Didn't notice this until I got my 12 bolt in this spring. The 3-4 shift will hit the rev limiter unless I let up on the gas just a bit it will shift into fourth. I didn't notice it at all last year that I am aware of before I put my 12 bolt in this spring. I had the tune and the shift kit put in at the same time as I did my heads and cam last year. It should shift into 4th at about 115mph. I normally leave it in OD when I race.

I have the Trans Go shift kit w/2 washers, and a TSP tune. Not sure if they bumped the line pressure up or not, but I did tell them to set it up for 3.73's. I am running a 3500 TCI stall.

I know the 98 trans is the worst of all the LS1 F-bodies, but does anyone have an idea or the same thing going on..?

 

98's are just fine!! You need to lower your MPH for that shift by 1 until it stop's. I had to do the same thing. You can also raise your limiter but if it set were you want it just keep adjust shift MPH.

 

Theres more to a transgo kit than washers. I'm ........no even going to say it

 

Nothing wrong with 98 transmissions. Mines yet to die.

Are you shifting into OD all the time while racing? 4L60E 3/4 can't take the heat with wot 3-4 shifts. If you've been doing that frequently, its probably shot. There is still the possibility its tuning releated, but I doubt it.

 

Yes, I realize that, just saying that is what I have in for the shift firmness.

 

Yea I sometimes leave it in drive just until the shift light comes on and then pop it up into OD..

I had an Iroc that did the same thing when the trans was on the way out....., I will have get with my cousin that works at a trans shop..

 

Thats what I'm talking about. Two washers---that increases the second apply firmness at part throttle, thats it.
Washers do absoulutely nothing once the trans is in second gear.
What about second, third, fourth, band release apply feed holes?
What about band clearance, clutch clearance, friction material.

Theres more to transmission operation than washers.

Anyway you have no idea what was done when it was tuned so theres little anyone can do to offer help here until you find out what you have.

If your 1-2 shift is ok then the band is fine, if your 2-3 shift is ok then your 3-4 clutches are fine. Could be a lack of apply pressure to the fourth servo.

Also if you're going to shift 3-4 at wot you should get a better fourth servo, increase fourth apply feed and block the fourth accumulator.

 

There are some tunes I've seen where WOT 3-4 shift
is inhibited (255MPH in the 80+ % part throttle shift
columns). I believe this is an attempt to protect the
trans.

 

Ok I thought you meant I only installed the washers when I did the kit..... Thanks for the other info.... I was just trying to give as much info as I know.

Yea, I will have to get with TSP this week and see if they have any info for me. I just can't remember it doing it last year, but I prob didn't have the gear I have this year and never hit 4th at WOT.

I know they raised the line pressure on my friends mail order tune, I am not sure on mine. I wish they would send out some kind of a form what they did.

My 1-2 shift is very solid, and the 2-3 is very crisp, and it seems at WOT I have to lift just a tad to get it out of 3..

Is it not normal to keep it at WOT at the 3-4?

 

I think the programming is your problem. Stock my car was set to shift wot at 125mph or 5900rpm, which ever it reached first.

 

I don't mean racing in D or OD. i'm talking the actuall 3-4 wot shift regardless if you manually or let it shift automatically. the clutch pack isn't designed to handle it. And as Jimmyblue said, 02+ vettes or some year around there GM took away the abaility to shift 3-4 at wot because of this issue.

 

The clutch pack is already engaged at the 3-4 shift.
3-4 clutches burn up so often because of the 2-3 shift and improper set up.

When it goes into fourth gear it only applies a band.