Paker481
Member
Serial #2WR00833
Approx. machine hours when first started job; 10800
Note: when I'm saying, "it was suggested" I'm referring to other work colleagues, friends and/or my dad (was an ex-mechanic).
Tis a long story with this machine and a lot of learning and want to vent here while hoping for an answer (Coming up 9 years being a mechanic and this is the first trans I gotten to split open and work on, naturally I was excited...but the excitement has long since gone as I'll explain below). I also feel like it's better to share the whole story instead of snippets.
So we initially got given the trans out of the grader to overhaul, not knowing exactly what had gone wrong, (the cat dealer had been to it, pulled the trans filter out and seen that it was wrecked/collapsed, it being an aftermarket one, assumed that that's why the trans had failed/wouldn't drive in the low range. Remember, we're learning this as we go and there's something to be said about that collapsed filter which I'll explain later).
And I'll also add, that we managed to get this job because the service manager (an ex cat mechanic) said we'd be cheaper than buying a remanned one...unfortunately that has not been the case.
So I stripped it all apart, replaced the clutch packs, piston seals, etc. (clutch 7/H, low range, was obviously burnt out).
Sent it back to the customer and he had his mechanic refit it, I went to it before he started the machine up to check all the clutch pressures (thankfully we have access to SIS). All the pressures checked out fine, except for clutch 7, it was 100psi below spec, I think from memory it was sitting at around 260psi, so it was suggested to put some shims in it, as a remedy. I believe it managed to bump it up 20-30psi. Unfortunately my optimism got the better of me and I test drove it, to then find the machine coming to a halt. Carried out necessary checks on the inching pedal, coils, solenoids, etc. all to find working fine. Jacked the machine up and found that it would drive through all the gears fine under no load. Dropped it down, found that it would drive in the High range, 5th upwards (in forward that is). Diagnosis, clutch burnt out. Removed the trans, stripped it again, found clutch 7 burnt, replaced the necessary friction discs and plates. Looking at it more in-depth this time round as to see if there was something to blame for the low pressure on clutch 7, but to no avail. Reinstalled it ourselves this time, only to find the clutch pressure was still reading at around 260psi. We stripped the control valve to have another in-depth look, also to no avail. Remedy was to replace the whole control valve. New one arrived, completely kitted out, coils, solenoids, reliefs and all. Only needed to switch over the loom and brackets, etc.
Installed the new one, finally, all pressures, including clutch 7, were reading within spec.
However, there was a harsh shift when changing from 5th to 4th (High to Low range). After all the time we'd spent on it then, we decided to leave it as it was, as it was driving just fine and the harsh shift seemed somewhat of a minor issue.
Few months went by, there was the odd complaint in-between from the operators about the harsh shifting, but relatively fine, (did find out it had failed an alternator in-between those months unfortunately...)
I got a call one Saturday afternoon saying the grader had lost drive. Went to it, plugged my gauge into the clutch pack test ports, to find not pressure reading at all. Plugged into the test port for the pump pressure, nothing. I removed the pump to find the input shaft had snapped and upon further investigation found part of a dipstick tube wedged into the pump gears. Apparently the dipsticks are prone to breaking. We found out through SIS that there was suppose to be a screen there that should have protected it. That was not the case. I believe the owners mechanic may have forgotten to install it, not pointing the finger, but I have the trans in bits at the moment, and you have to remove the pumps screen housing in order to remove the trans from the machine and I remember that when the trans arrived the first time, that housing was not attached. But that's neither here nor there. On top of the now broken pump, I find the oil to be rather milky. The cooler had failed.... I found bits of plastic inside it. Dropped the filter housing, yes, the filter had collapsed once again (was deemed this time round that the filter had collapsed because of the water/coolant in the oil, which is plausible). So, the owner decided to just put a new filter, new oil, pump and cooler into it and keep it going, with bits of plastic roaming around inside it...
So a month or so goes by, and you guessed it, grader had lost its drive. Go to it, find it doesn't drive in the Low range. Check the pressure on clutch 7 to find it was about 100psi below spec, carry out other necessary checks on the surrounding systems components, coils and solenoids, switching them around etc. Diagnosis, clutch pack burnt out. Few days pass and the machine arrives to workshop. Not being totally convinced on my diagnosis, I decide to recheck my work, and happen to think of removing the cover plate and seal retainer to have a look down the High Low shaft oil ports/galleries. What do I find at the end of the port for clutch 7, a bit of plastic.
So plan is to remove the trans, strip it, and give it a thorough clean. At this point it's Christmas and I'm sick of working on the machine and want a break. The customer wanted his machine for the new year. So the Service manager said he'd do it for me... was much appreciated at the time... but this guys being swinging spanners his whole life and he's very close to retiring. I'm sure you can see where this is going. The job drags way out past the point as to when it should have been done. It was suggested during this strip down to do a clutch run-out check on it. I don't remember the number but he did find 7 was out of spec. He didn't seem to think it would matter and thought that we could shim up the spool/relief to take up the extra clearance. Back in the trans went (the frustration obvisoly continued as I came back from break and I was observing this. Yes, in hind sight, I should have reclaimed the job from him). We attempted to adjust the relief for clutch 7 and putting in and taking out shims to fix the harsh shifting, to no avail. Customer wants his machine back and away it goes.
