Manitou MLT730 Transmission Problem

[RoFo]

Hi

I'm new to the forum - this is my first post.

I've recently acquired a very clean 2002 Manitou MLT 730 to replace our aging 1995 MLT 627. I factored in doing the usual things - replace/rebuild the 90 degree gearbox, replace the drive shaft to the box and upgrade the fan assembly to stop it rattling.

However, when warmed-up it's started to jump, lurch and be quite "notchy" in first and second gear, either in reverse or forward. It doesn't seem to do it in 3rd of 4th, and not when cold. There's oil in the gearbox. It's a fully manual 4-speed box, type COM-T4-2024, manufactured by Turner.

Does anyone know what this might be, and how to rectify it? Any help would be appreciated.

Many thanks, Roger

 

[icanshootwell]

@ACEngineering is the manitou go too guy and he is kept busy on the topic.

 

[Sparkplug]

Strange problem for a gearbox that is so reliable, fitted in hundreds of thousand Manitous from 1987 onward, and whilst TC Pumps do wear out or Break Up, and Clutch Packs Seals do leak or using it in the wrong gear you can burn the clutch packs out or weld the discs together, its the same gearbox as fitted in your old MLT626, so @ACEngineering will no doubt have come across a similar problem before and may have suggestions.
Dont forget to check Compensation Ram Pins Bushes For Excessive wear

 

[ACEngineering]

Strange problem for a gearbox that is so reliable, fitted in hundreds of thousand Manitous from 1987 onward, and whilst TC Pumps do wear out or Break Up, and Clutch Packs Seals do leak or using it in the wrong gear you can burn the clutch packs out or weld the discs together, its the same gearbox as fitted in your old MLT626, so @ACEngineering will no doubt have come across a similar problem before and may have suggestions.
Dont forget to check Compensation Ram Pins Bushes For Excessive wear

A mlt 626 gearbox is not the same as a mlt 730! Alot of differences! 626 were all cable operated. Had the pressure relief valves all in the top valve block were cable operated f/r. Totally different casings too.

Mlt 730 has pressure valves built in to ports in the main casing.
Has electric valve on to for forward reverse.
Different torque converter stall angle.

 

[ACEngineering]

Hi

I'm new to the forum - this is my first post.

I've recently acquired a very clean 2002 Manitou MLT 730 to replace our aging 1995 MLT 627. I factored in doing the usual things - replace/rebuild the 90 degree gearbox, replace the drive shaft to the box and upgrade the fan assembly to stop it rattling.

However, when warmed-up it's started to jump, lurch and be quite "notchy" in first and second gear, either in reverse or forward. It doesn't seem to do it in 3rd of 4th, and not when cold. There's oil in the gearbox. It's a fully manual 4-speed box, type COM-T4-2024, manufactured by Turner.

Does anyone know what this might be, and how to rectify it? Any help would be appreciated.

Many thanks, Roger

So firstly I got new 90 deg boxes on offer if your in uk?

Now transmission problem.
This sounds to me like it could be a soft shift valve problem.
The f/r solenoid block on top of the transmission has a plug next to each forward and reverse solenoid. Behind this plug is a spring or 2 and a spool. I have had these springs break before which means the oil feeding in to the clutch is unrestricted and goes in at full flow resulting in the clutch locking up very sharply!

Strip that valve block down and check springs and clean the spools.

You will have the early type valve now obsolete. The newer valve is called a super soft shift so obviously been improved. They are interchangeable. Sadly spicer Turner do not sell any parts for these valves other than the solenoids and the valve stems they silde on to. If your soft shift springs are broken you either replace the whole valve with new or used or find some secondhand springs.
New valve is over £1k I think!

If that doesn't fix it then your probably looking at leaking clutches. As the pressure is delayed going in via the soft shift valve it can take a while for the oil to build up enough pressure to overcome the leak and force the piston seal against the drum to fully seal. This also seems to create a fierce take up of drive or direction change.

Lastly check out the rear axle pivot to chassis.
Has 2 very good top hat bushes on them but the top hat bit wears off resulting in a lot of slop back and forth creating a load knock when changing direction etc.
Last one I did was still sloppy with new bushes in so made a 3.2mm shim for it which tightened it right up.

 

[Sparkplug]

OK not technically the same, but in principle it works exactly the same, with all the fine detail changes you mention -

 

[ACEngineering]

Here's one I did earlier?
As you can see theres nothing left of the springs in this one! Both shattered in to many pieces.

