If you wish to replace the filter in your DeLorean's automatic transmission, you may find that it is either not available or very expensive. The reason for this is because the DeLorean was the only car sold new in the United States that used this filter. In the rest of the world and particularly in Europe, manual transmission cars are far more popular which makes automatic transmission parts not as common as people in the US are used to seeing.
This article is about rebuilding the OEM filter. There may be other cross-reference filters out there that cannot be rebuilt the same way.
The OEM filter is made entirely of metal and does not wear out. Instead it merely clogs up. A simple fix is to reverse flush it without disassembling it, but this is not thorough. It may leave behind particles that will loosen up and find their way through. Some trapped particles are needle-shaped and will not easily dislodge. This article may help you decide whether to replace your filter, clean it without disassembling or go the works by disassembling it to make it like new. If you buy a new filter; by all means, please do not throw away your old one. It can be rebuilt. If you don't know who to give it to, send it to me or give it to someone at the next DeLorean show you attend.
The above picture is from under the car with the fluid drained and the pan removed. Notice the accumulation of metal particles stuck to the magnet. This is from VIN 03633 at 12,600 original miles. I do not know if this amount of accumulation is normal for the miles driven.
From here on we will use the following terminology: The "top" is the flat side of the filter that faces and attaches to the valve body of the transmission. The "bottom" is the input/suction side of the filter that faces the pan.
The above picture is of the filter after removing it from the car and wiping off the excess fluid. The view is from the bottom side of the filter.
The first step to cleaning out the filter is disassembling it. Notice that the filter is held together in a clamshell fashion with the perimeter of the top bent over and crimped around the bottom. Likewise, the three mounting holes are crimped through. To disassemble the filter, all of these crimps must be cut. To remove the crimp on the perimeter, use a bench grinder. Grind perpendicularly all along the perimeter just enough to open the seam. When you are done, there will be a thin band of the leftover crimp from the bottom that will lift off. To remove the crimps in the mounting holes, drill them through with progressively larger bits until the halves separate.
There are a total of 4 pieces in the transmission filter. In the photo above, the left is two pieces still lying together consisting of the top shell (1st piece) covered with the layer of coarse mesh baffle (2nd piece). The center (3rd piece) is the actual filter media made of a fine brass mesh. On the right is the bottom cover (4th piece). In comparing the filter media to the filter magnet in this example, the magnet captured more than twice of what showed up in the media. I do not know if this is normal. If YOU are going to drop the pan on your transmission, please send me a photo of your filter magnet and tell me the history of your transmission so that we may develop a reference for what is normal. When enough data is accumulated, this article will be updated.
As a side note, some people believe that the transmission performs better without using a filter. Their argument is that it is more important to allow unrestricted fluid circulation than to risk impeding circulation with a restrictive filter. From the looks of this filter, I disagree. You can draw your own conclusions and decide for yourself. Nevertheless, if you decide to go filterless, at the minimum make sure a good magnet is in place to trap particles.
Clean all the filter pieces with a solvent of your choice -- preferably something that will dry without leaving a residue. Disc brake cleaner works well. Use a toothbrush or strong magnet to work loose any trapped particles being careful not to tear or crease the brass media. Use a file to smooth down the rough-cut edges of the outer shell.
Going back together -- There are a total of 4 pieces as follows:
The above is the 1st piece.
This is a view of the 2nd piece in place over the 1st. This is a coarse mesh baffle whose purpose is to support the finer brass mesh from collapsing under suction.
This is a view of the 3rd piece in place -- the fine brass mesh. Be very careful to install the pieces in the correct order. Notice that enough light shines through the fine mesh that you can see the coarse mesh and top plate through it.
This is a view of the 4th piece in place -- the bottom cover.
Now the hard part -- holding it all together.
The above is the finished filter ready to be reinstalled. Notice the placement of the OEM magnet. The halves of this filter are held together with a piece of 1/4" copper tubing. Start with a piece of tubing long enough to wrap around the perimeter of the filter and overlap itself by about 2 or more centimeters. A 60cm (2 ft) long piece gives several centimeters to spare for practice cutting. Cut a straight line down one side and spread it open to resemble a "U" shape. Thoroughly clean both ends of the tube (inside & outside) where they will overlap so that solder will stick. Wrap the tube around the filter and hammer flat. Use a bench vice, vice grip pliers and "C" clamps to hold in place. Solder the overlapping ends. Electrician's solder works fine as well as plumber's solder. The important thing is to have the ends very clean so that the solder will stick. When choosing where the overlap would go, I put it on a straight edge to make soldering easier. If doing it again, I would try locating the overlap at the inside bend because this point had to be held with a clamp in addition to the part being soldered. It makes more sense to only need to clamp one area while soldering.
