Setting up Borg Warner 35 Auto linkage.
Discussion
Is there anyone on here that can assist me with some advice on how to set up the mechanical linkage to operate a 1965 BW35 auto gearbox.
This is an original fitment on a 1965 Sunbeam Alpine. We have owned this car since 2003 and the gear selection has often been a pain. You can engage all of the gears easily by moving the selector arm that comes out of the side of the gearbox but by the time the rod linkage gets to the actual shifter you can either have Park work successfully but not engage Lock/Low or have Lock/Low work but not be able to engage Park. Most of the time we have lived without Park and by passed the inhibitor switch to use the car.
I am trying to solve this problem now. Initially I thought this was a bushing issue so I had a new bush machined for the gearbox end of the linkage. That didn't work so I thought that it must be the Rose joint under the shifter, so I replaced that and set it to have less travel than the old one to give a more direct link between the bottom of the shifter and the gear selector lever, still I can't get both of the gears at the extreme ends of travel to operate, only one or the other.
There is an adjuster in the centre of the rod linkage that is like a track rod adjustment that allows the rod to be lengthened of shortened by turning it.
These gearboxes were used in numerous Rovers, MGs, Triumphs etc etc so other people must have experience of this issue.
Does anyone have any ideas? Is there a process that I should follow to get the settings correct?
This is an original fitment on a 1965 Sunbeam Alpine. We have owned this car since 2003 and the gear selection has often been a pain. You can engage all of the gears easily by moving the selector arm that comes out of the side of the gearbox but by the time the rod linkage gets to the actual shifter you can either have Park work successfully but not engage Lock/Low or have Lock/Low work but not be able to engage Park. Most of the time we have lived without Park and by passed the inhibitor switch to use the car.
I am trying to solve this problem now. Initially I thought this was a bushing issue so I had a new bush machined for the gearbox end of the linkage. That didn't work so I thought that it must be the Rose joint under the shifter, so I replaced that and set it to have less travel than the old one to give a more direct link between the bottom of the shifter and the gear selector lever, still I can't get both of the gears at the extreme ends of travel to operate, only one or the other.
There is an adjuster in the centre of the rod linkage that is like a track rod adjustment that allows the rod to be lengthened of shortened by turning it.
These gearboxes were used in numerous Rovers, MGs, Triumphs etc etc so other people must have experience of this issue.
Does anyone have any ideas? Is there a process that I should follow to get the settings correct?
Thank you so much for the responses. It is definitely conceptually simple but actually getting it to work correctly is remarkably complicated.
Every tiny bit of wear in any of the shifter mechanism and linkage (and there are a number of bushes and joints that all contribute) amplifies the sloppiness. I have spent the morning working on the selector mechanism itself getting rid of any excess play. I am trying to get to the point where as the shifter moves the selector moves with no slop or wasted movement. I am not there yet and will post an update when I have finished but it is definitely more direct now.
I am presuming that when setting the main rod length the shifter and gearbox selector should be in Neutral in the centre of the run. Is that correct?
Every tiny bit of wear in any of the shifter mechanism and linkage (and there are a number of bushes and joints that all contribute) amplifies the sloppiness. I have spent the morning working on the selector mechanism itself getting rid of any excess play. I am trying to get to the point where as the shifter moves the selector moves with no slop or wasted movement. I am not there yet and will post an update when I have finished but it is definitely more direct now.
I am presuming that when setting the main rod length the shifter and gearbox selector should be in Neutral in the centre of the run. Is that correct?
Puddles of Oil said:
I am presuming that when setting the main rod length the shifter and gearbox selector should be in Neutral in the centre of the run. Is that correct?
I would not assume that. The neutral position is more or less irrelevant. It is the end positions which are critical. So I suggest you need to find the point in space where you want the 'gearbox' end of the linkage to be at the end of its travel, and adjust the linkage lengths and end stops as necessary to achieve that. Then do the same at the other end. Hi GreenV85
There is only adjustment at the rose joint end and there is nothing that I would refer to as an 'end stop' at either end. There is a bush that fits over a peg on the selector arm at the gearbox end (there is no adjustment[possible here, I had a new bush machined to make it fit as snugly onto the peg as possible) and a rose joint at the other end that can be adjusted a little (when it is disconnected from the shifter) to change the rod length. The main adjustment in the mechanical linkage is by a piece that is like a track rod end in that it has a central body with a standard thread going in one end and a left hand thread at the other, By turning the centre of the body of the adjuster the overall length of the rod can be made longer or shorter. This is then locked by lock nuts once the correct length is set.
