An interesting theory.

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AlanS
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An interesting theory.

Post by AlanS » Sat Nov 12, 2005 8:54 am

A friend of mine has recently bought a BX16Trs auto.
When he bought it, service records indicated it had been operated on Dexron 3 which we have discovered out here is terminal on BX autos due to its glycol base and not an oil base thereby mixing two incompatable fluids.
In an attempt to be careful as careful, he bought 20 litres of Dex2 as specified and began a regime of filling and draining in an attempt to get rid of all traces of the Dex3. The difference in the performance of the gearbox has been spectacular until today when he went for a 30 klm trip @ around 120 kph.
All was going well until someone stopped to do a right hand turn just over a bridge and a tight intersection which caused him to stop. When he tried to take off again; nothing, nowt, ziltch....it just wouldn't move forward. Reverse, yes, but not forward, so he ran it back off the road, stopped the engine and sat there wondering what to do.
After 5 minutes, he re-started the engine, put into drive and off he went. A few klms further, he again stopped and went to re-start with same result. No forward, has reverse, wait a few minutes and off he goes.
The theory is that all the crap from teh Dex3 days has been washed out into the system and has got caught in the internal filters as the box can be heard rotating internally when it happens but will not move. If left, all systems seem to go. The theory is that the filters are starving the pump and if left, it drains back down and allows things to work again.
He's ripping the filters out to clean them so hopefully within 24 hours I'll have a result.
Does anyone agree with this theory or are we wishful thinking and has anyone here ever stripped a BX auto box and if so, how difficult are they to do work on and where do you get the parts?


Alan S
By the time you're old enough to know it all, you can't remember why you were learning.

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ken newbold
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Post by ken newbold » Sat Nov 12, 2005 12:14 pm

I did once dismantle one, knowing it was going to be thrown.

:shock: :o :o :o :o how anyone works on these things is beyond me.

You have to remove the sump just to fit a new kick down cable, this seem arkward enough with the gearbox on the bench. Doing in situ (upside down) I dont want to think about it. :o
They think it's all over, it is now!

AlanS
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Post by AlanS » Mon Nov 14, 2005 11:10 am

Well, just had the news; it worked.
Auto now performing better than it ever did. It seems there's a filter inside the sump of the auto that is like an LHM tank filter and this one was full of shyte. Washed out, it looked like the consistency of half melted chocolate but here's a word to the wise; when/if you take the base plate/sump off the auto, note exactly where the bolts come from. It seems that the service manual donates a full page to this and it is extremely important as if the screws or bolts go into the wrong holes, they actually snag on parts of the transmission and it don't work.
It also appears on the advice of the guy who pulled the base plate off and in the process studied the whole operation and principle of its operation, that the main problems that befall these transmissions isn't the actual transmission, but is actually the torque converter.
It seems he now intends ordering a new one for his second car, also a BX Trs auto and doing an autopsy on the current one in there to confirm his theory.
So it would be interesting to see how many autos have been dumped due to dirty filters, how many have been "reconditioned" by cleaning aforesaid filters and how many have been "fully reconditioned" by simply fitting a new torque converter.


Alan S
By the time you're old enough to know it all, you can't remember why you were learning.

jeremy
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Post by jeremy » Mon Nov 14, 2005 2:11 pm

As a matter of interest what is likely to have failed in a torque converter/ My understanding is that there are 3 presumably cast sets of vanes and that the centre one is mounted on a one way clutch. If the clutch fails presumably the thing won't work at all, but otherwise it can only leak?

jeremy

AlanS
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Post by AlanS » Mon Nov 14, 2005 7:59 pm

This is the reason for the autopsy.
The almost legendary constant failures of these boxes belies the fact that in racing circles and talking to engineers, they're considered to be the auto transmission when it comes to design and quality, yet we constantly get told they are inferior to Jap and other boxes who may have even used these to copy from.
Progressively we're "myth busting" the problems associated with them and when we degut the torque converter, it may be the final piece in the puzzle.
So far we've discovered that:
(a) The problems are caused predominantly due to using incorrect fluid, and
(b) The rectification may be more of a well kept trade secret and simple solution than a complicated expensive repair.

Withe the Torque converter, we may discover it is often repaired/replaced and in the process, the filters are cleaned and perhaps the TC didn't need replacing at al, or it may be that the TC may be identifies as the source of this gummy crap that blocks the filter and if this gummy stuff is actually from something that causes the final cracking up of the transmission.
When we do it, I'll post the results.



Alan S
By the time you're old enough to know it all, you can't remember why you were learning.