I have read a lot on BMW's and have never been able to find to what company BMW shipped their cars to make the M633. The frame and suspension on the car are completely different and much heavier than my 81 E24, and the engine has a significant amount of power over my other car.
I am wondering if the car was done up by Alpina.
Any help would be appreciated.
Bob

No company that i know of made an M633. Someone could have put an M badge on the car, done some motor work (cam, pistons, headers, etc) and beefed up the suspension. Its hard to tell without a little bit more. I know that Alpina has been around for awhile, but the only cars they made were notated as an Alpina B7 or B9 for the E24, as well as a few submodels i think.

-Jeff

I have read a lot on BMW's and have never been able to find to what company BMW shipped their cars to make the M633. The frame and suspension on the car are completely different and much heavier than my 81 E24, and the engine has a significant amount of power over my other car.
I am wondering if the car was done up by Alpina.
Any help would be appreciated.
Bob

Bob - not sure if M633 is a typo or not. There was never a model designated "M633". Your '81 is an E24 model, but the chassis is based on the E12 series cars. The M635, introduced as an '84 model, used the next generation body. All ///M cars have been done by the internal Motorsports group. Alpina did do a number of BMW-based cars as well, though these are very rare (posers abound, though).

No, it wasn't a typo, the car is registered as an 83, and the interior matches the 83 interior. The car has the front air dam and trim just like the picture of your car above, The chassis is completely different from the 81 and the stock 83 chassis I looked at. The frame is much heavier the rear end trailing arms and the crossmember that the rear end mount to are all different. I have a lot of experience building cars, and I can't believe that someone would graft a body onto a completely different frame for no good reason. I don't really care, other than to satisfy my curiosity because in everything I have read on the BMW they talk about the M635, but there is no mention of an M633. Thanks for the reply.
Bob

Bob,

I know you cant post pictures on this website yet, but if you have any pictures of the under-carriage, please send them to me. my email is jbd5015 AT psu DOT edu

Im really curious to see what the heck is going on. Sounds like you may have found a frankenstein 6er of some sort.

-Jeff

I won't be able to take pictures for awhile because I am in the middle of building my new garage and the car is in the my yard behind some of my other stuff. I will put it on my hoist and take some pictures as soon as I have moved into the garage.
Bob

please do - the informatino that Lee (E24Mpwr) gives is correct. there was never a factory M633. Now - what someone has done to it to decide to call is such is what has us all interested. Modifications are always neat to check out, to see what someone else came up with for a fix or their idea, etc.

now, the swap from E12 based chassis (your 81) to E28 based chassis came sometime in 83, IIRC, so there is a chance that you looked at an E28 based car (different of course from your E12 based one) that someone had done extensive modfication to for the track or otherwise.

Eitherway, you've got us all interested, we want to see those pictures.

take your time moving into the garage, and by the way - when you get the lift installed, can I come over and work on my car under it>? :lol :D

Bob,

Post or PM the last 7 of the VIN if you have it. That way we can see what model it was from the factory at least. From there you can figure out what the modifications are.

If you think the car might be an Alpina, you can email them through their website here (http://www.alpina-automobiles.com/en/) they take a week or so to respond, but they will answer you if they have a record of it.

The last 7 numbers of the VIN are 6725609
Bob

Thats a build date of 11/82 from plugging that into realoem.com, which suggests that it is based on the E28 platform. Correct me if im wrong guys, but i thought that 5/82 was the last month for E12 based cars.

-Jeff

What is the VIN number and what is the build date?

What is the VIN number and what is the build date?
Read the two posts before yours. ;)

I couldn't find any more info than that it is a US/CDN spec 633CSi with the build month as suggested above. The platform changeover from E12 to E24 likely occurred with the model year changeover in the summer, so this one should be on the E28 running gear. Any build date from 9/82 on could be an '83 MY car.

Nothing indicates any M involvement so far. The first production Motorsport car (other than the M1) was the e12 M535i in '80, followed by the E24 in '84 and the M5 in '85. In the early years they would do "special edition" stuff for BMW executives, but I don't think that was still going on by the early '80s, and I don't think it was done for US spec cars anyway due to DOT/EPA rules.

