vibration in 3rd (suffix a box)

[JayGoss]

About 4 years ago I commissioned a restoration of a 1960 Series II. The finished product arrived about a year and a half ago- and since then it has bounced back and forth from a local shop, to my garage. I've been able to put about 300 miles on it between trouble shooting and redoing various repairs. I thought I had most of the kinks worked out until recently I noticed a vibration in the floorboards accompanied by a hum when decelerating in 3rd gear (with and without Roverdrive engaged). The vibration used to go away when the accelerator pedal was depressed enough to take the load off the driveline- and it was absent upon acceleration. Now the decel vibration/hum has gotten worse and it is present on acceleration. My local mechanic describes it as feeling like the gears are "walking" on each other, as if there was too much end play. I'm fearing the worst- that my Series will require another gearbox rebuild, which translates to more $ and time sitting idle. To be perfectly honest, I'm getting sick of this Rover- as the ratio of spending money & watching it sit in the garage far outweighs the time spent enjoying it on the road. I'm hoping there may be a simple solution/fix to this that I haven't thought and can try before the car comes apart again. With the symptoms I've outlined above- is it possible that the problem can exist somewhere other than the internals of the gearbox? Here's a list of what has been done to the driveline:

-rebuilt suffix a gearbox
-new u-joints on both prop shafts; neither front nor rear have play in the slip joints
-new clutch, slave cylinder, pressure plate, machined flywheel
-front/rear diffs inspected; deemed sound and not rebuilt
-new Roverdrive installed (notchy action with resistance when engaged- I was told this should loosen up over time)
-rebuilt, blueprinted, balanced 2.25l motor w/8:1 compression, unleaded conversion, etc (runs like a dream- very smooth at all rpms)

Feel free to quiz me on other items I may not have mentioned. I'm assuming the gearbox will be pulled but I'm hoping for a miracle great idea from someone here & that the issue may be an external part. I'd rather not get into all of the, "who did the work? How much did he charge you for this?" Stuff- I just want to get this baby fixed and on the road. Next stop is ECR if I'm unable to find a fix here. It might take forever to get it in their shop- and will cost an arm and a leg with shipping from CO, I'm sure- but hopefully when I get it back it will be done right and all I'll have to worry about is routine maintenance. Thanks, in advance, for your help.

[SalemRover]

There is no such thing as a maintenance free 50 year old auto. To be honest I haven't a clue as to what may be causing deceleration vibration in 3rd gear, assuming no other gear does that. Does it pop out of gear when decelerating? Do all gears "walk" or just 3rd?

Series gearboxes are terribly simple, I doubt that shipping to ECR is worth it. Any decent transmission place with a green bible on hand and a list of suppliers should be able to do the job for you. If I can rebuild one in my basement with hand tools it cannot be past a professional shop to do the same locally. If its any condolence my truck hums and vibrates, to be honest if it vibrated a little more it could move sideways.

Best of luck!

-Jason

[JayGoss]

Thanks Jason. It doesn't pop out of gear- and it only seems to "walk" in third. I may have understated the hum/vibration. I've had 2 other series rovers in the past and I'm used to the usual squeaks, leaks, etc. This is a vibration which is definitely not right- I wouldn't trust this transmission to take me to the places my other non-restored Rovers have taken me.

With regard to the "maintenance free" comment, I agree with you...which is why I said I wanted to do routine maintenance; not tearing the vehicle down every couple of months. But I would think one could pay someone to restore a vehicle so that "nothing major" happens in the first 800 miles! To be honest, I could remove this box and figure out how to rebuild it- but my work schedule is prohibitive, hence the commissioning of the restoration.

I do appreciate the help and reply, though. If you have any ideas let me know.

[SalemRover]

I like to say that phrase to myself usually after I have a bout of swearing. Maybe a detent spring fell and was unfortunate enough to get chewed up in 3rd? I cant imagine that anything other than the gearbox is at fault here. If they updated a gear on the main without doing the layshaft as well that might do it. Have you tried draining the transmission oil to see if anything comes out? Wish I could think of some other easy gremlin but the tranny does seem to be at fault.

[Tim Smith]

Take a look and make sure the prop shafts are aligned correctly at the slip joint. If they were ever separated while getting those U-joints replaced, they could easily have been put together out of alignment.

I did that once and experienced a similar sounding shudder. It's an easy fix too. ;)

[JayGoss]

Take a look and make sure the prop shafts are aligned correctly at the slip joint. If they were ever separated while getting those U-joints replaced, they could easily have been put together out of alignment.

I did that once and experienced a similar sounding shudder. It's an easy fix too. ;)

Tim,

Great idea- I'll check that. Wait a minute...how can I tell if the prop shafts are "out of phase"? Are there markings on them (such as an arrow or a line on each half) to indicate the original orientation? I'll owe you a pitcher of beer if this works...and if it does I guess I'll have to make an interesting piece of artwork out of the rebuilt Series IIa gearbox I just ordered!!!!!

[jac04]

There should be markings on them.
Here's what I found on my original shaft after sandblasting:

[JayGoss]

There should be markings on them.
Here's what I found on my original shaft after sandblasting:

Perfect- thank you! My propshafts were disasssembled, powder coated and reassembled during the restoration, so a misaligned prop shaft is entirely possible

[jac04]

Powder coated - nice! The coating may have filled in the arrows, so look very closely. Even after painting mine, the arrows were not all that obvious.
I certainly hope you find a driveshaft issue and it solves your problem.

[JayGoss]

thanks Jac- fingers are crossed!

[brucejohn]

JayGoss and Jac04 thank you thank you.

I have been experiencing a nasty shutter when decelerating in 4th gear. Over the weekend I looked for marking alignment arrows to no avail. Resigned myself to try all 14 positions to find the sweet spot (many of them twice). After considerable time spent on trial and error I believe I have found the right alignment. What a difference it has made in her feel on the road.

Thank you for posting your answers and questions they led me in a direction I wouldn't have gone on my own.

I hope you find a good resolution as well JayGoss.

[JayGoss]

JayGoss and Jac04 thank you thank you.

I have been experiencing a nasty shutter when decelerating in 4th gear. Over the weekend I looked for marking alignment arrows to no avail. Resigned myself to try all 14 positions to find the sweet spot (many of them twice). After considerable time spent on trial and error I believe I have found the right alignment. What a difference it has made in her feel on the road.

Thank you for posting your answers and questions they led me in a direction I wouldn't have gone on my own.

I hope you find a good resolution as well JayGoss.

Wow. I had no idea that an out of balance driveshaft could manifest itself with vibration in only one gear. I may take mine in to a driveshaft shop and see if they can mount them on a jig and balance them- instead of going through the trial and error you had to! Thanks for the feedback- hopefully I can experience the same ad you.

[brucejohn]

I agree; I too was surprised. In addition to reducing the deceleration shudder in 4th it smoothed out the feel I experience by hand in the steering wheel and seat at all speeds. She is so much smoother and quieter (not quiet) now.

Taking her out of gear didn't stop my shudder, I believe it was velocity or driveline rpm not gear related. I think this makes sense if you think about a wheel out of balance.

If I didn't live a three hour round trip to a driveline shop I would have taken the driveline to be balanced.

Good luck!