Tdi with SIII transmission - noise

[Snagger]

Hi folks.

I'm just after your opinions on the likely cause of a gnashing noise and increase in floor vibration when accelerating and going over small bumps or undulations on the road. It's more prevalent in 1st-3rd and when accelerating hard, but happens at all speeds. It also happens on bumps when cruising in 4th, but not as harshly. Smooth tarmac results in none of this unless accelerating in low gears at full throttle. The gearbox and prop are in mint condition, having been rebuilt.

Now, I have a few ideas on what may be going on:

1) The torque going through one prop shaft instead of two is causing the slip joint to bind, so any bumps cause the axle to shove the transfer box;

2) The Marsland chassis was made with 19J engine mounts, and the right side one is about 1.5" too far aft, shoving the whole engine and transmission back about 1" (witnessed by the gear stick positions, turbo initially fouling the foot well and the engine mounting rubbers distortion) - the torque reaction could be bringing the flywheel housing into contact with the bulkhead (there's not a great deal of clearance);

3) Axle wrap from having all of the Tdi's torque sent to the rear axle, combined with the use of parabolic (albeit 4-leaf HD) springs.

I intend to realign the rhs engine mounting when the weather and time permits, and that would eliminate one potential problem. I also plan to eventually fit Defender/Discovery axles while retaining the leaf sprung suspension. If axle wrap is a likely candidate, would fitting HD standard leaf springs be of that much help, or should I use an anti-wrap bar to the A-fram ball joint bracket?

[FridgeFreezer]

I rather doubt the awesome power of the TDi is causing issues 1 or 3, I haven't had either problem with a 4.6 V8 in a RWD Series

[rusty_wingnut]

i agree i'd be mightily impressed if its 1 or 3 sounds to me like prop reverberation caused by misalignment.

[Timmy511]

theres two positions where the engine mount can be placed onto the block of the 200tdi, have you bolted it up in the wrong one?

when i put a 200 into my series i didnt have any missalignment issues.

[rjblank]

Snagger, it really sounds like you have either the floor panels or bulkhead coming into contact with the engine/gearbox, possibly due to misalingment of the engine in the chassis, under the conditions you specify (full load/accelleration and bumps). I had some of this with my Landy,, but it turned out to be a slightly bent center floor panel that was contacting the shifter...

[Phil Hancock]

I had a horrible heavy rumble type noise under heavy pulling(2.25d!!), it turned out to be soft gearbox mounting rubbers allowing the transfer gearbox to just contact the gearbox crossmember.

[joanh1]

hi

what engine did you join the gear box to if you dont mind me asking. only because i thought of using a series box to my 300tid to get max acceleration off the line.

thanks for your time

jonah

[Snagger]

OK, thanks for the answers so far.

The engine is a 200Tdi, and the transmission is standard SIII (except for the overdrive). The chassis is a Marsland unit, built with a standard left engine mount and a 2.5 diesel rhs mounting (12J/19J) as I was using a 12J at the time of the rebuild. The 12J and 200Tdi both used the left bracket from the original SIII engine, and a 12J right side bracket. Both had the same fitting problem:

The gearbox mounts went on fine, though the nut on the bottom side of the rubber didn't have much space inside its steel bracket. I later put large washers between these "feet" and the cross member lugs to raise the feet 1mm to make sure that the nut on the rubbers' bottom studs weren't vibrating against the cross member. This had no effect.

The engine mountings don't line up with the brackets, and the rubbers had to be forced, even though the gear box rubbers look straight. The rhs slopes forward, while the left one slopes aft, and they're at significant angles. Given that the left chassis mounting is standard SIII, and that the gearbox seems too far aft, I think this chassis and engine bracket are correct. The rhs chassis bracket is clearly in the wrong position, about 1.5" or so behind where it should be. Interestingly, I was contacted hrough my website by a fellow SIII owner who had Dunsfold LR rebuild his 88" with a Marsland chassis with the same engine bracket mods, and he had exactly the same trouble. DLR had to remove and refit the mountings.

A further result of this aft engine position is that when I fit the Tdi with Defender manifolds and turbo, the turbo's elbow fouled the left foot well. I shimmed the left bracket away from the block by about 1" to widen the engine's "V", raising it higher and shifting it a little to the right to gain the turbo clearance (it also helped line up the mounting rubbers a little). This, of course, means the engine axis is now pointing very slightly to the right at the front end. Do you think that's the cause? I do intend to modify the rhs mounting.

I also wonder whether the gearbox cross member is in the wrong place (too far aft) because the gearbox mountings all look fine.

[Gremlin]

hi

what engine did you join the gear box to if you dont mind me asking. only because i thought of using a series box to my 300tid to get max acceleration off the line.

thanks for your time

jonah

Sorry for the hijack..................................

Its the best way to destroy your series gearbox.....................................

G

[88inchthing]

Hi Snagger

The engine mount is by far the most likley cause of your trouble. I think you need to get it sorted befor you do anything else.I have a 200tdi in my 88 with a series 3 gearbox, and have had no such problems.However i have found that series rubber mounts are not really up to the job as the vibrations at idle are very harsh. I will at some stage change them for somthing more suitable.

Bill

[Snagger]

Thanks for all the replies. I'll treat the engine mountings as the prime suspect.

An interesting prospect has come up, though. I have access to a mint condition s/h Discovery II rear anti-roll bar. I am still planning to fit a 300Tdi Defender rear Salisbury axle and anti-roll bars, but this shorter anti-roll bar will fit between the chassis rails, ahead of the axle, so I don't need big drop-mounts from the chassis to clear the fuel tank. The interesting thing is that it would also work as an anti-tramp bar too. I might combine fitting this anti-roll bar with the axle swaps just in case - a LR mechanic friend was telling me how he saw the axles of a PS10 wrapping as it pulled away from his workshop.