Auto box experts - need some advice
Discussion
I've been having some issues with my car juddering when pulling away and also making vibrating noises at low RPM's when cruising. I did some research online and it seemed the most likely cause was glycol in the transmission fluid which was eating the torque converter.
I've just heard back from the dealer I bought the car from who sent the car to a transmission specialist, and they believe the problem to be a burnt out reverse clutch.
Admittedly I know very little about auto trans, but I would have assumed that based on the name - I would have had problems with the car in reverse if that was the cause?
I've just heard back from the dealer I bought the car from who sent the car to a transmission specialist, and they believe the problem to be a burnt out reverse clutch.
Admittedly I know very little about auto trans, but I would have assumed that based on the name - I would have had problems with the car in reverse if that was the cause?
First thing I'd try is an oil and filter change.
The last auto I had started groaning on take-up and shortly left me with only reverse and was due to the forward 'clutches' being worn out, because of lack of maintenance by the previous owner.
I don't know if yours is the same design, but my 'clutches' were actually brake-bands!
The last auto I had started groaning on take-up and shortly left me with only reverse and was due to the forward 'clutches' being worn out, because of lack of maintenance by the previous owner.
I don't know if yours is the same design, but my 'clutches' were actually brake-bands!
Plenty of YouTube vids explaining how auto-boxes work.
Clutch=brake band. if one of the brake bands has worn out (quite possibly the reverse if that's what they say) and is disengaging slightly, that'll deffo cause the judder. It'll only get worse.
Time to sell the car - quick!
Clutch=brake band. if one of the brake bands has worn out (quite possibly the reverse if that's what they say) and is disengaging slightly, that'll deffo cause the judder. It'll only get worse.
Time to sell the car - quick!
Edited by Dr Doofenshmirtz on Wednesday 4th January 16:12
Dr Doofenshmirtz said:
Plenty of YouTube vids explaining how auto-boxes work.
Clutch=brake band. Chances are one of the brake bands has worn out (quite possibly the reverse if that's what they say) and is disengaging slightly, causing the judder. It'll only get worse.
Time to sell the car - quick!
Ahh, so it's perfectly plausible that the reverse brake band could have an affect on the forward gears?Clutch=brake band. Chances are one of the brake bands has worn out (quite possibly the reverse if that's what they say) and is disengaging slightly, causing the judder. It'll only get worse.
Time to sell the car - quick!
Luckily I'm not paying for this repair, but I want to make sure they are on the right track.
Not that simple, a lot of auto boxes use bands yes, but some (ZF 5hp - 19 / 24 etc found in VAG and Porsche) use wet multiplate 'clutch packs', like in motorbike clutches, but there's a pack for each 'gear'. Hence a 5 speed auto would have a pack for each speed.
You have an alloy cage / basket which holds 7 or 8 cork friction plates and is interleaved with metal drive plates.
So when they say clutch, they probably do mean 'clutch pack', and these plates can be replaced, so don't worry.
The only thing to watch for is that when they're replaced, the cage / basket isn't cracked, this can sometimes happen.
To replace the packs, the entire box must be dismantled, so it's a VERY false economy to replace one pack; indeed if you suspect fluid contamination then you should replace all the packs. At the same time I would STRONGLY recommend a new torque converter too, as they rely on a small rubber seal in the middle to give 'lockup' when the box locks 1:1 once cruising.
And as the valve body will also be off the box, it's worth checking all the valves and bores for wear or scoring damage, done via a pressure test, and rebore / replace valves at the same time.
I have become a bit of an expert on auto boxes as I had a world of trouble with one in a Porsche once, and I learned that not reconditioning the entire box once it's out and on the bench is a false economy. Indeed, sometimes the wear inside an autobox can be so miniscule but significant to the operation of the unit, that replacement sometimes becomes the cheaper and easier option.
If you have glycol contamination, I'm guessing Mercedes Benz, right?
Hope this helps anyway.
You have an alloy cage / basket which holds 7 or 8 cork friction plates and is interleaved with metal drive plates.
So when they say clutch, they probably do mean 'clutch pack', and these plates can be replaced, so don't worry.
The only thing to watch for is that when they're replaced, the cage / basket isn't cracked, this can sometimes happen.
To replace the packs, the entire box must be dismantled, so it's a VERY false economy to replace one pack; indeed if you suspect fluid contamination then you should replace all the packs. At the same time I would STRONGLY recommend a new torque converter too, as they rely on a small rubber seal in the middle to give 'lockup' when the box locks 1:1 once cruising.
And as the valve body will also be off the box, it's worth checking all the valves and bores for wear or scoring damage, done via a pressure test, and rebore / replace valves at the same time.
I have become a bit of an expert on auto boxes as I had a world of trouble with one in a Porsche once, and I learned that not reconditioning the entire box once it's out and on the bench is a false economy. Indeed, sometimes the wear inside an autobox can be so miniscule but significant to the operation of the unit, that replacement sometimes becomes the cheaper and easier option.
If you have glycol contamination, I'm guessing Mercedes Benz, right?
