MadaboutKitcars

Richard drove it on Sunday for the first time, he was very impressed. Says it feels much more like modern tin tops. Much easier to be progressive with the brakes. I need to bleed it again to get rid of little bit of spongy feeling.

I have to say a big thanks from both of us for everyone involved, this sort it thing is why I really like this forum

Thanks Patrick. I think everyone who has fitted this servo has been genuinely very pleased with the improvement - there have now been over 50 of us who have bought one ( I say bought, because I am sure there are still quite a few who have not fitted them yet, waiting until winter sets in before taking their Marlin off the road to do all the jobs like this one).

Big up for GOO who spotted the original advert and started the ball rolling:

Servo / Rose Joints Update



Quick update.
The above rose joint will not suit most owners requirements - the bolt welded to the brake pedal is, in most cases, 10mm which is slightly larger than a 3/8" eye hole.

The best solution is a 3/8" UNF male thread rose joint with a 10mm eye , together with a 3/8" UNF female collar thread about 25mm long . The rose joint can be obtained from ABC (Anglia bearing Company) part no. MP061F39.

The latest kit has been upgraded to include the rose joint.



Existing adopters of the Dual servo might wish to consider adopting a rose joint to avoid misalignment issues? It is a cheap and relatively easy swap, and may avoid future problems?

I highly recommend using the rose joint

Rose Joint Now Fitted

There have been 49 Marlin members who bought one of our dual 7" servo upgrade kits - which must be a high percentage of all the non Ford engined Sportsters and Cabrio/Hunters, and says a lot about what the they thought of their original brake set up.

There has been one issue which affected a small number of owners, where the servo would continue to apply a gentle force to the brakes after taking their foot off the pedal, causing them to over heat.
It seemed to affect the Zinc plated servos more than the black powder coated ones. Initially these were returned to the supplier as faulty, but through time I have come to believe that it may have had more to do with the way the Marlin servo is aligned with the pedal in the Marlin designed pedal box.




Marlin offset the angle of the pedal pivot and the servo mounting face, to create more space in both the footwell and the engine bay. The angle is evident in the above photo: the pedal box is lined up with the grout lines in the tiles, highlighting the servo angle in the foreground......

Whilst this did not seem to affect the Metro servo, which would tolerate a significant offset, the vaccum seal in the rear of the new dual 7" servo seems much more sensitive, and if it does not seat correctly appears to lead to brake binding complications.

I drilled, and then slightly elongated, a hole through my brake pedal, and fitted a clevis around the pedal using a clevis pin to achieve the alignment I wanted. Other owners left the Marlin welded in bolt and chose to mount the clevis to one side of their pedal.

Patrick and a couple of others used rose joints which are a much better solution ( and I wish I had thought of this when putting the kit together). It allows the push rod/pedal connection to bolted up tight, yet freely accepts the offset angle, and also accommodates the change in angle as the pedal travels through its arc.
So, when my clutch master cylinder failed (due to poor alignment - caused by me!) and I had to remove my pedal box yet again! - I chose to replace my brake clevis with a rose joint at the same time.

For anyone interested in adopting the rose joint solution, the servo has 3/8" UNF threads, but the bolt that is usually welded into the Marlin pedal is 10mm. If you buy a straight forward 3/8" rose joint, it will come with a 3/8" hole in the rose joint (which is slightly less than 10mm). Also all the rose joints I have located were all just too short to screw onto the servo and allow the pedal to be set where I wanted it.

My solution was to buy a 10mm rose joint, and a 3/8" x 20mm collar, and to spot weld them together.
I have been very careful to then allow the rose joint to locate laterally against the pedal in its central rest position, and used a couple of washers on the pedal pivot to ensure they lined up perfectly laterally.
Job done.

Further update - hopefully the final solution!

Jason Cundall (GOO in these circles) had brake binding problems travelling home from Stoneleigh. After investigating the option to fit a rose joint, he decided it would not line up as well as his centralised clevis, so offered no solution to his problem.

In response to his reported problem in a post on the MOC, Jon Cox came back with this sound advice: - fit a pedal return spring - all modern vehicles have one: and offered a very simple, elegant solution.



Jason followed this advice, fitting a Landrover pedal spring (ebay £2.20 for 2)





and offered the following comment:

Courtesy of Jason on MOC Forum:

"It's fixed.
It only took one spring, and I basically followed the same idea as in Jon's picture. I made a small plate that sits on the clevis pin that has a hole for the spring to sit in, and then hooked the other end of it to a bracket I mounted on an existing bolt.

