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Clutch pressure 480 psi

ddstewie
Posts: 35
Joined: Thu Feb 18, 2016 8:13 am

Re: Clutch pressure 480 psi

Post by ddstewie » Fri Feb 02, 2018 9:56 pm

I have tested the pedal force required for the standard SP250 gearbox with the standard clutch and the Toyota w58 supra gearbox conversion with a diaphragm clutch.For the diaphragm clutch pressure plate The only mod required to the flywheel is to have three locating dowels instead of two,the attach bolt holes are as per original.Pedal force for SP250 gearbox and clutch = 30kgs;pedal force for supra gearbox with diaphragm clutch = 14kgs,very much lighter. P/N of diaphragm pressure plate (9 1/2 inch)AP driveline technologies P/N CA3769,throw out bearing P/N NSK 40TKD07 .Clutch plate 9 1/2 inch to suit supra input shaft splines.Master cylinder, std, 0.75" bore,slave cylinder 7/8" bore.Hope this helps.

Ozzsp250
Posts: 162
Joined: Tue Feb 16, 2016 12:35 am
Location: Arizona, USA

Re: Clutch pressure 480 psi

Post by Ozzsp250 » Sat Feb 03, 2018 6:08 pm

I was able to test the clutch hydraulic system with original SP250 clutch and pressure plate using standard 3/4" master cylinder. I added a test gauge at the bleeder port on the slave cylinder. I did not bleed the system - lazy as it was 23°F [-5°C] in the garage. The original system did develop 400 psi and takes 340 psi to release the system. There's no doubt with a 'bled' system it will develop enough pressure for the concentric system and I'll add a clutch travel stop.

The current concentric bearing a Quartermaster 721100 'flat face bearing', vendor states it fine for my system, I'm not comfortable using it and they said they can't supply a rounded face bearing. However I have purchased 2 other raised or rounded face bearings. One has identical ID 1.576" and OD to the flat face at 2.513", the second same ID 1.576" with the OD being slightly larger at 2.958" both are a little thicker than the flat faced bearing.

Next step is to pull the transmission again and weigh up the 2 rounded face bearings which due to slightly different thickness I need to repeat shimming hopefully for the last time.

daimlersteve
Posts: 299
Joined: Wed Mar 09, 2016 11:20 am

Re: Clutch pressure 480 psi

Post by daimlersteve » Mon Feb 05, 2018 4:15 am

My concern with the flat bearing was that if it was quite wide and wasn't the same I/D as the fingers it would tend to dig into the fingers as it went in.
Just not a good engineering design i'm sure you'd agree..
steve

Ozzsp250
Posts: 162
Joined: Tue Feb 16, 2016 12:35 am
Location: Arizona, USA

Re: Clutch pressure 480 psi

Post by Ozzsp250 » Sat Feb 24, 2018 4:37 pm

I pulled the transmission again today and removed the "flat faced" bearing and surprise its not the dimensions expected or stated by vendor.

It is a Nachi 45TNK804 bearing ID. = 1.765" OD. = 2.875" W. = .625" [45 mm x 73 mm x 16 mm]

Can't seem to find a rounded face here......but I found this, it appears that a Nachi 45tmk-1 bearing would fit shown on in Ebay in Oz

https://www.ebay.com.au/itm/20223224898 ... Track=true

Any body have other recommendations?

Ozzsp250
Posts: 162
Joined: Tue Feb 16, 2016 12:35 am
Location: Arizona, USA

Re: Clutch pressure 480 psi

Post by Ozzsp250 » Sat Feb 24, 2018 6:34 pm

Looks like I found an equivalent "rounded face" bearing a Koyo RCT45-1S

So project gets delay again.
RCT45-1S.jpg
Capture.JPG

daimlersteve
Posts: 299
Joined: Wed Mar 09, 2016 11:20 am

Re: Clutch pressure 480 psi

Post by daimlersteve » Sun Feb 25, 2018 3:21 am

have just fitted up a tilton version, but not without its mishaps.
The std. unit comes with a flat bearing for us rolled finger diaphrams .
The supposed replacement part though the same bore size is not a replacment at all, requiring machining of the Hydraulic housing to fit up. The T5 bearing retainer snout is also a tad big on dia. for the new bearing sleeve .Without a lathe and some skills you'd be stymied .
The toyota tube is smaller and may not have the same problems.

good luck, steve.
PS., What has Steve Sanett done for his kit with a concentric release ? ?

Ozzsp250
Posts: 162
Joined: Tue Feb 16, 2016 12:35 am
Location: Arizona, USA

Re: Clutch pressure 480 psi

Post by Ozzsp250 » Sun Feb 25, 2018 9:13 pm

I don't know what Steve Sanett uses, did not know he has a conversion kit.

I did come across this Brit kit: https://www.rwdmotorsport.com/toyota-w- ... g-kit.html

Looks pretty well made.

Ozzsp250
Posts: 162
Joined: Tue Feb 16, 2016 12:35 am
Location: Arizona, USA

Re: Clutch pressure 480 psi

Post by Ozzsp250 » Thu Mar 01, 2018 1:02 am

Fitted the new Koyo throw out bearing on to the Quartermaster concentric system. Attached line and pressure tested all's good so far. Unfortunately will be traveling starting tomorrow so no chance to install transmission back on engine and run it. So that will be delayed for a while but small steps forward are welcomed.
Although Quarter claim the flat face is fine for the size of clutch the new set up gives more confidence in final outcome.
P1040311.JPG
This is supplied flat face set up.
P1040288.JPG
Dennis

daimlersteve
Posts: 299
Joined: Wed Mar 09, 2016 11:20 am

Re: Clutch pressure 480 psi

Post by daimlersteve » Fri Mar 02, 2018 5:38 am

Hiya, Its a bit hard to see ,have you pressed a bearing sleeve onto the snout of the input shaft to increase the dia? Its what colin at conversion components does.
steve

Ozzsp250
Posts: 162
Joined: Tue Feb 16, 2016 12:35 am
Location: Arizona, USA

Re: Clutch pressure 480 psi

Post by Ozzsp250 » Mon Mar 05, 2018 8:43 pm

The piece on the left piece [inner] fits inside the the piece on the right - which as you surmised the bearing is pressed on to. The inner piece has an "O" ring internally to prevent travel along the transmission sleeve. The other piece has two "O" rings internally which permits the axial travel to depress the pressure plate fingers etc.
Capture.JPG

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