Few months go by, again the odd complaint about the harsh shifting in-between and then we get a call to say that the grader is slipping. Go to it to find it slips going up hill, in the High range this time though. Do all the routine checks as I've learnt along the way. Find pressure on clutch 8 is about 100psi below spec. Diagnosis, either a piston seal or another valve bank. They wanted to keep using the machine so I said if that's the case, don't drive in the high range. So, machine eventually comes back to workshop a couple months later. Was suggested to swap the old control valve over. Recheck over my diagnosing as it's been a couple months, same conclusion. So I switch out the valve bank and find the pressure for 8 up to spec. Not convinced its wrecked another control valve, I reinstall the new one, and switch out the spooling for clutch 8. And I find that the low pressure is due to one of the spool components. I switch out bit by bit to find out, what I believe to be called the modulating orifice, was the culprit. (Yes, I don't want to say it, but that is probably the reason the why the original control valve was deemed "faulty." I'm sure it'll be the modulating orifice, SMH).
I notice that the oil is rather burnt and has a burnt smell to it.
Customer decides to have us strip the trans once again. Thankfully he did as of now, I have the trans in bits and clutch pack 8 was on its last legs. I couldn't help but notice that there were bits of plastic throughout the trans as I was stripping it, I initially thought last time round that it hadn't be all that well cleaned. But I removed the filter to inspect, and yes, it was beginning to collapse once again. I decide to give the filter housing a thorough check this time round because there was something clearly not right. And I finally found the cause of the collapsing filter, the plate with which the filter sits on inside the filter housing was warped/bent, not only that, but once I removed it, I found that it had a big crack in it.
So that leaves me with final problem, being harsh when changed from High to Low. I've order the necessary bits that are in need of replacing, but I'm reluctant it reassembling it as I want to be absolutely positive that the trans itself is all within spec and working as it should.
I've rechecked the run-out clearance and its about 2mm above spec on clutch 7. I do struggle to see how 2mm extra travel for the piston would cause it to be harsh shifting. As of today, I've sprayed weld/crack check on the shaft but nothing found (Was thinking at a stretch, that if it was cracked it could be hydraulicing between the high and low range, fighting itself as it changes, but it would seem not).
Just sent the piston to the Cat dealer to be checked for measurement.
My dad suggested that it may be getting a spike of voltage on another solenoid when it changes from high to low, seems plausible, but can't be check until back together.
Any suggestions or help PLEASE!
Approx. machine hours when first started job; 10800
Note: when I'm saying, "it was suggested" I'm referring to other work colleagues, friends and/or my dad (was an ex-mechanic).
Tis a long story with this machine and a lot of learning and want to vent here while hoping for an answer (Coming up 9 years being a mechanic and this is the first trans I gotten to split open and work on, naturally I was excited...but the excitement has long since gone as I'll explain below). I also feel like it's better to share the whole story instead of snippets.
So we initially got given the trans out of the grader to overhaul, not knowing exactly what had gone wrong, (the cat dealer had been to it, pulled the trans filter out and seen that it was wrecked/collapsed, it being an aftermarket one, assumed that that's why the trans had failed/wouldn't drive in the low range. Remember, we're learning this as we go and there's something to be said about that collapsed filter which I'll explain later).
And I'll also add, that we managed to get this job because the service manager (an ex cat mechanic) said we'd be cheaper than buying a remanned one...unfortunately that has not been the case.
So I stripped it all apart, replaced the clutch packs, piston seals, etc. (clutch 7/H, low range, was obviously burnt out).
Sent it back to the customer and he had his mechanic refit it, I went to it before he started the machine up to check all the clutch pressures (thankfully we have access to SIS). All the pressures checked out fine, except for clutch 7, it was 100psi below spec, I think from memory it was sitting at around 260psi, so it was suggested to put some shims in it, as a remedy. I believe it managed to bump it up 20-30psi. Unfortunately my optimism got the better of me and I test drove it, to then find the machine coming to a halt. Carried out necessary checks on the inching pedal, coils, solenoids, etc. all to find working fine. Jacked the machine up and found that it would drive through all the gears fine under no load. Dropped it down, found that it would drive in the High range, 5th upwards (in forward that is). Diagnosis, clutch burnt out. Removed the trans, stripped it again, found clutch 7 burnt, replaced the necessary friction discs and plates. Looking at it more in-depth this time round as to see if there was something to blame for the low pressure on clutch 7, but to no avail. Reinstalled it ourselves this time, only to find the clutch pressure was still reading at around 260psi. We stripped the control valve to have another in-depth look, also to no avail. Remedy was to replace the whole control valve. New one arrived, completely kitted out, coils, solenoids, reliefs and all. Only needed to switch over the loom and brackets, etc.
Installed the new one, finally, all pressures, including clutch 7, were reading within spec.
However, there was a harsh shift when changing from 5th to 4th (High to Low range). After all the time we'd spent on it then, we decided to leave it as it was, as it was driving just fine and the harsh shift seemed somewhat of a minor issue.
