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Zamoraj
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Hello all,
Greg, great job running the jhps!!!
I am trying to finalize a replacement of front disks and pads (and bearings) for my JH. Got all the parts from Delta.  I was happy they suggested including bearings, as I found one on each side that definitely needed replacement (so I did all 4). 

However, I can't get the new pads and disk to thick to fit in the calipers (which I did not break apart, not up to that yet).  The pistons are quite hard and I can't get them to retreat inwards.  Any suggestions would be welcome. 

smcmanus
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Sounds to me like your calipers need to be rebuilt.  You can take a C-clamp and a block of wood across the piston and see if you can get it to move.  It is a good idea to open the bleeder first.  If it moves relatively easily, then you are probably OK.  If it takes much force to move, then a rebuild is in order.  When was the last time the calipers were done?  If it was '73, then they probably need it anyway.

Good Luck

Steve

Ron Earp
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Nice alternative is to use TR7 calipers. They bolt right on, and can be bought completely new for like $70 each. You will have a nice side effect of more pad choices, cheaper rebuild costs, and slightly larger pad area. TR7 pads are cheap, readily available, and can be had in race compounds if you desire. And no, the slightly larger pad area does not increase pedal effort.


And on yours, if I can't push them back with my fingers, granted with a lot of effort, I rebuild them. I still agree with the above posting about using a block and c-clamp since many times you can't get a straight shot with your hands, but a nice working caliper with bleed screw open should be doable with your hands/fingers.


Ron

Last edited on 05-12-2007 04:14 am by Ron Earp

Zamoraj
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thanks to both of you, very helpful suggestions. I will try the c clamp first and if not, I'll probably go with the new calipers.  The existing ones are the originals and it does not look like they've been touched since '74....when the bearings unpacked, the original oil seals were still there.

Ron Mau
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Hey Ron,

Where is a good place you suggest for the TR7 Calipers?  Mine just locked up on me 15 miles from home and by the time I got there the outside driver pad was metal to metal.  Granted I have a set of dells getting rebuilt now, but would like to continue to drive it in the mean time.

Thanks

Jeremy Mau

(at my dads house)

Mark Rosenbaum
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You can also use the calipers from a later Spitfire.  There are some minor differences but AFAIK they are not significant.  And JH pads will work on the Spit calipers.

Attachment: Spitfire 1970 vs JH 1973 calipers 1.jpg (Downloaded 123 times)

Jon Plowe
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I have recently improved the braking by a large margin by changing  the 'adequate' Girling Type 14 caliper fitted as standard to Girling Type 16 (probably the same as TR7) as fitted to TR6's, Ford Escort RS's, Ford Capri's and many other 70's and early 80's British cars. Bolt straight on. Also have gone from standard pads (feeble) to EBC Green Stuff (better) to Mintex 1147 (expensive but wonderful) which with the above has transformed the braking. Also found out that self adjusting rear brakes have about 20% more area of friction material.

Cheers

Jon

Ron Earp
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Jeremy,

I've used http://www.carparts.com before. They have reman calipers for $75, everything included, just bolt it on. They work well, will hold up to racing duty because everybody I know running TR7s/TR8s have used them fine. I'm sure they are some overseas made parts, but they do the job and offer you a much better selection of pad choices as Jon points out. I'm fairly certain they are same calipers that fit the aforementioned cars.

Ron

Joel
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Ron:

Great  INFO!  I'm putting on new brake lines and am considering replacing the calipers just because I'm sure mine are OE.  For 150 bucks it's worth it.  Then I can screw around with the originals if I want to - but for 75 bucks why bother?

Anywho, what pads do you like?  I've been known to work my brakes hard. . . I'm not on the track but I work em.

And I don't put that many miles on the car so I don't mind replacing them once in a while too.  It's not like I need to get 30,000 miles out of them.

Joel

Last edited on 05-16-2007 06:04 am by Joel

Ron Earp
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I got some Hawk Blues for the race car, and some Carbotechs, but don't use those.  Too little bite until they are hot and they won't be hot enough on the street unless you are braking from 100mph repeatedly.

I honestly don't have a recommendation for a street car since I unfortunately never got my JH on the street.  Sounds like Jon has some recommendations and I have heard the Green Stuff was decent based on another application.

R

Jensen Healey
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Hawk HPS street pads. I use the Spitfire pads in the JH calipers and even though they're slightly smaller  they're a real improvement over regular pads or simi-metallic pads.

