Nissan Stage Autobox Accumulator mod
Nissan Stage Autobox Accumulator mod
Now, despite having been a mechanic I never got into rebuilding auto trans or in fact got any in depth knowledge of how they work. To put it simply I changed the oil and filters on them and maybe swapped a few out that were knackered.
So I did a load of research and not being rolling in money enough to shell out hundreds on a valve body upgrade, decided to look for a cheap option, I prefer the challenge of doing my own mods anyway.
During my searches I came across basic info on the workings of the box and I was initially going to try some different springs and adjusting various things inside the box, but what put me off this was the fact that using trial and error would mean that I would possibly be draining, pulling off the sump and valve body and re-fitting and re-filling many times.
I considered changing the value of the resistor which controls the oil pump pressure, but I didn't want to be running the pump at higher pressure all the time and creating more wear. I was also concerned about the back effects on the ECU of running a different resistor that ultimately would affect the current in the circuit and possibly shorten the lifespan of the ECU.
Then I came across a couple of sites that mentioned using stronger springs/shims/spacers to modify the effects of the accumulators inside an autobox. Initially I was going to replace the springs with spacers but then buried in the midst of a forum post over on SAU about valve body upgrades was the mention of a guy that had just blocked off the accumulators with core plugs. No-one seemed to pay his comments much attention but a few PMs later and I decided to have a go.
He couldn't offer much technical advice since his autobox specialist had done the work, but I wasn't too bothered about the details.
Anyway I did this mod and went out for a test drive. Absolutely no flare between gear changes at very nearly 1 bar boost and WOT. I can go all the way around to redline with no horrible slipping and delayed changes so now I don't have to hold back like I've been doing.
The changes are instantaneous, the rev counter needle just jumps straight down rather than the lethargic drop it used to have and best of all even though I was worried a bit about how the normal driving would be, it's fine. Yes it's a pronounced gear change now, but not a big thump or anything. Tiptronic mode is better too.
So, all you need are two 50mm core plugs and some new oil. The core plugs cost me a couple of quid and I put 6 litres of Synthetic ATF in that cost me about 30 quid.
__________________
Here's a brief "How to" that I've done.
Tools required.
1/2" Ratchet and 12mm,14mm,19mm sockets and extention
3/8" Ratchet and 10mm socket and extension
Pliers
Rags
Drain tub
Jacks/Stands
Also required at least 6 litres of ATF, possibly more. And two 50mm diameter core plugs.
Start by jacking the car up or geting it on a ramp, you will need plenty of height and make sure that you support the car securely.
Using the 19mm socket, undo and drain the gearbox. Replace the plug afterwards, there will still be oil in the sump.
Using a jack, support the rear of the transmission and undo the four M8 nuts with the 12mm socket in the middle of the crossmember that mount to the transmission.
Now undo the four outer crossmember to body mounting bolts using the 14mm socket and remove the crossmember. This was necessary on my car to access the rear sump mounting bolts.
Now using the 10mm socket, undo and remove the Oil cooler pipe bracket retainers at the front of the sump and the M6 sump bolts. It will help to leave a couple in at the front and allow the rear of the sump to drop slightly first to let the remaining oil drain out.
After that has finished draining, remove the remaining bolts and manouevre the sump back and down out of the way, I had to ease it past the oil cooler pipes at the front of the sump.
Now undo and remove the M6 mounting bolts for the filter. I suggest making a drawing on cardboard and punching holes in it to store the bolts in the correct position. Some of the filter bolts also hold the valve body on.
Next disconnect the electrical connections on the bottom of the valve body. Be aware that the plastic plugs might be brittle and the retaining clips could break. If that happens you will probably need to use lock wire when you put them back together at the end.
![[Image: R34vb.jpg]](http://i188.photobucket.com/albums/z226/Dean33GTST/R34vb.jpg)
Red-mounting bolts
Blue-Elec connections
Green-Filter bolts
Before you go any further, have a quick look and familiarise yourself with the selector, so you know how to get it back together later.
Referring to my picture, use the previous cardboard storage method and remove the remaining M6 valve body bolts and carefully lower the valve body. Be aware, more oil will spill out and there will be 3 springs that will drop out, you will need to replace one of the springs so try to keep track of their positions. Be careful, the valve body is quite heavy.
![[Image: AccSprings.jpg]](http://i188.photobucket.com/albums/z226/Dean33GTST/AccSprings.jpg)
You will now have to remove the two middle accumulator pistons. They're quite tight and will need possibly working up and down before they pop out. If you are really struggling a pair of external circlip pliers opened up inside the piston should help to pull it out. Discard the two pistons and their springs.
Now fit the two core plugs in the empty accumulator pistons holes. Make sure you fit them in deep enough to allow clearance for the screws on the valve body to clear.
![[Image: 121120101046.jpg]](http://i188.photobucket.com/albums/z226/Dean33GTST/121120101046.jpg)
The next bit is probably the most difficult part, and that is getting the valve body back up into position whilst making sure that the forward most spring remains in place. I struggled quite a bit, but an extra pair of hands would have saved me.
Bolt the valve body back on, be careful to make sure the selector is properly aligned or you won't be able to select any gears.
Clean and re-fit the filter and sump.
Refit the crossmember. Re-fill with oil, check for leaks and go enjoy.
As far as I'm aware the R33 box (non tiptronic) are very similer to mine and this would work on those boxes too. Certainly as part of the well known modded valve body kits, these core plugs are fitted in conjunction with them anyway.