Hope this helps anyway.
Ray Luxury-Yacht said:
Not that simple, a lot of auto boxes use bands yes, but some (ZF 5hp - 19 / 24 etc found in VAG and Porsche) use wet multiplate 'clutch packs', like in motorbike clutches, but there's a pack for each 'gear'. Hence a 5 speed auto would have a pack for each speed.
You have an alloy cage / basket which holds 7 or 8 cork friction plates and is interleaved with metal drive plates.
So when they say clutch, they probably do mean 'clutch pack', and these plates can be replaced, so don't worry.
The only thing to watch for is that when they're replaced, the cage / basket isn't cracked, this can sometimes happen.
To replace the packs, the entire box must be dismantled, so it's a VERY false economy to replace one pack; indeed if you suspect fluid contamination then you should replace all the packs. At the same time I would STRONGLY recommend a new torque converter too, as they rely on a small rubber seal in the middle to give 'lockup' when the box locks 1:1 once cruising.
And as the valve body will also be off the box, it's worth checking all the valves and bores for wear or scoring damage, done via a pressure test, and rebore / replace valves at the same time.
I have become a bit of an expert on auto boxes as I had a world of trouble with one in a Porsche once, and I learned that not reconditioning the entire box once it's out and on the bench is a false economy. Indeed, sometimes the wear inside an autobox can be so miniscule but significant to the operation of the unit, that replacement sometimes becomes the cheaper and easier option.
If you have glycol contamination, I'm guessing Mercedes Benz, right?
Hope this helps anyway.
Thanks for the info mate. It is indeed a Benz. You have an alloy cage / basket which holds 7 or 8 cork friction plates and is interleaved with metal drive plates.
So when they say clutch, they probably do mean 'clutch pack', and these plates can be replaced, so don't worry.
The only thing to watch for is that when they're replaced, the cage / basket isn't cracked, this can sometimes happen.
To replace the packs, the entire box must be dismantled, so it's a VERY false economy to replace one pack; indeed if you suspect fluid contamination then you should replace all the packs. At the same time I would STRONGLY recommend a new torque converter too, as they rely on a small rubber seal in the middle to give 'lockup' when the box locks 1:1 once cruising.
And as the valve body will also be off the box, it's worth checking all the valves and bores for wear or scoring damage, done via a pressure test, and rebore / replace valves at the same time.
I have become a bit of an expert on auto boxes as I had a world of trouble with one in a Porsche once, and I learned that not reconditioning the entire box once it's out and on the bench is a false economy. Indeed, sometimes the wear inside an autobox can be so miniscule but significant to the operation of the unit, that replacement sometimes becomes the cheaper and easier option.
If you have glycol contamination, I'm guessing Mercedes Benz, right?
Hope this helps anyway.
I spoke to the transmission company this evening, and they say that it is the reverse clutch that is worn which is also having a knock-on effect on what would be forward 3rd gear. They seemed really knowledgeable and have tested for glycol (for which the result came back negative - yay), but will be pressure and RPM testing everything before handing back the car.
Fingers crossed for the weekend!
Brake bands are old school. Most stuff for the last 10 years will be multipack wet clutches.
The first thing to do with auto gearboxes when they start playing up, is check the oil level and condition, because everything works off oil pressure. Get an oil and filter change if needs be (and there will be a filter somewhere, usually under the sump pan) and then go from there.
They are quite simple essentially. It's getting around the electronics and the maths for the ravineux sets which is confusing.
The first thing to do with auto gearboxes when they start playing up, is check the oil level and condition, because everything works off oil pressure. Get an oil and filter change if needs be (and there will be a filter somewhere, usually under the sump pan) and then go from there.
They are quite simple essentially. It's getting around the electronics and the maths for the ravineux sets which is confusing.
Ray Luxury-Yacht said:
Not that simple, a lot of auto boxes use bands yes, but some (ZF 5hp - 19 / 24 etc found in VAG and Porsche) use wet multiplate 'clutch packs', like in motorbike clutches, but there's a pack for each 'gear'. Hence a 5 speed auto would have a pack for each speed.
You have an alloy cage / basket which holds 7 or 8 cork friction plates and is interleaved with metal drive plates.
So when they say clutch, they probably do mean 'clutch pack', and these plates can be replaced, so don't worry.
The only thing to watch for is that when they're replaced, the cage / basket isn't cracked, this can sometimes happen.
To replace the packs, the entire box must be dismantled, so it's a VERY false economy to replace one pack; indeed if you suspect fluid contamination then you should replace all the packs. At the same time I would STRONGLY recommend a new torque converter too, as they rely on a small rubber seal in the middle to give 'lockup' when the box locks 1:1 once cruising.
And as the valve body will also be off the box, it's worth checking all the valves and bores for wear or scoring damage, done via a pressure test, and rebore / replace valves at the same time.
I have become a bit of an expert on auto boxes as I had a world of trouble with one in a Porsche once, and I learned that not reconditioning the entire box once it's out and on the bench is a false economy. Indeed, sometimes the wear inside an autobox can be so miniscule but significant to the operation of the unit, that replacement sometimes becomes the cheaper and easier option.