I think I have a reasonable chance of getting this right next time I work on it, I seem to have eliminated a lot of the play that was due to worn parts. Now I just need to get the adjustment right.
There is only adjustment at the rose joint end and there is nothing that I would refer to as an 'end stop' at either end. There is a bush that fits over a peg on the selector arm at the gearbox end (there is no adjustment[possible here, I had a new bush machined to make it fit as snugly onto the peg as possible) and a rose joint at the other end that can be adjusted a little (when it is disconnected from the shifter) to change the rod length. The main adjustment in the mechanical linkage is by a piece that is like a track rod end in that it has a central body with a standard thread going in one end and a left hand thread at the other, By turning the centre of the body of the adjuster the overall length of the rod can be made longer or shorter. This is then locked by lock nuts once the correct length is set.
I think I have a reasonable chance of getting this right next time I work on it, I seem to have eliminated a lot of the play that was due to worn parts. Now I just need to get the adjustment right.
I have come to the conclusion that the wear must be in the actual gearbox, which after 54 years of regular use is perhaps unsurprising. The linkage is now free of all excess play and is very direct between the shifter and the selector arm but it is just not possible to have both P and L, it is always one or the other. Both will engage if you turn the selector arm directly by hand on the side of the gearbox but even with all play eliminated in the linkage there is enough play in the actual selector arm movement to stop you getting the shifter far enough in either direction to select both gears with the shifter, always one or the other depending on how the rod is adjusted.
Very frustrating but this is how this car has always been since we got her in 2003. I think there must be wear inside the gearbox on the shaft that the selector mounts onto. Apart from stripping the gearbox the only pragmatic way that I can see of overcoming this would be to physically file the edge of the gate at L and P to allow the shifter lever to travel a little further so that it can move the selector lever a little more but I don't want to do that, so I think I will just have to live with this.
Very frustrating but this is how this car has always been since we got her in 2003. I think there must be wear inside the gearbox on the shaft that the selector mounts onto. Apart from stripping the gearbox the only pragmatic way that I can see of overcoming this would be to physically file the edge of the gate at L and P to allow the shifter lever to travel a little further so that it can move the selector lever a little more but I don't want to do that, so I think I will just have to live with this.
You have not answered my question.
So in simplistic terms
Shortening the gearbox arm seems far more likely and may simply be a case of drilling a new hole in the arm for the rod to attach.
Disconnect the rod at the 'box and hold the shift in one of the positions. Move the gearbox arm to select the required gear. Offer up the rod and see where on the arm the new attachment point should be. This will indicate where the new attachment point should be. Do the same with the other gear and make sure both new positions agree. If they don't then you may need to adjust the rod length as you described before (known as a turnbuckle).
Steve
So in simplistic terms
- At the gearbox end a lever of a given length will select the gears at each end of its travel and I will assume there are end stops.
- At the shifter end I have to assume there are also end stop limits otherwise the shift lever would just keep moving until all slack had been taken up and the gearbox arm had engaged the gear.
- If the above is true and you have removed all the slack from the mechanism then you have to find some more travel from somewhere.
Shortening the gearbox arm seems far more likely and may simply be a case of drilling a new hole in the arm for the rod to attach.
Disconnect the rod at the 'box and hold the shift in one of the positions. Move the gearbox arm to select the required gear. Offer up the rod and see where on the arm the new attachment point should be. This will indicate where the new attachment point should be. Do the same with the other gear and make sure both new positions agree. If they don't then you may need to adjust the rod length as you described before (known as a turnbuckle).
Steve
Steve, Apologies for not responding previously.
I cannot see any end stops anywhere apart from the gate, perhaps they are inside the gearbox? To answer Greenv85 it is the extreme edges of the gate (Part 200 in the drawing ) that limits the travel at the top of P and the bottom of L.
R,N and D engage as required when the gear lever is moved through the gate. With the linkage disconnected at the rose joint (204) each gear can be selected manually by pushing or pulling the linkage.
The selector shaft (140) comes straight out of the side of the gearbox, this has a thread and 2 flat sides if I put a small spanner on the flats I can engage each gear easily. The gear shift lever (174) has a shaped hole with flat sides that locates over the end of the shaft (140). For some reason this car does not have Part 175 but I can't work out what that would actually do if I did have it. According to the parts book 174 bolts to 175 using 176, if that is the case (to reduce flexing of 174 perhaps?) then presumably the drawing is showing the slotted hole in 175 at 90* out of position.
There is no facility to lengthen the bottom of the shifter (193) or shorten the gear shift lever (174) but I can see the logic that it the gear shift lever at the selector rod end was shorter the shifter would move it more for the same amount of movement at the gear lever (186) in the cabin.
