The New And Improved Unofficial R65 Forum V2
Technical Discussion => BMW Technical Q&A, Primarily R65 => Topic started by: SCJJR65 on January 18, 2008, 04:32:33 PM
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Bad news today.... While getting my rear brake shoes inspected and adjusted, I found out that the splines on my rear drive unit are almost completely gone. Bummer.... :(
My mechanic said I probably don't have more than another 1000 miles before the unit fails. So I now need to find a replacement.
Any ideas? I'm not sure where to start. :-/ I know I can't afford a new unit. My dealer said a new one goes for about $500! Yikes!! :o
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Two places I know where you can send your final drive for repair of the splines. Ted Porter or Bob's BMW. I have not used them. I had my splines repaired over 20 years ago and the are still good.
Don
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John, not to panic, R65 rear drives pop up all the time on Ebay, and probably ibmwr.org and bmwmoa too.
In fact, here's one that Larry in Austin has listed now, with the 32/9 ratio that was standard on the '84 models. He's re-listed this one since last week, and there's not a huge demand so they usually go pretty cheap. Larry's also as knowledgeable and honest as the day is long, so no issues there.
http://tinyurl.com/yvx8ay
Good luck! [smiley=thumbsup.gif]
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John I am in complete agreement with Steve's recommendations - that rear drive on ebay in Texas IS the one that I was planning to buy. The splines on it look to be in very decent shape - If I were you I'd put a bid on it right away. You know what a new one will cost - If I were in your shoes I'd certainly consider a bid of 1/3 of that amount, and may well be plenty to snatch it up. There is also another R65 final drive for sale for the pre-91 bikes on ebay - don't get confused as to which one you bid on !
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If "drive unit" means "drive shaft" - just be careful when you buy second hand - the retired mechanic who replaced my driveshaft recently, told me that there are two different driveshafts for R65's , with different part numbers - aparantly driveshafts for monoshock models are slightly longer.
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Well, this morning I sent an inquiry to the seller of the drive on eBay, and we'll see what happens. I haven't had much luck with eBay, but I guess there's always a first time! ;)
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I have no experience with these guys but they have a good reputation:
http://www.hansensmc.com/service/spline_repair.htm
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If "drive unit" means "drive shaft" - just be careful when you buy second hand - the retired mechanic who replaced my driveshaft recently, told me that there are two different driveshafts for R65's , with different part numbers - aparantly driveshafts for monoshock models are slightly longer.
Quite correct, the R65 Monoshock models ('86 on) were the long wheelbase models and shared everything with the bigger brothers (except some of the engine parts), unlike the twinshock 65's. Makes it heaps easier sourcing parts for them.
Bill..................;-)
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HI John,
Have you called Nathan at Boxerworks in Watkinsville GA a call and see what he says about replacement. This way you get a new overhauled unit (with new seals). The pride of eBay may have old dry seals and no telling what else!
706-310-0699
www.boxerworks.com
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Below is a quote from the OEM spareparts catalogue for the European r65 produced in October 1983 ~ 1984 model
FINAL DRIVE DRUM BRAKE
I=31:9=3,44
09/1980
33111241092
$683.20
NC Steve writes in his posting:
...with the 32/9 ratio that was standard on the '84 models...
which is the ratio on the USA models produced in October 1983 according to the OEM catalogue.
This intrigues me, why are the ratios different?
Another question is whether the numerator and the denominator of the fraction denote the number of teeth on the two differential gears or are the numbers just the smallest possible integers constituting the correct ratio between the gears?
And lastly, what is the consequence of the higher ratio of the final drive of the USA model?
Many questions but I hope that you have an answer.
greetings from a windy, rather warm and wet north
trolle
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Hi Trolle,
I didn't know that the european bikes had different final drive ratios - are you certain that maybe there isn't a typographical error in the OEM catalogue information - it would only be a matter of one digit ?
Technically speaking, the ratio is supposed to be expressed as the number of teeth on the ring gear and the number of teeth on the driving gear , and not just the mathematically reduced ratio or simplified fraction.
