'81 Bertone (B28F) BW55 to AW71 swap

^^^ this and only this. Made this mistake twice.

Pump 'O' ring and bell housing o ring need to be genuine volvo.

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OK, bought an all external parts kit including the above questioned oil pump and bell housing to transmission 'O' rings.

I can understand the oil pump '0' ring comment. Less impressed with the bell housing to transmission '0' ring advice. Little oil potential there. Kit has two rings for the bell housing connection, a larger and a smaller one. (?)

Any further thoughts?

Kit had far more rings than needed. Common for such throw together kits. Soak them in ATF and use what fits.

Tail shaft has noticeable play. Certainly more than left the factory. Brass sleeve does not appear to be that hard to replace sitting on an oil drum.

Because I pressure washed the transmission upon arriving home there are no history of oil leaks so everything else just gets replaced.

I am planning on removing the pan and clean in there but that is as far as it goes.

Replaced the front shaft seal 40 years ago on a BW55 but that is the extent of my transmission experience.

You need the tail housing gasket also, if you plan on pulling it to replace the shaft bushing & rear seal (235878, 235728) - you may have to make one though - not sure that is sold anymore...

lookforjoe said:

You need the tail housing gasket also...

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The kit came with the gasket. I'll go look for the sleeve.

Next question: The overdrive unit cover bolts have what looks like gasket sealant under and over the washers. I loosened those bolts for apparently no good reason in removing the bell housing. Guess I should seal them up fresh. Is that some some specific sealing product or will something like RTV do?



Got the front seal in. Learned how not to use a slide hammer but it didn't bleed much. Not a beautiful day . . . read a book in isolation.

Looks like thread locker.

nel621 said:

Looks like thread locker.

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It is more like RTV in that it is rubbery and all around the washer and bolt head on both AW70 transmissions on by work tables. Without further guidance I am going with RTV as an oil sealant.

Wish I had not removed the overdrive unit. It was a PITA to get it aligned and back in. Maybe I got it back in correctly.

Now . . . the extension bushing . . . .

The output shaft . . . shaft . . . appears to have issues.



Not only are there obvious wear areas but the polished shaft appears to have been touched by hand with some emery cloth perhaps to address oil issues in the past.

Education on removing and replacing the brass sleeve are not encouraging. Removal tool is not generally available and replacement would appear to require a correct installation tool. Research says not to use a socket. Always wanted a hydraulic press but might require a lathe to cut the install tool. Instructions from one parts supplier says that a brake cylinder hone may be required to enlarge the aluminum housing enough to press the sleeve.

This may be too much fun.

I will remove the shaft from my other transmission and see what it looks like.

Advice on removing and replacing the brass sleeve appreciated.

Further reading . . . .

The UK Volvo forum is a great source of info.

At the bottom of the bushing is a milled oil return channel. A couple minutes with a hack saw blade in hand will cut the sleeve so that it can be easily removed without any damage to the housing.

Bushing orientation: There is an oil hole in the bushing that is supposed to be orientated to the milled channel to pick up oil for shaft lubrication. My bushing hole was not so orientated. It simply dead-ended into the milled aluminum housing.

Elroy has been inside this little darling.

A local NAPA is a full service engine rebuild facility. The bushing is fairly cheap and I will confirm with them that they can push it into place.

I am going to continue with my education/external refresh and will evaluate replacing the BW55 in the Bertone at some future time.

The tools to remove and install the bushing without removing the tail housing are available on eBay.

https://www.ebay.com/itm/254104239601

If you don't want to buy them I have them available to rent.

Transmission and tail shaft housing necked on the bench.

Out appears easy. I will discuss with NAPA machine shop tomorrow about pressing back in.

If my other transmission's polished tail shaft is not in better condition I will begin the search for a better one.

HondaBond would be appropriate for the bolts - jsut make sure to leave them enough time to setup before adding fluid..

It was a beautiful day in the Georgia Mountains . . . .

Dear diary . . . .

After a couple hours at the range trying to finish the Scout Camp restroom and a tank of fuel in the weed eater got back to the transmission. Replaced the carb on a 15 year old Ryobi weed eater power head to dedicate to a hedge trimmer. Runs as new.

Pulled the output shaft and the housing from my 'practice' AW71 to compare to the questionable one in the picture above. The polished AW71 shaft was in much better condition than the objective AW70 shaft. It is the correct diameter to fit the bronze sleeve but the negative is that the flange connection to the drive shaft is a different diameter.

I know that I will have to modify the length of the front drive shaft and was hoping that replacing the original Bertone front shaft with a front shaft from a AW70 car would take care of that. It is pretty clear the the length of the mid shaft bearing to the differential is the same over many years and many models. However . . . I am aware that there were at least three mid bearing sizes over the years. I know that because I have purchased all three and returned two. Now I have to obtain a better output shaft rather than the one from the AW71. And . . . I must make sure that the output shaft matches both the replacement front shaft and the center bearing.

Now the good news . . . found an one man transmission shop a few miles away that seemed happy to order the bronze sleeve and press it in.

The significant historical issue is that the oil hole in the objective AW70 transmission bronze sleeve was clearly installed incorrectly not over the milled oil drain channel.

Are those tail shaft bearings "splash oiled" or do they have a pressurized port to that bearing?

Somewhere in the AWXX lore here on TB, I've learned (correctly or not) that the near 95 model AW has a completely different (and much stronger) tailshaft bearing system that is near bulletproof. What I don't know is if the tailshaft housing from one of these late versions would bolt on to your earlier AW70.

Roy (2manyturbos) will know for sure. One of these days, I'm going to make my way to Elijay and have a look over your Bertone! Once I'm retired for sure.... but right now TOYO is keeping me far too busy.

I would call it 'splash oiled' with some engineering design.

he




The AW70 GreenBook rebuild says to install the bushing with the hole opposite the oil return grove in the housing. The hole is at 8:30 with the grove at 4:00 in the picture. I would have thought the hole should be over the grove. Elroy, if he did indeed replace the bushing got it almost right.

I will discuss this with my new BBF at the transmission shop this week.

It is a two man auto transmission repair shop

Took the tail housing to my new transmission repair best friend at a single car garage shop just inside NC. Both guys agreed that the polished shaft had been cleaned up at some time. Neither could feel anything with a fingernail and the slack in the shaft to bushing met their standards and they declared that it was fit for reuse.

I guess that ends this discussion. Don't fix what's not broken.

I asked what he would charge for a complete steels, friction disks and valve body do over if I should feel compelled. Answer was $450 on the work bench plus $150 parts. That's the best price anywhere short of doing it myself.

Lots of projects have required a do-over in my long and sordid automobile history but pulling a transmission more than once is not something to look forward to. I did that once 30 years ago.

Thanks for the conversation.

Got the bell housing back on which was quite a bit of work. I couldn't find metric bolts long enough to gently pull the bell housing onto the transmission so had to use carefully calibrated rubber hammer blows to seat it. Greased both the housing and the barrel but the least mis-alignment resulted in binding of the milled surfaces. This was obviously done with a precision aligned hydraulic press lo those 40 years ago.





That is a very rare, AW70 transmission with a PRV bell housing and a cable connected speedometer cable port with all new external gaskets, o-rings and shaft seals installed.

Wish I had 100% confidence on the internal operations of this transmission. A transmission swap is a little more than a tire change.