Strange gearbox/clutch problem (V8/LT77)
Discussion
That nut's as loose as ever Alan!
For the record the clutch replacement has fixed one other symptom - there was a lot of driveline shunting which made low rev tickover cruising (e.g. 30mph at 1000 revs) somewhat jerky and uncomfortable. I now think this is because the clutch centre was so broken, thus allowing torsional vibration rather than coupling the engine to the gearbox properly.
Not it drives a lot smoother at low revs.
For the record the clutch replacement has fixed one other symptom - there was a lot of driveline shunting which made low rev tickover cruising (e.g. 30mph at 1000 revs) somewhat jerky and uncomfortable. I now think this is because the clutch centre was so broken, thus allowing torsional vibration rather than coupling the engine to the gearbox properly.
Not it drives a lot smoother at low revs.
honestjohntoo said:
ant help thinking that the first observation above rules out a clutch problem and the second observation may have indicated running on a low oil level.
The LT77's generally mated with RV8's were specified to use ATF, but apparently that was a compromise to resolve earlier clunky issues too.
Then loadsa users started to experience symptoms similar to what you describe.
The classic 'old age' cause/solution was worn remote mounting bushes, but it seems you have ruled that out.
So if it ain't the clutch and it ain't the bushes and it ain't knackered due to low oil level, then it's likely to be down to the choice of lube.
I had this problem in 1996 and resolved it once and forever! Yes! 16 years and counting.
Thus:
Radical Cure for a Nasty 5 Speed Manual Gearbox
• Here is a radical solution to an unfriendly 5-speed gearbox. Truly nasty. It baulked at will and was notchy to a fault. In fact it was very, very hard work. This was my last resort.
• During a routine gearbox oil level check, I noticed how dirty the lubricant had become so it was obvious it had to be flushed and changed. It had the recommended ATF which Rover had been forced to specify, because the gearbox was unreliable when filled with conventional lubricant.
• By coincidence, I had been told by an Ex-Mobil employee that Mobil 1 or Castrol RS at 0W40 or 5W40 viscosity were considered by the trade to be a better replacement than ATF in the Rover 5 speed box and gave a much improved performance.
• With the car on axle stands and the back wheels off the ground I drained the box and re-filled it with a flushing mixture of 2:1 white spirit and ATF (I did say radical and it was a last resort!).
• With the engine running at idle speed only, I put the car through all the gears and let the drive train run off-load for 5 to 10 minutes.
• Upon draining the flushing mixture I was amazed at the filthy color and state of the drained fluid. It was as black as ebony with lots of sediment!
• I repeated the above with a clean batch of mixture to flush out the residues. One can imagine the washing machine action inside the box allowed the solvent component to reach into every recess.
• The box was then refilled with 5W40 "Castrol RS" (0W40 "Mobil 1" is virtually the same and I have subsequently used both with no discernable difference).
• I then added a recommended dose of Molyslip Gearbox Treatment. This stuff comes in a tube-like applicator and is available from Halfords, etc.
• The transformation was miraculous. It has run since the late 1990's without any of the original symptoms and is a total pleasure to use.
• The oil has been replaced thrice in that period with Mobil 1 and the same Molyslip gearbox additive each time.
• As an experiment I used the leftover Molyslip treatment in the rear axle differential.
• After thoroughly warming the axle with an electric fan heater I sucked out all the old lubricant with a large medical syringe and some flexible plastic tube. It was then refilled with fresh hypoid oil (as specified) and the mentioned Molyslip treatment.
• The rear axle differential was transformed. Taking both treatments into account, the whole drive train has been silky smooth ever since.
Refilling a Manual Gearbox
• When topping up or refilling a manual box, the oft recommended method using squeezy bottles and flexible pipes has the disadvantage of proving Newton's 2nd Law of gravity that states: "It's easier to oil your armpit than to fill a gearbox from below!"
• A neat method to refill or top up the gearbox is to run a large bore plastic hose from the filler hole, up past the bell-housing and into the rear of the engine bay.
• Fit and secure a suitable funnel on top and pour in the replacement oil without difficulty. Do it slowly to prevent overflow.
So! Was it the lube or was it the Moly? Or was it the combination of the two? Dunno! But there are many feedback testimonies from fellow LT77 users who took the courage to try my solution and came back smiling! You could be smiling too!!!!
