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Broken autobox


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That's the essence of my problem. The flex plate (which is part 6, more like a disc of 2mm steel with some holes in it) bolts to the torque converter via a spacer piece to make up the distance that the big converter ring provides between the flywheel housing and the bellhousing. I didn't install it all so I have trouble working out what's V8, Tdi, original and mod!

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Does anybody make a flex plate to attach a V8 autobox to a Tdi engine? I doubt Land Rover do, which might explain why it was bodged in the first place :)

Well landrover do..........

You need a 300Tdi flex plate, bellhousing and torque converter and the actual ZF box is interchangeable. In fact the only difference between a 300tdi box and a V8 box is the vlave block which controls the shift points. The ratios are in fact all the same.

My 300 auto rangie actually has a V8 box in it having evidently been swapped by a previous owner. Its then a nuts and bolts job to swap the torque converter and bellhousing over.

IMHO flex platres breaking is usually down to misalignment issues. It needs to be very precise! A mate of mine had a conversion plate made up years ago that turned out to be 40 thou out of true. The truck didnt make it to the top of the yard (about 50 yards) before the flex plate broke!

The one in my rangie broke becasue the muppet previous owner left the dowell pins out when he re-fitted the box. You'd have thought that with all the bolts holding the bellhousing on it'd be near enough, but no!

HTH

Jon

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Disassembly shows the following:

14072007052.jpg

14072007054.jpg

It's cracked around the edge bolts into the torque converter, and also nearly broken through at the centre. I'm going to reassemble it as before, without the washers, and see how it looks. I'm not impressed with the install though, when I came to pull the box backwards I find that difflock doesn't work, there's wiring resting on the turbo and some of the bellhousing bolts were either left out or worked loose. After I've taken the aircleaner off and looked down there's a visible gap around the bellhousing:

14072007051.jpg

I'll have a look again at the gap between the flex plate and the torque converter but it was around 8mm when it all came apart - I can see why washers looked like a tempting option.

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Hi,

this is a stock V8 flexplate FRC7081 with some extra hole drilled in it,

as Jon says they break due to misalignment from a poorly made adapter kit,

the M&D one will last longer but the underlying problem is the misalignment,

only way to fix it is :

leave adapter plate on engine,

remove bellhousing from autobox and fit to adapter plate without dowels

put mag mount DTI on crank and centralise bellhousing,

bolt bell to adapter plate

remove adapter plate and bell,

turnover and ream an oversize dowel hole through plate into bell,

fit new dowels and assemble,

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  • 4 weeks later...

Right, one weekend, 500 miles in a rented banger and several hours lying under the car, the flex plate and gearbox are now installed. I've found a number of issues which may have caused a misalignment and I'm now much happier that the gearbox is pointing squarely at the engine.

However, I'm back to the original point: there's a gap between the flex plate and the torque converter of about 5mm. I can pull the t/c forward until it touches the flex plate, it slides smoothly for 4mm or so and then there's a 'bump' as it takes up the last 1mm. It will then slide smoothly back home. Do I bolt it up like that and risk unseating the oil pump, or make four rectangular spacers which are the same shape as the t/c 'feet'? The bolts will not be overtight this time, but doused in threadlock.

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The simplest solution would be to use standard LR shims to move the flex plate towards the TC. These fit on the end of the crank and are used to set the drive plate height above the drive plate housing. They are available in thicknesses of 1.0 to 2.1mm in 0.1mm increments. From your measurements, 2.1mm would probably be close enough. Sorry, don't have part numbers to hand.

I've recently re-engineered a Motor & Diesel Mazda conversion to a 4 speed auto in a RR. M&D advised to check for ~2mm clearance between the flex plate and the TC (with the TC pushed fully home) before bolting them together.

why not take it back to the fitter.

he took your ££ and has some responsibility for the work

Tony has hit the nail on the head! I trust you have worked out some sort of financial settlement, as the responsibility rests with the guy who designed and fitted the conversion. You shouldn't be out of pocket and using your time to put right the shortcomings of someone elses (professional?) work.

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Dammit, the holes in the centre of the flex plate don't line up too well to start with. It took me three hours to get all ten in, then I made the fatal mistake of taking them out one at a time to apply loctite - the tenth refused to re-engage for another hour. If you have a 2mm shim I'd take it gratefully because this is the remaining worry about alignment. When the gearbox was installed first time, some bellhousing bolts were missing and the angle bracket across the back of the engine (holds the wiring?) was trapped between the adaptor and the bellhousing. These, combined with the gaping hole in the bottom of the bellhousing, are the suspected cause of failure.

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That'd do it! Mine broke simply because some one left the dowels out between the bellhousing and the flywheel housing, so that plate trapped between the two would kill it very quickly!

I've got two shims - 1.3mm and 1.7mm. You need to precisely set the shimming of the flexplate as described in the 300tdi manual. Have you done this?

Cheers

Jon

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I don't need a manual - I need an automatic :)

I didn't know there was a shimming process, I just bolted it all up. Nothing will please me more than taking it all apart again. Still, if it's coming apart again I can line the flex plate up with the four larger holes in the flywheel so I can fit the t/c bolts easily too. I would be very grateful of your shims, it sounds like both together will do the job nicely.

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Get yourself a copy of the 300tdi overhaul manual. The shims sit on the end of the crankshaft behind the boss that locates the flex plate. So in order of assembly you should have shim, then the stepped boss, then the flex plate, then the other thick plate that bolts on the other side. As I say - read the manual and work out what shim you need. You would normally only use one shim and it has to be accurately shimmed to within 0.1mm!!! No guesswork or M10 washers here!

That or take a look at the exploded diagram in the parts book and it'll explain all!

Cheers

Jon

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Thanks for that - I found the manual online. The torque converter slides a bit so it can't be that critical... can it? I don't have confidence in the dimension that the manual details because the adaptor plate has other "features" which suggest it isn't perfect.

I have a gap between the t/c and the flex plate of 5mm. Ashcroft's site says the t/c endfloat should be 2mm, so I'll shim it by 3mm (1.3 + 1.7!) and make sure that the boss still locates properly. If not, I'll have to get a 2.1mm spacer, the largest they do.

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