Above is a view of the top of the assembled filter showing how the tube overlaps at the solder joint.
Above is a collection of the files & reamers I used to clean & dress the clamshell halves.
Here is a photo of the dremmel tool used to cut the copper pipe. This was hard work both for me and for the tool.
The following are some DML posts, which this article is based on.
Date: Sat, 7 Jun 97 09:30:54 -0000
From: James Espey
Subject: Re: DML: Filters and such
>I'm having trouble finding an Automatic Transmission filter ? Anyone
know which one to use ?
I have been told that the DeLorean was the only car sold in the US that uses
this particular automatic transmission. It is used in other Renault autos, but
only those sold outside the US. If that is indeed the case, you probably won't
find a suitable filter at NAPA, Pep Boys or even an old Chrysler dealer that's
willing to order you an old Renault part. P.J. Grady sells a complete
"Automatic Transmission Filter Kit" (pan gasket, filter, and filter gasket) for
$74.85 plus shipping. I don't think that's unreasonable.
Date: Thu, 7 Sep 2000 18:30:34 -0600
From: James Espey <james(AT)usadmc.com>
Subject: Re: trans filter/Delorean Motor Company
The Renault transmission used in the DeLorean is a Renault R30. To my
knowledge, the DeLorean was the only vehicle sold in the United
States that used this exact transmission configuration. There was an
old Renault sold in the states in the early eighties that shared some
components with this transmission. Will a Jeep-Eagle be able to help
you find the part? Maybe. When you get it and have a question about
installing it, will the Jeep-Eagle dealer be able to help you as far
as it's application in the DeLorean? Doubtful.
When we used to get the filters, they were imported from France. The
price has gone up considerably, and we have taken to cleaning and
re-using them with excellent results. Another problem is the gaskets,
another difficult to obtain and expensive part.
DeLorean Motor Company
Date: Thu, 07 Sep 2000 21:43:19 -0000
From: "jtrealty(AT)webspan.net " <jtrealty(AT)webspan.net>
Subject: Re: trans filter/Delorean Motor Company
I can't believe that you couldn't get more help from DMC texas, they
are usually very helpful. Whatever the case the problem with the
filter is complicated. It is indeed a Renault part but is is made
special for the application in the Delorean. There are no more
available right now unless you can find an N.O.S. But all is not
lost.There is a very good workaround. After removing the filter
carefully hold the edge where it is folded over all around against a
grinding wheel removing only enough to expose the seam. Disassemble
the filter and keep track of the order of assembly, there will be a
top, a metal support baffle, a mesh screen, and a bottom.Clean all of
the parts being careful with the mesh screen.Cut a piece of 1/4"
copper tubing 19 1/2" long and then slit it lengthwise with a cutoff
wheel. Reassemble the filter. Place the slit tube around the filter
hold it together hammering as you go. Solder the ends together. Now
you have a filter that can be easily cleaned by just cutting off the
copper in the future. Make sure that what you are doing is ABSOLUTLY
CLEAN and that there are no loose pieces of solder or bits of metal.
After putting the trans back together check the line pressure as per
the manual, it is a good indicater of the general health of the trans.
Date: Sun, 10 Sep 2000 18:00:34 -0500
From: Bob Brandys <firstname.lastname@example.org>
Subject: Re: Oil Sending Unit
I heard a rumor at the BCD. Someone was crediting you with claiming that
removing the filter in the automatic transmission, improves its
performance.? You just have to change the oil more often. Is this true?
Date: Mon, 11 Sep 2000 15:27:44 -0000
From: "email@example.com " <firstname.lastname@example.org>
Subject: Re: Oil Sending Unit now trans filter
There should be no performance gains from removing a GOOD trans
filter. A filter has nothing to do with ratios. The only thing it
could affect is line pressure and that controls the shifts and the
pressure to keep the clucthes from slipping, and the flow to the
cooler causing it to overheat.The danger is that as the dirty fluid
goes around in the closed system it will ruin the pump, seals,
bearings etc.I don't know anyone who would try running without a
filter except for troubleshooting purposes. You wouldn't try running
without a fuel filter and that isn't a closed system.
