Buying an R100/7

[Dogface]

I'm considering buying an R100/7 and found one I really like...in the pics anyway. Only suspect area so far is the single front disc brake. Some had dual as I recall. Should I shy away from one with just the one? I'm not a 'hot rod' when riding and don't even do twisties very often...just 'round town and weekend cruise.

Is there any way to really improve the stopping power of the single ?

I'm still checking out LWB /5's but may end up with the /7.

Thanks,
Mark

[20774]

RE: the single disk...I think it's fine (I have a single on mine) and it should be a drilled rotor. The ATE disk can be good when adjusted properly. Also, people like to improve the brake by removing the undertank master cylinder to the handlebar one. Pesonnally, I like the clean lines of the handlebar... Steel brake lines...again, I prefer the stock lines, which need to be changed from time to time. One can also go with different rotors and/or pads.

You can hunt around for the other leg to convert to dual disks, but you'll have to play games with mastercylinder piston diameters in order to get the right brake lever action for stopping power.

I say the /7 is fine for general purpose riding, but if you're Ricky Racer, you're going to want to improve things. Not sure you can do a stoppie with the single disk setup, but it can be adjusted for good operation.

My $0.02...

[Isamemon]

the single disc can work good, and when your bike came out, it was competeting against the yamaha 750 with dual disc, and the honda 750......yet even with the singel disc, the BMW stopped faster, still to todays standard, they are not great brakes
so to help now
decent brake pads like ebe brand, stainless steel brake line, and a cast iron rotor will make a world of difference ( the cast iron will rust a little but the porus high friction is a big plus). you can even rebuild the mastr cylinder and put a new brake cable on , to tighten things up more
for me , wehn Im on the BMW, ( I have a 78 single rotor too) I just have to give my self more distance, and be more proactive with defensive riding
however , if you hunt around a watch e-bay and all the good sources, you can convert to a dual disc ( used) for under $500

[sumran]

The dual brake units are a big improvement. Part of it depends on how you are going to use the bike. If all your riding will be one-up and you are not carrying much gear the single will be more tolerable. If you plan on riding distance with a passenger, I would recommend the dual. You will also face a decision on the rear brake. Much discussion about whether the drum or the disc is better, though most seem to favor the drum brake. Even though I have the dual front brake, I would like more stopping power.

I bought my first BMW recently after owning only Japanese bikes. A bit of advice, if I may be so bold: If you are not very familiar with BMW's you might get someone in your area to help you on evaluating the bike. There is a substantial list of unique things to look for and another list of things that might concern you, but are in fact normal behavior. There are also certain years that are more desirable than others or important year-specific things to check.

I'm not sure where you are located, but you find this group to be friendly, knowledgable and more than willing to help out a fellow rider. Best of luck in your purchase.

[PAGoldsby]

The single-disc brake should not be a deal-breaker for this motorcycle, in and of itself. My R75/7 has the single disc, and it's more than adequate for ordinary riding. Sure, more would be great, but for a 30-year-old motorcycle, it's just fine.

Sumran has some very good advice in his post about getting another set of (familiar) eyes on the motorcycle. Good luck! Post photos tonight after you buy it! :D

[bikerfish1100]

Someone might correct me on this, but i believe that all /7 models were single disc only. If it's a /7 with dual discs in front, that was an upgrade done by some previous owner. All S and RS models came with dualies stock, as did the RT (and possibly the T model of '79/'80 vintage).

[1505]

I rode a 1978 R100/7 for about 145K miles from 1996 till this year. This bike had the single disk front brake and small carbs and valves as smost /7s do. I believe the RS & others had the bigger valves and carbs and dual front disk brakes.

When I got a 91 R100RT with dual disks and the bigger (40mm) carbs and valves I had found a much better ride. The stopping power and increased acceleration were very noticable as well as being able to easily handle superslab speeds with ease. Most of my riding is two-up and a lot is long distance and loaded.

The R100/7 was a very reliable and smooth ride with very little maintenance problems outside of the routine stuff. I ran all synthetics for the lubes. Just recently sold the bike with over 193K on the dial and it is still going.
Ray

[arhd63]

Single disc is fine, remember that's a factory design. Going to a dual disc adds unsprung weight.

My .02 cents

[lkchris]

Someone might correct me on this, but i believe that all /7 models were single disc only.

You are correct.

100/7 produced in only '77 and '78 and other major difference between it and S and RS models is lower compression.

