Technical Rear subframe type

[DerbyTwin]

Just wondering if theres a difference between the type of rear subframe for rear drum & disc brakes.
I've been perusing eBay & they all seem the same. Using my car reg to match parts also does not seem to work.
I have a 2012 Twinair, can anyone tell me if this is the one?

UPGRADED HEAVY DUTY REAR AXLE SUBFRAME FOR FIAT 500 (2007 ONWARDS) 51889561 | eBay

UPGRADED HEAVY DUTY REAR AXLE SUBFRAME FOR FIAT 500 (2007 ONWARDS) 51889561.

www.ebay.co.uk

 

[jrkitching]

Just wondering if theres a difference between the type of rear subframe for rear drum & disc brakes.

Yes there is.

If you're in any doubt, why not ask the company that makes them?

 

[DerbyTwin]

Yes there is.

If you're in any doubt, why not ask the company that makes them?

I have cross referenced the part number & done my research, which pointed to the correct part. The company retails hundreds of parts & simply quote the advert. Can anyone give me pointers to the difference? Basically how to tell which is the one I need to my car.

 

[John202020]

I used this company that advertises at the top of the forum, there's only two options discs or drums

https://www.imaxle.co.uk/new-fiat-500-axle

 

[jrkitching]

I used this company that advertises at the top of the forum, there's only two options discs or drums

Indeed.

Which is interesting because Fiat used two different versions of the twist beam during the production run, with the change to a stiffer beam in the 2010 model year. IIRC the springs are different , and the shocks may be also.

So folks replacing their beam with one of these aftermarket parts will be using the same beam, irrespective of whether their original was the later type with the steel stiffening bar.

I'm sure they'll work, and since we're generally talking about 10+ yr old cars that might otherwise be scrapped, it's a good thing that we've got these parts at all.

But I do wonder how closely the final result will match the suspension characteristics of the original car, and what is the best spring/damper combination to use with the IM axle beam?

 

[jrkitching]

Basically how to tell which is the one I need to my car.

That, at least, is easy.

If your car has rear drums, you need the beam for drum brakes.

If your car has rear discs, you need the beam for disc brakes.

It may be possible to modify the drum braked ones to accept disc brakes. Panda 100HP owners have done this, since the Panda beam is a different track to the 500 one, and there is no disc braked alternative for that car.

 

[DerbyTwin]

Would anyone that had done this swap know the book time a typical garage would charge to get this job done? I've asked at my garage, but they said it greatly depends on the number of rusty / seized nuts. The garage also advise to replace all the worn components while the beam was out. Drums, shoes, cylinders, brake hoses, shocks, etc. Any thoughts? Is it cost effective?

 

[DerbyTwin]

That, at least, is easy.

If your car has rear drums, you need the beam for drum brakes.

If your car has rear discs, you need the beam for disc brakes.

It may be possible to modify the drum braked ones to accept disc brakes. Panda 100HP owners have done this, since the Panda beam is a different track to the 500 one, and there is no disc braked alternative for that car.

As I'm not carrying out the work myself, I would rather it be a straightforward swap, rather than them charging me more to have to faff about, making it work.

 

[jrkitching]

Would anyone that had done this swap know the book time a typical garage would charge to get this job done?

On an old, rusty car, this isn't the sort of job where the book time is going to bear much relation to the time it actually will take.

I've asked at my garage, but they said it greatly depends on the number of rusty / seized nuts.

That's fair and honest. I'd expect a garage to say something like "we'll charge £xx per hour, and the cost will depend on how many hours it actually takes."

As I'm not carrying out the work myself, I would rather it be a straightforward swap, rather than them charging me more to have to faff about, making it work.

Regardless of who's doing the work, I'd say it's better to pay the extra £20 than faff about. Disc braked Panda owners only do this because they've no alternative.

The garage also advise to replace all the worn components while the beam was out. Drums, shoes, cylinders, brake hoses, shocks, etc. Any thoughts?

It makes the job easier for whoever is doing it. And if you're paying for their time, that may also make it cheaper for you - the parts might cost less than the labour to remove, clean and prepare the old ones. The brake hoses will almost certainly be perished, and may be impossible to remove without ruining them anyway.

Is it cost effective?

Certainly if it saves the garage more time (in money terms) than the cost of the parts. Plus you'll know that you won't have to spend anything further on the rear of the car for a good while.

 

[DerbyTwin]

On an old, rusty car, this isn't the sort of job where the book time is going to bear much relation to the time it actually will take.

That's fair and honest. I'd expect a garage to say something like "we'll charge £xx per hour, and the cost will depend on how many hours it actually takes."

It makes the job easier for whoever is doing it. And if you;re paying for their time, that may also make it cheaper for you.

Certainly if it saves the garage more time (in money terms) than the cost of the parts. Plus you'll know that you won't have to spend anything further on the rear of the car for a good while.

The rear beam of my car looks akin to the titanic! It's been coated with Lanoguard at the moment so it doesn't get any worse. I'll be getting all the associated bits changed as this is a car I'll keep for a few years. I'd be protecting it too as I'd hate for it to end up like that again in a few years.

 

[John202020]

Assuming drums

To keep the time down and therefore cost I suggest supplying the following parts which you will need anyway

New wheel cylinders
New brake pipes( can be bought on ebay as a pair ready made)
New hand brake cables(check star lock washers come aswell) probably well used
Consider new springs and shocks?

Only 4 bolts hold the whole axel on quick to remove, swapping over the parts/ assembling the new ones? I'd guess 3 hours in total, took me an entire weekend "on the road"
Note you need to disconnect the abs sensors at the car body end and carefully wiggle the cable away

 

[DerbyTwin]

Assuming drums

To keep the time down and therefore cost I suggest supplying the following parts which you will need anyway

New wheel cylinders
New brake pipes( can be bought on ebay as a pair ready made)
New hand brake cables(check star lock washers come aswell) probably well used
Consider new springs and shocks?

Only 4 bolts hold the whole axel on quick to remove, swapping over the parts/ assembling the new ones? I'd guess 3 hours in total, took me an entire weekend "on the road"
Note you need to disconnect the abs sensors at the car body end and carefully wiggle the cable away

Never thought about hand brake cables, good one, thanks!

 

[jrkitching]

Only 4 bolts hold the whole axel

John, how much play did you find in the bolt holes?

I ask because aligning the rear wheels with the centreline of the car is the first step to getting the 4 wheel alignment correct. If there is any slack here, it's important to make the best use of it you can.

 

[John202020]

None ,ours was out once done, bodge the tracking with the front
However I think you can loosen the 3 bracket bolts at the forward mounting positions and alter it that way but that will take far longer to track hence why most places will compromise by just doing the front, that said not noticed any odd tyre wear

 

[DerbyTwin]

That, at least, is easy.

If your car has rear drums, you need the beam for drum brakes.

If your car has rear discs, you need the beam for disc brakes.

It may be possible to modify the drum braked ones to accept disc brakes. Panda 100HP owners have done this, since the Panda beam is a different track to the 500 one, and there is no disc braked alternative for that car.

I bought another, this time specifically listed for drums & there was no difference to the first one, listed as for discs.

So I can only summise that the first one I bought, which the seller said was for discs, is in fact for drums!

Well, if the seller doesn't know, then what hope does a buyer have?

Anyhow it's all been fitted & the ride is superb, gone is the jitter on uneven surfaces. Now just need to sort the handbrakes.

 

[John202020]

Now, I just need to sort the handbrakes.

Remember, the cables are different lengths by only about 20mm but it makes a difference