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Post by jr on Mar 21, 2023 8:50:01 GMT 10
My grandson has a 2008 Suzuki Grand Vitara Diesel manual gearbox. About two months ago while taking the Suzuki out for a DPF burn out the engine revved up over a couple of seconds and the Suzuki started to slow down. Almost like placing your foot on the clutch pedal and pressing it down except this was a bit slower for the engine to rev up. History: about 14months ago a new clutch was fitted. The vehicle has a bit over 200,000Kms on the clock. The Suzuki is all wheel drive. I have now seen the phenomenon in different gears, clutch pedal was fully out, and gear stick had not moved. I have tested the transfer box neutral selection and it works as normal. Tested the clutch with foot on the brake and the clutch holds to the point the engine will stall. When the slippage occurs, I have pulled over and put my head under the vehicle and could not smell any clutch burning smell. When in this slip mode just select another gear once or twice and the problem goes. It could occur within five minutes of start off or may take twenty minutes of fast driving. Bleed the clutch hydraulic system twice. Suzuki forums did not help so just thought it may be of interest to some mechanically minded people. I am 95% sure this is a clutch problem but what could possibly happen within the clutch to slip and then work perfectly? JR  |
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Post by Old Techo on Mar 21, 2023 9:03:46 GMT 10
You mentioned selecting another gear to fix it but when in slip mode does simply operating the clutch pedal in the same gear not fix it?
Pre/post slip does the clutch pedal pressure and travel bite points feel any different?
I assume a hydraulic clutch?
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Post by jr on Mar 21, 2023 9:37:38 GMT 10
Pressing the clutch in and out does not seem to help but once you select another gear and go back to the original gear it comes good. This may take a couple attempts. Also pressing the clutch in releases the drive completely and the engine then revs up much quicker if you leave your foot on the accelerator pedal. Clutch seems to bite in the same location about 40% from the floor. Usually we are in 5th travelling at 110Km/hr so go back to 4th and then back to 5th usually fixes it. The slipping has also occurred in lower gears. Yes, the clutch is hydraulic, and I have twice bleed it. The slave cylinder lives inside the bell housing. The slave cylinder piston is like a donut with the gearbox input shaft going through it. There is two hydraulic lines to the slave one from the master cylinder and one feeding outside the bell housing for bleeding. The master cylinder gets its hydraulic oil from the brake reservoir.  JR |
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Post by Old Techo on Mar 21, 2023 10:29:21 GMT 10
JR,
It was a complete stab in the dark given the issue weirdness and my questions were along the lines of something (heat?) causing the clutch slave fluid to expand but be prevented from flowing back into the master cylinder as it would normally.
If so just pumping the clutch pedal would have some effect without the need for gear changes and the clutch pedal would feel strange. |
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Post by jr on Mar 21, 2023 11:15:41 GMT 10
OT, I was also originally thinking heat and air expansion as it was occurring after some time but only last week I took the Suzuki for a quick drive after bleeding the clutch again and it happened only minutes after starting. When I tried pumping the clutch the engine just revs up or goes to idle and the clutch feels normal, but the fault remains until I change the gears a couple of times. Just cannot visualise anything in the clutch system that would come and go. I went to a work shop that specialises in gearboxes, diffs and clutches and they could not come up with a solution. Only thing was when I told them the company that supplied the new fitted clutch a year ago they immediately said that they have had people come in with a clutch from that particular companies supplier of clutches asking to have it fitted but they said they will not fit it as they are rubbish. JR |
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Post by Old Techo on Mar 21, 2023 11:46:09 GMT 10
When you change gears to fix the issue do you actually drive briefly in a different gear or do you mean you just select different gears and then quickly return to the original gear that suffered clutch slip?
In other words does it only take a bit of gear lever wiggling to fix it or do you have to briefly drive in another gear?
I am wondering if engine therefore clutch revs have a centrifugal force factor.
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Post by jr on Mar 21, 2023 11:52:47 GMT 10
Yes usually drive in the other gear for a few seconds but sometimes it may take a couple of attempts. I was wondering if the clutch to gear box shaft spline is sticking or creeping one way. P.S. thanks for your input OT JR |
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Post by inca on Mar 21, 2023 12:51:19 GMT 10
From what you have described to OT about the clutch pedal and it feeling normal, and with the number of times you have bled the lines, there is a strong possibility there could be a problem with the pressure plate particularly if it is a reconditioned one .
I am not familiar with the clutch system of the Suzy but the symptoms seem to indicate a problem with either the pressure plate or the driven plate.
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Post by jr on Mar 21, 2023 16:35:32 GMT 10
Could be like you say Inca, the problem is it is very intermittent. The clutch was new with new slave cylinder and back of engine bearing and engine crank seal. I could take the Suzuki out again and when slippage starts roll off the road and just sit there with the engine revving and maybe after 30 seconds to a minute I might start to smell clutch burning. If this was the case I could be sure there is something going on in there and then would be comfortable getting the gear box out and replace the clutch. JR |
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Post by Old Techo on Mar 21, 2023 18:23:05 GMT 10
The possible centrifugal force action I mentioned was in terms of the whole clutch assembly.
Some clutch designs deliberately use such force to increase the pressure-plate pressure as revs/torque rises.
I think it is in the operator interests of making a lighter clutch pedal pressure at normal take-off engine revs and especially when sitting at the traffic lights holding the clutch pedal down.
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Post by jr on Mar 21, 2023 20:17:09 GMT 10
OT, I know about centrifugal clutches but was not aware of the type of clutch you refer to. I was going to attached a photo of what I believe is in his Suzuki but the 'Add Image To Post' does not seem to be working at the moment. Just the standard clutch used in most vehicles supplied from Clutch Industries. JR |
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Post by Old Techo on Mar 21, 2023 20:26:39 GMT 10
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Post by jr on Mar 21, 2023 21:18:09 GMT 10
Never heard of such a clutch, very interesting.
JR
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Post by loub on Mar 21, 2023 21:27:43 GMT 10
JR could it be the thrust race or pressure plate binding occasionallyon the shaft or one of the parts not being the correct spec therefore creating this issue.
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Post by spaceland on Mar 22, 2023 8:04:02 GMT 10
My grandson has a 2008 Suzuki Grand Vitara Diesel manual gearbox.ad not moved. Does it have a dual mass clutch? They can do some funny things if they have been badly treated.
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