The ultimate solution to Td5 vibration / knocking

I have read the many comments on this and other threads that all 5 cylinder diesels vibrate because of there basic design. But I can say that the RX270 5 cylinder in our SsangYong Rexton which is a engine made under licence from Mercedes hardly vibrates at all and goes like stink and is very quite and economical.

I know that my comments don't add anything to the discussion but its disappointing that Ssangyong a brand that many people laugh at can get it right when LR couldn't.

Still I have decided to drive a couple more TD5's to see if the first one I drove last week was an ordinary one or not before giving up on them completely as an alternative tow vehicle.

cheers,
Terry

This weekend I took the LT230 T-box apart. As the vibration is most noticable from the handbrake area and my rear propshaft was vibrating like hell while stationary at 2400 RPM (new shaft with new UJ made no difference) I came to the conclusion that something might have worn in the T-box after having to cope with the vibes for nearly 200000Km.

reading various treads about changing the input gear with bearings with the box in situ, and changing the bearing on the rear output shaft I just did it. You have to remove the brake drum and rear prop shaft. Drain the T-box for oil. Remove bottom plate as it helps a lot removing the forward bearing race from the T-box casing. Mark the rear output cover (6 bolts) with a screw driver so that the outer cover and the plate that holds the rear bearing can be aligned later-on. remove the rear cover & plate and pull out the input gear. There is a drive shaft adapter that is bolted on the ZF autobox output shaft, p/n FTC5090 that can be replaced simultaneously. I did not know initially that this was a individual part, otherwise I'd replaced it too. By the way: noticed that the ZF shaft had a lot of float, could easily move it 5 mm side to side! :o Checked with helpful as always Dave Ashcroft from Ashcroft Transmissions and he confirmed it to be normal. :) Spline wear inside the input gear was minimal, as it was the cross-drilled type. I modified a bearing puller to remove the front bearing race, and again, a great help if you can reach through the underside of the t-box to hold the puller. carefully drove the new bearing race into position after cleaning everything. You need a press to position the new conical bearings onto the new input gear, and there is a shim procedure (all described in RAVE) where you have to place the thinnest 3.15mm shim under the rear bearing race, put everything back together to measure end float of the input gear. The bearings should receive a certain preload. After that's checked remove input gear, grease-up bearings and use sealant between both cover plates and t-box. Job 1 done!

Next remove output housing (first vibration damper goes). Start by removing all bolts, they are a pain to remove as they are "loctited-in". Then with some knocks of hammer and a piece of wood the output housing can be removed from the t-box. Now remove output flange nut, and flange. Then remove large circlip. I removed spined output shaft with a hammer couple of hits and it is out. Used press to remove bearing. The bearing was SHOT. Could not even turn it freely, it was jamming all the time. Cleaned all, used press again to position new bearing. Circlip back in place. Then used press to position new output shaft. New oil seal, then used new prop flange with new mudshield, 4 new bolts etc. Flange back on the output shaft, anyway, this procedure is documented very well on www.discovery2.co.uk.

Output housing with sealant back in place, as well as bottom cover of t-box. read on US forums that slight overfill of T-box is recommended, so jacked-up rear of Disco and filled with correct gear oil. Finally propshaft back on and for the testdrive....

WHAT A DIFFERENCE!!!!! the "hot spot" around 2400 rpm IS GONE. It now goes through the whole range (under load) without any extra vibes.

I would well recommend replacing the bearing of the rear output shaft. It can be done in under 3 hours if you have the press and other tools at hand.

nice work ! so do you think it was most likely the rear output shaft bearing that was making noise ??

if so would disconnecting rear prop shaft stop noise by removing load on that bearing and thus point towards it needing replacement ?

I read several times when people were pursuing a vibration issue and the rear rubber coupling between diff and prop shaft was suspect - they removed the rear prop and the problem went away - this made me think towards the T-box bearing yes. So try without rear prop shaft first. I also found that the rubber between both steel blocks of the so very important harmonic damper on the RH side of the T-box was hard as stone. I ordered a new damper where the rubber is SO much softer. Will mount it as soon as I have time to see if it softens things even further. I read someplace that the damper is supposed to counter-resonate in the TD5 harmonic spectrum, but if the dampening rubber is nearly as hard as the steel blocks there is not much left to resonate. Keep you guys posted!

great thanks. i does sound familiar about not having the rear prop shaft connected. as when i replaced my handbrake, i ran around for a few days with no rear shaft and i swear i remember it being quiter than ive ever heard it. thought this was because the handbrake drum was off.

but it could likely be due to the bearing.

so next chance i get, ill take it off again.

Found this absolute great article that addresses EXACTLY why our TD5's suffer from harmonics and what a key role the torsional vibration pulley and damper plays: Balancer Tech.. And they are an Australian company too... The world is a small place. Welcome to the world of harmonics. Especially this part describes whats wrong in many Td5 cases:

"Modern car engines will probably pass through a number of vibration periods over their useable rpm range. Most are hardly noticed due to the fact that some harmonics cancel each other out. It is when a combination of harmonics build on one another to amplify the torsional vibration at the crankshaft we have a problem.

This is also known as "critical rpm’s". ;) (Sounds familiar) If the engine is held at or near this critical rpm for any length of time the crank will probably suffer fatigue failure. This critical rpm must be avoided or at the least damped.

A loose or sheared front pulley, a flywheel coming loose, a fatigued clutch cover etc. can be sure signs of running an undamped or incorrectly engineered damper."

Leaves me thinking that the crankshaft bearings probably got their share of abuse as well. Is is a feasible job to replace them yourselves?

Quote:

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Is is a feasible job to replace them yourselves?

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the thought makes me grimace... one probably could do it if i had too, but i really wouldnt want to do it unless it was totally stuffed, or i had heaps of time and the cash.


these do sound interesting though:
Pulleys & Balancers


thanks again, for now im content just thinking about a rear output bearing job

www.discovery2.co.uk / Crankshaft pulley* / TV damper replacement

Billet Harmonic Balancer - Engines - Triumph Rover Spares South Australia

So with everything replaced in the rear output housing the output seal still leaks. I noticed some scoring caused by the bearing inside the housing and wonder if it causes the whole bearing to move enough to cause the seal to leak?