| [ Total Views: 1790 | Total Replies: 11 | Thread Id: 84438 ] |
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 baghall
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Ben Hal Outlaw Bushranger
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| posted on June 23rd, 2010 at 08:49 PM |
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braking problems
Hey all
Had some scary moments in my 68baja this week with drizzling rain.
Front wheels are locking up under medium braking. Almost up the rear of 3 vehicles with 1 instance putting me on the wrong side of the road passing
the other car as we went over speed bumps (I was still under light braking). Fortunately the rears are not locking up and are keeping the car running
straight. All braking seems to be happening at rear.
Front tyres are a little too wide for the 15" standard (I think) rims. Rears are too narrow for the 15"x10.5" (I think) rims.
Fronts are close to neediing replacement but are still legal.
Advice on this would be appreciated. Particularly what tyres people are using and where I can get wider rims for front.
68 Baja - It's a growing pain!
58 Baja ute - and the pain spreads!
85 T3 Kombi - still growing
89 T3 Kombi - parts car
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 Bizarre
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| posted on June 23rd, 2010 at 09:39 PM |
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you running dics or drums up front??
Futue te ipsum!!!
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Smiley
A.k.a.: Daniel Stephens
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| posted on June 23rd, 2010 at 09:45 PM |
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If you running big tyres at the rear that's where all the braking happens. Large percent of the weight over large footprint tyres and the fronts stop
doing their job.
You can change this by putting smaller wheel cylinders in the front and larger ones in the rear.
If you have a copy of Jeff Hibbards 'Baja Bugs and Buggies' he goes into depth in the brake chapter. Very informative.
I would also check that they are adjusted correctly. Always make sure you back the handbrake cables off at the lever before adjusting the rear brakes,
then readjust you handbrake afterwards.
Smiley 
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Baja Wes
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| posted on June 23rd, 2010 at 09:46 PM |
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What diameter rear tyres are you running? Bigger diameter tyres reduce the effectiveness of the brake, as the bigger radius tyre gets more leverage on
the axle (that's my simple explanation).
On a Baja you will want to run some larger diameter drum brake slave cylinders, in order to give the car more rear brake bias. Depending on the brakes
and wheel cylinders you have, there are many options as to how to correct the problem. Drum brake slave cylinders will be probably 17, 19 or 22mm.
Standard bug is big at the front and small at the back. For a Baja you want probably the same size front and rear, or even bigger in the back
depending on your tyre size.
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Baja Wes
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| posted on June 23rd, 2010 at 09:48 PM |
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You should also check the condition of your current front brakes. Oil on them may cause them to be grabby. Also try grinding a chamfer on the front of
the shoe if it doesn't have one.
Also try braking hard in the dry and see if the front still locks up first. Maybe your front tyres are just crap in the wet.
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baghall
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Ben Hal Outlaw Bushranger
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| posted on June 23rd, 2010 at 10:05 PM |
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| Quote: | Originally
posted by Bizarre
you running dics or drums up front??
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Discs up front
68 Baja - It's a growing pain!
58 Baja ute - and the pain spreads!
85 T3 Kombi - still growing
89 T3 Kombi - parts car
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baghall
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Ben Hal Outlaw Bushranger
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| posted on June 23rd, 2010 at 10:11 PM |
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| Quote: | Originally
posted by Baja Wes
Maybe your front tyres are just crap in the wet.
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I am actually sus on this one!
Have been able to lock rear wheels if I need to in wet and dry.
Also I currently have 30"x9.5" on the rear but will be replacing with 31" or 32"x 10.5".
68 Baja - It's a growing pain!
58 Baja ute - and the pain spreads!
85 T3 Kombi - still growing
89 T3 Kombi - parts car
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matberry
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| posted on June 23rd, 2010 at 10:13 PM |
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Yep as above, with big diameter rears, normally 22mm type three wheel cylinders are used to increase the rear effectiveness to componsate for the
extra power the larger diameter requires. Also what front tyre pressure, if too high with small for tyre rim, the contact patch may be minimal with
the light front of the baja. Probably only need 16 - 18 psi in the front.
Matt Berry Motorsports...air cooled advice, repairs and mods Ph 0408 704 662
OFF-ROAD,CIRCUIT,DRAG,STREET,ENDURANCE
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matberry
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| posted on June 23rd, 2010 at 10:16 PM |
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To get the front to rear balance better, the next step is type 3 rear drums, they have the bigger wheel cylinders AND wider linings/drums. Makes a
huge difference.
Matt Berry Motorsports...air cooled advice, repairs and mods Ph 0408 704 662
OFF-ROAD,CIRCUIT,DRAG,STREET,ENDURANCE
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baghall
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Ben Hal Outlaw Bushranger
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| posted on June 23rd, 2010 at 10:22 PM |
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| Quote: | Originally
posted by matberry
Probably only need 16 - 18 psi in the front.
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Will definitely try this as I am running about 26-28 I think.
How easy is it to change to type 3 slaves etc?
68 Baja - It's a growing pain!
58 Baja ute - and the pain spreads!
85 T3 Kombi - still growing
89 T3 Kombi - parts car
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Baja Wes
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| posted on June 23rd, 2010 at 10:23 PM |
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Yep. Matt put type 3 rear drums on my Baja many years ago to cure it's front wheel lock-up problems.
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matberry
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| posted on June 23rd, 2010 at 11:16 PM |
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Slaves is easy, fit, adjust and bleed. Drums and backing plate's depends on what axles you have now, if late ie. long axles, bolt em on, if early
short axles, you need to machine the drums to fit. Normally new axle seal kits would be fitted at the same time.
Matt Berry Motorsports...air cooled advice, repairs and mods Ph 0408 704 662
OFF-ROAD,CIRCUIT,DRAG,STREET,ENDURANCE
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