[Dogface]

Thanks to all for the good info...

[Markst1]

I did a conversion to dual disks on my '74 R75/6. The improvement was less than spectacular, and not worth the money (much more than I thought in order to do it right). Not recommended by me (although it does look cool). The ATE brakes will never be more than "slowing devices". Don't expect aggressive stopping. Also adding the unsprung weight is a negative.
T Marks

[John832]

I have a 78 R100/7 just like you describe. It only has 15K on it and runs great and stops fine. Nothing like my wifes r1150r but adiquate and I run pretty hard...

[535is]

I did a conversion to dual disks on my '74 R75/6. ... The ATE brakes will never be more than "slowing devices".
:rofl :rofl :nod I gotta remember that one! :thumb

[Bigrider]

Think of the positives: You situational awareness will extend 1/4 mile further down the road (so you will apply brakes earlier) and your right arm will grow to Popeye size. Don't worry though, your left arm will catch up if you are in a lot of traffic and have to pull in the clutch often. Leave the brakes alone, spend the time learning to ride it and on ATGATT. :brow

Dave H
San Antonio, TX

[vanzen]

S & RS models concurrent with the /7s (1978 for certain – I owned a few) had dual ATEs – but unlike later S, RS, RT, etal, had a drum rear.
Dual brakes of the S & RS provided much improved braking at the expense of unsprung weight.

"You can hunt around for the other leg to convert to dual disks, but you'll have to play games with mastercylinder piston diameters in order to get the right brake lever action for stopping power."

Actually, the mc intended for the single disk works very well in a dual conversion by reason of the fact that BMW was VERY conservative with their mc to caliper piston ratios. A 'splitter' can be used to handle the additional plumbing.

A good set of pads, handle-bar mc, iron rotor, and careful adjustment will transform the stopping power of a single disc into something that might be described as "adequate".
Anyone familiar with current braking tech on BMWs or any other marques must agree:
The best you'll get is "adequate" – if you don't ride too fast.

Later Type 247s (1981-)with dual Brembo F08s are much improved vs the dual ATEs. Mono Type 247s (1984 –) with the F08s and larger K type rotors – better yet. The last of the Type 247s, the Paralever boxers, equipped with the 4-pot Brembos, are the best of the bunch, and still quite nice brakes even today. When you choose to ride a vintage bike, ride it as if it is a vintage bike, and expect it to behave like a vintage bike.

[535is]

When you choose to ride a vintage bike, ride it as if it is a vintage bike, and expect it to behave like a vintage bike.

Well, now I feel almost homeless. I already got 'smacked down' by the vintage guys (even the '77 'RS owners wouldn't let me hang with them in West Bend!) for having too new a bike. Now, you're telling me it's old? :banghead

[vanzen]

Well, now I feel almost homeless. I already got 'smacked down' by the vintage guys (even the '77 'RS owners wouldn't let me hang with them in West Bend!) for having too new a bike. Now, you're telling me it's old? :banghead

1978 R100/7 ? that makes it 29 years worth of old. LOL. ... but a nice machine ! I owned a '78 R100/7 bought NEW in '79 ... quickly converted mine to dual ATEs, S-bars & S-fairing. Had @80k when I sold it to buy a slightly used 1981 RS.

[535is]

1978 R100/7 ? that makes it 29 years worth of old. LOL. ... but a nice machine!
Nope; I wasn't trying to crash their RS party with a 'mere' /7. I have an RS! But it is 29 years old (30 in January) and IMHO, that qualifies as 'vintage' - except in women. :thumb

[Polarbear]

Since new, I've ridden 300+ thousand /7 miles with stock brakes, as is. One most important issue not mentioned to this thread as yet is, the rear brakes! The drums are most frequently not maintained well enough to "compliment" the front disk....A "clean" rear drum will lock the rear wheel and so many I've seen are not kept clean of oil and debris. The R/7 series bikes have fine brakes and a fair stopping machine, with good care on both ends, regarding brakes. The rear drum is subjected to grease and oils from the rear end occasionally and needs attention, every time the wheel comes off for "premium" braking:):thumb Randy13233....PS; this phenom is quite common in autos as well, with drum rears. The rear drums, even with auto adjusts on autos seem to go forever, where the disks up front need replaced so often! Wonder? The drums go unserviced and don't wear because nobody looks and adjusts the rears. The front disks are doing the lions share. Wake up folks:)