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DaveBMX

is a 1502 gearbox different to a 2002 box?

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Hi everyone hope you have all had a good new year. i'd like to clean up a 2002 engine to replace my 1502 engine and i am concerned there might be an issue with the gearbox. I know the 1602 and 1502 have a smaller clutch but does anyone know if that is the only problem or is the bellhousing different? i would imagine i would need to replace the final drive gear also? any help appreciated!

Dave

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a 1502 has a mechanically activated clutch and the 2002 has a hydraulic clutch. Since very early 2002s had a mechanical clutch the pieces should work together OK, but you may have to transfer any release pieces (if any) from the 1502 engine to the 2002.

If your 2002 engine has a VIN lower than 1665200 the clutch pressure plate and throwout bearing will be different from later roundies, and I believe the release leaver is also different. Those early 2002s have an adjustable clutch release pushrod, same as 1600s and 1502s; you'll need that adjustable pushrod if you stick with a mechanical clutch release.

If the engine is from a squarelight it'll have a 215mm clutch vs the 228mm found on roundie engines (and all tii's).

mike

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...and the 1602 got a smaller (210?) clutch, so the 1502 might, too...

I guess I'd take it all apart before I bought anything...

???

t

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You're wrong guys, but you're forgiven because I guess you haven't seen many 1502's over there in US.

1502 is late model -74 to -77. Therefore it has hydraulic clutch and the gearbox is the same as late 2002. You can throw in the 2002 motor with clutch - no problem. Sure you can change the rear diff but you don't need to. With the original 4.11:1 it'll be just like before, only you reach the top speed lot faster. Highway cruising will be a lot more comfortable with a 2002 3.64:1 diff.

Tommy

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1502s have mechanical clutch linkages; I'll have to make a note in the book to correct the information. And you're right, very few 1502s in the US. I think I've seen two or three over the years.

Not the first time I've found errors in both the parts book and the shop manual...

mike

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You're right, Tommy- the 1502 was only sold over here in the last year

of production, maybe?

And was it destroked, debored, or both?

t

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I don't believe the 1502 was ever sold in the U.S. through BMW N.A (or Hoffman, for that matter, in what might be termed his "late period"). I haven't seen near as many 02s as Mike, but I've never come across one in the States. Any 1502 here would have to be gray market or equivalent.

Steve

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Hoffman quit importing the 1600 in mid-1971 as 2002s were outselling the 1600 5 to 1. When BMW AG took over importing chores into the US (thus BMW NA) in mid-75, they continued importing just the 2002--in fact the US was the only market in 1976 that got the 02 (except Canada, maybe???). The rest of the world got the E21 320.

Both 1502s I saw in the US were grey market cars...

mike

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Hoffman quit importing the 1600 in mid-1971 as 2002s were outselling the 1600 5 to 1. When BMW AG took over importing chores into the US (thus BMW NA) in mid-75, they continued importing just the 2002--in fact the US was the only market in 1976 that got the 02 (except Canada, maybe???). The rest of the world got the E21 320.

Both 1502s I saw in the US were grey market cars...

mike

Thanks, Mike. I knew you'd know for certain.

Steve

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1502 has the same dimensions as all 1,6liter m10's. 84mm bore, 71mm stroke. I don't even know how they managed to get power down from 85 to 75hp compared to 1600-2 or 1602 ,which btw are also different models but often mixed.

In Finland taxes for new cars have always been so high that the models cheapest of the range have been the most popular. With average salary if you really saved money you could perhaps buy a luxury car such as BMW 1502. Times haven't really changed much :(

Tommy

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Thanks for the info! yes a certainly do have a hydraulic clutch so thats good! the engine is from a 74 2002 and has an e12 head. I had thought that the 1502 engine had a much low CR than the standard 1602 engine so that it could use cheaper fuels at the time? I had thought about trying to hop up the engine that is in it by fitting hi comp pistons an such but for the expense might aswell do it to the 2ltr engine. In regards to the final Drive ratio had had thought that since i would have more power i could fit a longer final drive ratio meaning that i could cruise with a lower rpm at a given speed as it will be a while before i can get to work on a 5 speed swap.

thanks guys!!

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I had thought that the 1502 engine had a much low CR than the standard 1602 engine so that it could use cheaper fuels at the time?

I think you're right. 1502 CR is only 8.0:1. I didn't find quickly the CR for other 1,6l models.

Tommy

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yeah Tommy that was another issue i had about beefing up the stock motor was lack of available info on the 1502. buying pistons and such like without knowing enough! but if the 1502 has a standard later model 02 box then there isn't a good reason to not stick in a 2002 engine! shrick cam and some bike carbs and we've got ourselves a sleeper haha

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There really isn't much sense to put effort to the 1,6. By swapping you get the first 25hp without actually doing anything :) Gaining that much from 1,6 would be a lot of work already.

I have a 2 liter both in my street 1502 and racecar. For the racer it would be interesting to make smaller engine because of class rules but still I wouldn't go as small as 1,6l.

EDIT: After seeing in the other thread how nice your car is - one might consider keeping it all stock. Do you still have original engine - matching numbers?

Tommy

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Yes Tommy its the original engine. Originality was why i considered altering the stock engine internals. I would keep the 1.6 engine and all the bits that go with it so i could swap it back if need be. unfortunately i just feel that 75 original horse (will have dropped some!) isn't enough these days. I had also thought that if the car had been a 2002 originally or an earlier 1602 i would have kept it stock but i cant imagine the 1502 being considered a true classic due to its reduced cr and displacement?

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