servo assistance required (see what I did there)

[MOD500]

I have a small car with no brake servo and I would like to fit a brake servo.

I have very little experience with such things and my main issue is finding one as small as possible.  plenty of images on ebay, but dimensions are never listed for standard replacement parts.

Can anyone suggest the smallest diameter servo they have come across? It doesn't matter if it's a bit longer than normal Preferably something easy to get parts for.

[spartacus]

Probably help if you told us what it was and maybe an under bonnet pic so we can see what space is available. The first course of action would be to find out if a higher model in the range had a servo, then you might be lucky and have a direct bolt in replacement.

Failing that you could fit a remote servo, a bit of homework might be needed for correct sizing, but something like this...

https://www.ebay.co.uk/itm/Powertune-Remote-Brake-Servo-LE72696-TT3949Z-Brake-Booster-1-9-for-MG-MINI-MORRI-/392694023176?_trksid=p2349624.m46890.l49292

[MOD500]

It's a fiat 126. There was no servo fitted in the series.  Although you've got me thinking it might be worth checking other fiats of a similar vintage as they may have shared a master cylinder. I'll take a few measurements this evening to see what space I've got.  

[spartacus]

Are the brakes really that bad. Before you look at fitting a servo it may be with making sure the standard braking system is in perfect working order. All a servo will do is decrease the amount of effort you need to put in, apologies if you know all this already.

[MOD500]

It is a fair comment.

I plan to fit disc brakes to the car which gives a simple improvement, but there is not enough mechanical advantage in the pedal box, so it's a  a lot of effort to get it to brake well. I'm hoping the servo will improve the mechanical advantage and improve the pedal travel.

[Mr Pastry]

Just now, MOD500 said:

It is a fair comment.

I plan to fit disc brakes to the car which gives a simple improvement, but there is not enough mechanical advantage in the pedal box, so it's a  a lot of effort to get it to brake well. I'm hoping the servo will improve the mechanical advantage and improve the pedal travel.

How do you know there isn't enough mechanical advantage in the pedal box?  

[Mr Pastry]

10 minutes ago, spartacus said:

Are the brakes really that bad. Before you look at fitting a servo it may be with making sure the standard braking system is in perfect working order.

This, 100 percent,

[Mally]

I've fitted one to an MGB. There is a  dedicated kit available though, and they are quite large.

People said the MG didn't need it , but I found a vast improvement.

Sorry can't help with small.

[MOD500]

I've been running a fiat 500 for a number of years and have no issues maintaining the brakes.

I am due to start restoring a 126 which I plan to make a little faster so I want to swap the drums for disc brakes for a bit ore stopping power.

With disc brakes added I would like to enhance the pedal feedback by adding a servo.

When disk brakes are fitted, the feel of the brake travel is rather flat, almost binary. It's quite common to fit disc brakes to these cars, although I don't think discs on their own are the best solution.

[Mally]

https://www.maxpeedingrods.co.uk/product/Remote-Brake-Servo-LE72696-TT3949Z-Brake-Booster-19-for-Austin-A30-A35-A40.html?tracking=adstrong_uk&code=GBP&origin=CjwKCAiA2O39BRBjEiwApB2Iknd9QNxE6uiUREr3h9Pu9Xk4tPzox7P6M2zJV9BoGx4XS1wFfPefZRoCDGMQAvD_BwE&gclid=CjwKCAiA2O39BRBjEiwApB2Iknd9QNxE6uiUREr3h9Pu9Xk4tPzox7P6M2zJV9BoGx4XS1wFfPefZRoCDGMQAvD_BwE

I'd ring someone like this and ask the size

[Mr Pastry]

Surely fitting a servo will give you less pedal feedback, not more?

Better to try a smaller master cylinder and no servo, though this will give a longer pedal travel.

Very easy to over-brake a small car with no weight on the front and it will just lock up  all the time.

If somebody else has done this successfully, copy what they have done, but with due respect, don't mess with brakes if you are not sure what you are doing.

[MikeR]

I used to cane my 126 when I was in my 20s and never had any probs with the brakes , to be fair I had more fun fixing the suspension and replacing alternator bearings .  I think the 127 had no servo fitted as well but it did have disc brakes , I would just make sure the auto adjusters work on the hubs and are not worn and backing off , a good slap on the brakes when reversing can help the self adjustment .

I would not over brake the front end as it can get to be a bit of fun when pushed and go wide into a hedge finding trip , I would keep it simple and looked after .

[MOD500]

Thanks to all.

As I said above, brakes on the 500 are good and well maintained.  Not looking to address a braking issue with a current setup, looking to improve braking on a car that will be going a little faster than standard.

I'll have a look at the remote setup and send a few emails. It looks like I could use the servo off an uno, but there's not many around to pull spares from.