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Joined: Feb 02 2018
Posts: 196

Gearbox has suddenly gone a bit snatchy/clunky on 2-3rd upchange in auto about 3 times out of 10. Heavy acceleration doesn't do it but if it's gentle-ish (fuel saving) it does. For example sat at traffic lights and drive away stuck behind the usual go - stop - slow - go - chug - while the cars work out they have to change gear AND drive forward on green! that's when it snatches badly.

If I use manual 2 -3rd it doesn't do it, or I can't feel it. One or 2 of the clunks were quite bad, a loud bang and a snatch in the transmission, but then I ran it around Oulton Park in low last weekend and that was clunky to start with but got smoother after about 15 minutes. Now it seems to still slip / snatch but nowhere near as clunky as it was before running round in low range for a couple of hours on the grass.

I changed the ATF and filter 6 months ago and I do have Lucas trans fix in there. So crap in the gearbox, worn clutch plates? I'm going to do another ATF/Transfix change this weekend as my plan.

Due another run to Limoges again at the end of May so I'd like to fix this.

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Joined: Dec 30 2015
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Mukiwa wrote:

Due another run to Limoges again at the end of May so I'd like to fix this.

I drive through Limoges now my mate has moved, went through there on Tuesday. It might be worth giving Ashcroft Transmissions a bell, see if they have come across the problem before and whether it is a simple fix or a sign of impending doom.

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Joined: Jun 16 2018
Posts: 67

Prior to my ownership of my 2000 4.0, it had been given a replacement torque converter. I have subsequently changed oil and filter (even though one could have assumed this would have been done at the time of TC replacement) and it is sweet.

As this all happened before I got the car I just wondered if it might have a bearing in this situation but I have no idea what the symptoms of a knackered TC might be........

From the paperwork I got with the car, it cost about £400 IIRC.

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If it is the TC, £175 for a new one (https://www.ashcroft-transmissions.co.uk/miscellaneous/torque-converters/torque-converter.html) so not a bad deal really.

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Joined: Jan 16 2016
Posts: 170

It could be the clutch plates are disintegrating. However the gearbox valve box could be also gummed up. It takes ATF Dextron 2/3.
Gear change is also affected by readings from the various sensors around the engine.
Dave Ashcroft also told me to clean the MAF first if there was a gear change issue, don't know why, but he is the main man.

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Joined: Feb 02 2018
Posts: 196

Ok guys thanks for the reply's. I'll clean the MAF first. Dextron + Trans fix this weekend. I'll call Ashcroft as well.

When I say Limoges it depends on the route I take down. Rochechouarte is the town but we fly to Limoges and it's only 30 minutes to the airport but have my trailer will take more stuff down. Got to use the P38's abilities now :thumbsup:

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Joined: Feb 02 2018
Posts: 196

I did change fluids on gearbox, TC and diffs 6 months ago. But I did have the problem of the mysterious cooler pipe undoing itself under the gearbox last October. Maybe I'll do a filter change again as well....

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Mukiwa wrote:

When I say Limoges it depends on the route I take down.

My route is A16 down to Paris, then round to the west and pick up the A10, A71 and A20 until J56. Limoges is about the only civilisation on the route....

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Joined: Feb 02 2018
Posts: 196

Ok I've cleaned the MAF with some cleaner (Amazon 12 hour delivery :thumbsup: ) and I can report that I do have some improvement. I'm guessing that the ecu will have to re-learn gear changes again. Will watch it closely over the next few days.
I'll keep you all posted. Thanks :-D

Gilbertd, I find the roads are brilliant except round Paris (I avoid when I can, go via Caen/Le Havre) until the last hour of driving. Horrible 50mph roads.

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Joined: Feb 02 2018
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Well today the car is now slipping heavily in 2nd. Won't really go past 50mph now. Finally got back from the airport, I'm guessing clutch pack or TC. Bugger

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Are you in the Norfolk/Suffolk area or am I getting you mixed up with someone else? If you are, East Coast 4x4 near Beccles had about 6 complete gearboxes sitting on pallets last time I was there. They look even bigger when off the car than when on it and are bloody heavy but it could be an option.

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Joined: Feb 02 2018
Posts: 196

Cheshire, Oulton Park. Funnily enough I had my engine swap done there! Dave and his dad were really great, very helpful and I fully recommend them.
Question is is it more cost effective for an Ashcroft rebuilt gearbox or a non provenance second hand gear box from a scrapper? Clutch packs could be in the same condition.....

