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Post by ricky8664 on Aug 9, 2023 21:41:53 GMT
Still awaiting return of the calipers and the SD1 heads and it looks like the respray cannot be done until early in the NY.
Whilst kicking my heels. I've been convinced that I should attempt to solve the auto box problems at home , rather than having a full rebuild. The main reason is the box always ran faultlessly before taken off the road and the problem is/are oil leaks from the box.
Main one is that the bell housing is always covered in the red trans fluid and when the car is off the road, it drips onto the two exhaust downpipes meaning that when the engine is next fired up, the oil burns off the exhaust for a good 5 mins, smoking out the garage. I have a complete new SS exhaust to fit but want to get the oil leaks fixed first.
So the plan is to remove the transmission and replace the front servo oil seal (which I assume seems the main culprit) but to also do the rear oil seal as well and take off the sump and clean the oil filter and put a new sump gasket on too, though that does not seem to be leaking.
Having looked at the workshop manual I cannot see any other obvious seal to replace, but also. its not clear whether you have to dismantle the transmission in order to replace the front servo oil seal which seems from the exploded diagram, to be right at the front of the box where it meets the bellhousing.
It looks to me that it is similar to the rear oil seal and can just be prised out of the housing.
Am I right on that point and are there any other seals that I could replace with the gearbox out, that do not require dismantling the trans?
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Post by enigmas on Aug 9, 2023 23:43:18 GMT
The front seal on the BW35 is the front pump seal. The nose of the torque convertor drives the front pump of the transmission. The seal is easy to replace once you've pulled the trans from the car. Check the nose of the torque convertor for any grooving or roughness. If so carfully linish with fine wet and dry and paper. Do this radially not logitudinally. If there's a deep groove evident you'll require a speedy sleeve (from a Bearing Supplier) to correct the surface.
Before reinstalling the transmission liberally oil the seal working surfaces with ATF otherwise you'll burn the seal lip on first startup.
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Post by lagain on Aug 10, 2023 18:17:44 GMT
I would be very surprised if the sump gasket is not leaking, they can also leak through the inhibitor switch and the seal for the selector lever, which is very easy to replace. It has taken me decades to stop my gearbox from leaking, but I think that I have, finally.
I bought a rubber gasket and support bracket from ebay. The support bracket is supplied with longer bolts and fits around the edge of the pan. I removed the oil pan, with the use of a ball pien hammer I knocked the bolt holes level again. I then glued the rubber gasket to the pan and nipped it back up to let the glue dry. With the mating surface having a smear of TQF I was able to remove it the next day, fit the support bracket and bolt it up to 6lb/ft, so not very tight. That was 6 months ago and so far so good and the rubber gasket has not spread. The cork gaskets available are totally useless and the composite ones not much better.
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Post by enigmas on Aug 10, 2023 23:32:38 GMT
Adding to George's comment above, the BW35 pressed steel sump pan can be made oil tight or leak free even with the cork gasket if due attention is paid to the sealing flange. This may mean spending time with both a panel hammer, a good flat file and a flat surface (a kitchen table or similar) and a feeler gauge of .010" or less.
If you can invert the pan and at every point where the flange touches the surface feel resistance when drawing the feeler gauge between the flange and the surface the pan is resting on, then the pan will form an oil tight seal when reinstalled to the transmission.
When fitting the gasket smear the pan flange surface with an appropriate gasket sealer (not silcone based. I prefer Loctite 515 or 518 anerobic sealant), fit the seal and lightly nip up the flange bolts. Do not crush the seal.
If you have carried out the process with due care and attention to detail, the pan will not leak or weep at all and remain oil tight. As a bonus it can also be removed and replaced without a gasket change if a band adjustment or similar service is required.
This process worked successfully on the BW35/hybrid trans in my coupe when I rebuilt the transmission 4 or 5 years ago. To this day still no leaks.
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