Reverse delay
- Thread starter Peter
- Start date
My first thought would be fluid level, I trust you are checking it on level ground, at normal working temperature and after running through the entire range, starting and finishing in PARK, taking the level with the engine still running?
Next I would check the rear band adjustment. If that is OK I would drop the sump and have a look inside, rear servos can come loose or crack. Hopefully it's one of those things, otherwise it's rear clutch, which is gearbox out to cure. Is there a delay in changing up into top gear?
Next I would check the rear band adjustment. If that is OK I would drop the sump and have a look inside, rear servos can come loose or crack. Hopefully it's one of those things, otherwise it's rear clutch, which is gearbox out to cure. Is there a delay in changing up into top gear?
Yes, I checked the fluid level as you described and checked rear band, 1,4kg, 1 turn return and locked.
When I rev engine carefully, than reverse jump in.
I haven't checked the kickdown-cable, could it be something with that? Read somewhere that it was important not only for acceleration,
but even for internal pressure, but I'm not sure.
No delay in top gear.
When I rev engine carefully, than reverse jump in.
I haven't checked the kickdown-cable, could it be something with that? Read somewhere that it was important not only for acceleration,
but even for internal pressure, but I'm not sure.
No delay in top gear.
Kickdown cable adjustment is important, but if it shifts at the correct speeds in DRIVE then it is pretty much as it should be. Changing up early would indicate low pressure which would affect REVERSE more than DRIVE as it works at a higher pressure.
I would re check the band adjustment, because if it tightens in more for the given torque it would indicate that something is wearing (band breaking up) or moving (servo coming undone). If it torques up to the same place, my guess would be to suspect the rear clutch, but I would still have a look inside first.
Sooner or later it will get to a stage where diagnosis becomes easy, ie you lose REVERSE altogether.
I would re check the band adjustment, because if it tightens in more for the given torque it would indicate that something is wearing (band breaking up) or moving (servo coming undone). If it torques up to the same place, my guess would be to suspect the rear clutch, but I would still have a look inside first.
Sooner or later it will get to a stage where diagnosis becomes easy, ie you lose REVERSE altogether.
Pilkie
Active Member
Cheers for that Harvey.
Lucky for me Ive bought, "sort of" a know "supposedly" good BW35 box with all 3 rods,torque and flexiplate.
Just got to get it from up north to me,which isnt a problem!!!
Just typical innit that as I got it to be a handy spare,mine would go wrong not long after!!
Good job ive fixed the TR!!
I really ought to get round to rebuilding the BW65 this year as well!!
Will let you know when Ive done a few more checks on it!
Dave
Lucky for me Ive bought, "sort of" a know "supposedly" good BW35 box with all 3 rods,torque and flexiplate.
Just got to get it from up north to me,which isnt a problem!!!
Just typical innit that as I got it to be a handy spare,mine would go wrong not long after!!
Good job ive fixed the TR!!
I really ought to get round to rebuilding the BW65 this year as well!!
Will let you know when Ive done a few more checks on it!
Dave
Now I have take off pan, not so much dirt at all, a little at the magnet, and very little in filter. But kd-wire seemed to be a little bit tight, if I take wire away I can put wires holding a few mm away, if you understand what I mean.
Maybe I should slack wire. How to adjust wire, I got no crimp on it so I can measure it? Anything else to check when pan is gone?
And I have a delay in 3rd gear.
Maybe I should slack wire. How to adjust wire, I got no crimp on it so I can measure it? Anything else to check when pan is gone?
And I have a delay in 3rd gear.
Starting at the end, if you have a delay changing into TOP as well, that points to the rear clutch rather than the rear band.
As for the kickdown cable, because you have the sump off you can adjust it properly. Tighten it up at the adjuster at the top until you can see that the heel of the cam at the bottom is away from the throttle valve that it operates, then back off the adjuster until the heel of the cam just touches the valve.
TBH I think you're going to end up with the failure of the rear clutch. If you up the pressure on the kickdown cable to improve the delay in selection, then at the same time you will increase the speed at which it changes into TOP, which is already happening late judging by what you have said already.
I know circumstances inevitably mean that cars/gearboxes are unused for 10 years, but in the case of autoboxes, they don't like it much. Seals end up half in and half out of the fluid which leads to cracking of the seal. Behind every failed clutch, in about 99.9% of cases there is a failed seal.
