Heavy drivetrane rumble

SPYDER ROVERS · Post by **SPYDER ROVERS** » Thu Nov 22, 2007 2:05 am

Hi gents, havent been on the site for a while as Ive been rebuilding the old girl(not my wife,although she would benefit from a good going over). I seem to have a problem i cant get rid of. I replaced the trans with a 5spd out of a 95 disco, transcase out of a 2000 disco, clutch and throw out bearing.and new pilot bush. Minimal axle play, both in very good order. Drive shafts custom made and balanced. Now when driving, everything is spectacular until the clutch is depressed for gear change. There is a rather bad heavy rumbling sound that reverbs thru the entire drive trane but seems to be originating from the clutch/trans area. It sounds alot like gear slap but heavy and deep. It is not as severe as stated all the time and is not always consistant. Usually most noticable when slowing down from higher speeds with or without clutch, but drives beautifully at constant road speed. I know this is alot, but i am a stickler for concise info and thats what I do when I dont know what I am dealing with. Any thoughts?

stirlsilver · Post by **stirlsilver** » Thu Nov 22, 2007 4:05 am

Ah hah!

I think I know the answer here... Are you using a front driveshaft that has 2 or 3 universals? You may find that you are using the wrong drive shaft for the the differential input shaft angle. Your symptoms of hearing that chatter with the clutch pressed in is identical to what mine has at the moment. The diagram below should help you out.

Ignore the wedges on the diagram I'm just reusing an old diagram here. The stage 1 axle housing angles the diff input shaft to be inline with the drive shaft. For this configuration you need the 3 universal drive shaft.

I would avoid driving the car until this is corrected as you will be putting a lot of strain on the central differential.

SPYDER ROVERS · Post by **SPYDER ROVERS** » Thu Nov 22, 2007 12:52 pm

That was a good idea but I do not have the double knuckle u-joint and have driven with one or the other shafts removed for the purpose of isolation. Same result. Still not sure but maybe I will get it up off the floor and try to duplicate the problem with a controlled run. that way I can get around to listen with the stethscope.Only thing about that would be lack of load and momentum. But Im with you, I dont really want to road test it much as it would probably kill the gears. Let me know if you have any other thoughts. I really do value you input. Thanks.

stirlsilver · Post by **stirlsilver** » Thu Nov 22, 2007 10:56 pm

The rumble has to be a universal. If the whole gearbox assembly is in at a different angle, the problem would be a misalignment on both the front and rear axles. Grab an inclinometer and check to see if that's the case.

The reason why I think it's uni's is beause if they are misaligned they accelerate and decelerate, when you put the clutch in it causes the pinion gears in the diffs to rattle as a result of the backlash between the pinion and ring gear.

Try to note the frequency of the rumble, in relation to the rate at which your tyres turn. Is it at the same rate as the tyres or faster? If faster roughly how much? You should identify where the problem is this way, because you can roughly visualise the ratios of the various turning components in the drive line.

Stirling

SPYDER ROVERS · Post by **SPYDER ROVERS** » Fri Nov 23, 2007 1:39 pm

I did what I said I would not and drove it carefully. With all floor pans off, it was easier to note that it was coming from the final drive, as you suspect and though I can not physically move the ujoints, two are new but I cant discount the other two. Without using the clutch,any change in the vehicles physical speed in relation to engine speed translates into the rumble. With the vehicle running along rather sweetly at 60mph, no clutch, letting off the gas or accelerating normally, that neutral area of relative speed will bring the noise. decelerating or accelerating even more abruptly will increase the severity. As you ponder this, I will either inspect ujoints or replace the remaining two at your suggestion. Hopping on it!!! THANKS.

gary_in_nz · Post by **gary_in_nz** » Sat Nov 24, 2007 7:03 am

hi, just been reading through this and i have a similar propblem on another truck i have (swb nissan safari/patrol) and what i have done to that is fit a 50mm suspension lift. are you running a lifted springs by any chance??
as stirlsilver said above it changes all the angles of the UJ's. as a general rule the faces of the gearbox to diff mountings for the drive shaft should be parralell with eachother.

