LOCK UP (Static or Base)

[AB Racing]

Hi Guys


Just fitted an MTC Lock up to my 1216cc Drag bike with the stock springs and one steel bolt,lock nut and two washers on each finger.


I tested the bike a few weeks back on a very unprepped track and the bike just lit the tyre for the first 60ft. Over the eight runs I made the 60ft times were all 1.61 to 1.60 with a best of 1.56, even with the spin. Before the next raceI put lighter springs in but kept the finger weight the same, This time the track was very sticky and the motor just bogged of the line with 60ft around 1.70, however after the 60ft the front end came up in the air. Next run took off the two washers on each arm but the bike still bogged of the line. Took more weight of arms on the next run to leave just an aluminium bolt and lock nut on each, but still bogged.


I'am running the weakest springs I have at the moment which are about 54lbs at 30mm height each. Would I be correct in getting some weaker springs to stop the bogging off the line As not sure if the bog is caused by the initial slip and then the abrupt lock up of weight on the arms or if the springs are just too heavy


By the way I'am launching with 2 step set at 7000 rpm, and have 60hp shot of gas coming in at 20% on launch up to 100%in 3.2sec.


Any ideas greatly appreciated


Andy

[Blackcloud]

MTC told me that even withthe weakest springs available it is still 2 stiff to dump off the line, they said to have 100 thousands taken off the shoulder of the top hat. it helped me. I'm getting full lock up by about 20 ft. 1100 no nos 7000 rpm dump 190 50 003U soft

[Ken Walker]

if your ignition timing is set up for nos ...when its only on 20% on the launch you could be killing bottom end that way

[AB Racing]

MTC told me that even withthe weakest springs available it is still 2 stiff to dump off the line, they said to have 100 thousands taken off the shoulder of the top hat. it helped me. I'm getting full lock up by about 20 ft. 1100 no nos 7000 rpm dump 190 50 003U soft

So by doing this then you would in theory decrease the air gap, or have I miss understood

[AB Racing]

if your ignition timing is set up for nos ...when its only on 20% on the launch you could be killing bottom end that way

Ken the ignition is set at 40deg static, it leaves the line with no retard until nos is at 50%when I knock out 4 degwith the controller.


Many thanks though.

[rosco15]

Yes you need weaker springs to stop the initial bog. Find some out of another bike.

[Kawi1500Vortex2]

machine .200 off the hat so you can shim it to where you want it using mtc light springs and their shims


jmo

[Blackcloud]

MTC told me that even withthe weakest springs available it is still 2 stiff to dump off the line, they said to have 100 thousands taken off the shoulder of the top hat. it helped me. I'm getting full lock up by about 20 ft. 1100 no nos 7000 rpm dump 190 50 003U soft

So by doing this then you would in theory decrease the air gap, or have I miss understood

No the gap is still 125 thousands. didn't have it taken off the top of theposts, but the shoulder that the spring rides on. when it is bolted down tight, the only thing changed is that the 4 springs are compressed 100thousands less ( actually 70 thousands less on mine ) after having it turned down I ended up using a 30 thousands shimover every post. Edited by: Blackcloud

[Kawi1500Vortex2]

So by doing this then you would in theory decrease the air gap......

no, all it does is increase the installed ht of theclutch springs(decrease static)


there is no air gap on a lock up clutch

[rosco15]

I think by air gap they are talking about the clearance between the arms and the pressure plate. You need .100 - .125