The gear shift lever 174 has two bends in it to form a gentle 's' shape. If I bent this to be a little more pronounced it would have the same effect as shortening it between its two pivot points but I am loathe to do this as it seems pretty drastic. I am wondering whether it might be worth getting a machine shop to make me a new, slightly shorter, gear shift lever 174. I have to work on this car outside and looking at the weather forecast it will be a few days until I get anything else done on her.
The help on this forum is simply amazing, thank you all for your thoughts and assistance.
[url]
|https://thumbsnap.com/40mvoeDB[/url]
I cannot see any end stops anywhere apart from the gate, perhaps they are inside the gearbox? To answer Greenv85 it is the extreme edges of the gate (Part 200 in the drawing ) that limits the travel at the top of P and the bottom of L.
R,N and D engage as required when the gear lever is moved through the gate. With the linkage disconnected at the rose joint (204) each gear can be selected manually by pushing or pulling the linkage.
The selector shaft (140) comes straight out of the side of the gearbox, this has a thread and 2 flat sides if I put a small spanner on the flats I can engage each gear easily. The gear shift lever (174) has a shaped hole with flat sides that locates over the end of the shaft (140). For some reason this car does not have Part 175 but I can't work out what that would actually do if I did have it. According to the parts book 174 bolts to 175 using 176, if that is the case (to reduce flexing of 174 perhaps?) then presumably the drawing is showing the slotted hole in 175 at 90* out of position.
There is no facility to lengthen the bottom of the shifter (193) or shorten the gear shift lever (174) but I can see the logic that it the gear shift lever at the selector rod end was shorter the shifter would move it more for the same amount of movement at the gear lever (186) in the cabin.
The gear shift lever 174 has two bends in it to form a gentle 's' shape. If I bent this to be a little more pronounced it would have the same effect as shortening it between its two pivot points but I am loathe to do this as it seems pretty drastic. I am wondering whether it might be worth getting a machine shop to make me a new, slightly shorter, gear shift lever 174. I have to work on this car outside and looking at the weather forecast it will be a few days until I get anything else done on her.
The help on this forum is simply amazing, thank you all for your thoughts and assistance.
[url] |https://thumbsnap.com/40mvoeDB[/url]Is there any scope to physically move the gate? If you can move the gate so there is more travel in the 'L' direction then the curve in 193 would give you a little extra travel on the pushrod 206.
Alternatively look for any scope to move 204 further out from the pivot on 193 or move the connection of 210 closer to the pivot on 174.
You would probably only need a tiny amount - if the connections are bolted, it might just need a few strokes with a file to oval the hole a fraction.
Given that the gate seems to be forming the end stops, what's causing your reluctance to modify that? It's out of sight under the bellows, isn't it?
Alternatively look for any scope to move 204 further out from the pivot on 193 or move the connection of 210 closer to the pivot on 174.
You would probably only need a tiny amount - if the connections are bolted, it might just need a few strokes with a file to oval the hole a fraction.
Given that the gate seems to be forming the end stops, what's causing your reluctance to modify that? It's out of sight under the bellows, isn't it?
I am still working on this problem and following the advice that you guys have given me.
I have made my own version of the gear selector lever. Having examined the one on the car it is clear that this is not an original Rootes part but is homemade. Why anyone would want/need to change this part I can't imagine. I think that their selector is incorrectly made and this is the cause of the problem. I think their selector is too long and has the slotted hole slightly in the wrong position making the selector angle to the linkage incorrect.
Mine is shorter and I think it will see less throw at the cabin selector end.
I'm not there yet but nearly...... (My version is on the right)
Puddles
I have made my own version of the gear selector lever. Having examined the one on the car it is clear that this is not an original Rootes part but is homemade. Why anyone would want/need to change this part I can't imagine. I think that their selector is incorrectly made and this is the cause of the problem. I think their selector is too long and has the slotted hole slightly in the wrong position making the selector angle to the linkage incorrect.
Mine is shorter and I think it will see less throw at the cabin selector end.
I'm not there yet but nearly...... (My version is on the right)
Puddles
As a closure for this post I can tell you that I followed the excellent advice that I received and made a completely new gearbox selector arm, slightly shorter than the one that was fitted (which was not original) and with the slotted hole moved around slightly. This enables all of the gears to be selected properly now and the problem is cured. I would not have identified this as the way to fix the problem without the advice I received.
Thank you for taking the time to respond, I am very grateful for your help.
Puddles.
Thank you for taking the time to respond, I am very grateful for your help.
Puddles.
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