On my 86 XJ6, I may need to replace the BW66. Since I acquired the car, the transmission has made a strange “moaning” noise in first gear. (Some say it sounds like a pump others say it sounds like the TC) If you take your foot off the accelerator while in first gear, you get what can be described as a “metal grating noise.” The transmission shifts very smoothly; however, these noises are concerning. Recently, the transmission slipped. I drained all that I could get out of it, which was about 5 quarts of fluid. I replaced the filter and refilled it with 5 quarts of type F. The old fluid was very oxidized. It appeared to have helped, although the noises are still present, and the trans has slipped once since the fluid swap while the unit was cold. I want to attempt a band adjustment. I’m not sure if this will have any effect. Is there anything else that can be done? At this point, I’m setting my mind on the fact that I may need to rebuild the unit (surprising, very hard to find someone to do the job) or swap it with another unit. Does anyone have any information that can help me get my hands on a rebuilt BW66? Does anyone have any advice? Transmissions are something I have very little experience with, so any guidance would be very appreciated.

I’m happy to post a video of the sounds I’m experiencing if that will help put a finger on this issue.

 

Hi Dakota,

I have a very similar issue with my BW 66. In first second gear I have a whining sound, that has not gone away even after adjusting the band. You said you drained the ATF fluid, what was in the sump of the transmission pan? Do you get a thumping noise wen the transmission is put into gear? Mine was very clean even though the oil was old. No metal no flakes or chips of any sort and kind.
I am still contesting if I should try to readjust the bands. It is a bit of a PIA job, as you have to remove the middle part of the exhaust system to get to the adjustment screw. I have read multiple post that said that after adjustment the noise went away.

Taking the transmission out is a 6-8 hour job if you haven't done it before. May be worth trying the adjustment screw first.

Rob

 

Hi Rob, thanks for your reply. When we drained the fluid, the sump pan had almost a liquid metallic silver at the bottom. To be honest, I wouldn’t be surprised if that fluid had never been changed throughout the car’s life. That’s how bad it was. It was completely oxidized black and had the texture of water. Apart from that concerning issue, there wasn’t much else to note. I’m really hoping the band adjustment makes a difference. I don’t feel a thump when I shift into gear, and it shifts smoothly. However, there’s this moaning noise along with the grating. Do you hear the grating sound when you remove your foot from the throttle?

 

there is a BW66 rebuilder in Atlanta Georgia, contact David at www.everydayxj.com he knows the contact info.
you can either have yours rebuilt or get another BW66 already rebuilt.

I installed a rebuilt BW66 that makes a whinning noise in first gear but disappears in second and third gears.

I replaced the original Flexplate with a steel Flywheel at the same time, maybe that's the reason, I did keep the old original transmission and flex plate, the garage that did the work advised me of the noise after they did the job.

So it's a mystery to me not being an expert in transmissions.

 

That’s great! Thank you. That’s really strange. You have the whining on your rebuilt unit. I’m curious, did you replace your torque converter?

 

you're welcome.

No, the old torque converter was reused.
should it had been replaced ?

I have the old original transmission and its parts, thinking of having it rebuilt.

I would also like to do John's Cars Chevy transmission upgrade to have the 4th gear overdrive. So I haven't decided, both options cost money.

 

I have a hunch that if your noise is the same as mine, and considering you recently installed a rebuilt transmission, it might be an issue within the converter. Did the installation shop have any suggestions about the possible cause? If you perform any further work on your transmission, I strongly recommend replacing the converter or having it rebuilt by a competent shop. When I replace my transmission I will replace or rebuild my converter.



If you go with the 4 speed I assume you’d get a different converter entirely and this problem would end.

 

the repair shop only told me about the noise in first gear, no suggestions.

the transmission shifts ok, and the car moves fine, so I have left it alone, undecided as to what to do.

Please let me know what you end up doing. Thanks.

 

will do!

 

Dakota,
probably there is still a good bit of old oil in the cooler lines+ the stuff in the converter that has turned your new oil into old very fast. I am not sure if the converter is the culprit. If they are not rusted through I do not think that they fail that easily.

Maybe you can get by by doing another oil change. More probably it is a new refurbished transmission or one out of a donor car.

Rob