Handbrake woes.

[limpabit]

Hi everyone.

Failed the MOT 15% (pass is 16%). Handbrake only just scraped past during the SVA, so was on the cards to sort out.

Ended up getting a refurbed set of calipers. Exactly the same outcome!

Anybody else have a crap handbrake?

I pumped the footbrake before attaching and adjusting the handbrake.

Thinking it could be the handbrake cable run causing problems.

[eaa53]

On my Pre IVA MoT I was warned that the handbrake was only just on the right side of the pass mark.. and I have the retest to include the brake test coming up soon.

If the mechanical set up was good enough for the Rover 200 what have we done different on the build?

May have to apply physics and increase the size of the disk to increase retardation when the H/B is applied.

I will be interested in your eventual solution.

[limpabit]

Mine was the same with the older suspension/small Rover disc as now (using 258mm discs).

What are other 5exi owners handbrakes like? Only thing left are the cables (Rover 200) and handbrake lever/rod etc.

Got some instructions with the new calipers to reset the self adjusting mech.

http://www.brake-eng.com/Global/Down...0Procedure.pdf.

I'll give that a go the weekend.

[bigrich]

Know what you mean..... mine is OK, but to get this I had to move the handbrake cable mount under the tunnel slightly.

[nutter]

I havent had mine MOTed or IVAed, but my handbrake feel excellent. From horizontal full bite is acheived in 3 or 4 inches of the button release above horinzontal.
As you know I have seat leon rear calipers. Probably doesnt help you out much

Cheers
Steve

[limpabit]

Hi Steve.

Is your car mobile yet? If so, I would be interested to see how the handbrake performs at say crusier at 10mph, then apply the handbrake.

I was thinking calipers alone with handbrake is not good. Maybe it's a Rover caliper thing.

[nutter]

My car is mobile, but a bit cautious about taking out on the road, the house on the corner is own by our local custody sargent and the police station, and many company cars get parked up outside.


When on the deck, with handbrake fully on, its really hard to get it to move, I can get it to the point where the clutch slips.
So in terms on handbrake it really has some bit. I think handbrakes turns will be easily acheivable.

Cheers
Steve

[limpabit]

Is the Seat rear caliper a single piston?

[nutter]

Originally Posted by limpabit

Is the Seat rear caliper a single piston?

Yes

[limpabit]

Righto. Little update. New calipers and pads. Adjusted as per caliper guide. Managed 18% at MOT. 2% more than the pass. Only thing I can think off is the contact surface not being enough. New hubs etc.

[eaa53]

Based on your experience and other comments both on and off this forum I have chosen to upgrade to the 260mm disks, callipers and carriers.

One comment I had was that the basic Rover 200 handbrake was useless at the best of times and they were surprised it ever passed the MoT. The MG F handbrake is the same I am told.

The only logical way out is the use of science and improve the retardation with friction at a greater distance from the rotational centre.

I will advise the % improvement of the 260 disk set up in due course.

Am I heading into any installation issues with standard alloys - callipers fouling or cable connection differences?

I am expecting to have to make changes to 6 different items to improve the handbrake efficiency if normal kit car engineering applies!

[limpabit]

Hi John.

Will be interested how you get on and what mods you do.

What type of type of hubs do you have? Are the later type as below?



If so, I have a set of ZR160 calipers and carriers I have tried with the Nissan Almeria 259mm discs. Unfortunatley, they don't help matters. I trail fitted them after removing my standard calipers/carriers. But the whole lot just moved away from the hub more, leaving the same surface contact on the discs as the standard ones. If that makes sense.

[eaa53]

I have similar rear uprights not the original ones.

The dimensions of the pads differers between the 200 (253mm disk installation) and the ZR 160 (259mm installation), see the comparison below.

In round figures the additional 20mm diameter 'disk and carrier' allows a 10mm increase in pad height. That must translate into greater retardation.

I agree the same pad size at a greater distance from the centre of rotation will provide no better braking. I would say that's simple maths to prove but I could not work it out, I stopped doing that sort of calculation years ago and now work on gut feeling!

By my calculations the increased pad size will yield a 35% surface increase (Pad to Disk), 35% of 16(%) will produce a (5.5%) improvement, so with luck the hardware that has just landed at my door will deliver closer to 20% brake efficiency on the test.

Happy for anyone to contest my maths but its a basic pointer to a solution that's heading in the right direction.

I will upload some pics as I progress the change.

--------------------------------------------------------

Rover 200 standard fitting
Rear brake discs are solid discs (single disc) 239mm diameter across with 4 stud wheel fixing
Height [mm]: 35.3
Length [mm]: 88.8
Thickness [mm]: 13

MG ZR 160
Rear brake discs are solid discs (single disc) 259mm diameter across with 4 stud wheel fixing

Height [mm]:47.5
Length [mm]:88.9
Thickness [mm]:15.4

-------------------------------------------------------

[limpabit]

Hi John.

I trial fitted them to my hub. ZR160 carriers/calipers and a new set of ZR160 pads. Only sat on the same section disc from the out disc to where the standard ones finished. Just used even less of the pad.

