T/A rocker

Referreing to, or course the infamous drill mod for the LS1 clutch hydraulics.
Getting a clutch installed soon, and the mechanic doing the install said he has done the drill mod on more than a few f-bods, and it has caused some to break gears, since the clutch then grabs instantly on release. He said he will do it if I want, but does not recommend it.
So bottom line, is the drill mod good or bad ? I thought it was pretty much a "must" for these cars from what I read

991LE

iTrader: (2)

If you want a girlie lazy don't grab clutch, then don't do the drill mod. The drill mod will solve a lot of your high speed shift problems. The dude is right though, it will be harder on the tranny and rearend.

LSWannabe

I was under the impression that the drill mod would allow the clutch to release in faster intervals. for example when making a drag pass. Without it the fluid wont be able to cycle back around fast enough to be used for pressurizing the release of the clutch in the 2-3 shift (most notoriously).

Why will it make the clutch grab super fast/hard???

SStillSSmokin

I have never heard that before, but I had been wondering the same thing lately. I put a Spec stg.3 in about 6 weeks ago, and did the drill mod. Went to the track once with it and it worked great! Then on Xmas night while coming home from the folks I got on it a little to get some jerk in a prelude off my ***. Did WOT 3rd, hit 4th WOT, then went to let off and put it in 5th... and was stuck in 4th. I finally got it out of gear, but neutral felt like the shifter was full of rocks and I was locked out of 5th and 6th. From searching around sounds like I broke the slider keys. I will be getting it rebuilt with the steel shift fork and billet slider keys, but it seemed like alot of ppl had this same thing happen shortly after the drill mod was done.
I think your mech. may be right, but I just figure that means I have replaced the clutch restriction with the tranny as the next weakest link. Both will be better soon!

Tranzor

The slider keys could be a problem with any hard shifting like you do when drag racing... especially with a grabbier clutch that is harder on the transmission. I say do the drill mod and the clutch, but also have some billet slider keys put in the transmission. That's what I'm doing... I want to be able to shift my car hard at the track and not have to worry about chewing up the slider keys.

Camaro99SS

iTrader: (4)

I just had a Z06 clutch installed with the updated slave cylinder and had him do the drill mod. I haven't noticed any sort of abrubt engagement or anything of the sort. The clutch starts to engage maybe less than an inch off the floor but doesn't really grab until maybe halfway up. I don't see how the drill mod can hurt the transmission or rear any more than a stage 3 clutch from Ram or McCleod that grabs far harder than my clutch does.

Jason

matts22

iTrader: (2)

If you don't mind, or if someone else will reply...what's a rough figure on the cost of putting in better slider keys? Is that the only easy upgrade on the T56?

1ScrudeDude

You took the words right outta my mouth...

SStillSSmokin

I found the billet slider keys for $99(actuallly, someone here directed me to them).Do a search for slider keys. The Gearbox sells a rebuild kit with the kevlar synchro rings for the T-56 for around $160, and the steel 3-4 shift fork for around $75. This would be considered a stage 3 build, parts around $350 plus labor to install. TTP is doing this for $850 right now,parts and labor (post in this forum).I'm not sure if I will do it myself or have a guy I know do it. I'll prob. try to pin him down on a price this weekend. A guy had a link to instructs. w/pics on how to do this, and it didn't look too hard, but I'm a little nervous about screwing something up and trashing the tranny.

Redlinez

iTrader: (5)

The guy who's doing my trans right now said the billet struts have even broken. He thinks the issue causing it is the aftermarket shifters overshifting. I set my Pro 5.0 by the book and he said I need to back each bolt up 1/2 turn. You have me convinced to not do the drill mod now. go to d&dperformance.com if you want them. I'm spending about $650 for my overhaul with a new Z06 slave figured in.

SStillSSmokin

I'm glad I did the drill mod, and recommend it. Your tranny will be able to handle it now and you have the shifter stops so you should be good to go. I will either be getting a Pro 5.0 w/stops, or I may try to see if I can drill and tap holes for stops on my factory Hurst shifter.

Redlinez

iTrader: (5)

Alright, if it doesn't screw up normal driving I"m ok with it. Hell, it was a nightmare figuring out how to get the master out. Would I bleed it like normal or is there a procedure to bleed the master while its out?

SStillSSmokin

I used the instructs. from www.installuniversity.com for the drill mod. Worked great! My master came out easy, but going back in was a Bitch!
Good Luck!

'02 SLP#686

iTrader: (1)

Mine did this before and after the drill mod - it is caused from over zealous shifting. Bent fork, Slider keys, Etc... If you have an aftermarket shifter, adjust bump stops so you do not over-shift the 3-4 shift.

SNAKSLYR

The abrupt clutch action would be from a Spec, they either like being engaged or not. There is not much in between for them. The drill mod is a must, or high RPM shifts will be a problem.

RedLinez, how's it going man. Been a long time since we talked.

Will