Date: Mon, 11 Sep 2000 17:55:38 EDT
Subject: Re: Tranny Filters
Bob, I assume you're directing this at me, since I did attend the BCU show in
Chicago this past weekend and I did speak with one of the "D" guys about auto
Like all rumors that have been told over and over, the answer is: Yes and
What we've found on about a half dozen auto tranny's we've worked on is:
the filter is very restrictive, even new, almost to the point of starving the
tranny for fluid during normal operation. We do have a few tranny's
currently running without filters installed and, to date, they have performed
very well, especially for automatic Deloreans. These cars have only been
running for a couple of years so, at present we do not have any long term
info concerning possible additional wear.
As far as just changing the fluid more often to offset not having a
filter, that's NOT the case. These owners realize there is a risk of
additional wear and / or possible damage involved in not having a filter
installed. The "performance vs wear" thing is a trade off which involves
some risk, and each owner must decide for themselves if they want to accept
I was only passing along information we have gained thru personal
experiences working with these cars. Each owner must decide for themselves
what to do with this information and what risks they want to accept in using
You've probably played with auto tranny's as much as anyone has,
especially with the setup you've got in your BTTF car. What is your
experience with this ?
Date: Mon, 11 Sep 2000 19:01:56 EDT
Subject: Re: Re: Oil Sending Unit now trans filter
It's not the filter which causes the problem, it's the restriction it
creates in flow which causes the problem. If you took an engine which
required a 1/2" fuel line to properly feed it and installed a 1/4" filter in
this line, even tho the filter was brand new, you would still hurt the
engines performance by restricting the flow to it.
It's the same with the tranny filter. Like you said, the tranny operates
on fluid flow and when you restrict this flow, you hurt the performance. And
I'm not talking about old, dirty filters, I'm talking about brand new tranny
filters being restrictive to the point of causing a performance loss.
We're not directly increasing the performance of the tranny, only allowing
it to perform better thru less restriction. Now someone just needs to come up
with a tranny filter which allows this to happen.
As far as running a tranny without a filter. Again, like you said, a
tranny is a closed system. By being a closed system, it is far less prone to
being contaminated then an open system, such as a fuel system, where you are
constantly adding fuel and /or whatever to it from an outside source. Thus a
tranny filter is cleaning the same fluid over and over again. You are
correct, a tranny thru normal operation does create it's own internal
contaminates thru clutch slippage, etc, and these contaminates will cause
wear to other internal parts. But so will restricting / starving the system
for fluid flow cause transmission wear.
Again, running the tranny without a filter is a trade off with a risk
involved. You must decide for yourself what to do.
Date: Wed, 13 Dec 2000 03:44:39 -0500
From: "Walter" <Whalt(AT)att.net>
Subject: rebuilding transmission filter
I rebuilt my transmission filter like David Teitelbaum said to do and it
went great. The hardest part was keeping the flattened copper pipe from
working loose as I was putting it on. I used a Dremmel tool with a small
cutting bit to slit the copper pipe. This was a bit more of a job than the
tool was meant to handle, so I divided it up into 4 cutting sessions so that
it wouldn't over heat too much. I soldered the ends of the pipe together
using a 250 Watt soldering gun meant for electronics. A better choice may
have been oxy/acetleyne, but I didn't feel like dragging the tanks out or
getting the brass screen too hot.
One step David didn't mention is that you will have to drill out the 3 bolt
holes as these are crimped around also.
I cleaned the screen with a disc brake type degreaser. It worked great. I
used a magnet and my fingernail to get a few stubborn metal flakes out of
it. Be aware that tri-chloro-ethane is VERY poisonous to breath.
When you are done, be sure to put the magnet back on the filter in the same
place. At 12,600 miles, my filter magnet had way more than twice the amount
of particles stuck to it than was stuck in the brass screen inside the
filter. In fact, the magnet didn't look like it had any more room for
particles to stick to it, but the pan had no residue to speak of other than
a thin film of gray that wiped out with a paper towel. I went to Radio
Shack and bought a 2 pack of high energy rare earth magnets. I put both of
these on other spots of the filter keeping them out of the way of the inlet
port. I would have stuck some magnets in the pan, but I bought the only
pack they had on the shelf.
