Andy1966 Posted September 16, 2020 Report Share Posted September 16, 2020 Guys I am looking for some advice on my Tr6 it a 1975 Cr uk market PI My Clutch master cylinder has developed a minor weeping leak which has resulted in the paint lifting, clearly it needs fixing. QUESTIONS 1. Should I repair with new seals or replace with new master cylinder. 2. Would you opt for a 0.7 or 0.75 inch bore master cylinder (there are no marking visible indicating bore size on the casting) 3. Where would you purchase replacement unit ? 4. Where would you purchase seal kit ? 5. What is the best clutch fluid grade or type, Cap states Dot 3 but would prefer grade that doesn't attack paint when I complete the repaint of the area. 6. Any little nuggets of advice to complete the job would be appreciated. Many Thanks in advance Andy Quote Link to post Share on other sites
RogerH Posted September 16, 2020 Report Share Posted September 16, 2020 Hi Andy, I would start with new seals and keep the unit you have. TRGB are in your neck of the woods DOT 5 would work well in the clutch - it doesn't strip paint. Roger Quote Link to post Share on other sites
rcreweread Posted September 16, 2020 Report Share Posted September 16, 2020 Andy - there's a similar query to yours in the General TR Technical Forum about a TR5 brake master cylinders which you may find helpful to look at. If there are no markings on your unit, it sounds like it may be a repro unit to start with - do you have any idea how long it's been on the car? Past Parts are just down the road from you in Bury St Edmunds and restore OE units but I'm not sure if they can/will restore repro units - best to ask them if you are interested. If you don't want to risk stripping your paint with future leaks, then you need to use Silicone brake fluid, but to do so you will need to replace the slave cylinder and pipe work as well. TR Shop in London do a full kit covering all the components for only £69.50 which they claim is a best seller ( seems like a very good price to me) but I have no experience of how good the quality is - no doubt others can comment Cheers Rich Quote Link to post Share on other sites
RogerH Posted September 16, 2020 Report Share Posted September 16, 2020 1 hour ago, rcreweread said: but to do so you will need to replace the slave cylinder and pipe work as well. Hi Rich, would you need to replace anything other than the fluid when going from DOT4 to DOT5 as water content is of no interest. It will never get to a high temp to boil off. Roger Quote Link to post Share on other sites
Andy Moltu Posted September 16, 2020 Report Share Posted September 16, 2020 Rebuild with new seals. M/Cs tend not to fail because of wear or corrosion to the bores so replacing the seals should suffice. Quote Link to post Share on other sites
JochemsTR Posted September 17, 2020 Report Share Posted September 17, 2020 (edited) Greyish fluid is the first indication of the steel piston rubbing in the aluminum housing. Leaking is the second. Open up the Cylinder, you will find scratches....don't bother refurbishing. I use a TRW 0,70 Bore and have peace for about 7.000 mls....using DOT3, with a spare on my shelf. Jochem Edited September 17, 2020 by JochemsTR Quote Link to post Share on other sites
astontr6 Posted September 17, 2020 Report Share Posted September 17, 2020 12 hours ago, rcreweread said: Andy - there's a similar query to yours in the General TR Technical Forum about a TR5 brake master cylinders which you may find helpful to look at. If there are no markings on your unit, it sounds like it may be a repro unit to start with - do you have any idea how long it's been on the car? Past Parts are just down the road from you in Bury St Edmunds and restore OE units but I'm not sure if they can/will restore repro units - best to ask them if you are interested. If you don't want to risk stripping your paint with future leaks, then you need to use Silicone brake fluid, but to do so you will need to replace the slave cylinder and pipe work as well. TR Shop in London do a full kit covering all the components for only £69.50 which they claim is a best seller ( seems like a very good price to me) but I have no experience of how good the quality is - no doubt others can comment Cheers Rich Hi Rich, I have used the TR Shop Silicone Kit four 4 years and had no trouble. I would always use the 0.75 bore master cylinder as the TR Clutch needs maximum movement to dis- engage. Any wear in the pins or bores for example can give you trouble with clutch operation. Bruce. Quote Link to post Share on other sites
Andy Moltu Posted September 17, 2020 Report Share Posted September 17, 2020 1 hour ago, astontr6 said: Hi Rich, I have used the TR Shop Silicone Kit four 4 years and had no trouble. I would always use the 0.75 bore master cylinder as the TR Clutch needs maximum movement to dis- engage. Any wear in the pins or bores for example can give you trouble with clutch operation. Bruce. The larger bore gives slightly more travel at the slave end. The smaller bore requires less pedal effort. Both should be fine if your clutch mechanism is fine in terms of slack and the 10% difference in pedal effort is barely noticable. If the bores (of the slave cylinder) are worn you will get a leak long before any meaningfull difference in play is perceived. Using the larger bore m/c to cover up defects is probably unwise. Quote Link to post Share on other sites
Andy1966 Posted September 17, 2020 Author Report Share Posted September 17, 2020 Roger, Rich, Andy, Bruce & Jochen Looks like best coarse of action is to remove and inspect before making the decision to refurbish or replace unit. Thank you for your support Andy Quote Link to post Share on other sites
Chris 0644 Posted September 18, 2020 Report Share Posted September 18, 2020 On 9/17/2020 at 8:49 AM, astontr6 said: Hi Rich, I have used the TR Shop Silicone Kit four 4 years and had no trouble. I would always use the 0.75 bore master cylinder as the TR Clutch needs maximum movement to dis- engage. Any wear in the pins or bores for example can give you trouble with clutch operation. Bruce. Rich - If your clutch needs full movement to disengage please check the thrust bearings movement on the crank shaft these are small and have tendency to fall out which will cause the crank case to be scrapped. measure the movement on the crank shaft fan belt by getting someone to press the clutch for movement. you want very minimal movement ideally not noticeable to the eye. Chris Quote Link to post Share on other sites
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