If you have glycol contamination, I'm guessing Mercedes Benz, right?
Hope this helps anyway.
Cork frictions? Really? Basket?You have an alloy cage / basket which holds 7 or 8 cork friction plates and is interleaved with metal drive plates.
So when they say clutch, they probably do mean 'clutch pack', and these plates can be replaced, so don't worry.
The only thing to watch for is that when they're replaced, the cage / basket isn't cracked, this can sometimes happen.
To replace the packs, the entire box must be dismantled, so it's a VERY false economy to replace one pack; indeed if you suspect fluid contamination then you should replace all the packs. At the same time I would STRONGLY recommend a new torque converter too, as they rely on a small rubber seal in the middle to give 'lockup' when the box locks 1:1 once cruising.
And as the valve body will also be off the box, it's worth checking all the valves and bores for wear or scoring damage, done via a pressure test, and rebore / replace valves at the same time.
I have become a bit of an expert on auto boxes as I had a world of trouble with one in a Porsche once, and I learned that not reconditioning the entire box once it's out and on the bench is a false economy. Indeed, sometimes the wear inside an autobox can be so miniscule but significant to the operation of the unit, that replacement sometimes becomes the cheaper and easier option.
If you have glycol contamination, I'm guessing Mercedes Benz, right?
Hope this helps anyway.
Low fluid level can cause auto box issues. Easy to check and top up.
However, a PH myth has grown up that fluid and filter change will fix all auto box problems. It won't.
As RayLY has said, once your auto box is coming apart for repair a full rebuild (or replacement) is the only sensible way forward.
Auto box protection tips,
However, a PH myth has grown up that fluid and filter change will fix all auto box problems. It won't.
As RayLY has said, once your auto box is coming apart for repair a full rebuild (or replacement) is the only sensible way forward.
Auto box protection tips,
- Avoid full-throttle downshifts. A competent driver will rarely need kickdown.
- Make sure the car is absolutely stationary before engaging reverse.
- Use the handbrake as well as Park.
Ozzie Osmond said:
Low fluid level can cause auto box issues. Easy to check and top up.
However, a PH myth has grown up that fluid and filter change will fix all auto box problems. It won't.
As RayLY has said, once your auto box is coming apart for repair a full rebuild (or replacement) is the only sensible way forward.
Auto box protection tips,
However, a PH myth has grown up that fluid and filter change will fix all auto box problems. It won't.
As RayLY has said, once your auto box is coming apart for repair a full rebuild (or replacement) is the only sensible way forward.
Auto box protection tips,
- Avoid full-throttle downshifts. A competent driver will rarely need kickdown.
- Make sure the car is absolutely stationary before engaging reverse.
- Use the handbrake as well as Park.
- Avoid full-throttle downshifts. A competent driver will rarely need kickdown. - true, but competent and fun are not the same!
- Make sure the car is absolutely stationary before engaging reverse. - Yes, both autos i had really don't like being put in reverse even when moving forward a few mph.
- Use the handbrake as well as Park - does anyone with an auto use the handbrake/parking brake?!
I always find the car wobbles a bit with only the parking pin engaged.Morba said:
esvcg said:
- Use the handbrake as well as Park - does anyone with an auto use the handbrake/parking brake?!
Zwolf said:
Morba said:
esvcg said:
- Use the handbrake as well as Park - does anyone with an auto use the handbrake/parking brake?!
I've always wondered if it would be more beneficial to leave an auto in 'neutral' rather than 'park' when parked up. I've heard stories of autos getting shunted when parked and then needing a transmission rebuild.
Obviously its something insurance would pay for, but I'd rather just have a bumper scrape that needed repainting than a shafted transmission.
Obviously its something insurance would pay for, but I'd rather just have a bumper scrape that needed repainting than a shafted transmission.
jimxms said:
I've always wondered if it would be more beneficial to leave an auto in 'neutral' rather than 'park' when parked up. I've heard stories of autos getting shunted when parked and then needing a transmission rebuild.
No harm in it, however most autos have a shift interlock that prevents you from extracting your ignition key from the barrel unless the gearbox is in Park. There's often a way to get around this, but it's usually a deliberately fiddly procedure and would rapidly get tiresome. Zwolf said:
jimxms said:
I've always wondered if it would be more beneficial to leave an auto in 'neutral' rather than 'park' when parked up. I've heard stories of autos getting shunted when parked and then needing a transmission rebuild.
No harm in it, however most autos have a shift interlock that prevents you from extracting your ignition key from the barrel unless the gearbox is in Park. There's often a way to get around this, but it's usually a deliberately fiddly procedure and would rapidly get tiresome. esvcg said:
* Use the handbrake as well as Park - does anyone with an auto use the handbrake/parking brake?!
Ohhh Yus [/churchilldog] always 
As we're on this subject, does anyone know of a decent specialist in the Berks/Surrey area to do a filter & fluid change? (not got a problem just a bit of preventative maintenance)
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