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Post by Deleted on Feb 9, 2010 20:47:21 GMT
I know this is going to raise a groan as this subject has been discussed ad-infinitum in the past but I can't find the thread despite searching, sorry!
I have a totally original BW35 box in my 1971 car. It's never been rebuilt or adjusted in anyway. I did change the oil a few years back and don't have the original container but I remember using some sort of comma product. The box behaves perfectly and is silky smooth etc.
I seem to remember a big debate about Dextron? and whether or not it should be used and I would like to know what is recommended for an ORIGINAL box?
Thanks in advance.
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Post by enigmas on Feb 9, 2010 22:01:24 GMT
If it's an original non rebuilt English gearbox do not use dexron fluid.
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Post by harvey on Feb 9, 2010 22:17:19 GMT
I would like to know what is recommended for an ORIGINAL box? The original recommended fluid was Type F, which was later superceded by Type G, one of the original recommended makes being Castrol TQF. Now ATF-G is available from the likes of Comma, and providing it meets the Ford specification M2C-33G it is ideal for the BW35. (& 65) Don't use any of the Dexron type fluids, unless recommended to by someone who rebuilt the box, but if that's the case then a) they should know better, & b) you would have been better off getting the job done somewhere else.
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theroveringmember
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P5B Saloon - P4 110 - P6B x2 - 2200TC - 2000TC (S1) 2000SC........How Many Is Too Many?
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Post by theroveringmember on Feb 9, 2010 22:33:32 GMT
;D
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Post by Phil Nottingham on Feb 9, 2010 22:40:06 GMT
I still use Comma AQF (BW/Ford & no Dexron)
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Post by Deleted on Feb 10, 2010 15:07:34 GMT
Oh, hells bells! I've found the original container and I used Comma AQM to be used with vehicles where Dexron 11 is recommended I only changed the oil in the transmission sump so there will be a few pints of original fluid sloshing around in the transmission. So what have I done by using a fluid with Dexron in it in an ORIGINAL UNBUILT box? Is this serious and what exactly is Dexron? The box is behaving beautifully at the moment, changing when it should and no sqeaks, rumbles etc. I do treat it with kid gloves as I know the BW35 isn't the strongest unit around. Do I need to drain and refill?
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Post by harvey on Feb 10, 2010 15:23:08 GMT
Personally I'd suggest draining out what you can, and refilling with the correct fluid, although now you have a mix in there you would need to do it at least a couple of times to increase the proportion of the correct fluid relative to the Dexron.
As said in previous posts, and not just the ones by myself, using Dexron is not a good idea, although there are plenty of "Automatic Specialists" who will tell you otherwise. I would expect the first signs of problems caused by the Dexron would be slip or "flare" on the changes, and if you really are treating it with kid gloves then it will take longer for you to notice anything, if indeed you ever do because you don't give the box a hard time. On the other hand you may find yourself in a situation where you have to boot the car to get yourself out of trouble, and all it does is slip. The box is on its limit behind the V8, but you should be able to use it as intended, rather than being frightened and pussyfooting around all the time.
You could buy yourself 10 litres of the correct fluid for about £30, drain out what you can when it's hot, measure this, and replace with the same amount. You should be able to do this in about 20 minutes a time, and you'll probably get 3 changes out of the 10 litres. If you put the same amount back in each time you wouldn't even need to check the level, providing it was correct beforehand.
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Post by Deleted on Feb 10, 2010 16:28:43 GMT
Excellent advice, thankyou.
So what is Dexron and what purpose does it serve when it is correctly used?
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Post by harvey on Feb 10, 2010 16:47:19 GMT
Dexron contains friction modifiers which help to smooth out the changes on boxes that were designed to be used with it. The DG used in the early 3 Litres uses Dexron, as does the GM180 in the later SD1's. The BW35 was designed for use with Type F, (Later G) fluids.
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Post by Deleted on Feb 10, 2010 19:02:51 GMT
Now I understand. Many thanks.