What caused you to think it might be an M633? You might have some aftermarket mods that beefed up the suspension, but it's doubtful they're installed by the Motorsport Division. For the record, up to 1988 the Motorsport Division (///M) did the M1 (their first M-car), two variants of the M535i (the second on the E28 hull was really just a stock 535i with some ///M suspension components and a body kit), the M635/M6 and the M5. Anything else they did was strictly for racing.

Read the two posts before yours. ;)

I couldn't find any more info than that it is a US/CDN spec 633CSi with the build month as suggested above. The platform changeover from E12 to E24 likely occurred with the model year changeover in the summer, so this one should be on the E28 running gear. Any build date from 9/82 on could be an '83 MY car.

Nothing indicates any M involvement so far. The first production Motorsport car (other than the M1) was the e12 M535i in '80, followed by the E24 in '84 and the M5 in '85. In the early years they would do "special edition" stuff for BMW executives, but I don't think that was still going on by the early '80s, and I don't think it was done for US spec cars anyway due to DOT/EPA rules.

What caused you to think it might be an M633? You might have some aftermarket mods that beefed up the suspension, but it's doubtful they're installed by the Motorsport Division. For the record, up to 1988 the Motorsport Division (///M) did the M1 (their first M-car), two variants of the M535i (the second on the E28 hull was really just a stock 535i with some ///M suspension components and a body kit), the M635/M6 and the M5. Anything else they did was strictly for racing.


If it is a US/CDN car with that build date, then is it surely not an ///M car of any description. Most likely it was badged later in life...

Most likely it was badged later in life...

Or by the dealer if they added spoilers.

No, it wasn't a typo, the car is registered as an 83, and the interior matches the 83 interior. The car has the front air dam and trim just like the picture of your car above, The chassis is completely different from the 81 and the stock 83 chassis I looked at. The frame is much heavier the rear end trailing arms and the crossmember that the rear end mount to are all different. I have a lot of experience building cars, and I can't believe that someone would graft a body onto a completely different frame for no good reason. I don't really care, other than to satisfy my curiosity because in everything I have read on the BMW they talk about the M635, but there is no mention of an M633. Thanks for the reply.
Bob

sounds similar to a car i get parts from occasionally. it's a 633 and has an e28 front suspension, but appears to still have an e12 rear set-up. i'll check build date next time i go over there.

Well, I figured I had better do some more looking, and I found something interesting. In the book BMW Buyers Guide, by Ken Gross, he lists that the M635csi was produced in Europe from model year 1983 to 1989. He does not comment on the numbers of this variant that they built. According to BMW, Bavaria's Driving Machines, the book states that the m635 had a 24 valve engine, and this one is only a 12 valve engine with Motronic injection. I didn't think they put a 24 valve engine in any other coupe than the M6.
When I look at all the things that are changed on this car, the more probable scenario is that someone changed the 635 on the trunk to a 633 for some advantage at the racetrack. This could have easily been done when the car was imported. Like I posted earlier, the frame and running gear on this car look like it was all done at the factory. I would think that if the factory did make a m633 that it would have shown up somewhere in the literature. I have read a lot about these cars because I have owned and had at least one for all of the last 20 years.
It matters not to me because the car is going to be a graduation present to my son, but wouldn't it be neat to find the long lost missing diamond?
Bob

The M635CSi was the first Motorsport car to use the M88-derived engine. It's a 24 valve, 286hp engine that also fitted the e28 M5. The US-spec M6 and M5 had the S38 engine, which was based on the same lump, but modified in a number of ways so it would comply with US DOT and EPA regs, which resulted in reduced compression and HP.

The M6 and M635 are really mostly the same car, just as the Euro M5 and US M5 are. The badging at the time was something BMW was just working out, which was why the e28 M535 was a contemporary of the M635/M6 and M5.

