Rear calipers same as BX front calipers? well almost but no

I agree ,I'm always locking the fronts ,it's a bit hairy as they aren't the best to start with .What's the bias ? Would seem the rears do very little .What's the score with removing the rear balance ? Literally just substitute with a ' T ' piece ?

[mettersl]

I suspect Renault were playing safe. In all cars if you lock the rears you dramatically increase the risk of a spin, in fact so much its pretty much certain in an extreme situation.

This was a cause of lots of deaths in the USA' muscle car craze in the 50/60's, until the government acted and made front bias a requirement.
If the fronts lock up you go straight ahead.

With a rear engine you already have the already questionable stability under heavy braking, caused by the heavy rear engine- increasing the probability of a dangerous spin.

Renault, by providing front bias, make sure that the front always locks up first- this in braking terms is like under steering handling- it means you will plough on straight- rather than spin.

As most motorists cannot catch spins (myself included) this is safer behaviour on the road as you are less likely to have a serious accident by ploughing on forwards, rather than spinning- potentially into the path of another car.

So Renault have sacrificed the best possible braking, for a safer on road behaviour during extreme braking.

Racing is different and you often find much greater rear bias, or brake bad adjustment. Here the driver will be much more competent and able to anticipate and plan for rear locks and the over steering that goes with it.
Lee

I agree with what you're saying and the logic.

Does that mean though that they adjusted the bias to correct levels for the A610 and Le Mans where they had ABS and, in theory at least, you can't lock the wheels up?

Interesting that Porsche achieve class leading braking on the 911 - OK they use excellent disks and calipers, but they clearly set the brakes up to exploit the layout.

The reason the 911 achieves fantastic braking is the same reason the DeLorean achieves good braking from 4 solid discs, and the GTA achieves excellent braking in spite of a stupid brake pedal ( - kidding) - because you can actually put a lot of load on the rear and have it do some work thanks to the weight bias.

Funnily enough there has been a debate raging in the DeLorean community for a few days on this very subject. Brief synopsis: Jag XJS rear calipers x-ref to the DeLorean but have 43mm pots whereas a stock DeLorean has 48mm. Muddy the waters further that the original 68/32 split master cylinder has been replaced by a lot of owners with a bog standard Saab 50/50 split and a large fight has erupted (mainly from the vendors supplying original original parts vs the much cheaper alternatives).

Funny how the same discussions cross these borders. Don't start about unreliable speedos

[mettersl]

You'd think that ABS would make greater rear bias possible wouldn't you- of course it has to be working......
My 610 still has a rear pressure limiter as well as the ABS (fitted that is, but still not working...for reasons that are defeating me).
I haven't driven a GTA so cannot do the comparison, but I can tell you that I still get front lock ups but have never had a rear lock, so I guess the safety police have still decided the bias.

Lee

I am not looking to get the rears to lock, only to get a bit more bias onto the rear to increase the amount of retardation available from the system. ie. more Gs under brakes.

GT5's just got his rear calipers back from the local motor factors (£140 for both i think) they were supposed to be reconing the old units, but on the box it has Citroen looking at them they seem the same with the exception of the handbrake levers what do you reckon give em back and ask for the GTA ones returning, or make do with them?dont want to get them fitted and find out theres more probs using these

The handbrake levers aren't the problem as that can be accounted for with the cable.

It's the seals you need to check for as the Citroen ones are for LHM fluid I believe so won't last when exposed to normal Dot4 etc.

does anyone know where you can get a new pair of handbrake cables for the gta as thats the only thing stopping mine getting an mot now cheers

i got mine from renault about 6 months ago or so think i paid around £65 for the pair