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Post by Phil Nottingham on Feb 10, 2010 19:36:31 GMT
Have to disagree with Harvey on 3 Litres with BW DG box these too must not use Dexron type - the fluids Rover/Jaguar and Humber specified are identical to the BW35 which was a lightweight and simpler replacement for the DG
Originally only GM Hydramatic and the ZF boxes used Dexron - more complicated in the 70'80's though
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Post by harvey on Feb 10, 2010 23:19:00 GMT
Have to disagree with Harvey on 3 Litres with BW DG box these too must not use Dexron type - the fluids Rover/Jaguar and Humber specified are identical to the BW35 which was a lightweight and simpler replacement for the DG Originally only GM Hydramatic and the ZF boxes used Dexron - more complicated in the 70'80's though I did some research on the oil recommended for the DG box, and found that it was originally specified to have Type A, which is the forerunner to Dexron, and what was originally specified for GM, as opposed to Type F which was the recommended fluid for BW35 and Ford boxes of the period. I won't challenge anyone over what they want to use in a DG, because I have little interest in working on them, but I would still say it should be Dexron, but from now onwards I won't recommend its use here in that application then.
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Post by Warwick on Feb 10, 2010 23:20:54 GMT
Dexron is a GM brand name for fluids that it developed (or had developed) for its own transmissions. It licenses AFT manufacturers to use the name when their product meets the GM spec for use in GM gearboxes. Other transmission manufacturers then began designing boxes to use Dexron spec fluids.
The problem with ATF is that it has to act as a hydraulic fluid for operating pistons, valves, etc., it has to act as a power transmission fluid in a turbine (the torque convertor), it has to act as a heat transfer medium, it has to act as a lubricant and minimize friction in bearings and gears, but it also has to allow friction with the various wet clutches and brake bands that operate the gear selection process.
An almost impossible task on the face of it.
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Post by enigmas on Feb 11, 2010 4:46:03 GMT
If you have an Aussie box (BW35/40/51) with the larger 'flex' brake bands and wider drums it will run perfectly well with the dexron stuff as the friction material was upgraded (both band and clutch) many moons ago. These boxes were used in big engined chryslers (hemi's - 245 ci), Fords both 6cyl and V8s up to 5 litres. My Rover P5 V8 4.4 litre (P76 engine) has been on a diet of dexron for as long as I can recall (15 plus years). I run 3 cars Ford, Chrysler/Valiant and my P5 on the stuff but they are all Aussie spec gearboxes.
The original P76 gearbox was the precursor of the BW40 fitted to bigger engined Fords (4.1 & 3.9 EFI) of the 1980's which put out considerable amounts of torque. The internals are a direct fit in a BW35 case. My P5 has the English casing fitted with the full internals of the Aussie BW40 with the last manifestation of the valve body which allowed for an automatic low speed shift into first gear. (for the auto nerds out there...there is a hole bored throughj the centre of the 1-2 shift valve.) It also runs a larger torque convertor and pump than the one used in P5Bs. Running these boxes on the fluid Harvey suggests would cause very hard and firm shifts (lets go racing) Amen.
Crossplies...it's not sudden death...the gears and seals won't dissolve! Flush the system out with the stuff Harvey recommends for your English BW35 and don't add any additives. If you don't know what you're doing take it to an auto specialist and have them do it for you. DYI is not always the best solution or the cheapest (to give piece of mind) without specific technical knowledge.
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Post by Phil Nottingham on Feb 11, 2010 18:37:52 GMT
I think we have come full circle again on this - the concensus then (2? times?) was to use the fluids that Rover specified or their nearest modern equivalents UNLESS the box has been rebuilt then use the fluid the rebuilder recommends.
If you do know know what the rebuilder recommended or whether its been rebuilt anyway then tough luck! If its going OK then carry on if its not you have nothing to lose by swapping. These boxes can last 100k miles+ or less than 50k depending on how they are driven and have been looked after - on a car up to over 50 years old you are expecting too much really by applying modern standards. In the UK if in doubt if its been rebuilt try non-Dexron first - as Harvey says its unlikely to make alot of real differnce unless box is driven hard (or its past it anyway)
Old Rovers are not so fussy what they need other than regular attention and use - when it gets less then you will get problems.