Given the VIN you gave us, unless the VIN doesn't match the car, you have a bog-standard 633CSi, possibly with some suspension mods. It's a US spec car, and the 635CSi wasn't available for the US market that year. You're right, if they made an M633 it would have shown up somewhere. I'm not typing here to rain on the possibility that you found something unusual, I just hope you aren't looking at paying a premium to the seller for some fictional "///M" status that looks highly unlikely. It would be much easier if you had some pictures. Incidentally, it wouldn't be too obvious to someone just looking at the undercarriage of an M635 to tell the differnece between it and a "normal" 6-er that had the e28 running gear.

Here's some production figures for the M635CSi/M6:
Euro-spec non-cat = 3283
Euro-spec cat (hp reduced to 260) = 117
US Spec M6 = 1767
Euro (RHD) = 524
Japan (RHD) = 164

The first ones were in the Euro non-cat category, for the '84 model year. The first one completed came off the line in Nov '83. Mine was the 74th, and came off the line in April '84 (and my suspension is modified a bit as well - Racing Dynamics progressive rate springs and Bilsien sport shocks - all after-market). They didn't start doing the catalytic versions 'till the '87 MY.

Finally, if you don't mind answering, what made you think it's an M? Just the beefier suspension?

Y'all should check out the ///M Registry (http://http://www.bmwmregistry.com/). Some good reading there...

Jay,
I bought the car 12 years ago and wasn't even aware at the time that BMW had made the //M series cars. The car had the //M badge on the grille, and I didn't really pay any attention to it. I had to do something under the car way back then, and I started noticing all the differences in the suspension between my wife's 633 ( 81) and this car, and it turned out that everything was heavier. I read some books on the BMW and can't remember where I saw the M635 mentioned, but I just got curious.
Another possibility that I hadn't thought of, is that the LH grille, that just happened to have the //M badge was purchased from an auto wrecker to replace a damaged unit. I went out and had a very careful look at the badge and my guess is that they have always been together.
As I said, it is just a matter of curiosity, and if all the M635's were 24 valve engines, I can't see why BMW would have put out an M633 version with the 12 valve engine, it wouldn't make sense.
Bob

I just finished reading the write up on the //M Registry site, and am convinced that someone installed a lot of the pieces from an //M car. If what I read on the registry page is all 100%, there are trim items that match an //M car, and items that don't. The mirrors are painted, but the speedometer is a 240km unit with a 6300 red line and no special markings. Someone spent a lot of money on this car at some time in its life, and it sure would be interesting to find out who and why. My first priority after I get my garage finished, will be to make some changes on my 454 Chevy powered 55 Cameo half ton, so I won't be doing any serious work on this car until I have caught up a little.
Thanks for all the help, especially the link to the //M registry. You have all helped a little in solving this mystery for me.

Bob

Bob,
You may never know what a previous owner intended or did, and it's amazing what some will do. I've seen ///M badges on 318s, and once saw a full e36 front end welded on a Skoda pickup in the Middle East. Another popular bit of "badge engineering" is Alpina parts - slap on an Alpina steering wheel and shift knob, maybe glue an Alpina badge to the dash, and claim it's an Alpina car (in fact I saw just such a 633CSi here in the Ottawa area a few months ago).

Yours may well have had ///M parts added to it at some point. It'll be interesting to see what you find once you can get to work on it. Keep us informed.

since there has been some talk about the VIN, have you verified the other VIN's on the car. the VIN is stamped into metal in front of the blower/fan on the engine side.should also be on a sticker on the drivers door. someone could have swapped the out the dash and not swapped the VIN plate. this can change things if different.

No - it really won't. There is no such thing as an '83 car that is an ///M car. It is pretty easy to tell in any case - just lift the hood:
http://members.roadfly.com/iam4ecu/hood1.jpg

(apologies if I sound testy - just back on the redeye)

yeah, i didn't mean to say that it could me an M. it's more of a sure check that the VIN's match. just raising the hood is the real check of what engine you do have.

Oh man, I did a lot of redeyes. 30 years on overseas meant that you lost one days sleep iin three.
I checked the numbers on the registration against the numbers stamped on the firewall when I bought the car. The numbers match, and that area has never, to the best of my determination, been modified. As far as I am concerned, there is no question that it is not an //M car. I would sure like to talk to the previous owner that made all the changes to the body and suspension.