Front brake caliper "connection adapter". What is it for?

[martin calva]

I have just replaced the front brake calipers and hoses on my ABS equipped 940.

I noticed there was an M10 male/M10 female adapter between the old brake hose and the caliper on each side. I assumed it had been fitted for some reason by the mechanic who last changed the brake hoses.





I did not refit them; I simply screwed the new hoses directly into the calipers. But then on the Skandix site I noticed that the adapters were apparently fitted by Volvo when the car was constructed.

Adapter, Brake hose Front axle
Genuine product from vehicle manufacturer
Adapter, Brake hose Front axle 1329693 (1017377) - Volvo 700, 900, S90 V90 (-1998) -
Product No: 1017377
Reference: 1329693
Your price: 23,95 EUR
Brand: Volvo
Connection between: Brake hose - Brake caliper
Connection adapter for the brake hose, screwed into the brake caliper. Factory installed at all Volvo 700, 900, S/V90.
(my emphasis)

My two questions:
- What purpose do these 'adapters' serve? Converting M10 to M10 seems a bit redundant. Their presence made virtually no change to the geometry of the hose installation.

- What could be the consequences of my not having refitted them? Should I take the front wheels off, refit them and bleed the brakes once again?

Thanks for any advice.
Martin

[Laird Scooby]

Originally Posted by martin calva

I have just replaced the front brake calipers and hoses on my ABS equipped 940.

I noticed there was an M10 male/M10 female adapter between the old brake hose and the caliper on each side. I assumed it had been fitted for some reason by the mechanic who last changed the brake hoses.





I did not refit them; I simply screwed the new hoses directly into the calipers. But then on the Skandix site I noticed that the adapters were apparently fitted by Volvo when the car was constructed.

Adapter, Brake hose Front axle
Genuine product from vehicle manufacturer
Adapter, Brake hose Front axle 1329693 (1017377) - Volvo 700, 900, S90 V90 (-1998) -
Product No: 1017377
Reference: 1329693
Your price: 23,95 EUR
Brand: Volvo
Connection between: Brake hose - Brake caliper
Connection adapter for the brake hose, screwed into the brake caliper. Factory installed at all Volvo 700, 900, S/V90.
(my emphasis)

My two questions:
- What purpose do these 'adapters' serve? Converting M10 to M10 seems a bit redundant. Their presence made virtually no change to the geometry of the hose installation.

- What could be the consequences of my not having refitted them? Should I take the front wheels off, refit them and bleed the brakes once again?

Thanks for any advice.
Martin

'Tis indeed a puzzle! A bit like a 1:1 transformer, apparently no use to man nor beast as it doesn't alter the voltage.

However it does provide isolation from the mains supply so serves a useful purose by reducing the risk of electric shocks when using appliances in the bathroom eg electric shavers, toothbrushes etc.

On that basis, i'd suggest the purpose might be something to do with one of the minor details of the thread, perhaps one is tapered and the other isn't, maybe it's to give clearance for the flexi over another component or some such strange anomaly.

I would think it would have been cheaper and easier to fix the root cause of the problem rather than bodge it like this but if Volvo themselves bodged it this way and had the car approved for sale then it's no longer a bodge.

Will be intersting to learn the reason on this one!

[martin calva]

I did notice I had to be careful screwing the hose termination into the new caliper not to get the threads crossed. As a blind guess, maybe the 'adapter' is there to avoid crossed thread situations on the production line or in the Volvo garage when the hoses are replaced.

[J liddy]

Hi martin
My 1995 940 has the same set up .i replaced my calipers last year. And put the fitting back .its stainless steel i think so no corrosion . save them and put them back next time you work on brake system !my opinion only!

[Whyman]

Many years ago I was a progress chaser in a large earth moving equipment manufacturer.

One of my jobs was to source parts that were in short supply. Sometimes we were short of hoses and I had to check with engineering if a hose that was slightly shorter or longer would be an acceptable alternative.

Maybe Volvo had a similar problem and fitted the adaptor to use a slightly shorter hose or the adaptor moved the hose away from the suspension or other components when the car is on the road but it is not obvious when jacked up.

If it was me I would refit them as soon as possible.

[TonyS9]

How about standardisation of flexi-hoses or corrosion resistance?

Volvo used a number of different caliper + disk designs, perhaps this just made sure the positioning was the same.

It also might 'save' the caliper from having a rusted in hose connector if the adaptor is more corrosion resistant.

[Laird Scooby]

Originally Posted by Whyman

Maybe Volvo had a similar problem and fitted the adaptor to use a slightly shorter hose or the adaptor moved the hose away from the suspension or other components when the car is on the road but it is not obvious when jacked up.

It wouldn't work with a shorter hose on full lock as it would kink the hose but i agree it might be something to do with clearance that isn't obvious with the wheels hanging in the air.

[martin calva]

Originally Posted by TonyS9

(...)

It also might 'save' the caliper from having a rusted in hose connector if the adaptor is more corrosion resistant.

That could make sense. But since the rear calipers were not so equipped, protection against corrosion seems unlikely to have been the reason.

The presence of the adapter only changes the position of the end of the hose by about 2cm. The equivalent of a 2cm change in the compression of the front suspension.

[martin calva]

Originally Posted by Whyman

(...)
Maybe Volvo had a similar problem and fitted the adaptor to use a slightly shorter hose or the adaptor moved the hose away from the suspension or other components when the car is on the road but it is not obvious when jacked up.

If it was me I would refit them as soon as possible.

Thank you.

It changes the position of the end of the hose about 2cm in a direction 90° from the main line of the hose - in other words it has no effect on the effective length of the hose. The hose itself is about 35cm long.

It's equivalent to the front of the car being lowered less than one inch due to an extra load on the front suspension.

But knowing that Volvo installed them as standard I will refit them when I get around to it.

[Laird Scooby]

Originally Posted by martin calva

The presence of the adapter only changes the position of the end of the hose by about 2cm. The equivalent of a 2cm change in the compression of the front suspension.

Correct me if i'm wrong but don't those adaptors go into the caliper horizontally? If so, the compression of the suspension will be for the most part irrelevant.

However, i have thought of one viable reason why these adaptors are on the 7/9xx cars and that comes down to Volvos penchant for carrying things over to successive model ranges. Is the caliper shared with the 240 series by any chance? Also is the flexi hose shared with the 240 series?

The track on the 7/9xx is wider than the 240 series, at the back it's simple because a wider axle is used and the body is natuarlly wider to accomodate that.

The rigid pipes are taken to the extremes of the body then go to flexis to the caliper.

Similar at the front but to increase the track, it's highly likely the lower control arm is longer (which will also give longer suspension travel so an added bonus) which will move the wheel a bit further away from the body where the rigid pipes end. Following this theory on of using "legacy" components, it would then make sense to fit a 20mm long adaptor to bring the flexi to caliper union 20mm further inboard.

I suspect if you do some digging you'll find the calipers and/or flexis were quite likely also used on previous incarnations including the 240 series - it's an edumacated guess and logic says why didn't they just move the end of the rigid pipes 20mm outboard on a bracket or make a new flexi but as someone said to me in a PM the other day, Volvo and logic are two words that should never be used in the same sentence!