Clutch release bearing 4 speed vs 5 speed?

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anthony
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Clutch release bearing 4 speed vs 5 speed?

#1 Post by anthony » Fri Dec 07, 2018 6:25 am

Hello,
Sorry if this is a common question - I've searched the tech and tech archive section with no luck.

I've just replaced the clutch/pressure plate in a 929 wagon running a 13b and 4 speed gearbox. I installed a new spigot bearing/seal and release bearing.

I foolishly have mis-placed or thrown away my old release bearing, so can't compare the two.

My question is, do the older 4 speed gearboxes run a different release bearing to the series 1 rx7 style release bearing? Searching on line seems to tell me yes (via Atkins website having two older style release bearings listed).

The clutch pedal now feels really 'soft', i've bled approximately 250mls through the system until there was no air bubbles from the slave cylinder, cannot see any leaks from the slave or master cylinder, and the car was driving fine (apart from the stuffed old clutch) a few months ago.



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Re: Clutch release bearing 4 speed vs 5 speed?

#2 Post by Rota_Motor » Fri Dec 07, 2018 8:33 am

Yes they are different, I used same clutch in S1 RX-7 gearbox but the release bearing was different and would not fit the RX-4 4 speed I put in after correctly.


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Re: Clutch release bearing 4 speed vs 5 speed?

#3 Post by bumpstart » Fri Dec 07, 2018 10:38 am

the earlier fork for the four speed was not kinked. and down inside the bell housing it had narrower across flats and the bearing is pressed onto a "carrier" / this works for rx4 and rx5 5 speeds

the s1 rx7 has a kinked fork. it uses a bearing that is integral with the carrier .

you can use either setup , given that you adjust the length of the throw rod in the slave to compensate so it does not ride or have tension in the unengaged position

in fact i used to use the later fork for many years, welded up inside flats to use the earlier carrier ( with its $10 replacement bearings )

mindful also that 13bt fork and bearing looks similar ( to s1 ) , but is subtly different , and the 13bt is also using a slave with different feet positions that drastically alter the required length of the throw rod


you need to check that the slave can be unbolted when at rest and provides no force on the fork , yet throws fully back when someone rests the foot on clutch and holds it there .
hold it for 30 secs to test to see if the issue is hydraulic . it should stay fully thrown
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Rx7fb spirit r (Fri Dec 07, 2018 4:29 pm)


when the going is hard, don't retard, remember your lubrication
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Re: Clutch release bearing 4 speed vs 5 speed?

#4 Post by anthony » Fri Dec 07, 2018 5:57 pm

Great thanks for sharing your experiences!

The slave cylinder rod definitely stays at full throw with the clutch pedal pressed, but the fork is really close to hitting the fire wall / trans tunnel so not an option to lengthen the rod unless I massage the tunnel some more , so will look at finding the older style bearing and post my results



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Re: Clutch release bearing 4 speed vs 5 speed?

#5 Post by bumpstart » Sat Dec 08, 2018 11:21 pm

for the 4 and 5 speed "R" type boxes you can also try shimming the pivot out from the gearbox


when the going is hard, don't retard, remember your lubrication
28 years of rotary DIY
tech forum is for tech questions.. private message box is for private messages
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