We have a D8T with worn/damaged clutch pack #1. Are there any pitfalls or issues that we need to be aware of removing the transmission? Never done one of these before so any assistance in preventing problems will be greatly appreciated. Once it is out we have a mobile Cat specialist calling in on his way through to do the rest of it. Thanks in advance.
It's not difficult but if you want the procedure from the Service Manual drop me a PM with the machine Serial Number and your email address.
thanks for the procedure. we are having difficulties as the tranny will not come free. It appears that something is catching on the Lh side in the axle area. we have had other things come up which have prevented us from giving it full attention, maybe tomorrow ill be the day. Trucks with wiring issues, diggers leaking and the usual tyres etc. fortunately summer has been on holiday this last week so the days have been mid 30's rather than 40's
Did you separate the differential steer carrier from the transmission after pulling the axles. You have the reach in with the tool which is basically a washer on a shaft and pull the carrier back about an inch.
yes we did that. the procedure we were sent gave us a picture of the tool which we made. it didn't say how far it should move but it sounds as though it is fully moved and is about 30 mm or an inch and a bit. the tranny appears to be twisting as it it comes out. It appears to be catching on something around the area of that sliding sleeve. I woke up this morning with the idea of biasing the lifting chain to try and prevent it twisting. We will know in a couple of hours. Thanks for your help
Well the beast is out. Rockin and rollin a bit and suddenly out it did pop. The box wanted to come out biased to the left and it reduced a normally minimal clearance to zip. Hopefully putting it back in will be a lot easier.. Thanks for your help
So I thought I should share the results. Blown seal/ring on first piston. Cooked the clutch pack as a result and that was about it. Strip and rebuild was a walk in the park compared to some of the auto boxes I have done before. Everything back together and we struggled to get it back in a little. Same problem as getting it out and same result. It popped in when it was ready. Getting the left shaft to engage splines was interesting. Procedure talks about pump to release brakes, jacking tractor up and then turning final drive to engage. Seemed a little over the top, so we blocked the ripper carriage, tilted the blade and raised the left side up. Steered very slowly to the right and in popped the shaft. As usual I got called away to other things while all this was supposed to be happening so it took longer than expected. We gave the old girl a birthday and stripped the hydraulic cooler out to clear all the debris from between that and the radiator. Amazing that the machine didn't cook with all that stuff blocking the fins. She has just finished a large clearing project in the scrub so it is not really surprising. She goes to work next week ripping and pushing gravel. Today was 43 degrees C so the extra cooling will be a saviour. Thanks again for all the help.
The piston seal on #5 (1st speed clutch) is a classic tractor failure because they do all their hard pushing in 1st gear. It's a toss-up between that clutch and the forward direction clutch. The piston seal failure is often the result of excessive wear in the friction plates of the clutch pack then when the wear gets to a certain point the piston has so much travel to engage the clutch that the seal actually pops out of the piston housing and that tears it to shreds. Do you think that could have been what happened to your transmission..? Kudos for cleaning the cooling system out, lots of people forget that the wear material from the clutch failure can get everywhere in the system and especially the cooler resulting in the rebuilt transmission being fried in short order. It may pay you to use cleanout filters in the power train (converter and transmission) for a short while to clean out the fine sediment of the failure that will still be circulating. If your tractor already uses the 132-8876 Element that is a High Efficiency element used as the regular service filter on a 500-hour change period. After the failure with the transmission you should run that Part Number of element no more than 50 hours or until it plugs, whichever comes first, then change it and repeat the process. When the filter plugs it's best to stop the tractor immediately and change the filters because as soon as the light comes on the oil is not being filtered. When you can get the filter element to go at least 50 hours before plugging you can revert back to the 500-hour change interval, but be prepared for the possibility of more filter changes if the elements plug prior to that. Also if one element plugs it's best to change them both at the same time if you don't want to be going back and forth to the tractor like a yo-yo.
Only a small portion of the seal was damaged, perhaps an inch, so I think it was seal failure first and clutch destruction second. The tractor was a second hand machine and began failing fairly early on. We have no service history as it was imported from the states by the local cat agency. Having spent many years in the automotive business, the lesson to clean up after, when replacing an auto tranny was learnt a long time ago. We had a policy of fitting new aftermarket coolers to all auto tranny jobs. If the customer didn't want to spend a little extra we wouldn't do the job. Automotive tranny's are stressed enough without adding contamination from previous failures. We had planned on changing filters after twenty hours and then fifty followed by one hundred. I agree that it is a false economy to not replace filters after spending money on a minor rebuild. We replaced a few other bits while it was apart. Some brittle friction plates and all new seals on all pistons etc. Now she has to get to work and earn her keep. The muppets are all excited to have first gear again and we will be able to get one of the R's in for some much needed TLC.
I agree. While you're in the tranny it's false economy not to replace all the gaskets & seals, maybe treat it to a set of bearings as well, plus to overhaul the first speed (failed in your case) and forward direction clutches as a bare minimum whatever the reason for failure. I like your plan to clean the system out. So long as you can respond rapidly to a plugged filter event in the field the way I'd do it is to let the tractor run until the filter plugs and then change it. Doing it that way you know exactly how many hours it took the filter to plug as opposed to changing it at X hours and having no idea how much material it had trapped when you removed it. By changing the filter when it plugs you should see the period between plugged filter events extending which is a sure sign of the system becoming cleaner. My 2c.
We made a steel seal for # 5, as the old transmissions of the D8 came, do you think it can be a solution?
Are you talking about making a steel piston seal..? I don’t see how that could be possible because the seal has to be somewhat elastic in order to stretch to fit over the piston. Then it snaps into place in the groove.
This is a steel piston seal
What Part Number is that seal..? I assume from the yellow packet underneath it that it is a Cat seal.
It is not cat, I made it.
From your other thread you have two almost identical D8T tractors, one of which performs OK and the other one keeps burning #5 clutch. Would you mind explaining your thinking of why a home-made steel piston seal for the #5 clutch will solve your problem..? Personally I would have thought that there is either contamination in the system as a result of previous failures that has not been successfully cleaned out, or there is a problem with the piston housing for the #5 clutch that is either damaging the replacement seals when they are being installed or when the clutch is operating.