If the European and USA spec-final drive ratios were indeed different during that time period, one possible explanation is that during this time, we had a national speed limit of 55 MPH, so operation at higher speeds was perhaps less common over here. However, I think that the sport of drag-racing originated over here in the U.S, so we've always had an emphasis on acceleration capability over true top speed. Hhaving a 32/9 (3.56) rear end instead of a 31/9 (3.44) would give slightly better acceleration from a standing start, assuming bikes/riders of equal weight and engine torque output. Now that the national speed limit is no longer fixed, nor at 55 mph, we are consuming more gas than ever before. I wonder if the folks in our congress have pondered the idea of re-instituting the 55 MPH speed limit to conserve fuel again ?
Note, I was not and am not a fan of a 55 MPH speed limit, but I suppose if things get as bad as they were in the 70's/early 80s with fuel costs we may see history repeat itself. Conservation is a much easier thing to do than implementing a global hydrogen fueling infrastructure, though not as sexy...
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John,
Removing the final drive from the bike for shipping is very easy.
I had my splines rebuilt several years ago. I boxed up the final drive and shipped it to Bob's.
That was 1998, and the cost was $333. And I declined the shimming and adjusting that should have been done while they had it apart, but I couldn't afford it at the time.
That price included 2 seals, Bob's labor to take it apart and put back together, and the subleted labor for having the work to the ring gear done.
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Over here a spline replacement cost me about £100 last time I repaired the Bimbo's, and it was done by a bloke a Birmingham who came recomeded by a friend in the Guzzi club.
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Poor John got skunked by 6 frikkin' cents!! :o
Yo, check your PMs, dude... [smiley=thumbsup.gif]
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Yes, I noticed that too ! Looks like it was a final few minute thing, too..
so sorry for you, John !
I always make my bids for some odd value, like instead of $70 for something, I'll bid $70.95, or $72.85, or something like that.
I'll also try to watch the last few minutes of the auction if it is something I really want so I can try to counteract any snipers..
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Hi nhmaf
I have been doing a little research in the OEM catalogue and came up with these results:
r65 LS October 1983 European: FINAL DRIVE DRUM BRAKE I=31:9=3,44 09/1980 33111241092 $966.97
r65 LS October 1983 USA: FINAL DRIVE DRUM BRAKE I=32:9=3,56 1 09/1980 33111241093
r65 October 1983 European: FINAL DRIVE DRUM BRAKE I=31:9=3,44 1 09/1980 33111241092 $966.97
r65 October 1983 USA: FINAL DRIVE DRUM BRAKE I=32:9=3,56 1 09/1980 33111241093
r45 October 1983 European: FINAL DRIVE DRUM BRAKE I=35:9=3,89 1 09/1980 33111241091
If I understand you right, the r65 will accelerate better but have a lower top speed in all gears if mounted with a final drive having a higher ratio like the drive of the R45.
With the 31:9 ratio the fifth gear speed at 1000 rpm is 13.75 mph thus giving a (hypothetical) top speed of 110 mph, with the 35:9 ratio of the r45 the fifth gear speed at 1000 rpm will be 12.16 mph with a top speed of 97 mph.
The speed limit on Danish highways is 130 kph ~ 81.5 mph, with the European ratio this corresponds to 5900 rpm, a level at which my engine has no vibrations and sounds real nice. If I mount the r45 drive the rpm will increase to 6700 at the same speed. At this level the engine is still running very nicely but there is more wear and fuel consumption.
On the other hand I will have more power for acceleration when driving in town or on the small roads.
I have just bought an R45 final drive for $110.
Sorry for the thread degradation.
greetings from a stormy, wet and warm (45 F) north
trolle
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Hey John, There's a rear drive on the ibmwr.org marketplace under airhead parts!
BTW I got a email failure notice with what I had as your email address.
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John,
Did you ever get this sorted out or a replacement final drive ?
I ask, because I recently purchased one on fleabay as a backup for my R65LS and for use on a future sidecar project. But if you are still stuck without a final drive
for Britta and want one to fix her up again, in the pursuit of good karma I will sell it to you for what I bought it for. Otherwise I'll keep it in my box of critical airhead parts,
with lumps of kryptonite hahaha !