I bought some used TR7 calipers to check them out and the pad size is very slightly larger than the JH. They weigh a ton. The TR8 calipers and pads would be a real improvement but those are rare. Best to go with the JHPS Big Brake Kit.

Joel
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Only problems with the 'big brake' kit is: 

1)  it's expensive
2) i need either the spacers (expensive) or to buy all new rims and tires (even more expensive). 

On the 2nd JH I have I figure I'll go big brakes and larger rims.  For the one I'm running now - I just need better brakes.  The brakes on this thing SUCK.  I can't lock them up at 35mph - not good.  And every once in a while - it feels like only one front brake is working - even worse! 

So, I just got new lines from Greg and I'm deciding whether or not to just put the damn calipers on while I've got it all apart.  I'm strongly leaning towards putting on the Reman TR7 calipers.  Cheap and lots of pads available.  It's GOT to be an improvement over what's currently on it. 

Jon Plowe
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Apologise I meant to say the type of pads I use are Mintex 1144 (not 1147) which with the type 16's give real bite.  It might be of interest to know that spacer kits for type 16's are readily available.  Unfortunately I've not been able to find a set on vented discs to match, but then unless you are thrashing your car around a track do you need them?

Jon

DeDub
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 I've installed JHPS's big brake kit and stainless lines and I have a couple of observations and a complaint.   First, the braking is superb; linear and strong and though I haven't raced it, I haven't felt any fade.  Second, they're an easy bolt-on affair.  FYI, I've simply installed a pair of spacers under the front rims so I can continue using the stock rims and I think it's fine for street use.  Third, the pads contact the rotors farther outboard than stock which causes a few things to happen: the outer edge of the pads overhang the outside of the rotors by a small amount, a couple of millimeters, and consequently as the pads wear, a little ledge of unworn pad forms outside the rotor and it looks as if they would eventually contact each other and prevent the pads from squeezing the rotor.  A minor problem that a little occasional filing would fix.

My complaint it about noise.  The pads are loose in the calipers, rattle like crazy while driving, and make a clacking sound if I hit the brakes quickly.  It's a pretty loud rattle.   I don't see an easy way to lock the pads in place while still allowing their movement but am pretty unhappy with the amount of noise they make.  Has anyone else dealt with this and/or found a fix?

Dave,
JH 19377, now in a red dress with black trim

Greg Fletcher
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This is the first time I've heard about noise from the pads/calipers. Is your master cylinder and the rest of the brake system working properly? If the noise is from pad vibration, that can happen on any disk set up. Try using some disk brake quite compound or hi temp silcon between the pad and the caliper pistons.

Joel
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HMMM, I purchased some rebuilt TR7 calipers.  They don't fit and certainly are not bolt on replacements. . .

Did TR7 use several different calipers?


At least the shop I bought them from said  (and reconfirmed) they are TR7 calipers. 

I hate to go get another pair just to see. . .


Art DeKneef
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The way I read the info is that the calipers were from a TR6 and might be the same as a TR7. So I went to two web sites, Victoria British and the Car Parts one Ron mentioned and compared calipers for 1976 cars.

I checked both sites for calipers for each car. On each site the parts number for each caliper is different as well as the price. I would think if they would be the same the part number and price would be the same. Wanting more information I looked up the pictures of the two different calipers and they look different. Now there are no dimensions or scale listed so it is impossible to tell from the pictures which would fit.

I even checked a 76 Spitfire that Mark mentioned might fit. The part number for the front caliper is the same as the Healey. So I think we can say the parts are the same.

The only way to be sure is for those who have changed calipers to supply part numbers or to take your Healey calipers to the place and compare them with a TR6 and TR7.

Sounds like a trip to Delta is in order as I need a few more parts any how.

Art

Jon Plowe
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I was speaking to an elderly gentleman yesteray who had the dubious privilage of being a manufacturer and supplier of parts to British cars in the 1970's. He said it was common practice to use different part numbers for the same item depending on which vehicle it was going onto e.g Rover more expensive than Austin

Ron Earp
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Art DeKneef wrote:

The only way to be sure is for those who have changed calipers to supply part numbers or to take your Healey calipers to the place and compare them with a TR6 and TR7.


I can tell you for sure some 1977 TR7 calipers will bolt right on the Jensen with no trouble at all. Bought brand news ones from Vic Brit when they were on sale year or so ago. Cheap, new, and work great. Cheaper than the rebuild kit, use readily available TR7 pads and components.

