Author Topic: Cushman Truckster brake job  (Read 336 times)

Offline pycoed

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Cushman Truckster brake job
« on: July 11, 2020, 10:47:40 AM »
Warning! Real Engineers please look away now

I’ve been using a Cushman Turf Truckster groundsman’s “mule” for the last decade or so as a runabout (all offroad). VERY useful – hi/lo gears, PTO, hydraulic connectors & good strong hydraulic tipping. Sadly no 4wd.

Only the rear brakes have ever worked,  I so capped off the front line years ago. For the last couple of months, only the right rear wheel had a working brake, then 2 weeks back that failed as well! Since there is a steep bit to descend to get to the rest of my fields, I thought I’d better do something at last.
It’s all American apart from the Kubota D950 engine, so everything is in US imperial sizes i.e. UNF & UNC threads everywhere.
Brake system is apparently lifted from the wartime Willy’s jeep, so parts came a bit expensive at ~£100 for the 1” bore master cylinder & £40+ apiece for the wheel cylinders 1” bore rear & 7/8” front. Hmmm that is considerably more than I paid for it so a solution has to be found.

Master cyl wasn’t too bad, so I honed the bore  & refitted the original seals – so far so good.

Every wheel cylinder was seized solid & when dismantled the bores were badly pitted – new rubbers not an option (& again £22 per wheel!)

Much perusal of wheel cylinder data online showed that some FIAT slaves were pretty near – sadly I couldn’t find the pair I knew I had somewhere (don’t tell the wife) so 4 new ones it would have to be. Got 4 sent from, made in Italy via Germany, for £28 all in.

Had to modify the backplates a little to accommodate slightly different fixing bolt centres but they fitted fine.

Soaked all the brake shoes in petrol overnight (fronts were fine, left rear wheel had some oil on them from a breather blockage) then burnt off with a blowtorch, cleaned in brake cleaner & away to go.

Rear brakes just needed two new pipes making up from the centre tee at 3/8UNF to the wheel cylinder at 10X1.25M. Luckily my mate had a box of 10X1.25m ends, so got 2 from him & made the pipes up reusing the original 3/8UNF at one end.

Front brakes were a bit more trouble: flexis were 3/8UNF male, but cylinders were 10X1.25M so I had to make a 3/8UNF Female to 10X1.25M adapter.  I drilled a bit of 19mm hex bar a tapping drill for 3/8 UNF & reground the tipo to approximate the brake hose nose angle Tapped 3/8UNF easy peasy.
Don’t own a 10mm X1.25 die & my Harrison M250 lathe is mothballed behind another lathe & a mountain of junk & I haven’t got around to wiring up an inverter, so a bodge was called for (real engineers look away now please)
 1.25mm pitch is 20.3 tpi in Christian units…near enough 20 right? Kerry lathe it is then.

Turned the 19mm hex to .394” & screwcut 20 tpi – result a 10X1.25m male thread (ish). Cut the nose to the approx angle & job done. Fitted the adapters & connected up the flexis.

Bled the brakes using a vacuum pump I got when fiddling with Merc OM602 engines – saves annoying the wife by trying to give her instructions (never a good idea, I’ve found). Result: for the first time in my ownership I can stop on a hill without a hernia.

Don't know why the pics appear down the bottom, I was sure I'd fitted them into the text, ho hum...

Offline awemawson

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Re: Cushman Truckster brake job
« Reply #1 on: July 11, 2020, 11:06:23 AM »
Excellent  :clap:

A "Proper Engineer" solves a problem using what is available at the time, and draws on his skill and knowledge. Unlike 'garage mechanics' who now a days 'change what the computer tells them'.

I reckon the job you did was proper engineering  - go have a  :beer: to celebrate.
« Last Edit: July 11, 2020, 02:22:50 PM by awemawson »
Andrew Mawson
East Sussex

Offline PekkaNF

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Re: Cushman Truckster brake job
« Reply #2 on: July 11, 2020, 01:27:28 PM »
I think you have all the bragging's fixed by using the method and material you had available. Absolutely nothing wrong with it. I too have to dig often something behind of the lathe or on the junk pile...sometimes I find stuff that I didn' know I own.

My fried has a Kerry lathe and I though that it has all the ungodly imperialistic threads there have saved me often from pickle.

Good job :beer: