Fitting a Hartz 4

[tzsteve]

A practice assembly on the kitchen table.


















The Hartz clutch needs to have all parts assembled within the engine case

because the clutch basket will not fit into the case as an assembled unit.

so it starts with assembling the clutch basket, gear pinion, cush drive

all assembled in the case.

then the clutch circlip is fitted as normal.





this took a little time, the clutch holding tool helps.


after assembling the rest of the engine

the next task is fitting the clutch spider

this has no woodruff key slot, so the tab washer is of no use here.

i got the clutch centre nut to about 40 Ft.Lb ( not the 33 recommended )





i then removed the clutch centre nut to allow my compressor to be fitted

as this was torqued to very tight the clutch spider will not drop off

next assemble the clutch. again all inside the engine.

fit the springs and place the domed clutch plate in.



my clutch compressor is a clutch extractor with an M8 bolt inserted from the inside

and a spacer over the extractor to press down on the top of the clutch centre.












the plates are dropped in and the top clutch plate screwed down with the Torx screws

these screws need to be the flanged type as they have a low profile

i managed to find some A4 Torkx screws ( allen bolt types are higher profile )

these only need to be nipped up ( DO NOT USE LOCTITE HERE ).



now the clutch compressor is removed and the centre nut refitted, loctited and

torqued down to 40-45 Ft.Lb ( i used a serrated flanged nut that i had reduced in height )



when i was refitting this nut i used a copper 2P coin to lock the primarie gears

this was great until i dropped the coin into the engine case "bugger"

luckily i was able to fish this out with a couple of allen keys.






all fitted
and time for a coffee
tying the coin to a  piece of string would have been a good idea

it is necessary to use a clutch cover spacer to lift the clutch cover

by about 1 to 1.5mm a spacer kit is also needed for the hub back plate and rear hub.



i ended up using a pk type clutch centre button with the ball bearing fitted

this will be replaced with a different type that i am going to make.





i went for this clutch because i only get about 600 miles out of a

4 plate clutch before the clutch dogs are worn and mushroomed over

these clutches have 10 dogs on the steel plates not 6.

the steel plates are also 1.2mm not 1mm like most of the 4 plate clutches.

the friction plates are 3mm thick alloy and have 8 dogs.

most of the other "race / performance " clutches are 1mm thick and have only 6 dogs



the hope is that these plates will last a lot longer



it has to be said that the clutch springs are heavier than needed for my 17 BHP

i am hoping that the springs will soften a little with use.







on my original fitting of this clutch i did the classical mistakes

i did not use a torque wrench - stupid, so the clutch came of the taper.

twice i got the gear cables the wrong way round - again stupid.



the next job is to fit a much better clutch cable.

[henri]

ive been in the "dropped tuppence" scenario myself ,luckily on a fresh build with no oil ,so a quick shake over the bench an it fell back out .you say no loctite on the top plate torx screws ,why ,because i'd be tempted to use the tinyest drop of the weakest type .H

[gugne]

Instead of the 2p coin I use a 12 inch piece of copper water pipe flattened at one end. That bugger will never drop in the engine.

[tzsteve]

Jul 29, 2021 8:29:39 GMT gugne said:

Instead of the 2p coin I use a 12 inch piece of copper water pipe flattened at one end. That bugger will never drop in the engine.

Damned good idea 
and i had a pile of scrap copper right next to me

[tzsteve]

Jul 29, 2021 6:04:05 GMT henri said:

ive been in the "dropped tuppence" scenario myself ,luckily on a fresh build with no oil ,so a quick shake over the bench an it fell back out .you say no loctite on the top plate torx screws ,why ,because i'd be tempted to use the tinyest drop of the weakest type .H

i dont know of any motorcycle that uses loctite on those screws
i think on my yam those screws are taken to about 4 or 5 NM
so they stay in by magic
also as eean said it can be a bugger to get them back out

[henri]

same here ,its not in any building manual ive ever seen to use loctite on motorcycles with that kind of clutch top plate .an ive not heard horror storys of errant bolts that i can remember .H

[tzsteve]

so my review of the Hartz 4 after a bit of use

fitting is not a beginer task
very strong springs,,, even with an XL2 cover its heavy and snatchy
great if you want to pop wheelies which i don`t
there is no slip on my 17 BHP must be good for a lot more
i have had to alter my clutch style a little
on the surflex i could gently let the clutch slip while i increased the revs
with this one i need to hold at plenty of revs and carefully let the clutch out

it works well,
not cheap
but feels reliable
a top quality cable
and XL2 cover with a spacer is a must

[jonnysnatchsniffer]

strangely ive replied to this thread and others but they are not showing for some reason
try using standard pkxl2 springs the lever is light even with a primmy clutch cover and will take over 25hp
i used xxxl springs and its not too bad with an xl2 cover, as for the grabbyness, i think that lth do some plates that sort this out with the strong springs
or there are carbon ones that may help
what oil are you using ? sae 30 is not suitable for these plates really, i use motul 10/40 7100 ma2 oil which is really good and is what my local mx dealer
recommended for the honda plates
it is nice to have a 4 plate clutch that you can put in gear and move the scoot backwards

[tzsteve]

hi mate thanks for all the info
the spring tip will be looked at during the next plate replacement
i didnt realise they took xl2 springs
oil is silkolene sae90

[tzsteve]

well i did less than 100 miles before the cable snapped and turned into the usual
bundle of wire wool at the top end.

so following the advice of Mr. jonnysnatchsniffer it was time to look at the springs
i removed 5 leaving 5 in,
the clutch is light enough its a little lighter than a cheap 4 plate clutch.
but the carbon plates still provide enough friction to hold my meagre 17 BHP

its super smooth gives plenty of separation
i think you only need the full set of 10 springs if you are getting 30 BHP and sprinting

10 softer springs would be nice.

[jonnysnatchsniffer]

i think its cos ive got big hands and years as a sparky and builder have given me a good grip, you really need the thickest nylon lined outer and normal stainless inner bowden as
ive found some of the cables that purport to be nylon lined are only coated on the inner which is wank, also graphite powder works a treat to coat the inner in, but no oil or grease
if using the nylon lined outer
i may have some standard xl2 springs, give me yr address and ill post some to you. i didnt like the feel of the clutch with less springs or half hard and half soft,
after riding mine to mersea and back my inner stretched 2 complete adjustments of the adjuster lol so about an inch, just make sure you dont have too much outer
and use 10w40 as sae 30 will be too thin on hot days

[tzsteve]

If you fit one of these clutches and use all 10. Springs I would recommend that you do not use a pk ball bearing type clutch button , I originally fitted all ten springs it seems that this was too much for the ball bearing and the bearing was damaged to some extent. I have just spent a little time fishing the balls cage and race out of the case, the centre race was pushed right though the bearing, so that’s a lesson learnt

[henri]

its a constant it seems with bearing race pressure plates ,the bearings just dont hack it . i saw sumting interesting today ,will see if i can find it again . a 3 piece pressure plate ,bottom plate/middle cage with rollers/top plate thingy .
an for carbon plates ive been advised to use "light gear oil" ,its what the crossers with carbons run .H

[tzsteve]

Yes I just fitted that 3 part thingy, the brass pusher thing will need to be remade about 3 mm longer than standard, ( lucky I’m pretty good with the lathe ) one of the hero’s on here sent me a wide selection of springs to try, I ended up using the shortest and strongest out of the lot. , I think they are xxxl2. The feel is right, so with a bit of luck the reliability will be back,

why don’t these mega expensive parts and kits come with hints and tips? It often seems the makers and dealers really don’t care about the end user and simply take the money and run

[eean]

Thinking back Im sure I used to use loctite on everything, Im sure of it, they were buggers to get out but Id rather have that than one come out going down the strip 😎
Im sure I used to torque the clutch nut to 70lbs with loctite too, I never lapped anything either, never had a problem
Is yours the Hartz 4 ?

[tzsteve]

Your posts are always a good read mate,
Yes mate mines the four mr JSS sent me a selection of springs to try I currently have a set of xxl2 springs in I’m using the 3 part thrust bearing but I made a few mods to this to help with bearing lubrication, I’m making a slightly longer bronze clutch pusher thing and will be using a set of standard springs in the future,
The franz4 is fantastic but don’t put 10 springs in