The filter and mounting bolts may be slightly different on the earlier boxes, but the procedure is not significantly different and even though I'm an experienced mechanic, I would say a decent home mechanic who knows how to remove and re-fit bolts evenly
would have no problems doing this.
As usual, take all safety precautions and I can't be responsible for any damage/injury caused, even if it's just grazed knuckles.
Borrowed from elsewhere
Now, despite having been a mechanic I never got into rebuilding auto trans or in fact got any in depth knowledge of how they work. To put it simply I changed the oil and filters on them and maybe swapped a few out that were knackered.
So I did a load of research and not being rolling in money enough to shell out hundreds on a valve body upgrade, decided to look for a cheap option, I prefer the challenge of doing my own mods anyway.
During my searches I came across basic info on the workings of the box and I was initially going to try some different springs and adjusting various things inside the box, but what put me off this was the fact that using trial and error would mean that I would possibly be draining, pulling off the sump and valve body and re-fitting and re-filling many times.
I considered changing the value of the resistor which controls the oil pump pressure, but I didn't want to be running the pump at higher pressure all the time and creating more wear. I was also concerned about the back effects on the ECU of running a different resistor that ultimately would affect the current in the circuit and possibly shorten the lifespan of the ECU.
Then I came across a couple of sites that mentioned using stronger springs/shims/spacers to modify the effects of the accumulators inside an autobox. Initially I was going to replace the springs with spacers but then buried in the midst of a forum post over on SAU about valve body upgrades was the mention of a guy that had just blocked off the accumulators with core plugs. No-one seemed to pay his comments much attention but a few PMs later and I decided to have a go.
He couldn't offer much technical advice since his autobox specialist had done the work, but I wasn't too bothered about the details.
Anyway I did this mod and went out for a test drive. Absolutely no flare between gear changes at very nearly 1 bar boost and WOT. I can go all the way around to redline with no horrible slipping and delayed changes so now I don't have to hold back like I've been doing.
The changes are instantaneous, the rev counter needle just jumps straight down rather than the lethargic drop it used to have and best of all even though I was worried a bit about how the normal driving would be, it's fine. Yes it's a pronounced gear change now, but not a big thump or anything. Tiptronic mode is better too.
So, all you need are two 50mm core plugs and some new oil. The core plugs cost me a couple of quid and I put 6 litres of Synthetic ATF in that cost me about 30 quid.
__________________
Here's a brief "How to" that I've done.
Tools required.
1/2" Ratchet and 12mm,14mm,19mm sockets and extention
3/8" Ratchet and 10mm socket and extension
Pliers
Rags
Drain tub
Jacks/Stands
Also required at least 6 litres of ATF, possibly more. And two 50mm diameter core plugs.
Start by jacking the car up or geting it on a ramp, you will need plenty of height and make sure that you support the car securely.
Using the 19mm socket, undo and drain the gearbox. Replace the plug afterwards, there will still be oil in the sump.
Using a jack, support the rear of the transmission and undo the four M8 nuts with the 12mm socket in the middle of the crossmember that mount to the transmission.
Now undo the four outer crossmember to body mounting bolts using the 14mm socket and remove the crossmember. This was necessary on my car to access the rear sump mounting bolts.
Now using the 10mm socket, undo and remove the Oil cooler pipe bracket retainers at the front of the sump and the M6 sump bolts. It will help to leave a couple in at the front and allow the rear of the sump to drop slightly first to let the remaining oil drain out.
After that has finished draining, remove the remaining bolts and manouevre the sump back and down out of the way, I had to ease it past the oil cooler pipes at the front of the sump.
Now undo and remove the M6 mounting bolts for the filter. I suggest making a drawing on cardboard and punching holes in it to store the bolts in the correct position. Some of the filter bolts also hold the valve body on.
Next disconnect the electrical connections on the bottom of the valve body. Be aware that the plastic plugs might be brittle and the retaining clips could break. If that happens you will probably need to use lock wire when you put them back together at the end.
Red-mounting bolts
Blue-Elec connections
Green-Filter bolts
Before you go any further, have a quick look and familiarise yourself with the selector, so you know how to get it back together later.
Referring to my picture, use the previous cardboard storage method and remove the remaining M6 valve body bolts and carefully lower the valve body. Be aware, more oil will spill out and there will be 3 springs that will drop out, you will need to replace one of the springs so try to keep track of their positions. Be careful, the valve body is quite heavy.
You will now have to remove the two middle accumulator pistons. They're quite tight and will need possibly working up and down before they pop out. If you are really struggling a pair of external circlip pliers opened up inside the piston should help to pull it out. Discard the two pistons and their springs.
Now fit the two core plugs in the empty accumulator pistons holes. Make sure you fit them in deep enough to allow clearance for the screws on the valve body to clear.
The next bit is probably the most difficult part, and that is getting the valve body back up into position whilst making sure that the forward most spring remains in place. I struggled quite a bit, but an extra pair of hands would have saved me.
Bolt the valve body back on, be careful to make sure the selector is properly aligned or you won't be able to select any gears.
Clean and re-fit the filter and sump.
Refit the crossmember. Re-fill with oil, check for leaks and go enjoy.
As far as I'm aware the R33 box (non tiptronic) are very similer to mine and this would work on those boxes too. Certainly as part of the well known modded valve body kits, these core plugs are fitted in conjunction with them anyway.
The filter and mounting bolts may be slightly different on the earlier boxes, but the procedure is not significantly different and even though I'm an experienced mechanic, I would say a decent home mechanic who knows how to remove and re-fit bolts evenly
would have no problems doing this.
As usual, take all safety precautions and I can't be responsible for any damage/injury caused, even if it's just grazed knuckles.
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