Author Topic: Second front disc brake  (Read 273 times)

Offline Adrian

  • Posts: 516
  • The Old Hairy Biker Sez...
Second front disc brake
« on: October 02, 2020, 08:32:51 PM »
Hi brains trust - now I'm finally on the road with the 860 conversion - enjoying the ride - still tinkering with fine tuning - but running well.
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What exactly must I do to add a front disc? The front brake has always been adequate but it would be nice to improve the braking.
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I found a post on here about the change but it seemed lacking in detail.
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So take pity on an old guy and please explain in very simple language what I must do.
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I already have a 15mm handlebar mounted mastercylinder and steel braided lines. I also use DOT 5 brake fluid - as I have done for over 20 years.
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Thanks for all your help - by the way the front and rear cameras work really well with all the vibration stabilized by the unit - well worth the money.
1984 R65 (860)

Offline mrclubike

  • Posts: 1437
  • Jungheinrich Master Tech
Re: Second front disc brake
« Reply #1 on: October 03, 2020, 12:08:47 AM »
I  have been thinking about doing the dual disc conversion also
But I think I am going to keep my 12mm master Cyl
The lever is so high now that I think it will have plenty of stroke to fully apply the dual calipers
I thought it was good with the single 40mm Brembo F08 caliper but after ridding my R1150R I find it just adequate :-/
1982 R65 running tubeless Snowflakes
2004 R1150R

Offline Tony Smith

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  • Graduate, Wallace and Gromit School of Engineering
Re: Second front disc brake
« Reply #2 on: October 03, 2020, 02:21:07 AM »

I have twin 38mm Brembos fed by a 12mm master cylinder. They really are a bit fierce in that I can lock the front wheel with my little finger.

I am used to it, but on the odd occasion I let someone ride it I brief them about the brakes and get them to do a few practice stops before they venture into the highway.

I think 13mm would be better, 14mm not As good as 13mm and that 15mm would require too high A hand pressure.
1978 R100RS| 1981 R100RS (JPS) | 1984 R65 | 1992 KLE500 | 2002 R1150GSA |

Offline Tony Smith

  • Posts: 2274
  • Graduate, Wallace and Gromit School of Engineering
Re: Second front disc brake
« Reply #3 on: October 03, 2020, 02:34:27 AM »
To answer Adrian's question, you need:

RHS caliper that matches your existing caliper
 Bolts to mount caliper to form leg
2nd disc (stock ones aren't handed
Set of longer disc mounting bolts.

If you are lucky your R65 will already have a brake fluid junction fitting attached to the instrument supports, if so you only need a new boss from there to the new caliper. If you don't it is worth while getting one as there is another blanking bolt you can remove and attach a hydraulic brake light switch.

If you don't want to go that way, have a new hose made from m/c to LHS caliper with banjo fittings on both ends. Have a second hose, also with banjo fittings made to go from the LHS to RHS caliper. You will need 2 std M10 banjo bolts, one double height banjo bolt and 6 soft copper washers.
1978 R100RS| 1981 R100RS (JPS) | 1984 R65 | 1992 KLE500 | 2002 R1150GSA |

Offline dogshome

  • Posts: 116
Re: Second front disc brake
« Reply #4 on: October 03, 2020, 07:11:47 AM »
Hi Adrian, I fitted the 860 about 500 miles ago. No tuning required. I rebalanced and set the timing, but the jetting feels spot on. Mine has quite large main jets, needles at top position as stock and identical to R80 settings, so no surprise.

Regarding dual brakes, luckily mine came with them. As standard, they are adequate/good, not fierce by any means. The 860 has transformed my bike and I too would want to upgrade fairly immediately with only one!

The other option is a different caliper or bigger disc. This seems to have been done a few times. R65 discs are quite small. I've done this on several cars as I tend to use brakes on the country roads I take to work. A longer lever / diameter is noticeable in increase in power. It will be quite obvious on the small front wheel of the R65 though.
肉(r?u)包(bāo)子(zi)打(dǎ)狗(gǒu) (meat+bun(2nd and 3rd)+hit+dog)
* Literally: To hit a dog with a meat-bun.:-O

Offline Bob_Roller

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Re: Second front disc brake
« Reply #5 on: October 03, 2020, 02:45:57 PM »
Just an observation from a member that has ridden an '81 with dual front discs for coming up on 40 years, I don't think you will be impressed with the braking performance with addition of a second disc .
'81 R65
'82 R65 LS ?
'84 R65 LS
'87 Moto Guzzi V65 Lario
'02 R1150R
Riding all year long since 1993 .
I'll give up my R65, when they pry my cold dead hands from the handlebars !!!!!

Offline mrclubike

  • Posts: 1437
  • Jungheinrich Master Tech
Re: Second front disc brake
« Reply #6 on: October 03, 2020, 05:27:02 PM »
Quote
Just an observation from a member that has ridden an '81 with dual front discs for coming up on 40 years, I don't think you will be impressed with the braking performance with addition of a second disc .

True
I don't think you will notice much difference with the the 15mm MC
but going down in size on the MC is what will make the dual disc stop better

I am already at the limit with the single at 12mm MC X 40 MM single F08 caliper
It stops well but takes more effort than the R1150r
« Last Edit: October 09, 2020, 10:53:18 PM by mrclubike »
1982 R65 running tubeless Snowflakes
2004 R1150R

Offline Adrian

  • Posts: 516
  • The Old Hairy Biker Sez...
Re: Second front disc brake
« Reply #7 on: October 06, 2020, 06:07:07 AM »
okay guys thanks for all the advice ;)
1984 R65 (860)