The TR7 caliper is different than the Jensen caliper, but is cheap, and has more pad selection as well as being a tiny bit larger.

R

Art DeKneef
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Ron,

I don't doubt you. I was hoping you might have a part number to use for reference so I don't go through what Joel did and maybe help Joel out.

I'm going to Delta sometime this week and will take some of my parts with and see if Jim and I can come up with something for reference.

And Jon, I figured as much.

Art

Joel
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Just to let ya know.  I got tired of dinking around w/ the calipers.  It's not so easy to find extra TR7 calipers just sitting around to compare w/ what I have.  I could order another pair from elsewhere and see if they fit - but if they don't it's just more time wasted.  I don't know if I was sent the wrong calipers or if there are different TR7 calipers or what. 

So, I ordered some reman's of JH calipers from Delta at 100 bucks a pop.  About the same price as the TR7's.  If I want to get fancy w/ the pads - ala Judson?? - I can send them my pads and they'll put their own magical braking substance on them for the same price as buying their stock TR7 pads. 

Now, I'll keep ya posted on whether the car quits deciding to let one or the other front brake work and have the other take a break (pun intended) or if I have another problem.  I'm hoping that new lines and new calipers do the trick.  I already have a new master cylinder and pads. . .

I don't want to get hard on the brakes to find that she's diving one way or the other any more.  it was kinda fun once.. .




Ron Earp
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Sorry I couldn't be of more help with the part numbers. I just ordered TR7 replacements and used them, but I can understand your reluctance to do so - none of this stuff is cheap. Remans from Delta at $100 really isn't too bad as the TR7s are remans too, in some sense.

Ron

Joel
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Ok, so they worked fine for a day or so.  I gave them more of a workout today and the pedal is almost to the floor and no more lock up.  I'm thinking bleed them again.  But maybe there's a problem w/ the vacuum?  I'll bleed and check again.

I replaced all the lines and the front calipers (and front pads).  For 2 days or so they seemed to be MUCH better.  I could actually lock them up.  Now, no go. 

Gotta send back the TR7 calipers.  I appreciate the lead Ron.  Not your fault.  Who knows, mebbe I was sent the wrong calipers.  Mebbe there are several TR7 calipers.  Who knows.  I would try again but the savings wasn't worth the hassle. 

Now, I need to find what to change next. 

I already replaced the master cylinder.  So, new master cylinder, front calipers, lines, and pads all the way around.  Still shitty brakes. 

At least she's running pretty good!  Always something to deal w/.  That's why we own them.


edward_davis
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Joel,

I'm sure you've checked it already, but you might want to make sure that the PDWA is working properly, or is properly taken out of the system.  Leaks across it could cause a loss in pressure at the front calipers.  Also, and I'm sure this isn't the case, a fellow at the MG club this weekend related a story about an old Jag he'd bought and tried to drive home, only to discover the brakes were poor.  Turned out that a PO had switched the lines from the front and rear parts of the M/C, so that the front brakes were getting rear brake pressure and vice versa.  That would do it, too, but it's an extreme long shot.

Edward

Mark Rosenbaum
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Joel wrote: Ok, so they worked fine for a day or so.  I gave them more of a workout today and the pedal is almost to the floor and no more lock up.  I'm thinking bleed them again.  But maybe there's a problem w/ the vacuum?  I'll bleed and check again.

I replaced all the lines and the front calipers (and front pads).  For 2 days or so they seemed to be MUCH better.  I could actually lock them up.  Now, no go. 

In addition to the other suggestions provided, this could be caused by either a defective master cylinder front brake piston seal, or a leaking tipping valve (also part of the master cylinder).  If the former, you can rebuild or replace the master cylinder (and yes, even new ones can fail, though it's rare).  If the latter, tiny particles in your brake fluid are preventing the tipping valve from sealing, thus preventing your front brakes from being activated, and the cure is to bleed the brakes with copious amounts of new fluid in the hope of flushing away the debris.  If the problem is intermittent, it's almost certainly the tipping valve.

Attachment: Master cyl cross section.jpg (Downloaded 44 times)

DeDub
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Nice, useful sketch, Mark.   Thanks.  But that brings up a question for me: what's the tipping valve do?  I can't discern it from the drawing and I've never had a master cylinder like this apart.

