Diesel Manual feeling resistance when driving
 

Hi,
I've got a 2001 75 manual diesel with ~75k miles. I tend to use the car only at weekends but noticed something strange again today. I was doing 30mph in 3rd gear and when I lifted my foot of the accelerate and the car started to slow I detected some sort of resistance. It was a sensation pulling the car speed down a little like if you are driving on shingle or if you have a flat tyre.

Tyres are all inflated.
Clutch is good.
Brakes are all good and recently had new front calipers and pads.
Car doesn't feel like it's got a brake jammed on - doesn't pull to one side or anything

There isn't a loud sound however I can sense an almost rubbing sensation a bit like driving in gravel / a rough surface or flat tyre

I took the car for a 20min journey and it cleared completed. I've noticed this before. Any suggestions on what this can be appreciated, is there anything I can do now as I wonder if this is the start of some problem?

Many thanks.

hi mate, I know you've mentioned that your brakes are ok, but I had the same on my diesel ZT and it was due to a sticky rear caliper. It wasn't completely seized, it just wasn't releasing completely so was slightly applied at all times and every now and again it would fully release. Could feel it dragging the car's speed and power down and after some time it would cause a slight vibration too.

After a long journey the brake disc and even the wheel would give off quite a bit of heat, and you could smell burning from the brake, which made it clear it was a sticky caliper.

On short journeys it wasn't too obvious that the caliper was sticking, was more noticeable once the brake + disc got hot. It never caused the car to pull to one side either.

Thanks for that. I had a front brake stuck on last year so maybe what you describe is the back ones playing up. This would make sense. It seems to clear up after a short drive.

If you only drive it at weekends, with the winter weather, you can get quite a build up of surface rust on the discs, and if the pads do not back off much, they will be wearing this off for the first few miles. Look at the faces of your discs before you set off next weekend, and then check them once the sound has disappeared- they will be much shinier.

A quick update. My mobile mechanic jacked up the car the other day. He notice the drivers side wheel rotate freely. The passenger side wheel did not. He checked the calipers and all good.
He took it for a drive initially and noticed nothing so it's not that bad yet. We think it could be a wheel bearing although he also mentioned the diff... Any suggestions of what it could be?

Everyone should have one of these at home https://en.wikipedia.org/wiki/Infrared_thermometer . After a drive immediately check the brake rotor temps through the wheel spokes, if possible, or even the wheel itself by the lug bolts (same place on every wheel). If you have a sticking caliper (or even a worn bearing, but less obvious until it gets bad) you will see a noticeable temp spike.

Ravinder is having a similar problem, isn't he? Do these cars have a limited slip differential?

Cheers,
Glenn

watch out for emissivity or false readings from shiny surfaces like brake discs...
if you want to know the real temperature then put a bit of masking tape on the surface and measure that after a few seconds...
The matt finish will give a much truer reading...

Here is a pic of my stainless steel kettle at home....

Freshly boiled and full and look at the temperature range due to reading reflections and not the surface...

https://www.the75andztclub.co.uk/for...e525212faf.jpg

Have you checked that the park brake is not sticking? If the linkage inside the drum is corroded it would easily drag, then release with vehicle movement.

The front wheel bearing can be discounted with the following test ;)

Jack up the car, and squeeze the piston back into the caliper so the pads are not contacting the disc.

Put the wheel back on, and spin the wheel, it should rotate freely, and if you place your hand on one of the coils of the front spring, any roughness in the wheel bearing will be transmitted to the spring and will be able to be felt.

Unless proven otherwise, a sticking brake caliper, be that caused by poor fitting of brake pads, a defective caliper, or indeed a flexible hose that is breaking down internally, restricting the brake fluid return would be my first thoughts.

You can of course drive the car for ten miles, come home and feel the comparative temperatures of the front wheels with the back of your hand, a tight wheel bearing is unlikely to result in a major temperature differential between the two front wheels, and would be howling in protest if causing the type of drag you suggest.

However I would be highly suspicious of a diagnosis of a defective gearbox differential, this sounds like the mechanic is either clueless, or aiming to wipe your eyeballs with an expensive or unnecessary repair ;)

Let us know how you get on please

Brian :D

Spit on your finger before quickly dabbing it on each of the discs - too hot, or if really bad, too much sizzle on a particular wheel and you have found the problem. :}