Weird clutch slip?

[Dom B]

Ok Manual VR4

Stock Clutch not that old at all maybe 6-10000 miles

When cold you can launch the car and it goes great and leaps away. loading it up in high gear no problem.

However. Cruise on the motorway for an hour and get everything hot, then pulling out in 5th gear and it slips.

Are the casings expanding?

The clutch slave has been off the car and emptied, checked it is free and total fluid replacement and bleed.
The clutch pedal has been off the car and investigated and tweaked in case it was holding residual pressure on the master.

Is something dropping on the clutch? water oil? No signs of any leaks or drips.

Can oil from the main seal find it's way onto the friction surface?
But then next time you start it it is great and grips well.

Highly confusing.

[exevoowner]

Clutches are funny with heat as this can cause them to leach on to the flywheel in other word the glue holding the friction material can melt which is why when it hot you get slip do you know what clucth is in there also a heated presure plate can cause slipage as it losens preasure from friction plate ,in short it means you need to change it and main seal on crank at same time

[Dom B]

The car Dynos at over 310bhp at the flywheel, is it time to upgrade the clutch? It's not that much over std.

[elnevio]

Torque is more of the issue though - 10% more power on these is often accompanied by a torque increase nearer 30% or so.

[exevoowner]

As nev said its more a case of torque increase on the clutch it a spining mass thats used to disingauge drive when cold its great but induse heat and uv got extra play had same issue on the evo i had after stroker upgrade lol

[pbaron]

I had a similar problem with a manual legnum I had a few years back. I got the car cheap with a stuffed clutch and fitted a new factory unit to it. Occasionally after it got hot it would slip in 4th and 5th under load and this was straight from new.

I came across a post somewhere that indicated the clutch damper in the line could be the culprit. The recommendation was to remove the damper and replace it with the pipe from an Evo. I order the evo pipe from the local dealer for $25 odd bucks, fitted this and bled the clucth and never had any more problem with it slipping.

Part number for the evo pipe is 2348A038, for the price it may be worth fitting this to see if it fixes your problem before getting a new clutch fitted. FYI the bolts used to mount the damper and slave cylinder are a bit long to use when you remove the damper, get some shorter ones or use some spacers on the originals.

Legnum with damperLegnumPipe.png Evo without damperEvoPipe.png

Cheers

The car Dynos at over 310bhp at the flywheel, is it time to upgrade the clutch? It's not that much over std.

[kzv76]

Clutch damper, interesting why they feel the need to fit those.

[Dom B]

I had a similar problem with a manual legnum I had a few years back. I got the car cheap with a stuffed clutch and fitted a new factory unit to it. Occasionally after it got hot it would slip in 4th and 5th under load and this was straight from new.

I came across a post somewhere that indicated the clutch damper in the line could be the culprit. The recommendation was to remove the damper and replace it with the pipe from an Evo. I order the evo pipe from the local dealer for $25 odd bucks, fitted this and bled the clucth and never had any more problem with it slipping.

Part number for the evo pipe is 2348A038, for the price it may be worth fitting this to see if it fixes your problem before getting a new clutch fitted. FYI the bolts used to mount the damper and slave cylinder are a bit long to use when you remove the damper, get some shorter ones or use some spacers on the originals.

Legnum with damperLegnumPipe.png Evo without damperEvoPipe.png

Cheers

Ok that sounds worth a go. The part number for the evo one looks the same as the part number for the lower VR4 one? 20464? Is that the only part number?

[exevoowner]

They fit same damper to the galant v6 just remove and aline pipe work to fit with out it may solve your problem for a short time lol

[Dom B]

Ok So looking at the clutch, I have to say it looks brand new. It is an exedy stock clutch nothing special.

There are no signs of oil contamination and no signs of water leaking onto it, i.e. no coolant residue.

The plate looks like new and is 8.4mm thick, does anyone know how much under the thickness of a new clutch this is?

The flywheel despite the photo, is smooth as you could ever hope and with your fingernail you can feel the original machining marks over most of it's surface. It certainly doesn't look any different from any other flywheel I have seen. The pressure plate is as smooth.

There really looks like no reason why it would slip. Especially since the slip was never under high load but simply changing lanes in 5th gear on the motorway.

Your thoughts ladies and gents?

Really confused now.IMG_3273E.jpgIMG_3275E.jpgIMG_3276E.jpgIMG_3278E.jpgIMG_3279E.jpg

[adaxo]

I have similar issue before, clutch slipping after few miles of driving, never when cold or on short journeys. So I get new one and while I start to take gearbox out I find reason why it was slipping, rubber grommet on top of gbox was missing and one of small water pipe above it has been split and pissing coolant right in this hole and on to clutch. Leak was small enough to not notice but in so unfortunate spot that is causing clutch to slip.

[Trotty]

Did u get the clutch put in? Or bought the car with it? I would say that the clutch has been fried and its lost clamp pressure. I've done the same thing high rev dump and glazed the clutch. Never been the same. Holds good most of the time but every now and then on a cold morning 3rd gear pull ill get a flare. But then it'll be good. I'm waiting for new hd exedy before full tune and winding the boost right up.

[Subaru ETA]

Pressure plate and flywheel look stuffed! Looks like they have been very hot! (May just be the pictures tho?)

[Dom B]

Pressure plate and flywheel look stuffed! Looks like they have been very hot! (May just be the pictures tho?)

They feel very smooth but do look like they have hot spots, but then again if you launch 300bhp through a 4wd system you expect that a little surely? It must be designed for it? Does anyone know if the thickness is new/worn/fubared? I would say the clutch release lever looked very close to the bell housing when it was all together maybe indicating wear.

I only really want to figure out what was the problem. Either way I am taking the damper off and putting a new clutch and flywheel in. I am going to fiddle with the engine whilst it is out so should be thinking along the lines of upgrading the clutch but don't know which way to go. What I don't want is to have a stall a minute brute to pedal along everywhere.

[wintertidenz]

Nick Mann adaptor and Evo clutch appear to be the way to go. Probably a bit cheaper than finding a heavier duty clutch for the VR4 too.

[Nick Mann]

The thickness looks good. Not much wear at all. Clutches are usually rated with torque rather than power in my experience. My car used to slip under load on a stock clutch at 300 bhp but then my torque was 370lbft which is a huge increase from stock.

[Kenneth]

Looks like contamination to me. The coolant idea is plausible looking at the picture on the far right... I have never seen flywheel bolts with rust on like that personally, and I have done a few gearboxes now.

[Dom B]

Hi Ken,
I have been looking and I am struggling to see where it would get in as I replaced every hose and clip going, as I searched for the problem. The coating on the bolts looks like dried coolant but it's hard to say. On the plus side I found the problem with the engine now I have taken it apart and why it was leaking water, it was a head gasket. Post with photos will be up in a short while just for fun. Trouble is now I have the engine out I want to fiddle with everything.