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Post by Deleted on Feb 11, 2010 21:03:10 GMT
I went into my local friendly Kevin Coopers today and bought 10 litres of Comma AQF so I can change most of the existing ATF in the box. I also picked up a QH fan belt which should fit ref QBA 1150. I find KC's to be very helpful and good value.
Looking back through my records, I was amazed to see that it was 8 years ago I put the AQM in but in terms of mileage not very many I'm sorry to say! Even if I had the right fluid in there already I would still be tempted to put some fresh in at this stage.
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Post by Warwick on Feb 11, 2010 22:41:56 GMT
I think this is the most concise and uncluttered thread on the subject that we have had to date. Even the heading says it all. It was good that Vince highlighted the reference to Australian versions of the BW35 as there are a lot of us antipodeans reading this site, so it needs to be clear that there is a difference between the P5B BW35 and more common BW35s down here.
Phil, perhaps it could be made a sticky.
I think there is only one piece of information not covered. I think I know the answer but it wouldn't hurt to ask it here anyway so that Harvey and Vince can record the appropriate answer for each country.
If you have a box of unknown history, is there any way of identifying the type of fluid required by inspecting the friction material inside - either personally or by a specialist?
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Post by enigmas on Feb 12, 2010 1:56:56 GMT
Warwick, at various times I have rebuilt these boxes (BW35) mainly for my Rover. As my Rover has a grunty V8 (4.4 litre) I tend to rebuild using the internals of a BW40. I still run the rear pump (Mk3). I know of a least 3 types of clutch material used for these boxes depending upon the intended purpose. I even have some plates set aside but I do not have all the technical details. Some appear scintered like higher quality brake pads and others are not. I'll take a look at what I've got stored.
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Post by harvey on Feb 12, 2010 12:28:56 GMT
I can't think how you'd identify the friction material and its suitability for any particlar type of fluid in a used box just by looking at the worn friction plates, but once you get to the stage that the box is in pieces I would assume it's going to be rebuilt anyway so you can then choose your fluid type, but my choice would always be the original spec, never Dexron. What I would say though, is that it's not only the friction modifiers in Dexron that can cause problems, it is meant for use in boxes that are built to much finer tolerences than the BW35, and runs a lot thinner when hot, and I have experienced other problems which were directly attributable to the use of Dexron in a 35.
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Post by harvey on Feb 12, 2010 15:38:40 GMT
Here is a link to a warning posted by Castrol on the dangers of using Dexron in boxes designed to be used with Type F or G (M2C-33G) fluids. It's posted with regard to a Citroen DS with a 35 box, but it's all applicable to any BW35 (or 65,66) www.aussiefrogs.com/forum/showthread.php?t=62208Scroll down until you see the warning signs.
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Post by Deleted on Feb 12, 2010 16:34:46 GMT
Link not working for me Harvey
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Post by harvey on Feb 12, 2010 17:03:33 GMT
Link not working for me Harvey Well it worked for me when I posted it, and now when I just tried it again, but it does take a little while to load up, so give it some time and all should be revealed.
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Post by Deleted on Feb 12, 2010 17:21:17 GMT
Now it's working Harvey. Very interesting but quite technical for an auto-novice like me . I get the drift of the warning and I now have the Comma AQF to partially change the fluid. As a matter of interest, you recommended getting the ATF hot before the first replenishment and I assume that is to help draw it in from the torque converter and pump. On the second and third ATF changes will it be sufficient for me to simply move the gear selector through the range to circulate the ATF or will I have to take the car out on two additional runs to help flush the converter and pumps etc? Could I just move the car backwards and forwards a few times?
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Post by harvey on Feb 12, 2010 17:36:38 GMT
The hotter the fluid is, the easier it will run out of the drain plug, and the quicker you can get the job done, but it won't actually enable you to get any extra fluid out from the places that won't drain. As said earlier it won't actually cause problems sitting there it's only when you use the car, so I'd do the drains after you've been out for a run, whenever that might be, rather than making special runs just to do it. After all the fluid has been in there and in use for a good while already.
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Post by Deleted on Feb 12, 2010 17:45:39 GMT
Sorry if I'm a bit thick here but if I do the second and third drains without starting or moving the car, won't I be draining the new stuff I've just put in? I assume that the filler tube leads straight to the sump?
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