- it works like a charm. After fitting it after work today, I blatted round town for 45 mins in all sorts of traffic (fast dual carriage way, town centre, etc etc), and it's been fine. Pedal comes up fully and immediately after taking your foot off, and there's no noticeable extra effort in pushing the pedal down now there's a spring on it. No more binding / squeaky brakes, takes off like missile now, probably doing the world of good to the fuel economy. Happy "

I did a write up of the mod with a diagram of where the bits go here:

http://www.greatoldone.co.uk/blog/2014/5/21/spring-brake.html

I'm not entirely clear as to why my clevis lines up so well with the pedal on vikki, when everyone else's seem to be off... But this mod should work with the rose joint solution as well.

You were not alone with the clevis pin lining up. Mine also was a perfect fit but never had issues with binding brakes either.

Hi All,

A long shot here, but does anyone have one of these kits which they are yet to fit or no longer want?

I am looking to modify the brakes on the Sportster so it actually stops in what I would call a normal amount of time, any help would be appreciated.

Cheers Jono

Hi Jono

I don't have one but I was looking at these a couple of days ago for another project http://www.ebay.co.uk/itm/like/300803456966

Nigel

Or this - http://www.ebay.co.uk/itm/7-DUAL-ZINC-GM-POWER-BRAKE-BOOSTER-HOT-RAT-STREET-ROD-UNIVERSAL-CHEVY-FORD-NEW-/300799070247?hash=item4609059027

This is the 7" version which should fit in the Sportster.

Hi Jono
I have some adaptor plates left over but no servos
Be careful about the links you have been given
The black servos are a different make to the zinc servos . We had everyone using the zinc servos come back with sticking brakes
Regards
Mike

Jono

Have sent you a PM, with an email address of someone who may still have their servo kit, but no longer intends to fit it.

If you do fit one of these dual servos - whatever the source - and they are well worth it, you must fit a reasonably pedal return spring - Jason used a couple of Landrover springs off ebay (around £4.00) which work very well.

regards

Mike

Did you follow this up Jono?

Jono

Did you receive my PM?

Did you follow it up?

Mike

Slightly off topic but the BMW e60/e61 brake servo's look like pretty neat and compact units.

http://www.ebay.co.uk/itm/BMW-5-SERIES-E60-E61-520d-BRAKE-SERVO-MASTER-CYLINDER-LAC115THE-296765937051-/221679808603

Looking at the pictures and it's construction it looks like it could be a dual diaphragm design. Lot's of used ones on ebay and new ones made by TRW on Amazon.com

Interesting spot Peter.

Do you know what diameter they are?

No, I've not bee able to find any dimensions on-line. Perhaps someone on here has a newish 5 series beemer could get there tape measure out?

I'm not planning on using one or I would have bought one off ebay but I thought it might be of interest to other builders.

The squatness of the master cylinder definitely looks a useful feature, even if the diameter of the servo turns out to make it less space friendly in a kit car.

Peter, have you actually already purchased one of those fancy servos designed to be remoted? With something like this you may be able to just use a slave cylinder pushing the input of the servo to get the same effect but at significantly lower cost. I can see this arrangement fitting sideways in the battery box area of the sportster quite nicely making room for the wide heads of an M60/62 engine

I've just brought my MBM dual servo from Pirate Jack in the USA. I ordered a 7" dual servo, but on receiving it and measuring the overall outside diameter its 8" in diameter not 7". I assume the 7" servo relates to the overall diameter. ? Can anybody advise me ?

Hi Nigel

The MBM 7" Dual Servo is 8" outside diameter: I remember having the same concern when I recieved the first batch!
I can only guess the 7" refers to the internal diaphragm size?

regards

Mike

Yes, I have bought my Iruna dual circuit remote servo.
I just found the e60 BMW servo looking for something else and thought it might be useful for other builders.

Hi, I got one of these E60/E61 servos this day just for looking how it looked like - they are quit big - overall diameter is 250 mm/10" but it is almost the same thickness as the Metro - 150 mm
C/C to the bolts for brake cylinder is 102 mm
C/C to the fastener is square 72,5 mm or near....they have M8 bolt on one side and a 9 mm diameter guide peg on the other so outside measurement is 80 mm. Then with a diameter to the part that goes inside as 61,5 mm
I have added some pictures at my Flickr site - https://www.flickr.com/photos/our_marlin_sportster/albums/72157661278726615

Servo Issues

I have now got my black powder coated MBM servo fitted and linked up to the pedal with rose joint and all bolted in place and nicely aligned. I used an endoscope camera to watch it all working! The m/c is not fitted nor the tried with engine running but the pedal action has the initially stickiness before it frees. It just feels odd , like you have to press hard to make it move, after which its fine.

Can any one tell me is this normal without any engine vacuum and m/c attached or have i got a faulty servo .I so hope its not the latter as Hot Rod Jack already sent the wrong servo the 1st time .

Nigel