Bike rack causing Clutch Slip on motorway?!

pault123

Hey,

This only happens when I have my bike rack on the car and bike attached. (I have a full suss bike which is very heavy)



I have the above Mont Blanc rack and the bike wheels sit on the shelf so the bike protrudes quite high above the back of the car.

Now I know you wouldnt think this would cause any drag but it does affect the car handling and somehow is causing my clutch to slip.

I get the car to 50mph on the motorway and as soon as I try and go above 50 by accelerating the rev meter flies into the 5000-6000 just below the red and the engine overrevs

almost like ive just pushed my clutch in and the car is no longer in gear, I let off on the accelerator and the revs go down to 2000-3000 and i'm back at 50mph. Its possible to get to 70mph by very slowly putting my foot down but if I as much as push the gas in an inch too far the clutch slips.

Without the bike and rack my car can comfortably do 90mph.

Any one else experienced or have any thoughts on this?

rusty-london

It seems very strange that the clutch only slips when the bike rack is on the car. Does it slip when you've got a car full of people or a boot full of luggage?

To be honest, if the clutch is slipping at all it's pretty much done for. One way of checking is to apply the handbrake fully, start the car up, pop it in first gear, then let the clutch pedal right out. If the engine stalls, the clutch is fine, if it doesn't, there's a problem with the clutch.

Hope this helps.

mikey-mike_2

It’s a strange one, might be the extra weight of the bike causing the clutch to slip but seems unlikely, try putting some passengers in the car and see what happens then.

Only other thing I can think of is the weight of the bike plus the aerodynamic drag plus the acceleration is lifting the front wheels off the road but that is really really silly

pault123

Not had chance to try car full of people and boot of luggage yet. Earlier today I tried the clutch test with handbrake on in 1st gear and 4th and 5th. The clutch in all instances started to bite towards the top and the car would pull like it wanted to drive off.

The car would stall before the clutch was fully out?!

With passenger in front seat its ok I need to try people in the back.

At the moment i'm starting to wonder if the clutch is starting to go and its only apparent when the car is under extreme load (ie. 30kg bike rack and 18kg bike combined with aerodynamic drag) some people first notice clutch wearing out when towing something in the higher motorway gears?

Wig

Park on a hill, put into 2nd and drive away (up hill), if your clutch slips it's on its way out.

I'd say this bike rack thing is just indicating that your clutch is going.

northern_munky

pault123 wrote:

Not had chance to try car full of people and boot of luggage yet. Earlier today I tried the clutch test with handbrake on in 1st gear and 4th and 5th. The clutch in all instances started to bite towards the top and the car would pull like it wanted to drive off.

The car would stall before the clutch was fully out?!

The handbrake clutch test should be carried out in top gear. If the car stalls then it's generally assumed it's not slipping. As the clutch wears the biting point will move to the top of the pedal travel. Have you got some freeplay at the pedal? What car is it, maybe it can be adjusted?

rusty-london

One other thing I'd mention is that clutches are generally made in such a way that they are more prone to slipping when they are hot. This could be part of the reason that it is more noticeable when you are on the motorway. When the clutch disc cools down again, it basically starts to work properly again.

I know it sounds strange, but I remembered this last night as a problem we had on a customers vehicle a while ago!

greyteam1959

To be honest that bike rack looks extremely dangerous to me on that small car. It will dramatically affect the handling and performance of the vehicle to the point of being dangerous to drive.
I would think the law might take the same view.
Having said that it should not cause the effect of a slipping clutch.
My vote is for a knackered clutch.....cant you smell burning !!!!

pault123

Morning

Wig wrote:

Park on a hill, put into 2nd and drive away (up hill), if your clutch slips it's on its way out.

I'd say this bike rack thing is just indicating that your clutch is going.

Tried this and it was fine

northern_munky wrote:

The handbrake clutch test should be carried out in top gear. If the car stalls then it's generally assumed it's not slipping. As the clutch wears the biting point will move to the top of the pedal travel. Have you got some freeplay at the pedal? What car is it, maybe it can be adjusted?

Tried the clutch test in 1st 4th and 5th and the car stalled just before the pedal was fully out.

Its a VW Golf 1995. The pedal had no free play at the top so I adjusted the cable under the bonnet and added an inch of play on the pedal in the car.

Now instead of the biting point being very close to the top of the pedal it now bites almost as soon as I lift the pedal off the floor?

rusty-london wrote:

One other thing I'd mention is that clutches are generally made in such a way that they are more prone to slipping when they are hot. This could be part of the reason that it is more noticeable when you are on the motorway. When the clutch disc cools down again, it basically starts to work properly again.

I know it sounds strange, but I remembered this last night as a problem we had on a customers vehicle a while ago!

It seems to happen when I get anywhere around 50mph which tends to be the motorway. From cold start I can be on the motorway in 2 mins from my house and it will slip.

mervyn11 wrote:

To be honest that bike rack looks extremely dangerous to me on that small car. It will dramatically affect the handling and performance of the vehicle to the point of being dangerous to drive.
I would think the law might take the same view.
Having said that it should not cause the effect of a slipping clutch.
My vote is for a knackered clutch.....cant you smell burning !!!!

Compared to some bike racks which dangerously hang the bikes over the registration plate and cover the lights I spent extra money and went for this one as it doesnt obstruct any of this and is securely attached to the top and bottom of the boot.

Take a look

http://www.leisureshack.co.uk/osb/itemdetails.cfm/ID/Mont%2DBlanc%2DEasy%2DGrip%2DS2%2DBike%2DCarrier_1102/Cat/17

its a very expensive bit of kit :mad:



Thanks for all the input guys :beer:

Murielson

Not able to offer much technical input but has the clutch ever been changed or are you still on original? Do you do mostly motorway travel or around town etc, ie, clutch used a lot or not too much?

pault123

Original clutch, car has done 45000 miles and an even mix of motorway and town miles.

Cheapest quote ive had on a new clutch VW brand is £250 inc fitting! (and I was trying to clear some debt this year arghhhhhh )