production x240032069 has been updated Pn-37110-6a480 , that is the new spline vin start -
so far all the ones we lap in have been good -long term if you dont clean the compound out it will continue to wear while in opperation -- if its clean we see no lasting defects,----
has no bearing on the lifespan of slip or joints,
all the ones that were lucky to git a new shaft with the smooth splines are allready ahead of the game,
on my 55 i am experementing with the new slip ( it takes bolth sides so you have to cut the shaft and install the assy) or send to shop
ttfn
so far all the ones we lap in have been good -long term if you dont clean the compound out it will continue to wear while in opperation -- if its clean we see no lasting defects,----
has no bearing on the lifespan of slip or joints,
all the ones that were lucky to git a new shaft with the smooth splines are allready ahead of the game,
on my 55 i am experementing with the new slip ( it takes bolth sides so you have to cut the shaft and install the assy) or send to shop
ttfn
One other question you might have some input on:
When I removed my rear driveshaft, I didn't feel I was getting the grease that is packed between the driveshaft and the dust cover, out very well (sprayed up in there with break cleaner). So I removed the dust cover. Cleaning from that point was good and easy, but the dust cover was hell to beat off and get back on. Are you typically removing the dust cover to get the old grease out or do you have a better suggestion/technique for get the grease cleaned out without removing the dust cover?
Thanks again,
Rookie2
When I removed my rear driveshaft, I didn't feel I was getting the grease that is packed between the driveshaft and the dust cover, out very well (sprayed up in there with break cleaner). So I removed the dust cover. Cleaning from that point was good and easy, but the dust cover was hell to beat off and get back on. Are you typically removing the dust cover to get the old grease out or do you have a better suggestion/technique for get the grease cleaned out without removing the dust cover?
Thanks again,
Rookie2
tranny flush.
do it twice for good measure. Clunk will leave.
do it twice for good measure. Clunk will leave.
wrong post area, sorry.allen_ajones said:
fj55-100 said:
Evan, your posts have cleared up alot of misinformation going around with the 120.
I had this thump when new but is now gone- never occurs anymore (at 20,000 miles). I lube the zerks every once in a while... so could there be long-term issues or am I good to go?
thanks
I have two thumps/clunks, both of which think are different.
I fixed or drastically reduced (90%) the first which ocurred after I had accelerated and then let off the gas, almost like the truck was pissed that I didn't keep accerlating. I could lessen the clunk by not letting off the gasing but by just decelerating. That said to me automatic transmission fluid needs flushing. Well, it looked pink. But when I saw the old pink next to the new pink. Well, you could tell it needed come out. Well one of my clunks is gone. I will probably do one more tranny flush for good measure. But, just because the tranny fluid is pink doesn't mean it's good.
Now the clunk does not have "metal linkage clunk sound: but just a dull lower sounding thump. Still trying to figure what that is. I gues I gotta look for loose u-joint or unsecure rear drive shaft, etc.?
I fixed or drastically reduced (90%) the first which ocurred after I had accelerated and then let off the gas, almost like the truck was pissed that I didn't keep accerlating. I could lessen the clunk by not letting off the gasing but by just decelerating. That said to me automatic transmission fluid needs flushing. Well, it looked pink. But when I saw the old pink next to the new pink. Well, you could tell it needed come out. Well one of my clunks is gone. I will probably do one more tranny flush for good measure. But, just because the tranny fluid is pink doesn't mean it's good.
Now the clunk does not have "metal linkage clunk sound: but just a dull lower sounding thump. Still trying to figure what that is. I gues I gotta look for loose u-joint or unsecure rear drive shaft, etc.?
I had the same problem but mine was a bad front axle on the 100. The inner joint was worn. I replaced it and all is good. Now my other thump is coming from a worn ring gear in the front diff.
After learning the construction of the drive shafts here, would it not be good to grease to the max so the grease gets to the splines, THEN to remove the zerk and drive to let surplus grease escape?
semlin
curmudgeon
as i posted earlier in this thread (eleven years ago), i tried that and no grease came out.
the grease added at the zirk does not distribute well to the splines. it is localized on the splines near the zirc and the excess seems to slide down into the reservoir where it doesn't seem to do much except potentially add preload to your driveshaft that will wear out your driveline components.
so the best thing to do is periodically remove the driveshaft and manually grease the splines.
if you were ambitious you could machine away a short section of the driveshaft splines to create a distribution ring/channel that roughly lines up with the zirc. then your method would likely work much better.
