GIRLING 74660152 90s Cat MC replacement ideas

[IamScotticus]

3 hours ago, BrianE said:

By the way, I like your tagline though I don't keep this mistress hidden!

I stole it from a bloke on the Westfield forum

[IamScotticus]

I sent a question to the ebay seller of the Morgan types and learned its a stepped cylinder.

 

Hello
I have this MC on my 95 Caterham made by Girling.
I can't determine what cars this is original equipment on.
Do you know?
Thanks,

SCOTT

 

New message from: emeraldvalleyclassicmini

 

The ones we sell for the Morgan were also used on some Caterham and a few other very low volume cars because it is a step bore and does a bias internally without the need for a separate bias valve and extra brake pipes. Its not used onfferent than these. I think the most common application for these is the Morgan which is low production but still almost common compared to some things.

 

[MV8]

Good to confirm the fitment. Could be bias, but step bores are usually quick fill where as soon as any significant pressure is present, the large piston stops and the main bore takes over. My understanding is that CATs don't normally bias at all.

A proportioning valve would be inline so no additional pipes. Some oems screw directly into the master cyl ports.

 

I still think it is just an mk4 1500 spit master with a special reservoir.

Edited August 27, 2023 by MV8

[IamScotticus]

You could be right.   I don't see Girling making a MC  "kit car" specific.  Race, yes, but very low production doesn't please the bean counters.

[BrianE]

7 hours ago, MV8 said:

I still think it is just an mk4 spit master with a special reservoir.

I ordered one the other day from Amazon (Chinese import I believe) and it appears to be identical to the inexpensive ones various British car part suppliers provide as well.  I also have one of the Morgan MCs on order, from the eBay seller, and that should arrive on Monday.  I compared the Amazon one to my Cat MC and it does appear to be identical other than the reservoir tank just as you pointed out.  The ports are M10x1.00 on both.

 

The band on my Caterham Girling MC is "66147 03 50/50" and the one on the Amazon MC is "66070 05 38/62."  I will be curious to see what the band says on the eBay one.

 

My understanding is the 50/50 and 38/62 represents the rear/front pressure differential based upon the bore sizes of the MC.  I can understand the 50/50 since it's a straight .7" bore but if the Amazon one is indeed a Spitfire replacement (which I thought was a straight .7" bore as well) I do not understand the 38/62.  Of course I am most likely incorrect about it representing a pressure differential.  I am not taking pressure differential valves into consideration of course.  Any viewpoints as to whether those numbers do indeed represent pressure differentials?

[MV8]

For the sake of discussion and no first hand knowledge (I have an MK4 Spit but not the original brake system), If the larger bore is 0.70" then a 62/38 split bore would have (approximately) a 0.62" bore for the front circuit (more pedal travel/higher pressure/softer pedal/less feel), not counting the ratios at the wheels. A bore stepped like this would be like a balance bar with dual master cylinders but not adjustable. A proportioning valve is a completely different function.

[BrianE]

I wasn't very clear for which I apologize.  I was simply trying to make sense of the band on the MC with the 62/38.  I was thinking that if the bore is indeed .7" I would think the band would say 50/50.

[jbcollier]

I do not know what the tag numbers refer to but the Spitfire cylinder is indeed a stepped bore.  It is only marginally smaller though.  Not enough, to my mind, to give a 62/38 split.

 

Just a general comment, cheap-Chinese-knock-off is not something I would want for a master cylinder on any of my cars.  I only use genuine Lockheed/Girling cylinders.

 

I’m a retired 35 year mechanic.  Most of that time was working on British and European sports cars.  Here are the failure rates, measured over a year, of the various cylinders I have installed over the years — and I have installed lots.

 

- carefully rebuilt, cylinder only required light honing, genuine kit used: 10%

 

- rebuilt or remanufactured from a jobber: 40%
 

- aftermarket, new cylinder: 20%
 

- genuine, OEM, new cylinder: I think I can only remember one and that was an owner installed cylinder.

 

I have road tested vehicles where the pedal suddenly goes to the floor.  It is not a happy moment.  I don’t care if a company offers a great guarantee.  I only want cylinders that work.   I only fit new, genuine master cylinders, period.

 

YMMV

[BrianE]

32 minutes ago, jbcollier said:

Just a general comment, cheap-Chinese-knock-off is not something I would want for a master cylinder on any of my cars.  I only use genuine Lockheed/Girling cylinders.

Why I will be returning it to Amazon.  The quality of the casting is poor in my opinion.

[IamScotticus]

@BrianEBrian,

Regarding the Amazon MC (please put up a link to or clip of the item) could you tell if the CAT MC reservoir would transfer onto that unit?

That would kinda tell me if my CAT MC tank would go onto a Spitfire MC.  I would get a new OEM Spit stepped MC and switch the tank over.

 

Also, if you don't mind, since I don't have a tag on my MC, I found the casting numbers on the bottom to be"74660152 Q42".

Could you try to read your casting #s to see if they are similar? Our MCs shouldn't be too far apart, one or three years.

A pic of your CAT MC would be cool too.

