Thwaites 6 ton all drive 1998

[Johnny]

Hi
I have a 6 ton thwaites all drive dumper 1998 and it’s been lying a few years. Dot 4 brake fluid was put in instead of mineral fluid and swelled the brake seals. I recently pulled it out and took skip off and power washed it and put into shed.
It has got a brakes sorted, full service, niggly electrical problems etc., all sorted. I took it out of shed today for a drive and very quickly it started to put a pull on the engine. I got it back into shed and took bottom prop shaft up. Jacked it up at front and lifted back end with forks. I started it up again and transmission is tightening up and the housing was starting to warm up. Also it appears to be trying to blow the transmission dip stick out. Checked hand brake as I put on new pads and it is running free. Has anyone any ideas

 

[Diggerdave]

Hi
I have a 6 ton thwaites all drive dumper 1998 and it’s been lying a few years. Dot 4 brake fluid was put in instead of mineral fluid and swelled the brake seals. I recently pulled it out and took skip off and power washed it and put into shed.
It has got a brakes sorted, full service, niggly electrical problems etc., all sorted. I took it out of shed today for a drive and very quickly it started to put a pull on the engine. I got it back into shed and took bottom prop shaft up. Jacked it up at front and lifted back end with forks. I started it up again and transmission is tightening up and the housing was starting to warm up. Also it appears to be trying to blow the transmission dip stick out. Checked hand brake as I put on new pads and it is running free. Has anyone any ideas

Could it be the linkage not allowing the brake pedal to return all the way up causing the brakes to bind on? Had similar problem on mine.

 

[Johnny]

Could it be the linkage not allowing the brake pedal to return all the way up causing the brakes to bind on? Had similar problem on mine.

No. Both axles are turning freely. That’s why I jacked it up and removed the prop shaft. This has narrowed it down to transmission problem of some sort.

 

[V8Druid]

No. Both axles are turning freely. That’s why I jacked it up and removed the prop shaft. This has narrowed it down to transmission problem of some sort.

over full / contaminated or both

 

[Bri963]

Water in trans oil?

 

[Gecko]

Just checking, but it is the transmission box and not the drop box that's developing pressure?

 

[Johnny]

Thanks for your comments. ATF (red) was changed and new filter put on. It was slightly milky in colour probably due to lying outside and water getting in by the gear lever boot. I never thought of the drop box possibility being half seized.I shall take a look at drop box in the morning to see is it free and get back .

 

[Mick-the-fitter]

Could you take the floor plate off and send some pics? Also yes drop the prop from gear box to drop box then try it!

 

[Johnny]

I have the floor plate off already as I’ve been doing hand brake etc., just generally anything it needed . A winter project as this dumper is really missed around the farm. I can send some pictures tomorrow.
Thanks

 

[Johnny]

Hi Everyone
I attached photos as requested. Drop box without taking top prop shaft off appears to be free

 

[Johnny]

I took another quick look at dumper as I was going past the shed. It’s sitting all four wheels off the ground and bottom prop shaft off. I started it up and when a gear is selected and shuttle in neutral it still wants to drive front wheels. Something must be pressurising inside transmission? Looking back when I started it up first time after lying a few years the transmission oil pressure switch had to be replaced as it was split. I thought it was wear and tear or frost that split it but maybe it was whatever is causing the excess pressure?? Anyone any ideas ? Thanks

 

[V8Druid]

I took another quick look at dumper as I was going past the shed. It’s sitting all four wheels off the ground and bottom prop shaft off. I started it up and when a gear is selected and shuttle in neutral it still wants to drive front wheels. Something must be pressurising inside transmission? Looking back when I started it up first time after lying a few years the transmission oil pressure switch had to be replaced as it was split. I thought it was wear and tear or frost that split it but maybe it was whatever is causing the excess pressure?? Anyone any ideas ? Thanks

sub. the pressure switch with a gauge, see what you're getting and whether it's continually climbing or reaching a stable pressure ..... anyone have any ideas about what it should sit at? .. @Mick-the-fitter ???
try dropping off / disconnecting one solenoid in case they're fighting each other?? ... may be an electrical issue at the switch? ... what's it doing in the neutral position ... try getting some meter readings at the solenoid DIN plugs??
must be a PRV in the system some where? - maybe stuck?

