Thread: The ultimate solution to Td5 vibration / knocking

A land rover mechanic told me the other day that the fly wheel sometimes cracks around the bolts or something and this could cause some of the vibrations.. has anyone seen their flywheel in this condition?

I've seen really badly burnt flywheels cracked through the face to the bolts and ones used in drag racing (with high shock loads) crack around the bolts.

mine is auto so im not sure how relevant this is

Yup, mine being an auto too - they don't have a flywheel. In "our" case the flex plate bolts the engine via the torque converter (TC) to the ZF gearbox. You can remove the little inspection cover at the bottom of the bell housing, held by three bolts. With a flashlight you can pretty well spot if any cracks are visible around the three bolts holding the flex plate to the TC.

Have now ordered new output housing, they are around GBP 115. Will keep you posted on result: waste of time&money or fixing the leak and lessening the remaining vibes.

I also replaced the harmonic damper on the RHS of T-box with a new one and dare write that it further softens the vibes.

Before attacking the transfer box I had a real sharp vibration at 2400 rpm, in motion or in Park, now you feel the engine "peaks" its harmonic between 2200 and 2300 but the effect is softened that much that someone not aware of it would not notice it.

Originally Posted by dutchviking

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?

Does not have to much of a score in the seal area for the seal to leak.

True. However when replacing the output bearing I used a new output flange, new output shaft and of course new seal using the correct LR tool. Since the seal still leaks I suspect the bearing to move enough in it's housing to be the cause of the leak. I ran out of clues...

Originally Posted by dutchviking

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! 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.

Hi DV, can you post a diagram pointing out which bearing it is. I was thinking of buying a bearing and seal kit and replacing the lot but don't have the press etc so will more than likely have to take it to a specialist. Either way, the vibes are annoying and I want them gone.

ive recently being getting annoyed by the vibration, its seems like its getting worse but then its hard to tell if i just think that coz im paying more attention to it...

can't wait to have some time to have a closer look.