Wedge braking or lack of it......

[350matt]

Chaps
I was wondering the other dauy why is it the wedge brakes leave a certain something to be desired - stopping mainly.
The basic hardware is fairly respectable 238mm vented Ø discs, servo assisted ,large opposed piston solid calipers. I've fitted better pad material, braided hoses and ducting for the rear inboard discs and fitted a brace for the master cylinder as the pedal bulkhead can move alarmingly.

yet still in hard braking it feels like I'm having to kick the pedal through the bulkhead to get it to stop.

I know the later wedges had 4 pot calipers but I've driven these and they're not much of an improvement, I think the basic problem is a lack of pedal or hydraulic leverage has anyone tried a smaller bore master or experimented with the pedal geometry?

Matt

[deetes]

Tower View 300mm discs with 4 pots and braided hoses. Stops fine.

[350matt]

Well thats rather my point, my mundaneo has smaller diameter discs , single pot calipers and is a heavier car yet stops very well.
Beefing up the existing set-up is all very well but it seems to me to be the expensive way of fixing the problem

Matt

[jchase]

You could always go to the gym and build up some muscles in your braking leg...

Or you could add an auxiliary booster for the brake master cylinder, as in some older Alfas ( the guilia coupes used this ) .

-jim

[350matt]

Sorry buts its already got a servo...

[tallbloke]

I though the original discs were 260mm
I've uprated from solid to vented and some alloy 4pot calipers and it has transformed the braking. Didn't cost a fortune either. The pedal box is more rigid on the earlier cars though, is the brace you've fitted really doing it's job?

[James MK]

On my original setup I often had only brake working, rear pads fell off and one front calliper seized, but even when all was well it wasn't up to much. Hard to believe how contemporary press reviews didn't slate it. Anyway, had grooved Granada discs fitted by Tower View a few months ago and now it works ok, not going to win any prizes but it's good enough not to scare me!

[jchase]

Hi Matt,

The auxiliary booster is IN ADDITION to the main brake vacuum assist servo. Essentially , under the bonnet you have TWO of the diaphraghm housings, and some plumbing. This, I understand significantly reduces the pedal effort required to the lock the wheels up under braking. Something Alfa added to increase sales to the USA of thier 105 series Spiders.

The other alternative is to fit a Servo with a larger mechanical advantage, such as off a van.

-Jim

[kevsmev]

Drive a MK2 2.3 Granada. The brakes are, and feel better even with drums on the rear and its a heavier car. This to me means that TVR never got the compatibility/balance right between the various components.
This also applies to the hand brake. Jag handbrakes are generally very good. It is only when you introduce a handbrake lever from another car that has much less actual leverage and then reduce the leverage again by extending the point where the cable is attached!
Kev

[SLB]

I tend to agree with Matt on this one, but isn't this TVR's ABS system? Certainly on one occasion faced with a head on collision, panic braking would have sent me in spin due to one side of the car being on damp road, the other on dry. I reckon the initial poor braking saved me that day.

[jchase]

Hi Matt,

Just out of curiousity, did the brakes start to seem ineffective after you changed to power steering ?

-Jim

[350matt]

No can't say they did
I've made small improvements like I said but the pedal effort is far too high to modulate the brakes properly.
Smaller bore master is probably the way

Matt

[keri]

Hi Matt, I have a sneaking suspicion about this...

Is yours a late 350i ('87-'89 seems to be the one)? And does the disc go between the hub and the wheel or bolt to the rear of the hub?

Do you have any photos of your setup you could email or post here?

I've not got my hands on the late-type tasmin (that apparently uses a more modern disc-behind-wheel setup), but if this is what you've got, and the discs ARE 240mm I think I know why - and it will explain why your brakes are hopeless...!

Message / email me if you prefer to talk off-forum.

Cheers, Keri

PS Does ANYONE have the late type Tasmin with the disc-behind-wheel setup, and again any photos?

[jchase]

Matt, I have an ancient car DIY book, and it says you can sometimes improve the servo by cleaning a small felt disc that surrounds the push rod. Apparently fresh air is drawn through this felt disc, acts upon the diaphragm and is drawn into the engine intake. Never tried this myself, but must be worth a go.

It's My turn to try the power steering upgrade - luckily I have the bent chassis tube. How long did it take you?

-Jim

[350matt]

Mine is a '86 350i, one of the first series II's and its got the bolt to the back of the hub type discs.
I misposted earlier the disc Ø is 263 - std ford Mk II vented granada

I have adjusted the pre-load rod between the booster and the master cylinder as well, to the point where it was nearly locking up all the time ( since backed it off a bit...)



Matt

[nads]

350matt said:

Chaps yet still in hard braking it feels like I'm having to kick the pedal through the bulkhead to get it to stop. Matt

I know what you mean. We changed my wife's Morris Minor drum brakes for Marina disks and it now stops just as well as my wedge does without a servo!

And the old banger XR4x4 feels like it stops in half the distance of either car!

Braking at speed does make me nervous in the Wedge - and I've never managed to lock the wheels yet!

[leorest]

It could be worse, the hydraulics could be as bad as the handbrake! That won't lock up even on gravel!
Leo

[adam quantrill]

How often do you drive it? I found the 400SX brakes were pants when I got it, but have now bedded in and are great. On the other hand the 350i ones were tip-top when I was driving it every day, but now not so good as I havent driven it for a few weeks.

Give it some monster stoppies and get those discs cleaned up!