Front Brake Upgrade 278mm Discs - Ford Callipers
Discussion
Top Gear TVR said:
Sorry my calipers are the earlier ones, may be different
Steve, loosely connected to the purpose of this thread.Whilst I was trying to establish what pads I needed for the 887/888 callipers I discovered that the 278mm and 283mm discs are available in both the 48mm and 58mm heights which negates the need for spacers (in any form) or turning down of discs.
Of course, using 58mm high discs moves the disc closer to the steering ball joint which some may not wish to do.
As per my first post, I'll do a complete list of relevant bits etc... The disc information will be relevant to both the 887/888 set up and the 557/558 set up I've suggested on this thread.
Edited by mk1fan on Monday 29th June 18:55
Just to add my 2p
I recently had a similar issue with the puny 260mm dia disks. I decided to go for the 58mm high ones rather than spacers and the 53mm ones. This leaves me with 6mm between disc and track rod end. If this turns out to be too little clearance then I will have to use the other disks and Spacers I suppose.
At least I found out the steering arm on the RH upright was twisted as I went through the learning process!
Tony.
I recently had a similar issue with the puny 260mm dia disks. I decided to go for the 58mm high ones rather than spacers and the 53mm ones. This leaves me with 6mm between disc and track rod end. If this turns out to be too little clearance then I will have to use the other disks and Spacers I suppose.
At least I found out the steering arm on the RH upright was twisted as I went through the learning process!
Tony.
A bit short notice but if you're looking for a 5 stud conversion this guy has the rear parts as well. If they don't sell at the last minute I've got his ebay message details if anyone is interested.
http://www.ebay.co.uk/itm/271917488066?_trksid=p20...
http://www.ebay.co.uk/itm/271917488066?_trksid=p20...
phillpot said:
Two chunky spacers or one big block, I can't see what difference having a lump of metal between the two holes makes? The caliper is a big solid chunk as is the hub carrier it's mounted to, what can flex?
I am afraid there is quite a big difference from an engineering point of view. Two spacers as shown creates the likelyhood of a turning 'moment' or stress attempting to bend the bolts. That stress will be repeated and relaxed every time the brakes are applied and will gradually change the nature of the steel and raise the likelyhood of a fracture. The solid plate, if the holes are of the correct dimensions, virtually eliminates the bending moment and the stress is in sheer. As there is now no deformation of the bolt the steel does not change in nature with time.Mounting the 278mm discs as shown is not acceptable engineering. Not only will there be a significant and changing bending moment on the bolts, the bolts are bound to be pushed against the edges of the mountings with the result that there will be a very big localised stress, and a critical point for a crack is created. That point will also be at, or close to, the last thread of the bolt.
I am going to ask another two engineering questions.
Is the distance between the centre of the disc and the original mounting face for the calipers the same, in other words has the centre of the braking load moved further away from the caliper mounting?
Are the bolts that have been used of a rolled thread type and of a steel type specified as adequate for the enormous load that now exists? Do you KNOW that they will not snap like carrots when braking hard from 100mph?
Prophet of doom again, I know. But messing around with brake mountings without a VERY good knowledge of the stresses involved, and how to deal with them, is a clear recipe for killing someone and destroying an innocent car! Are you prepared to justify to your insurers that the modification you have carried out is proven good practice. Can you demonstrate that the modifications have been approved by a suitably qualified automotive engineer. Put yourself in the minds of the people who would investigate AFTER an accident. We have seen the post above when one owner came close to a MAJOR accident, how long will it be before one set of 'modified' brakes does result in a death?
Head below parapet I think!
v8s4me said:
do heavier calipers have any noticeable influence the handling.
Not to drivers of our capability Joe 
The bigger, and therefore heavier, disc's are perhaps more of an issue because they are adding to the un-sprung weight?
Does it sound like I know what I'm talking about?
Edited by phillpot on Tuesday 4th August 09:25
No offence intended Stewart but the idea of using spacers and bolts of unknown quality justs puts you and that car at an unacceptable risk so I had to speak out. If you find it hard to accept my opinion, then see if you know anybody who knows an RAC 'blue book' scrutineer, show him the mod and see what he says!!
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