Do you think this flush method would be safe to use on my BMW M3 (E46) ZF box ?The LT77's generally mated with RV8's were specified to use ATF, but apparently that was a compromise to resolve earlier clunky issues too.
Then loadsa users started to experience symptoms similar to what you describe.
The classic 'old age' cause/solution was worn remote mounting bushes, but it seems you have ruled that out.
So if it ain't the clutch and it ain't the bushes and it ain't knackered due to low oil level, then it's likely to be down to the choice of lube.
I had this problem in 1996 and resolved it once and forever! Yes! 16 years and counting.
Thus:Radical Cure for a Nasty 5 Speed Manual Gearbox
• Here is a radical solution to an unfriendly 5-speed gearbox. Truly nasty. It baulked at will and was notchy to a fault. In fact it was very, very hard work. This was my last resort.
• During a routine gearbox oil level check, I noticed how dirty the lubricant had become so it was obvious it had to be flushed and changed. It had the recommended ATF which Rover had been forced to specify, because the gearbox was unreliable when filled with conventional lubricant.
• By coincidence, I had been told by an Ex-Mobil employee that Mobil 1 or Castrol RS at 0W40 or 5W40 viscosity were considered by the trade to be a better replacement than ATF in the Rover 5 speed box and gave a much improved performance.
• With the car on axle stands and the back wheels off the ground I drained the box and re-filled it with a flushing mixture of 2:1 white spirit and ATF (I did say radical and it was a last resort!).
• With the engine running at idle speed only, I put the car through all the gears and let the drive train run off-load for 5 to 10 minutes.
• Upon draining the flushing mixture I was amazed at the filthy color and state of the drained fluid. It was as black as ebony with lots of sediment!
• I repeated the above with a clean batch of mixture to flush out the residues. One can imagine the washing machine action inside the box allowed the solvent component to reach into every recess.
• The box was then refilled with 5W40 "Castrol RS" (0W40 "Mobil 1" is virtually the same and I have subsequently used both with no discernable difference).
• I then added a recommended dose of Molyslip Gearbox Treatment. This stuff comes in a tube-like applicator and is available from Halfords, etc.
• The transformation was miraculous. It has run since the late 1990's without any of the original symptoms and is a total pleasure to use.
• The oil has been replaced thrice in that period with Mobil 1 and the same Molyslip gearbox additive each time.
• As an experiment I used the leftover Molyslip treatment in the rear axle differential.
• After thoroughly warming the axle with an electric fan heater I sucked out all the old lubricant with a large medical syringe and some flexible plastic tube. It was then refilled with fresh hypoid oil (as specified) and the mentioned Molyslip treatment.
• The rear axle differential was transformed. Taking both treatments into account, the whole drive train has been silky smooth ever since.
Refilling a Manual Gearbox
• When topping up or refilling a manual box, the oft recommended method using squeezy bottles and flexible pipes has the disadvantage of proving Newton's 2nd Law of gravity that states: "It's easier to oil your armpit than to fill a gearbox from below!"
• A neat method to refill or top up the gearbox is to run a large bore plastic hose from the filler hole, up past the bell-housing and into the rear of the engine bay.
• Fit and secure a suitable funnel on top and pour in the replacement oil without difficulty. Do it slowly to prevent overflow.
So! Was it the lube or was it the Moly? Or was it the combination of the two? Dunno! But there are many feedback testimonies from fellow LT77 users who took the courage to try my solution and came back smiling! You could be smiling too!!!!
rev-erend said:
Do you think this flush method would be safe to use on my BMW M3 (E46) ZF box ?
Only one person can make that decision, methinks?However, the flush method I invented (for myself) was a no-load live-action mixture of ATF and white spirit.
ATF as recommended by Rover was clearly going to be benign in my all metal gearbox, with a few plastic parts and a few rubber seals.
If I had taken the same box and stripped it all down to its component parts and washed them all in paraffin and/or white spirit, and protected them temporarily from moisture with ATF prior to re-assembly, I would not give that process a second thought.
The only difference with my live-action method is that the box does not have to be dismantled, the ATF provides a light lubrication during the proscribed low-load running and the washing machine like action inside box cleans all the innards using the white spirit - just like a new pin. Especially so by doing the process twice.
Following the above scary bit, you have several recommendations regarding what lubricant to choose, but IMHO the telling difference is the moly.
Good luck.
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