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Joined: Feb 02 2018
Posts: 196

Will a 98 box fit my 99 DSE? I have an older gearbox which I will confirm the serial number / part number tomorrow

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According to Microcat (or LRcat anyway) there's 3 differnet variations, 94-97MY, 98MY and 99 onwards. Can't tell whether that is the same with diesel and petrol but the 4.6 petrol has the 4HP24 and the 4.0 litre and diesel has the 4HP22, so it looks like there are differences. Ashcrofts want £725 plus VAT for a reconditioned one which will come with a warranty and I suspect you be looking at something over £200 for a secondhand one of unknown condition so for the difference it would be worth spending the extra if you intend keeping the car. You'd still need to pay someone to change it or do it yourself whichever way you go. If it were me I'd go for the recon as I have no intention of ever selling my car and I want it to keep going with the trips I do (later this year I've got a trip to Holland and two trips to Latvia and probably a few to France as well).

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Joined: Jan 16 2016
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If you are going to change your gearbox, change it for the HP24 out of the 4.6. It has stronger internals, particularly if you have chipped the engine. Use your old diesel bellhousing and torque converter. You need to get the later HP24 box marked 065, which is a direct swap. I can advise on the details as I have done it.
Doing it via Ashcrofts (as I did) is expensive. The cost does not include fitting. They farm it out to other garages they use.
They do a very good job but knowing what I know now I think I would buy a S/H box and get a local indy to fit it.
You see plenty of gearboxes on Ebay or contact Emmotts of Colne, not too far.
There are three variations of auto box used in the P38. The HP22 used in the diesel and the 4.0, and two versions of the HP24, early and late, used in the 4.6.
The early version of HP24 is 15mm longer but the later one is exactly the same overall. The bellhousings and TC's are different between the diesel and 4.0/4.6.
The early HP24 box can be made to fit by fitting a later tailend housing according to Ashcrofts . Or maybe just redrill the gearbox cross member? Don't know as I haven't done it.
Other things to consider: Ashcrofts can fit beefier HP24 internals in a HP22 box as an alternative. Also you can get an uprated TC for the diesel. I have fitted one.

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Joined: Feb 02 2018
Posts: 196

Thanks for the info guys

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Joined: Feb 02 2018
Posts: 196

dave3d wrote:

If you are going to change your gearbox, change it for the HP24 out of the 4.6. It has stronger internals, particularly if you have chipped the engine. Use your old diesel bellhousing and torque converter. You need to get the later HP24 box marked 065, which is a direct swap. I can advise on the details as I have done it.

The bellhousings and TC's are different between the diesel and 4.0/4.6.

Also you can get an uprated TC for the diesel. I have fitted one.

Hi Dave3d,

I've tracked down a 065 :thumbsup: So even with the 065 I still need to swap the tc and bellhousing? Where do you get a beefed up TC from? Does it come from a supplier or from another P38 family?

And thanks for the coffee :thumbsup:

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Joined: Feb 02 2018
Posts: 196

I have changed the ATF, changed the burned out lift pump and still getting the slipping and lack of power, top speed 50mph and no more no matter what.
Guess the box really is shagged hahaha

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Joined: Jan 16 2016
Posts: 170

Hi Hoppy,

I guess "shagged" is a technical expression? Yes, use your old diesel bellhousing and TC. The V8 bellhousing is wider and has different bolt hole spacings. The 4.6 petrol TC won't fit either. It is bigger and won't physically fit inside the diesel bellhousing, so you don't have much choice.
I got my uprated diesel TC from Ashcrofts. They are expensive to buy but I did a deal with them and part exed a brand new 4.6 TC. New, I think they would be around £1000. I don't think Ashcrofts make them. I think they may be based on another L/R model but don't know for sure.
Whether it is worth the money? Not sure. It does slip less and the lockup in top occurs at 46-48mph whereas before it was maybe 52-54mph. I have chipped my diesel and Ashcrofts recommended it , so it was part of a package deal.
Good luck with the new box. Labour to change a box? Two guys x 2 hrs. 4 man hrs total?

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Joined: Feb 02 2018
Posts: 196

SOLVED:
Unplugged the MAF sensor plug (after the air filter) now going like a rocket. New one will be ordered. Must have been on the way out when I cleaned it as it did improve for 24 hours. Cheaper than a gearbox, but I will be getting an HP24, txfr box and uprated tc lined up in the future for when the inevitable happens

Thanks to all for your advice :thumbsdown:
MAF not MAP