291mm Discs or 322mm ??

[SmokinV8]

Have got brake judder on my 97 4.2 and need to replace the front discs. Ive been told that some have 291mm and some 322mm discs and mine has the former. Is it possible to replace the discs with the larger ones without having to change the calipers? Or is there no real performance advantage to be had anyway?

[ridds]

You'll need caliper sapcers that fit between the caliper and the hub.

I think you need to upgrade to the 6 Bolt calipers as well.

[Ed FM]

I have just had the same issue. In my case I had to upgrade to the 4.5 caliper as well as disc. The bolts to suit the new calipers with the spacers are also difficult to find, I ended getting them made. Looking back at it I would probably left the calipers alone and just upgraded to a grooved/drilled disc of the original size. The job turned into a bit of a pain in all honesty.

Regards,

Ed

[Ed FM]

I have just had the same issue. In my case I had to upgrade to the 4.5 caliper as well as disc. The bolts to suit the new calipers with the spacers are also difficult to find, I ended getting them made. Looking back at it I would probably left the calipers alone and just upgraded to a grooved/drilled disc of the original size. The job turned into a bit of a pain in all honesty.

Regards,

Ed

[volospian]

Ed FM said:

I have just had the same issue. In my case I had to upgrade to the 4.5 caliper as well as disc. The bolts to suit the new calipers with the spacers are also difficult to find, I ended getting them made. Looking back at it I would probably left the calipers alone and just upgraded to a grooved/drilled disc of the original size. The job turned into a bit of a pain in all honesty.

Regards,

Ed

I umm'ed and ahh'ed about this, and then just decided to stick with drilled standards. Much simpler and perfectly up to the job for even fairly spirited road driving.

[SmokinV8]

volospian said:

Ed FM said:

I have just had the same issue. In my case I had to upgrade to the 4.5 caliper as well as disc. The bolts to suit the new calipers with the spacers are also difficult to find, I ended getting them made. Looking back at it I would probably left the calipers alone and just upgraded to a grooved/drilled disc of the original size. The job turned into a bit of a pain in all honesty.

Regards,

Ed

I umm'ed and ahh'ed about this, and then just decided to stick with drilled standards. Much simpler and perfectly up to the job for even fairly spirited road driving.

Must say my standard discs seem well up to the task, but as always when replacing stuff got to look into upgradeing! Except I dont wanna be messing about with calipers/bolts etc. My standard discs are vented but does anyone do cross drilled/ grooved discs for a cerb?

[trackcar]

I've done quite a few AP grooved upgrades on 4.2 cerbs but you have to get a pair of alloy bells machined up to take the rotors. Once youve done the hard work though things get far easier and nice and cheap at replacement time.

[jesfirth]

racing green have just got a delivery of new 291mm vented drilled disks. I fitted them last week and abused them for 3 days over the weekend at Pembrey and they were great - oh and it only takes about 20 minutes a side as they just drop stright on with no modifications

Edited by jesfirth on Tuesday 3rd June 21:43

[volospian]

SmokinV8 said:

Must say my standard discs seem well up to the task, but as always when replacing stuff got to look into upgradeing! Except I dont wanna be messing about with calipers/bolts etc. My standard discs are vented but does anyone do cross drilled/ grooved discs for a cerb?

Racing Green (http://www.thetvrshop.com/TVR/Parts_details/TVR%20J7000/e%7C/Cerbera%20V8.htm) do a 291mm drilled version. That's what I have on mine now.

[SmokinV8]

Think Im calling Racing Green in the morning now! Thanks for the help guys.

[Mr.Cerbera]

SmokinV8 said:

.....My standard discs are vented but does anyone do cross drilled/ grooved discs for a cerb?

Somebody does....

[ridds]

Did, I can't find anyone now apart from Tarox that can supply a size close.

They only do grooved.

[Duke Thrust]

Will 4.5 discs fit using 4.2 calipers and the 4.5 spacers?

[Ireland]

The judder may be caused by more than just the brake discs.

Have a look at all the bushings in the front suspension and see if any of them are knackered.

Also check the suspension bolts for damage.

A very light skim of the discs may also help.


I speak from experience.

[volospian]

He speaks the truth there!

I had a particularly bad judder at speed that got much worse under braking and assumed it was the brakes, but I've now had them changed, and while the judder under braking has gone, there is still a vibration at speed.

I've had the wheels balanced already, but I'm going to take them somewhere else and try again. They're spiders and not in great nick, so they may have been bumped at some stage and be a bit warped and/or the previous balancer was a monkey, or... the previous owner living with the vibration from the warped disks (and of course, the age of the car) could have just knackered the bushes.

When I can find the time (daily driver) I will replace the bushes and tidy up the wishbones, etc. and get some new wheels for it.

And then it'll turn out to be something to do with the rack, lol

[SmokinV8]

Thought the vibration was discs but my favoured independant garage found wear in some bushes and replaced them, for me to find the vibration was now worse as the excess movement was no longer taken up by the play in the bush! Hence... need new discs. Havent ordered any yet as been way too busy at work and no time to do the job anyway at mo. As usual guys thanks again for all your opinions.

[motorsportrescue]

So can you get a drilled/grooved/disc & Bell upgrade for a stadard caliper set up?

[Brummmie]

Duke Thrust said:

Will 4.5 discs fit using 4.2 calipers and the 4.5 spacers?

No, you need 6 bolt calipers if you have the 4 bolt. I have longer bolts if you need them. I had to buy a box full to get 4. I also have some spacers. PM me if you need them.

Those ones pictured are 6 bolt ones, but discs are also on bells so not standard and possibly 330mm? You are better of with grooved and NOT drilled. Less prone to cracking.

Edited by Brummmie on Monday 29th December 08:54

[brogenville]

What about the 304mm discs used on later tuscans/cerberas? Will they under 4.2 calipers?

I've just loked on Power's website and they're only 110+vat each, so a good bit less than the 291mm discs.

Edited by brogenville on Monday 29th December 19:30

[baztvr]

When I bought the cerb. It had new discs all round, nice. But If I burn them I will go for groved standard dia. Cheap upgrade and although a bit sad I like the sound and feel of the groves when they get warm under presure.