Hello all. I took my 1967 Mk2 340 automatic on the road for the first time this spring. I noticed that it doesn't seem to be shifting correctly. When I put the trans in drive (D1), it seems to be starting in a higher gear. Its very sluggish. When I put it in D2 - it starts in first gear and shifts to second - but then will not shift to third. I did some research on this forum and now wonder whether the anti-creep solenoid failed and will not allow the car to start in first gear. Any thoughts? I appreciate the help.

Mike

 

This must be the BW35 box, I guess. As far as I'm aware, cars with this gearbox were not fitted with an anti-creep switch, so I don't think it's that.

I don't have an operating manual for BW35 cars, either, but if the Wikipedia article is correct, D2 will start the car in second and should then move to third; D1 will start the car in first, then move through second and third. This seems the opposite from what you are observing.

When working correctly, in third, the car should be doing about 3,000rpm at 70mph.

In the DG box (admittedly a completely different design) failure to move from second into third would generally be a lack of oil pressure, so the first thing to do would be to check the ATF level. Is it safe to assume you've already done that?

 

Hello,

Tha anti creep device has not much to do with the gearbox, only a pressure switch to release the brakes.
At least on the DG250 , as far as I know the BW35 does not have that switch ( but a switch between the carb's if I am right )
I would indeed check the oil level first ( with engine running in Dx )
Was the oil ever refreshed?

Regards,
Peter Jan

 

This was helpful. I now see I have the BW35 box. For some reason I thought I had the older BW box. So, I took the advice and changed the trans fluid and filter. I also noticed that the accelerator pedal was bent and not allowing full throttle - so I fixed that. I finally adjusted the kick-down switch cable. I will have her on the road this weekend and report back. Thanks again.
MG

 

I thought I had the same issue as OP with my '61 MK2 Auto. I have the DG-250 3-spd. Before I got it worked on I questioned why I could never drive at 70 without feeling that I was over-revving the engine. If I just went by the in-dash speedo it showed 70 at about 3000rpm, but when I use the "Speedometer" Android app it shows I'm only going about 55 at 3K.

So I have been trying very hard to check when I'm up-shifting. I "believe" that, if anything, my transmission is starting in second, then up-shifting to 3rd around 30mph. I believe that the XK engine can handle 70mph speeds (4K-4.5Krpm) for extended periods of time but I also believe it will eat LOTs of gas in the process.

I'm thinking of swapping out the DG-250 for a 700R4. Is this a good option? Should I start my own thread? Thanks for your attention, and thank you MXG for bringing up this issue.

 

This does seem quite odd. The only plausible reason I can think of why the speedo should be under-reading to such an extent is that the instrument is gummed up and is in need of refurbishment (not a particularly expensive exercise).

So, assuming the Android app is telling the truth, your car is doing 3,000rpm at 55mph, if the rev counter is to be believed. Rev counters and the rev counter generators do fail. The generators usually under-read as they get older, as the magnets inside them weaken. So the car may be doing more than 3,000rpm.

However, referring to the Operating, Maintenance and Service Handbook, I see that cars for USA and Canada were fitted with 3.77:1 rear axle ratio, which would mean that at 70mph in top, the engine should be doing 3,400rpm. And at 55mph in top, the engine should be at 2,700rpm.

By the engine revs/speeds you are reporting, it seems unlikely you are not getting all three speeds, if the rev counter is to be believed. The normal change points on a light throttle are low-intermediate at 11mph and intermediate-top at 23mph, though I think these speeds are for the 3.54 axle ratio. But, you get the idea.

However, with the DG, you can easily check you are getting all three speeds:

1. At standstill, engage the Intermediate Speed Hold, by switching it to the IN position.
2. Select L on the quadrant.
3. Set off (theoretically in Low)
4. When engine revs reach say 2,500 rpm, move the gear change lever from L to D. The car should change to intermediate and the revs will drop.
5. When engine revs reach say 2,500 rpm, switch the Intermediate Speed Hold to OUT and the car should change to top and the revs will drop.

I'm not familiar with this conversion, but I understand it is quite common in the North America, because those transmissions are plentiful. The trouble is, the conversion will cost a great deal of money and, at the end of it, the car will be non-original and worth less.

Possibly an easier, cheaper and reversible route is to source an alternative longer-geared rear axle crownwheel and pinion and have that built into your existing differential. You will find these are available in ratios 3.54 (3200rpm at 70mph), 3.31 (3,000rpm at 70mph), 3.07 (2,800rpm at 70mph) and 2.88 (2,600rpm at 70mph).

 

Lots of info here so please forgive me if I leave something out.

"This does seem quite odd. The only plausible reason I can think of why the speedo should be under-reading to such an extent is that the instrument is gummed up and is in need of refurbishment (not a particularly expensive exercise)."

This is quite possible. The speedo came with the car so I assume it's 50+ years without a calibration. I have worked with a calibration shop for my Tach but I have not sent them my speedo yet. They told me about the PMA generator on the back of the RH cam-shaft so I replaced that with a new one. IMO the tach reading is believable

Reading your subsequent statements I believe I can interpolate that 3000-ish rpm at 55-ish mph is plausible. Thank you.


As far as the Trans troubleshooting, I disconnected my "Intermediate hold" switch when I removed the wood trim around my instruments (I removed it so I can get it re-finished). I have not re-connected it yet. I have assumed that, since Intermediate is disconnected, the transmission will work completely automatically. Is that a bad assumption on my part?

Is "L" First gear?

Value of the car: I am keeping all major parts of my car in storage in case of future sale. But I am never going to make my money back on this vehicle after restoration - these cars sell between 20-30K USD these days. I expect to pay that(or more) just restoring/replacing my interior and redoing the exterior paint. If I had it to do over again would I do it differently? I don't know. I'm in love with my car. I plan on getting her looking beautiful again, and I plan to make her mechanically sound enough to take her out a lot. I am not intending to sell her anytime soon.

 

No, I don't think so. It should just work normally without the switch connected up. Though obviously you would need to connect the switch up again to follow my test for whether you are getting all three gears.

Yes.

 

Orlando, you are correct that I can't do your test properly the way that I have things set up now. It's apparent that I have 3 gears though because I get another kick-down after I shift out of Low gear. It will be a while before I can afford to replace this transmission but I'm going to pursue options in the meantime.

Thank you for your help!

 

All

Thanks for the responses. The trans shifts nicely after a fluid change - I used type F. The car had been sitting a long time and the new fluid likely made a difference.

MG