As for the kickdown cable, because you have the sump off you can adjust it properly. Tighten it up at the adjuster at the top until you can see that the heel of the cam at the bottom is away from the throttle valve that it operates, then back off the adjuster until the heel of the cam just touches the valve.
TBH I think you're going to end up with the failure of the rear clutch. If you up the pressure on the kickdown cable to improve the delay in selection, then at the same time you will increase the speed at which it changes into TOP, which is already happening late judging by what you have said already.
I know circumstances inevitably mean that cars/gearboxes are unused for 10 years, but in the case of autoboxes, they don't like it much. Seals end up half in and half out of the fluid which leads to cracking of the seal. Behind every failed clutch, in about 99.9% of cases there is a failed seal.
Saab-master
New Member
As for the kickdown cable, because you have the sump off you can adjust it properly. Tighten it up at the adjuster at the top until you can see that the heel of the cam at the bottom is away from the throttle valve that it operates, then back off the adjuster until the heel of the cam just touches the valve.
Hi all,
I have been following this topic with intrest as I have an auto box which does some odd things and I put this down to me taking three years to do all the other jobs on the car. I was wondering if you could put an idiots guide of what to check and how to adjust things, you mention about adjusting the kickdown cable any chance of a diagram of what your describing.
Also the gear selection is by guess work as you cannot seem to feel gearbox detents, any ideas?
My car is a 1968 V8 with a bw35 box fitted.
Many Thanks
Saab-Master
Hi all,
I have been following this topic with intrest as I have an auto box which does some odd things and I put this down to me taking three years to do all the other jobs on the car. I was wondering if you could put an idiots guide of what to check and how to adjust things, you mention about adjusting the kickdown cable any chance of a diagram of what your describing.
Also the gear selection is by guess work as you cannot seem to feel gearbox detents, any ideas?
My car is a 1968 V8 with a bw35 box fitted.
Many Thanks
Saab-Master
So now I've adjust kd-wire, clean up sump and filter, inspect inside, retorque rear band.
But I'm not really sure about adjusting kd-wire, should it be activated DIRECT from idle?
I tested at stands and everything seemed to be ok, no delayed reverse at.
Tomorrow I should check ignition. warm it up and then take a testdrive.
But I'm not really sure about adjusting kd-wire, should it be activated DIRECT from idle?
I tested at stands and everything seemed to be ok, no delayed reverse at.
Tomorrow I should check ignition. warm it up and then take a testdrive.
Have you altered the selector linkage at all? Can you get it to change into TOP (3rd) by lifting off the throttle? If so then the pressures are too high, and the kickdown needs backing off a bit. Setting the cable on the road is by far the best way as it takes into account the condition of the engine.
If it's not either of those things, and it was OK before you had the sump off, then it's possible that something has not gone back the way it was before.
See what happens next time you drive it and I'll try and be more specific, but it is far more difficult trying to sort things out without driving the car. There may be things happening that you don't notice, but are obvious to someone with experience of doing the boxes.
If it's not either of those things, and it was OK before you had the sump off, then it's possible that something has not gone back the way it was before.
See what happens next time you drive it and I'll try and be more specific, but it is far more difficult trying to sort things out without driving the car. There may be things happening that you don't notice, but are obvious to someone with experience of doing the boxes.
Back again, had to clean up gastank so I can testdrive it without gastrouble. Much things in tank after 11 year under a tree...
I also changed two rear brakehoses, not so easy but now it's ready.
Now back to gearbox, when it's cold reverse work's fine but no third gear, when it's warm delayed reverse and still no third gear.
I've adjust kd-wire in different ways but no difference, now I've got full trottle and then backed wire a little bit, then it work's best which means best 1-2 shift.
Rear brakeband adjusted earlier.
I've also cleaned governor, valve was stuck, fixed it but no changes 2-3... Not even when I lift off throttle.
There's no changes made to linkage, when Park is i P, and Drive in D and so on, then it would be rigth adjusted?
What to do next? Clean up valvebody?
I also changed two rear brakehoses, not so easy but now it's ready.
Now back to gearbox, when it's cold reverse work's fine but no third gear, when it's warm delayed reverse and still no third gear.
I've adjust kd-wire in different ways but no difference, now I've got full trottle and then backed wire a little bit, then it work's best which means best 1-2 shift.
Rear brakeband adjusted earlier.
I've also cleaned governor, valve was stuck, fixed it but no changes 2-3... Not even when I lift off throttle.
There's no changes made to linkage, when Park is i P, and Drive in D and so on, then it would be rigth adjusted?