Also, and on a possibly related note, since I installed the 'big brake' kit from JHPS the front brakes work so well that they overpower the rears, even with new cylinders and shoes in the rear.  The fronts now lock up way before the rears which is not the best for hot cornering.  Is there a fix for this at the master cylinder or at the PDWA on the fenderwell, any proportioning adjustment?

David
#19377

Mark Rosenbaum
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Re tipping valve.

The tipping valve shuts off the connection between the brake fluid reservoir and the bore for the master cylinder's rear piston.  When the piston is all the way to the rear (i.e. brake pedal not pressed), the valve is tipped, and open, as shown in the drawing attached to my previous post.  The valve is supposed to seal when the brake pedal is pressed and the rear piston moves forward.  When the valve seals, pressure can build up in the rear piston's bore, and this pressure is applied to (a) the front brakes and (b) the rearward face of the front piston, which operates the rear brakes. 

However, if the tipping valve fails to seal, pressure can not build up in the rear piston's bore.  Under such a circumstance, the front brakes are inoperative, and the rear brakes don't activate until the rear piston comes into physical contact with the front one, which occurs only when the brake pedal is close to the car's floor.

The most common reason for a tipping valve to fail to seal is debris in the brake fluid.  Even barely-visible particles can prevent proper operation.

Re brake balance.

The JH has no native means to alter the balance between the front and rear brakes.  The easiest way to change the balance is probably to install rear wheel cylinders having pistons of a different diameter.  Since the rear brakes came from a Vauxhall, it's reasonable to think something suitable might exist, but you'd have to research the subject.  As an alternative, you could use two master cylinders along with an adjustable mechanical linkage.  Perhaps one of our racing members could offer advice on such an arrangement.

Last edited on 06-20-2007 05:48 pm by Mark Rosenbaum

Joel
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Update -

Since the problem I was having was what felt like intermittent failure (or sticking or something) of ONLY ONE front brake - it doesn't make sense that it would be the Tipp valve.  If it was the valve the front or the back would fail in it's entirety.   Just feeling like one front brake is working, and that flopping back and forth doesn't sound like the valve.

Anyway, I have new calipers and pads up front now.  And I put on all SS brake lines.  This was a big improvement and I have not felt any 'diving' one way or another.  So, hopefully that solved that problem.

The car still didn't stop the way I wanted it to.  So - off to someone that was supposedly more of an expert.  He took a look and declared the rear shoes to be total crap.  We put on a new set of shoes, turned the drums, bled the system.  She's stopping now!  It's the best it's ever stopped.  So, all it took was replacing the entire system!


edward_davis
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Sounds familiar, Joel.  I've had to do the same thing, but without as dramatic replacement: all new rubber lines/seals, and new rear shoes.  Sometimes you just have to tear out all of the old, worn out stuff and replace it with new.  If only we could do that with ourselves as well...

Edward

Ron Earp
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Mark Rosenbaum wrote:

The JH has no native means to alter the balance between the front and rear brakes.  The easiest way to change the balance is probably to install rear wheel cylinders having pistons of a different diameter.  Since the rear brakes came from a Vauxhall, it's reasonable to think something suitable might exist, but you'd have to research the subject.  As an alternative, you could use two master cylinders along with an adjustable mechanical linkage.  Perhaps one of our racing members could offer advice on such an arrangement.


Easiest way to do this is with a brake bias valve. These are about $50, available from Wilwood and others, and are simple to install. Just put on the rear line and it will essentially pinch the fluid down and reduce, or increase, the braking depending on how it is set.

But if you need to increase only, that is a different matter.....

Ron

normv
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Those wanting to upgrade the front brakes the easiest way is to visit your local ebc dealer, they have at least 4 different compounds to suit the jensen, although only standards and Greens are listed in the catalogue I have also brought Yellow and Red (these are track only) you will find these pads listed for several other cars as well, including

Morgan, Lotus, Morris, Volvo, triumph, Vauxhall and others

http://www.ebcbrakes.com/automotive.html

http://www.ebcbrakes.com/Assets/2007ukautocat.pdf  (best one to use for crossover)

http://www.ebcbrakes.com/Assets/USA%202007%20automotive.xls USA catalouge


 

Also here is a link to a proportioning valve on ebay, I have used the seller several times and recomend them

http://cgi.ebay.com/ebaymotors/Wilwood-Proportioning-Valve-NEW_W0QQcmdZViewItemQQcategoryZ42605QQihZ017QQitemZ270157539588QQtcZphoto

Last edited on 08-22-2007 10:47 am by normv



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