If using the ZR160 bits, it's as if the whole lot needs moving in towards the centre of the disc and bit more.

[eaa53]

Ok lets get technical...





This is the MG 160 (259mm disk) disk and pad compared to the Rover VI 235mm disk and pad. Remember there are two sizes for the MG 160 rear disk, this same disk was also fitted to the uprated ZS 180. White paper background added to the pads for visual effect!



This second picture is less clear to see the differences



It shows the MG 160 (259mm disk) calliper piston (on the right) 33mm compared to the Rover VI (235mm disk) 28mm piston.

I have not shown the carriers as its understood they are longer and place the pad further away from the centre.


Now with bigger pads and larger pistons applying more force for the same pressure, how can it not provide better braking.

If your trial set up used the same size pads as the old 200 but placed it further out on the bigger disk, you have the smaller MG 160 calliper and pad set up on the larger disk size and carrier and that will improve nothing.

Same friction area, same pressure applied to a larger diameter disk that's no different based on physics!

Does that sort it?

[limpabit]

Hi John.

Thanks for all the information John. I was not aware there were two different sizes for the MG 160. Could be I have the wrong size pads.
I'll check over the weekend.

[limpabit]

Originally Posted by eaa53

If your trial set up used the same size pads as the old 200 but placed it further out on the bigger disk, you have the smaller MG 160 calliper and pad set up on the larger disk size and carrier and that will improve nothing.

Just realised what you said here John. When I trial fitted the MG160 calipers/cariers and pads that came with the calipers, it did not move the end edge of the pad further out on the bigger disc. It used the same clean line on the disc as the old 200 caliper setup. So sounds like I have the right MG 160 setup as though the carriers have move the MG 160 setup further out, it still reaches the same in disc as the old setup. Does that sound right?

Will be interested in your before and after results. Now this has passed the MOT, this little project came sit on the back burner for me for now. Got another couple of projects I want to get my hands dirty with on this car.

How is the handbrake on the Elise John?

[eaa53]

Sounds like you have the smaller 160 set up not the 260mm uprated version fitted to the higher BHP VVC engined cars.

The higher rated set up has larger disks, bigger pads and a larger piston. If your trial fit placed the original sizes pads in the same place on the disk as the original 200 set up you have the wrong 160 set up.

The Nissan Almeria 259mm disks sound ok, and if you are placing the smaller pads on the outside of the bigger disk your carriers are the bigger ones, could just be the wrong pads you have. You should be aware that you can fit standard callipers on the longer carriers and end up with the smaller piston calliper and the smaller pads just on a different diameter.

For the full improvement you need the 34mm calliper piston and the larger pads. For the correct MG 160 2001/- your caliper casting should be stamped with the following numbers (Left and Right) 2243 & 2244

I will complete the clean up and do a picture progress and comparison to assist builders.

The biggest problem I have is finding a seal kit to O/H callipers, hens teeth and rocking horse excrement are easier to find.

May have a lead now 'Bigg Red Ltd Specialist Brake Caliper Re-manufacturer'


JC

[limpabit]

Righto, I thought I would try and find the answer to my 160 brake upgrade today. Not come up with an answer, but a possible future mod that will make the braking better. Thoughts welcome.

First of all, the setup as it is at the moment. Standard 220 rear brakes (same as 1.6 bubble). Using 259mm Almera discs. You can see the silver clean line on the disc where the pads stop and the rust starts.

Using standard 200 carriers, refurbed calipers and pads. Notice the outer edge of the disc and how much pad is wasted to the left of the edge of the disc.



With the setup removed, here is the new standard pads in the picture above on the left. Pads on the right, are the pads that were supplied with the 160 setup. Also notice, the standard pads and not being used to there full height.



The picture below, is the comparison of the spare standard calipers (on the left) and the 160 calipers on the right. A noticeable difference in piston diameter.



Here is the MG160 setup (Calipers/carries and pads) fitted to the car.


Notice the sliver line on the disc? Roughly the same contact area as the standard setup. Just more of the height of the pad is wasted, going off the edge of the disc.

I'm no expert. But if the the width of the pads are the same (standard and mg160), I'm gaining nothing with the height of the pad. The only advantage is the piston diameter.

Now I think I have three options. Comments welcome.
1) This was my mod I thought of above. Modifiy the standard carriers to fit the mg160 calipers. This will bring the caliper in quite a bit using more of the pad.
2) Send the whole lot back to Marlin. Though I have been in contact with Marlin some time ago, supplied pictures etc and they could not see what was wrong).
3) Take it to another company to modify the setup so it fits correctly.

[eaa53]

Are you sure the disks are 260mm or did they shrink in the wet?

The pads are hanging over the edge so either the disk is too small or the carriers are holding the callipers too far away from the centre line of the wheel.






I will measure the carrier for you..... 60mm ctr of mounting hole to ctr of slider.



I also notice that the disk does not run up fully into the calliper and there should be only mm's of clearance between the inside edge of the carrier and the outside edge of the disk.







This shows the calliper casting number