when you put the new gear box in, is the outputs in the same place as the orriginals?? ie, its not to high/low or left or right of where it used to be??

hope you understand what i have just said.

primsil · Post by **primsil** » Sun Nov 25, 2007 7:00 am

My 110 has the same problem, about to replace the unis in the rear shaft, most likely cause as it is all standard. When I do rebuild it with the auto and borgwarner transfer I will fit a stage 1 front prop.

stirlsilver · Post by **stirlsilver** » Sun Nov 25, 2007 1:45 pm

It has to be the angles. If there is no play in the original universals there is no real point changing them. Especially since this problem didn't exist before the changes were made.

SPYDER ROVERS · Post by **SPYDER ROVERS** » Mon Nov 26, 2007 1:11 am

I am so happy that others have had this problem and this forum exists with such great people. I am taking stirlsilvers suggestions to heart and greatly appreciate the input. I am not certain if the suspension has been altered. This unit came from jolly old, and with all the other malfunctions and noises I cant be sure that an angle change did not occur after needed component replacements. Since my coworker has landed in the hospital all weekend, I have yet to start, but I believe you are all correct and will keep you posted. thanks guys.

primsil · Post by **primsil** » Mon Nov 26, 2007 2:41 am

The stage one front axle has a misalignment from factory, that is why it uses the cardan type front driveshaft. The misalignment is because the axle is rotated 10deg toward the transfer case front flange as the driveshaft length is too short and creates too large a universal angle without it.
If you have replaced the front shaft with a normal universal this will give vibrations.
I believe the driveshaft will now be longer than original so a the diff could be rotated back to flat using a normal series housing, but would be better off with lengthening the stage 1 cardan shaft.
You need to check the alignment of the engine, box and transfer in relation to the original, but if you have used all factory mounts then there should be no problem there.

My 110 has a noise on decelerating which is most likely the universals as nothing else has changed, so that may not be your problem but is another possibility.

SPYDER ROVERS · Post by **SPYDER ROVERS** » Tue Nov 27, 2007 3:17 pm

Thanks Prim, you all have given me a great deal of practical knowledge and can only benefit from it. My friend is still hospitalized so Ive not continued but am eager to return to ironing out the problem. With all the hands on knowledge from so many, I am sure to have a wonderful ST-1 that I will enjoy and cuss at for years.

SPYDER ROVERS · Post by **SPYDER ROVERS** » Wed Nov 28, 2007 9:08 pm

UPDATE! The source of the rumbling is the slop between the transfer case output shafts, internally. Took it to the local power train folks to confirm. Told them everything done to date and they even checked out the driveshaft alignment and complimented me on the fine job I did for being a complete idiot. I suppose I will have them correct the problem for a scant $30,000. I love all my rovers but the English company that sold it to me just flat out lied and it is going to cost me a mint by the time I am done. I am getting very frustrated and hope that at the end of this ordeal I will have a stage-1 that I can be proud of,because I will not quit until it is. By the way, does anyone need a wife or spare children. they are on sale this week! Thanks guys.

primsil · Post by **primsil** » Wed Nov 28, 2007 11:25 pm

So they are saying it is slop in the transfer case which I think is an LT230 you have just fitted, not the LT95 that came with the vehicle?

SPYDER ROVERS · Post by **SPYDER ROVERS** » Thu Nov 29, 2007 6:27 pm

That is what was said and on top of that, the sound can be duplicated on the stands, albiet slower. It is the exact sound I here. Ive no idea why as this is my first major overhaul of any of my rovers and I am with all honesty treading new ground, but it may appear that the T-CASE sold me as spectacular in actuality may not have been. It realy bothers me when peaple are not honest.

stirlsilver · Post by **stirlsilver** » Fri Nov 30, 2007 1:03 am

That is unfortunate news... Was the Transfer case a private sale or commercial?