This was off a new Holland LM410 1999. Slightly different gearbox but same type of valve on the top.
There was at least 2 newer versions of this valve block after this early one. Not sure what years they changed though but your definitely wont have the latest one on it that's for sure.

 

[ACEngineering]

OK not technically the same, but in principle it works exactly the same, with all the fine detail changes you mention -

It's all in the detail?

 

[ACEngineering]

Hi

I'm new to the forum - this is my first post.

I've recently acquired a very clean 2002 Manitou MLT 730 to replace our aging 1995 MLT 627. I factored in doing the usual things - replace/rebuild the 90 degree gearbox, replace the drive shaft to the box and upgrade the fan assembly to stop it rattling.

However, when warmed-up it's started to jump, lurch and be quite "notchy" in first and second gear, either in reverse or forward. It doesn't seem to do it in 3rd of 4th, and not when cold. There's oil in the gearbox. It's a fully manual 4-speed box, type COM-T4-2024, manufactured by Turner.

Does anyone know what this might be, and how to rectify it? Any help would be appreciated.

Many thanks, Roger

See above posts, but circled in red here is the soft shift valve with broken springs and the plunger you should check out.
This machine drove fine other than when changing direction or selecting drive, you couldn't select drive at anything above idle speed and even then it felt like it would snap the prop shafts off as it took out the slack in the drive train!

 

[RoFo]

Many thanks for this. Is this an easy job to do? Do you have an image of a gearbox to see where the valve block is fitted?

Are the technical specs of the spring known - whilst it wouldn't be cheap to get springs made from scratch, it should certainly be less than £1,000.

Finally, I'm assuming that there are two valves, one for gears 1-2 and a second for 3-4, which might explain why it is only a problem in the lower gears. Is this correct?

 

[ACEngineering]

Many thanks for this. Is this an easy job to do? Do you have an image of a gearbox to see where the valve block is fitted?

Are the technical specs of the spring known - whilst it wouldn't be cheap to get springs made from scratch, it should certainly be less than £1,000.

Finally, I'm assuming that there are two valves, one for gears 1-2 and a second for 3-4, which might explain why it is only a problem in the lower gears. Is this correct?

its right on the top of the transmission you cant miss it. its hard to get the block off with out dropping the transmission a bit i think and thats if the screws are not rusted tight. Sometimes have to drill the heads off and pry the valve off!

you should be able to remove both the soft shifts with out removing the block from the transmission though.

There is only one on a 4 speed manual. one is forwards and one is reverse. 3rd and 4th gears will be smoother as they are higher geared so the torque converter absorbs more of the shock load. IMO ignore 1st gear its completely useless, you only need 2nd and 3rd around a yard and 4th for road.

 

[ACEngineering]

Many thanks for this. Is this an easy job to do? Do you have an image of a gearbox to see where the valve block is fitted?

Are the technical specs of the spring known - whilst it wouldn't be cheap to get springs made from scratch, it should certainly be less than £1,000.

Finally, I'm assuming that there are two valves, one for gears 1-2 and a second for 3-4, which might explain why it is only a problem in the lower gears. Is this correct?

Ah of cause i maybe missing the obvious here! on the dash there is a yellow rocker switch with a cog in it. make sure you dont have that turned on! if you do it dumps the transmission drive with the brake pedal and is a total waste of time as the machine is simply horrible to drive with it on.

 

[RoFo]

Many thanks for your advice - it's much appreciated. I'll check the switch.

I have no idea how old the oil is in the transmission, so I should do an oil and filter change as a matter of course. What oil should I put into the transmission? Also, do you now where I can get a user manual and parts book?

 

[ACEngineering]

Many thanks for your advice - it's much appreciated. I'll check the switch.

I have no idea how old the oil is in the transmission, so I should do an oil and filter change as a matter of course. What oil should I put into the transmission? Also, do you now where I can get a user manual and parts book?

Use ATF Dexron 3 in the transmission. Genuine paper manuals are only around £10 each so dont go buying PDF copies off ebay for £30 odd plus quid!

 

[RoFo]

Hi. As an update I replaced the oil in the gearbox and now all is fine - I've worked the machine really hard and I no longer have any problems. It's amazing what a difference new fluids and filters will do. It wasn't overly apparent from the colour of the oil on the dipstick just how filthy it was. Thanks for all your suggestions.