 

[Johnny]

Thanks Mick
When gearbox is in neutral it’s stops driving. When in gear and I select forward or reverse it does what it should. Problem is the transmission warms up quickly and then the drive gets tight and won’t move until you rev the engine and it gradually gets worse. Could it be circulating problems/ blockages

 

[V8Druid]

Thanks Mick
When gearbox is in neutral it’s stops driving. When in gear and I select forward or reverse it does what it should. Problem is the transmission warms up quickly and then the drive gets tight and won’t move until you rev the engine and it gradually gets worse. Could it be circulating problems/ blockages

the gear box, TC or drop box warms up quickly?? ... get a gauge tee-ed in where the pressure switch lives and see what the pressure is doing?

 

[Johnny]

Sorry. The transmission housing warms quickly.

 

[jd6820]

I took another quick look at dumper as I was going past the shed. It’s sitting all four wheels off the ground and bottom prop shaft off. I started it up and when a gear is selected and shuttle in neutral it still wants to drive front wheels. Something must be pressurising inside transmission? Looking back when I started it up first time after lying a few years the transmission oil pressure switch had to be replaced as it was split. I thought it was wear and tear or frost that split it but maybe it was whatever is causing the excess pressure?? Anyone any ideas ? Thanks

Probably worth pressure checking to see if you have any clutch pressure when neutral is selected on the shuttle, hence a stuck solenoid or one that is active. I'm thinking that maybe you have a warped pack that is dragging or slipping due to the water ingress swelling the linings on the clutch plates? But I'd expect to see it trying to drive when a gear is selected but shuttle in neutral. Driving in the opposite direction to this drag would then load the engine up the second the shuttle was moved and the relevant pack applied. i.e. if forwards was selected when the reverse pack is dragging then it would load the engine but if reverse was selected as that is the pack dragging it would drive as normal.

Pressure testing forwards and reverse packs individually if you can will eliminate the valves and solenoids as being an issue. However I cannot see how they can both apply as it esentially shuttles a valve from one side to the other, backed up by springs, so I'm thinking an internal fault. But pressure check first before tearing down the gearbox. Pressures should be around 150-175psi, from memory.

Edit: Also maybe pressure switch isn't working and its driving with low clutch pressure that is causing the packs to heat up during use and causing your issues. So check pressures are within spec any less than 90psi and light should be illuminated.

 

[Mick-the-fitter]

Can you get it into gear manually when the engine running (manual box, no dump pedal) I suspect the clutch packs dragging and metal plates have got hot and warped!

 

[Johnny]

Hi Everyone
Sorry for delay getting back. Been busy on the farm. We took the bull by the horns one evening and took the transmission out and split the box. It is pretty simple inside . All was very clean and no filings etc., we took the clutch pack out and put it in the Vice. Again all looked good until we went to turn the cogs at each end. Theses should turn freely with a slight drag. We could not get them to turn . We had to use a pry bar. We then decided to strip it. The circlip was also tight to remove. The plates all removed easily and all in good condition. We turned the pack in the vice and this time maybe tightened it slightly tighter and we heard a sharp click and remaining plates freed up to normal. We got speaking to a local mechanic and he knew of the problem right away. These older packs have a hard plastic ring? Plate ? Spacer? Inside and when they heat they expand and when engaged they stick and cause the plates to be pressurised and won’t release when neutral is selected. An aluminium conversion kit is available to replace this so we have this and a seal kit ordered. It seems some guys just remove these hard plastic plates? Spacer? and give them a run with the lathe but we didn’t want to chance this in case it was a quick fix and happen again. We shall you all posted on our progress and send some photos in. Thanks

 

[Johnny]

Photos

 

[Mick-the-fitter]

Good stuff, definitely was clutch packs then, be totally different when it’s done.