Few months went by, there was the odd complaint in-between from the operators about the harsh shifting, but relatively fine, (did find out it had failed an alternator in-between those months unfortunately...)
I got a call one Saturday afternoon saying the grader had lost drive. Went to it, plugged my gauge into the clutch pack test ports, to find not pressure reading at all. Plugged into the test port for the pump pressure, nothing. I removed the pump to find the input shaft had snapped and upon further investigation found part of a dipstick tube wedged into the pump gears. Apparently the dipsticks are prone to breaking. We found out through SIS that there was suppose to be a screen there that should have protected it. That was not the case. I believe the owners mechanic may have forgotten to install it, not pointing the finger, but I have the trans in bits at the moment, and you have to remove the pumps screen housing in order to remove the trans from the machine and I remember that when the trans arrived the first time, that housing was not attached. But that's neither here nor there. On top of the now broken pump, I find the oil to be rather milky. The cooler had failed.... I found bits of plastic inside it. Dropped the filter housing, yes, the filter had collapsed once again (was deemed this time round that the filter had collapsed because of the water/coolant in the oil, which is plausible). So, the owner decided to just put a new filter, new oil, pump and cooler into it and keep it going, with bits of plastic roaming around inside it...
So a month or so goes by, and you guessed it, grader had lost its drive. Go to it, find it doesn't drive in the Low range. Check the pressure on clutch 7 to find it was about 100psi below spec, carry out other necessary checks on the surrounding systems components, coils and solenoids, switching them around etc. Diagnosis, clutch pack burnt out. Few days pass and the machine arrives to workshop. Not being totally convinced on my diagnosis, I decide to recheck my work, and happen to think of removing the cover plate and seal retainer to have a look down the High Low shaft oil ports/galleries. What do I find at the end of the port for clutch 7, a bit of plastic.
So plan is to remove the trans, strip it, and give it a thorough clean. At this point it's Christmas and I'm sick of working on the machine and want a break. The customer wanted his machine for the new year. So the Service manager said he'd do it for me... was much appreciated at the time... but this guys being swinging spanners his whole life and he's very close to retiring. I'm sure you can see where this is going. The job drags way out past the point as to when it should have been done. It was suggested during this strip down to do a clutch run-out check on it. I don't remember the number but he did find 7 was out of spec. He didn't seem to think it would matter and thought that we could shim up the spool/relief to take up the extra clearance. Back in the trans went (the frustration obvisoly continued as I came back from break and I was observing this. Yes, in hind sight, I should have reclaimed the job from him). We attempted to adjust the relief for clutch 7 and putting in and taking out shims to fix the harsh shifting, to no avail. Customer wants his machine back and away it goes.
Few months go by, again the odd complaint about the harsh shifting in-between and then we get a call to say that the grader is slipping. Go to it to find it slips going up hill, in the High range this time though. Do all the routine checks as I've learnt along the way. Find pressure on clutch 8 is about 100psi below spec. Diagnosis, either a piston seal or another valve bank. They wanted to keep using the machine so I said if that's the case, don't drive in the high range. So, machine eventually comes back to workshop a couple months later. Was suggested to swap the old control valve over. Recheck over my diagnosing as it's been a couple months, same conclusion. So I switch out the valve bank and find the pressure for 8 up to spec. Not convinced its wrecked another control valve, I reinstall the new one, and switch out the spooling for clutch 8. And I find that the low pressure is due to one of the spool components. I switch out bit by bit to find out, what I believe to be called the modulating orifice, was the culprit. (Yes, I don't want to say it, but that is probably the reason the why the original control valve was deemed "faulty." I'm sure it'll be the modulating orifice, SMH).
I notice that the oil is rather burnt and has a burnt smell to it.
Customer decides to have us strip the trans once again. Thankfully he did as of now, I have the trans in bits and clutch pack 8 was on its last legs. I couldn't help but notice that there were bits of plastic throughout the trans as I was stripping it, I initially thought last time round that it hadn't be all that well cleaned. But I removed the filter to inspect, and yes, it was beginning to collapse once again. I decide to give the filter housing a thorough check this time round because there was something clearly not right. And I finally found the cause of the collapsing filter, the plate with which the filter sits on inside the filter housing was warped/bent, not only that, but once I removed it, I found that it had a big crack in it.
So that leaves me with final problem, being harsh when changed from High to Low. I've order the necessary bits that are in need of replacing, but I'm reluctant it reassembling it as I want to be absolutely positive that the trans itself is all within spec and working as it should.
I've rechecked the run-out clearance and its about 2mm above spec on clutch 7. I do struggle to see how 2mm extra travel for the piston would cause it to be harsh shifting. As of today, I've sprayed weld/crack check on the shaft but nothing found (Was thinking at a stretch, that if it was cracked it could be hydraulicing between the high and low range, fighting itself as it changes, but it would seem not).
Just sent the piston to the Cat dealer to be checked for measurement.
My dad suggested that it may be getting a spike of voltage on another solenoid when it changes from high to low, seems plausible, but can't be check until back together.
Any suggestions or help PLEASE!