 

Another interesting thing, looking at MCs on Spitbits, there is a note about the TRW Lucas MC to only use UK spec brake fluid like Castrol.

Edited August 27, 2023 by IamScotticus

[IamScotticus]

Found this gem.

Thanks to everyone on the thread. 

https://locostbuilders.co.uk/viewthread.php?tid=18950

[MV8]

I located the girling master that came with my spitfire. I'll take some measurements and pics of the internals.

[jbcollier]

Land Rover part number AEU1045 fits on the later, metric Triumph Spitfire master cylinder and is a horizontal reservoir.

 

https://www.sp-4x4.com/product_p/aeu1045.htm

[BrianE]

14 hours ago, IamScotticus said:

@BrianEBrian,

Regarding the Amazon MC (please put up a link to or clip of the item) could you tell if the CAT MC reservoir would transfer onto that unit?

That would kinda tell me if my CAT MC tank would go onto a Spitfire MC.  I would get a new OEM Spit stepped MC and switch the tank over.

 

Also, if you don't mind, since I don't have a tag on my MC, I found the casting numbers on the bottom to be"74660152 Q42".

Could you try to read your casting #s to see if they are similar? Our MCs shouldn't be too far apart, one or three years.

A pic of your CAT MC would be cool too.

 

Another interesting thing, looking at MCs on Spitbits, there is a note about the TRW Lucas MC to only use UK spec brake fluid like Castrol.

Link for the Spit MC:  https://www.amazon.com/dp/B0066QUSW2?psc=1&ref=ppx_yo2ov_dt_b_product_details

 

Not sure if the tank will swap over or not but it appears that it will.  Based upon jbcollier's comment I will be returning the Chinese knockoff one.  I'm on another forum with jbcollier and his opinions are very well respected.  If he says he would not use one that's good enough for me!

 

The casting number on the bottom of the Cat MC is "74660152 Q44."  Not certain what the Q44 represents but I believe the first 8 digits are the important ones.  My Cat MC looks identical to the one you started this thread with.  I'd be happy to post a picture though if you would still like to see it, let me know.

 

I've seen that before as well, using only Castrol brake fluid with TRW/Lockheed/Girling MCs.  I honestly do not know if there is any substantial difference between Castrol and other brands.  Just DO NOT USE DOT5 if you've been using DOT4 or DOT5.1.  Why in the world they didn't come up with a different nomenclature for silicone brake fluid is beyond me, I have no doubt that people have mixed the two by mistake unfortunately.

 

This is where some older Girling catalogs from the 80s and 90s would be very helpful!

Edited August 27, 2023 by BrianE

[MV8]

16 hours ago, IamScotticus said:

Found this gem.

Thanks to everyone on the thread. 

https://locostbuilders.co.uk/viewthread.php?tid=18950

I don't have the plastic ring to show the ratio, but I believe this is a 50/50 due to the length of the piston stop for the secondary piston. A shorter tip would allow more secondary piston travel. The bore is not stepped and the piston diameters are .703". The small pin is what holds the pistons in the bore; no snap rings. It is stepped and drops into a hole above the secondary bore between the secondary piston lands. This is from a drum rear brake mk4 1500 spitfire.

I agree a rebuild with a quality kit using seals compatible with all brake fluids is probably going to be better than a new knockoff.

 

Edited August 27, 2023 by MV8

[BrianE]

The MC for the Cat is identical to the one you posted the picture of just now including the pin that drops into the the secondary bore from above.

 

It's interesting, yours is from a Mk4 Spitfire and the casting number on yours is identical to mine.  Other things I've read say the MC on the Spitfire 1500 is identical to the Cat MC.  I do not know much about the Triumph marque but I believe the 1500 was the successor to the Mk4, please correct me if I'm wrong.

 

The only difference between your MC and the one from my Cat is the reservoir.  My reservoir looks identical to the one on the initial post for this thread.  Oh, of course, because its sloped!

Edited August 27, 2023 by BrianE

[MV8]

I thought the mk4 was the 1500. My spit is a '78 (1500) and was just a shell when i bought it.

[IamScotticus]

Thanks, MV, this is a lot of help.

The list of Spit parts on the classic Seven just keeps going up.

Which is a wonderful thing because of the long running support for those cars.

Now to find these in new condition.

Edited August 28, 2023 by IamScotticus

[BrianE]

Just out of curiosity I removed the reservoir from the Spitfire MC I purchased on Amazon.  The reservoir port for the secondary piston is smaller than the reservoir port on the Caterham MC hence the ID of the rubber seal is smaller as well.  If the seal was in good shape (granted, this seal sees no movement) you could perhaps transfer it from the old MC to a Spitfire one.  I don't know about the safety factors involved in doing this of course.

Edited August 27, 2023 by BrianE

[IamScotticus]

Back to MIChina.  They will copy something exactly but for one small detail.  

I will have to get a genuine Girling or TRW unit to know if tanks will swap.

 

Just snagged a TRW GMC226 off David Manners Group

Edited August 28, 2023 by IamScotticus