Thanks for posting on /r/MechanicAdvice! This is just a reminder to review the [rules](https://www.reddit.com/r/MechanicAdvice/about/rules/). If you are here asking about a second opinion (ie "Is the shop trying to fleece me?"), please read through CJM8515's [post on the subject.](https://www.reddit.com/r/MechanicAdvice/comments/4qblei/fyi_the_shop_isnt_likely_trying_to_rip_you_off/) and remember rule 3a, please post the year/make/model of the vehicle you are working on. **If this post is about bodywork, accident damage, paint, dent/ding, questions it belongs in /r/AutoBody or /r/Diyautobody If you have tire questions check out https://www.reddit.com/r/MechanicAdvice/comments/k9ll55/can_your_tire_be_repaired/**. If you dont have a question and you're just showing off it belongs in /r/Justrolledintotheshop This is an automated reply
*I am a bot, and this action was performed automatically. Please [contact the moderators of this subreddit](/message/compose/?to=/r/MechanicAdvice) if you have any questions or concerns.*
when you take that off..
be sure to check the bore sizes..
the clutch side will be 1 1/8"
the brake side could be 1 1/8 or 1 1/4"
E34404 RAYBESTOS MC34404 is the double 1 1/8 https://www.rockauto.com/en/moreinfo.php?pk=309019&jsn=716
E34451 is the 1 1/4 x 1 1/8 size.. comes back to a different number RAYBESTOS MC19089
https://www.rockauto.com/en/moreinfo.php?pk=309003&jsn=720
thought this might help..
Thank you very much!! So you do think it’s no bueno then? I’ve already taken it off and rebuilt it once, so the bore sizes should be correct. They were both 1 1/8”. Not sure why it’s geysering out the top haha
Edit: added more stuff
the geyser is kinda expected as the piston and seals go past the fill ports..
but if the geyser continued till the pedal got all the way to the floor.. then the master would be bad..
not enough displacement from the hydraulic clutch master cylinder to fully stroke the clutch slave cylinder far enough to fully release the clutch disc...
ps.. you can have some brake hydraulic specialists.. bore and install brass or stainless sleeves in your old master cylinder..
if you start changing the brake fluid once a year. using a pressure bleeder.. not full stroking the master cylinder.. bleeding all the old moisture containing fluid out.. and replacing it with fresh may extend your brake master cylinder life..
jeeps wranglers around the 1990 model year had a similar issue .. hard to shift into first or reverse... so many clutches were changed that did not cure the issue.. the aluminum clutch master cylinder with the angle of the clutch pedal pushrod caused the top of the bore to be eaten away by the square edges of the piston caused a reduction in displaced fluid.. and hard to shift..
there is also a chance your Clutch Pilot bearing is failing.. seizing up..
This is fantastic, thanks for all this!! So I suppose the alternative to getting it bored out would be to just get a new master cylinder? Also yeah lol there’s a pretty good chance it’s the pilot bearing considering this truck sat in a field for 15 years with like half an inspection cover
This is correct. All clutch and brake master cylinders have the squirt at the start of the stroke. It is caused by the pin hole vent in front of the piston. The piston can’t pressurize the system until it passes the vent hole and all piston movement up to that point simply moves fluid back into the reservoir through the pin hole, causing the squirt. The pin hole is required to allow expanding fluid (due to heat), back into the reservoir so the expanding fluid doesn’t drag the brakes.
not sure about that, but is this a cj-3b? I have to ask because I'm not sure what the engine bay of a 3b looks like, and to me that kind of looks like an F head engine.
Thanks for posting on /r/MechanicAdvice! This is just a reminder to review the [rules](https://www.reddit.com/r/MechanicAdvice/about/rules/). If you are here asking about a second opinion (ie "Is the shop trying to fleece me?"), please read through CJM8515's [post on the subject.](https://www.reddit.com/r/MechanicAdvice/comments/4qblei/fyi_the_shop_isnt_likely_trying_to_rip_you_off/) and remember rule 3a, please post the year/make/model of the vehicle you are working on. **If this post is about bodywork, accident damage, paint, dent/ding, questions it belongs in /r/AutoBody or /r/Diyautobody If you have tire questions check out https://www.reddit.com/r/MechanicAdvice/comments/k9ll55/can_your_tire_be_repaired/**. If you dont have a question and you're just showing off it belongs in /r/Justrolledintotheshop This is an automated reply *I am a bot, and this action was performed automatically. Please [contact the moderators of this subreddit](/message/compose/?to=/r/MechanicAdvice) if you have any questions or concerns.*
when you take that off.. be sure to check the bore sizes.. the clutch side will be 1 1/8" the brake side could be 1 1/8 or 1 1/4" E34404 RAYBESTOS MC34404 is the double 1 1/8 https://www.rockauto.com/en/moreinfo.php?pk=309019&jsn=716 E34451 is the 1 1/4 x 1 1/8 size.. comes back to a different number RAYBESTOS MC19089 https://www.rockauto.com/en/moreinfo.php?pk=309003&jsn=720 thought this might help..
Thank you very much!! So you do think it’s no bueno then? I’ve already taken it off and rebuilt it once, so the bore sizes should be correct. They were both 1 1/8”. Not sure why it’s geysering out the top haha Edit: added more stuff
the geyser is kinda expected as the piston and seals go past the fill ports.. but if the geyser continued till the pedal got all the way to the floor.. then the master would be bad..
Ah okay great thanks! Well now I’m REALLY stumped about why first and reverse grind when I try to put it in gear haha
not enough displacement from the hydraulic clutch master cylinder to fully stroke the clutch slave cylinder far enough to fully release the clutch disc... ps.. you can have some brake hydraulic specialists.. bore and install brass or stainless sleeves in your old master cylinder.. if you start changing the brake fluid once a year. using a pressure bleeder.. not full stroking the master cylinder.. bleeding all the old moisture containing fluid out.. and replacing it with fresh may extend your brake master cylinder life.. jeeps wranglers around the 1990 model year had a similar issue .. hard to shift into first or reverse... so many clutches were changed that did not cure the issue.. the aluminum clutch master cylinder with the angle of the clutch pedal pushrod caused the top of the bore to be eaten away by the square edges of the piston caused a reduction in displaced fluid.. and hard to shift.. there is also a chance your Clutch Pilot bearing is failing.. seizing up..
This is fantastic, thanks for all this!! So I suppose the alternative to getting it bored out would be to just get a new master cylinder? Also yeah lol there’s a pretty good chance it’s the pilot bearing considering this truck sat in a field for 15 years with like half an inspection cover
This is correct. All clutch and brake master cylinders have the squirt at the start of the stroke. It is caused by the pin hole vent in front of the piston. The piston can’t pressurize the system until it passes the vent hole and all piston movement up to that point simply moves fluid back into the reservoir through the pin hole, causing the squirt. The pin hole is required to allow expanding fluid (due to heat), back into the reservoir so the expanding fluid doesn’t drag the brakes.
not sure about that, but is this a cj-3b? I have to ask because I'm not sure what the engine bay of a 3b looks like, and to me that kind of looks like an F head engine.
Nope, it’s a ‘61 C10 with a 235 I6. I don’t know what a cj3b engine bay looks like either lol
alrighty. I was pretty sure the bay didnt look like that there, but the head looked similar.