I have seen old posts on the DML that some people had the opinion that the
Delorean automatic transmission would last longer without a filter. Based
solely on my observations from rebuilding my filter, I disagree. Besides
the magnet appearing to be saturated, the brass screen inside had very
little debris outlining one corner. The screen appears to offer little
resistance to fuild flow. If you decide to run it without a filter, at the
very least put some magnets around there. They pick up more than the
Walt Tampa, FL
Date: Thu, 5 Jul 2001 12:46:33 EDT
Subject: cleaning trans filter
Today I removed the transmission pan and also removed the old
transmission gov/computer. As long as I have the pan off I would like to
clean the filter. I know that there are no more available right now. It
really doesn't look too dirty and there is not much on the magnet.(car has
17k miles) Can I soak it in a parts cleaner? I really don't want to take it
apart. Mr. Grady told me that you really don't need to take it apart to
clean it in most cases.
When should the final drive oil be changed? I want to switch it over to
Amsoil in the near future. Any info would be greatly appreciated.
Date: Thu, 05 Jul 2001 18:58:17 -0000
Subject: Re: cleaning trans filter
You cannot tell how dirty the filter is unless it is disassembled. If
you soak it you may loosen some of the dirt but some will stay to
loosen up later after you reinstall the filter. To clean the filter
involves grinding the edge off all the way around and separating the
pieces noting the order of assembly so as to be able to reassemble
correctly. You also have to drill out the 3 holes. After cleaning
thoroughly reassemble. YOU MUST REASSEMBLE IN THE PROPER ORDER THE
MESH AND THE SUPPORT BAFFLE! To hold it together get a piece of 1/4
copper tubing 19 1/2" long. Slit lengthwise with a cut-off tool or
hacksaw. Using little "c" clamps to hold the filter together hammer
the tubing all around soldering the ends together. Now in the future
you only have to remove the tubing to clean the filter. The oil in the
final drive really doesn't ned to be changed too often, just keep it
at the proper level. Any good quality 80-90# gear oil will do fine,
synthetics are not needed.
Date: Fri, 06 Jul 2001 03:44:41 -0000
Subject: Re: cleaning trans filter
Your magnets will only capture steel and cast iron particles. The
filter is meant to keep out the big chunks and any friction materiel
which is a natural by product of the aging of the automatic
transmission, not metal. You should not expect to catch much metal,
especially magnetic, although you will see flecks of brass and bronze
from the thrust washers as they wear normally. If you find large
amounts of friction materiel or any significant amount of magnetic
particles the transmission is nearing the time for a rebuild. If at
this point you continue to drive on it you will only cause more
damage, like driving on a worn out clutch, it tends to wear much
faster as it approaches the end of it's life. When the fluid becomes
overburdened by particles it wears out the pump, the seals, the torque
converter, and the thrust washers and shims. Even if you reseal they
won't last if the fluid is full of grit (microscopic particles of
metal and friction materiel). The only cure is complete disassembly
and replacement of all of the wearable parts, the friction plates, the
steel plates, seals, bushings, thrust washers, and gaskets. If you
drive the trans to destruction then you risk of ruining hard parts
like gears, housings, shafts, etc. These parts are not normally
replaced and are expensive. Think of it like driving on worn out brake
pads and ruining the rotors. If you stopped and did the pads for say
$50 you wouldn't have to go for rotors for $500. On the Delorean you
cannot properly flush out the trans fluid unless you dismantle it. Too
much remains in the torque converter and you can't drain it without
removing it. Cleaning the filter is involved but since there is no
more stock and I cannot find a replacement this is the best I can come
Date: Fri, 6 Jul 2001 23:48:23 -0400
From: "Walter" <Whalt@att.net>
Subject: cleaning trans filter
After I drained my fluid and dropped my pan, I took a digital picture of the
filter with its attached magnet. Some filtrate is to be expected, but I
would like some second opinions. For those of you who are familiar with
what a normal transmission change should be like, give me your opinion about
what you see on this filter magnet. Is it a reasonable amount for what
should accumulate after 12,600 original miles?
Walt Tampa, FL
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