UKCRC Forum

Technical => Maintenance and Servicing => Topic started by: chris27_blue on Sep 21, 2024, 04:50 PM

Title: Clutch adjustment
Post by: chris27_blue on Sep 21, 2024, 04:50 PM
Could someone advise if adjusting the nut on the shaft of the clutch slave cylinder will reduce the height of the biting point on the clutch? Possible make gearshifting smoother?  I could just try it, but thought would ask first.

Also, do those leak stopper fluids have any detrimental effect on my Tremec T5 transmission. 1000013768.jpg TIA.
Title: Re: Clutch adjustment
Post by: JON1D on Sep 21, 2024, 06:27 PM
Adjusting the rod length will change the biting point. But if you lengthen to much you might you might be disengaging the clutch. Take up any slack first. If the clutch is worn then no matter how much adjusting will not solve the problem. I have a T5 Tremec and its a great box that is very positive short shift into gears and very smooth.

Do you having difficulty selecting gears?
Title: Re: Clutch adjustment
Post by: GDCobra on Sep 21, 2024, 10:52 PM
I don't think it will help.
Say you adjust the nut to affectively lengthen the rod, it may make a change initially (first stroke) but when released the spring in the clutch plate will push the lever back to the same position (relative to the fixed parts of the assembly, bell housing for instance) and push the piston further back in the slave bore with the excess fluid returning to the reservoir (and all over your engine bay/floor if you have too much in).
Same will happen in reverse if you shorten the rod.  This is what allows a hydraulic clutch to be self adjusting.
Obviously (I hope) this will be effected if the clutch slave reaches either end of its stroke.
Title: Re: Clutch adjustment
Post by: Eggbert on Sep 22, 2024, 11:56 AM
Once the hydraulics are adjusted correctly, changing the bite point ought to be done with changing the pedal height.

As can be seen below, the small bell-crank at the lower right of the top, left picture has an adjustment rod between it and the master cylinder. You lengthen or shorten it to change pedal height.

(https://i.imgur.com/kz6LdAy.jpg)

Of course, this is my car and yours is undoubtedly different, but you may be able to achieve something similar there.

The adjustment you show in your picture should be to take out the free-play between the clutch fork/throw-out bearing and the pressure plate fingers. Or almost all of the free-play depending on whether you use a constantly rotating throw-out bearing or not.

I have mine so the bearing is not rotating with the pedal up. I removed the slave cylinder internal spring and go with an external spring. If you don't remove the internal spring, you need a very strong external spring and that noticeably increases pedal effort.

If your bearing was designed for constant rotation, adjustment will not be so touchy thanks to self adjustment. GDCobra mentions the self adjustment.

(https://i.imgur.com/u0i47QE.gif)

Here's some more info on clutch adjustment requirements (which is important as JON1D points out):

(https://i.imgur.com/1VMYCpf.jpg)

Title: Re: Clutch adjustment
Post by: chris27_blue on Sep 22, 2024, 07:00 PM
Quote from: JON1D on Sep 21, 2024, 06:27 PMAdjusting the rod length will change the biting point. But if you lengthen to much you might you might be disengaging the clutch. Take up any slack first. If the clutch is worn then no matter how much adjusting will not solve the problem. I have a T5 Tremec and its a great box that is very positive short shift into gears and very smooth.

Do you having difficulty selecting gears?

Sometimes at idle gears are a little tricky engaging, especially when cold

Otherwise, reverse is the pain to get, graunches a bit most of time

Forward travel when up and running gear changes are fine
Title: Re: Clutch adjustment
Post by: JON1D on Sep 22, 2024, 11:23 PM
Before selecting reverse. Select first and then reverse. Seen this a few times especially on new box.
Title: Re: Clutch adjustment
Post by: RussHowell on Sep 23, 2024, 07:07 AM
The tremec T5 does not have syncromesh for reverse. (I could have terminology wrong).

You have to put it into a forward gear before putting it into reverse.
(all one movement, stick it in 5th, then into reverse)

However, if reverse is that bad to get into then I would look at adjusting.
Even just one turn on the bolt to lengthen the stroke could help, but I would talk to Brian at Roadcraft to get the full SP,

Russ
Title: Re: Clutch adjustment
Post by: Chris on Sep 23, 2024, 10:09 AM
Quote from: RussHowell on Sep 23, 2024, 07:07 AMThe tremec T5 does not have syncromesh for reverse. (I could have terminology wrong).

You have to put it into a forward gear before putting it into reverse.
(all one movement, stick it in 5th, then into reverse)

However, if reverse is that bad to get into then I would look at adjusting.
Even just one turn on the bolt to lengthen the stroke could help, but I would talk to Brian at Roadcraft to get the full SP,


Russ
I don't know of any boxes that have syncro for reverse but I am proberbly out of touch .
My RV8 Sd1 box will graunch a bit if I try to hurry it when selecting reverse, perfect if the rev's are allowed to drop
to 750 rpm's !
In the past I have had issues with heat build up around the master cylinder causing aireation that was rectified with a decent heat shield .
Title: Re: Clutch adjustment
Post by: Eggbert on Sep 23, 2024, 11:22 AM
Reasons I've seen for difficulty in getting into first or reverse are as follows;

1/ clutch plate not fully disengaged as too much slack for full clutch fork travel. Adjust (lengthen the pushrod length as shown in your original picture. As mentioned, this is not likely of the slave cylinder self adjusts (unless it's out of range).

2/ lack of grease on input shaft splines or disc to P-P is tight as all parts are new. May get better with time.

3/ dual face clutch disc with organic side facing flywheel. Depressing clutch pedal brings P-P face back, but the disc may stick to flywheel. I have this problem though it's getting better.  I should have used a clutch with the organic side facing the P-P and the metallic side facing the flywheel, but that sort of defeats the purpose of the flywheel acting as a heat-sink for the organic side (see below). Mine is a RAM clutch disc. McLeod makes one like in the picture.

(https://i.imgur.com/6N41izK.jpg)
Title: Re: Clutch adjustment
Post by: GDCobra on Sep 24, 2024, 07:33 PM
Quote from: Chris on Sep 23, 2024, 10:09 AMI don't know of any boxes that have syncro for reverse but I am proberbly out of touch .
My RV8 Sd1 box will graunch a bit if I try to hurry it when selecting reverse, perfect if the rev's are allowed to drop
to 750 rpm's !
In the past I have had issues with heat build up around the master cylinder causing aireation that was rectified with a decent heat shield .

I fitted an R380 to my RV8 a couple of years ago and recall reading that one of the benefits over the earlier LT77 'box as fitted to the SD1 is that is does have syncromesh on reverse, I've never had any issues which indicate this is bogus.