Author Topic: 4LO lc350 Front Brakes  (Read 335 times)

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Offline Fredswat

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4LO lc350 Front Brakes
« on: October 04, 2020, 09:18:00 AM »
Anyone out there done an overhaul on the front brakes on an LC 350?  I have a pre tie-bar £50 circa 1981 .  I left it standing for quite a while and recently decided to do some small jobs on it to get it back into fine fettle. Well it's become a more major task than I originally planned, It was just going to be fit some indicators and change the fluids.  I have thus far rewired it (replaced lots of bullet connectors in the headlamp and elsewhere with proper multi plugs), stripped the engine down, fitted a rebuilt crank, New cylinder head, new selector shaft with bush mod to stop oil leaks, replaced the clutch push rod and clutch plates,  New oil seals throughout, new water pump impellor and bearing plus seal, Carb jet kits, re-painted the exhausts.  Had to make a rear indicator mounting bar and weld it to the rear sub-frame when I discovered that mine had been cut off back in the day.  Quite an extensive list really

I decided to turn my attention onto the front brakes which appeared to be working but a crusty brake fluid residue was present around the brake lever.  I bought a master cylinder overhaul kit and stripped down the assembly and cleaned it all up and fitted the new parts.  When I came to bleed the system I could not get the air out of it.  I have been using a vacuum tool to pull the fluid through the system.  I read some threads on the RD LC Crazy forum and decided to go the whole hog and check out the callipers to see if they were ok.  Sure enough when I dismantled them I discovered that the pistons were stuck in the callipers and  would never have worked. So now I am waiting for the new calliper seals to arrive.  I have blasted and painted all of the parts and polished the pins, Shims etc .  My issue is that on none of the diagrams I have found does it show the dust covers/ rubber boots that go on the sliding pins.  I cannot find a part number any where.  Does anyone out there know if it is possible to get replacements for these? 
74 RD200a
74 RD350A
77 RD400c
81 RD350LC
89 TDR 250
72 Kawasaki H1d
75 Kawasaki Z1b 
06 Kawasaki Z1000
71 Suzuki T500R
76 Suzuki Gt750
89 Suzuki RGV250 Vj21
76 Honda cd175 
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03 Aprilia RS125
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Offline Tailchaser

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Re: 4LO lc350 Front Brakes
« Reply #1 on: October 04, 2020, 09:47:06 AM »
Hi Fred,

Are these what you're looking for?

https://yambits.co.uk/rd350lc-brake-caliper-pin-boot-kit-p-1795.html

cheers,

Jeff
RD250E

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  • Peter
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Re: 4LO lc350 Front Brakes
« Reply #2 on: October 04, 2020, 12:10:53 PM »
Put the original callipers in the cupboard for posterity and find some blue spots plus adapter plates....
Might even also save your life one day!
Rev 'em till they rattle

Offline Fredswat

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Re: 4LO lc350 Front Brakes
« Reply #3 on: October 04, 2020, 01:27:29 PM »
Put the original callipers in the cupboard for posterity and find some blue spots plus adapter plates....
Might even also save your life one day!
Got a blue spot calliper from an R6 on my TDR .  It works fine but is just as wooden as the original calliper.  You really have to change the Master cylinder as well for something with a smaller bore. On the LC I never had a problem with the original brakes power.  It has braided brake lines.  It was just my fault for leaving them untouched for ages.  Being a bit dramatic reference "saving my life one day" . Think about it air cooled 350's and 400's have a single disc which stops them.  I am not going to be riding at 10 tenths. So the original; stoppers should be ok
74 RD200a
74 RD350A
77 RD400c
81 RD350LC
89 TDR 250
72 Kawasaki H1d
75 Kawasaki Z1b 
06 Kawasaki Z1000
71 Suzuki T500R
76 Suzuki Gt750
89 Suzuki RGV250 Vj21
76 Honda cd175 
85 Honda c90
03 Aprilia RS125
48 Royal Enfield J2

Offline Fredswat

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Re: 4LO lc350 Front Brakes
« Reply #4 on: October 04, 2020, 01:28:14 PM »
Hi Fred,

Are these what you're looking for?

https://yambits.co.uk/rd350lc-brake-caliper-pin-boot-kit-p-1795.html

cheers,

Jeff

Thanks Jeff didn't see them on the Yambits sight thanks
74 RD200a
74 RD350A
77 RD400c
81 RD350LC
89 TDR 250
72 Kawasaki H1d
75 Kawasaki Z1b 
06 Kawasaki Z1000
71 Suzuki T500R
76 Suzuki Gt750
89 Suzuki RGV250 Vj21
76 Honda cd175 
85 Honda c90
03 Aprilia RS125
48 Royal Enfield J2

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  • Peter
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Re: 4LO lc350 Front Brakes
« Reply #5 on: October 04, 2020, 01:50:01 PM »
Agree, smaller M/C is also key to improvement.
I used to race my 4L0 with the 1/2inch M/C from the 4L1...more travel but with braided lines you did get a hard stop.
That’s the thing, whilst hand strength is the variable that effects max braking force, single or double disks make little or no difference.

The early calliper (licences design from Lockheed/girling)  was far better , then yam put what are in context dreadful designs on the bikes from 78 onwards. Only after the patent expired could they use that opposed floating pad knowhow..

And yes...save your life...is a bit dramatic...but glad the point was noted...no scope for cutting corners when brakes are concerned.

« Last Edit: October 04, 2020, 03:31:01 PM by betty foRD »
Rev 'em till they rattle

Offline ajh

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Re: 4LO lc350 Front Brakes
« Reply #6 on: October 04, 2020, 03:11:28 PM »
I feel that the single disc dual piston brake on my 250d is better than the dual disk set up on my 4L0. Not sure whether its because Im also generally going a lot slower on the AC 250d  :)
in Chiswick, West London

77 RD250d, 80 DT175mx, 81 4L0 350LC

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Re: 4LO lc350 Front Brakes
« Reply #7 on: October 04, 2020, 03:30:05 PM »
I feel that the single disc dual piston brake on my 250d is better than the dual disk set up on my 4L0. Not sure whether its because Im also generally going a lot slower on the AC 250d  :)
I should have said 78! (Now corrected)
Yes, the D was last with the decent caliper.
Rev 'em till they rattle

Offline chrisg.007

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Re: 4LO lc350 Front Brakes
« Reply #8 on: October 20, 2020, 10:55:23 PM »
Norbo does them as well.

There is a full kit on EB, the piston is chromed and appears to seal better than the machined type, although I have had chromed pistons and they were approx. 3mm too long, so needed some material removing with a linishing belt.

https://www.ebay.co.uk/itm/Yamaha-RD350lc-RD250lc-Brake-Caliper-Repair-Kit-Piston-Seals-Nipple-4L0-4L1/123308846679?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m1438.l2649
« Last Edit: October 22, 2020, 08:51:24 PM by chrisg.007 »
Growing old is compulsery, growing up is optional.

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