What to do next? Clean up valvebody?
Peter said:
I don't think that will do any good. I know I'm not with the car, but from what you say I'd be inclined to think you're at the point of having to take the box out. When cold you have a higher pressure due to the fluid being a bit thicker, so REVERSE engages, but TOP (which works at a slightly lower pressure anyway) doesn't. As the fluid heats, and thins you get the delay into REVERSE, and even less pressure when trying for TOP.
I'd expect to find a problem within the rear clutch, which would cause a lowering of the effort available to clamp the plates, eg, a damaged seal, a chip or crack in the piston, or the piston sticking.
One thing to remember is that once you've removed the pistons from the clutches, you won't get them back in without the correct installers.
Thank's very much for your answer. Installers, is it special tools you mean?
Which year came this gearbox with P,R,N,D,2,1 ?
Could I use a older P,R,N,D2,D1,L-box?
Here in Sweden we got a lot of old Volvo with BW35-boxes, could I take part's from these boxes? Or just change bellhouse?
Which year came this gearbox with P,R,N,D,2,1 ?
Could I use a older P,R,N,D2,D1,L-box?
Here in Sweden we got a lot of old Volvo with BW35-boxes, could I take part's from these boxes? Or just change bellhouse?
Peter said:
Yes, there are two special sleeves which allow you to fit the pistons back intop the drums without damaging the seal.
Peter said:
I can't give you an exact time for the introduction of the later selector pattern, and even if I could most have been modified to it over time anyway. I did have one thought, in as it is a possibility that you're not getting what you think you are, in other words what you think is a loss of TOP could be a loss of FIRST and the 1-2 change is in fact a 2-3 change, which could be a consequense of using an early pattern box with a later selector pattern at the lever. If you have the PRND21 selector in the car, select "2" and pull away and see what happens if you don't move the lever.
Peter said:
You could use an early pattern box, but it isn't as user friendly as the later type. Providing you know what parts to "mix & match" you can use parts from any BW35 box, but other than a Rover P5B/P6B they won't be a direct replacement as a complete unit. You can fit the PRND21 valve block to change from early to late type, or just change the "D2D1" valve on the block for a Range Control Valve.
You will still end up with the problem of getting the pistons back into the clutch drums, because it just isn't worth taking the risk of not changing the seals. Behind 99.99999% sets of worn out clutch plates is a faulty seal.
I don't know the costs of shipping a pair of clutch drums to the UK and back would be. If it was reasonable I could install the pistons into the drums for you, or rebuild the drums complete for a sensible price.
I still think the box will end up being removed.
Pilkie
Active Member
Have just had the replacement BW35 box delivered,complete with torque,flexi,dipstick,etc
My thanks to Brian-Northampton for picking up and transporting it!!
Its the 7FU 17221,which is the PRND21 type!!!
LUCKY!!
As I forgot to check that it wasnt the early PRND2D1L type first!
I can only hope that it all works ok when it comes to fitting it!
But the guy I got it from,has stated that it was all working fine before it was removed!!
I, or Brian,who sort of knows him, have no reason to not believe what he says is true!!!
Harvey!!!
The fault with my knackered,so called recon,BW65 box is the rear clutch/band drum is scored,and that lead to speedy wear of the rear band!
It lasted over the 12 months/12k miles warranty they gave me! JUST!!!
Would you be able to provide me with a replacement rear clutch/band drum,all ready to fit with piston seals all done?
Am just thinking ahead,about refurbing it,but I may do the 35 instead,as I am sure its just the rear band that needs doing on that!!
Dave
My thanks to Brian-Northampton for picking up and transporting it!!
Its the 7FU 17221,which is the PRND21 type!!!
LUCKY!!
As I forgot to check that it wasnt the early PRND2D1L type first!
I can only hope that it all works ok when it comes to fitting it!
But the guy I got it from,has stated that it was all working fine before it was removed!!
I, or Brian,who sort of knows him, have no reason to not believe what he says is true!!!
Harvey!!!
The fault with my knackered,so called recon,BW65 box is the rear clutch/band drum is scored,and that lead to speedy wear of the rear band!
It lasted over the 12 months/12k miles warranty they gave me! JUST!!!
Would you be able to provide me with a replacement rear clutch/band drum,all ready to fit with piston seals all done?
Am just thinking ahead,about refurbing it,but I may do the 35 instead,as I am sure its just the rear band that needs doing on that!!
Dave