Why only 125mph but no faster?
#1
Junior Member
Thread Starter
Join Date: Jan 2002
Location: B-Town
Posts: 35
Likes: 0
Received 0 Likes
on
0 Posts
Why only 125mph but no faster?
Ok I got my gas rammed to the floor I get my car up to 3rd gear where you have to let off the accelerator for the automatic trans to shift into 4th gear, well when its in 4th gear the car wont go over 3000 rpm and if I give it more gas it shifts down to third. Has anyone else had this problem??? If so how did you fix it?
Thanks Chad
Thanks Chad
#3
Supreme Member
Join Date: Jan 2001
Location: Someone owes me 10,000 posts
Posts: 7,164
Likes: 0
Received 1 Like
on
1 Post
Car: 99 Formula
Engine: LS1
Transmission: T56
Axle/Gears: 342
Are you referring to the downshift problem. If so, go to you local GM dealer they sell a part just for this. I hear it's better than the B&M one.
#4
Supreme Member
Join Date: Dec 2001
Location: Greenville S.C.
Posts: 1,158
Likes: 0
Received 0 Likes
on
0 Posts
Car: 87 Grand National
Engine: 3.8 SFI Turbo
Transmission: BRF 200R4
You need a new upshift valve. Go to a GM dealer and get a new one. They should know exactly what you need.
#5
Junior Member
Thread Starter
Join Date: Jan 2002
Location: B-Town
Posts: 35
Likes: 0
Received 0 Likes
on
0 Posts
Thanks for all of you that knew what you were talking about. I am only a new member but I think that people that dont know what there talking about such as patrick007 shouldn't be allowed in these forums. Thanks to all the knowledgable 3rd gen owners.
#6
Supreme Member
Join Date: Jul 2001
Location: Pueblo Co
Posts: 3,974
Likes: 0
Received 0 Likes
on
0 Posts
Car: 1989 C4
Engine: L98
Transmission: 700r4
Axle/Gears: 307
Originally posted by FoREEL
Thanks for all of you that knew what you were talking about. I am only a new member but I think that people that dont know what there talking about such as patrick007 shouldn't be allowed in these forums. Thanks to all the knowledgable 3rd gen owners.
Thanks for all of you that knew what you were talking about. I am only a new member but I think that people that dont know what there talking about such as patrick007 shouldn't be allowed in these forums. Thanks to all the knowledgable 3rd gen owners.
Kinda harsh dude
Patrick does have a point. Its quite possible that your car hit the limiter (top speed set into your ecm) or your just maxed out. My old 305 would max out at 4k 115 mph and it was a 3 speed 200c non computer controlled. But it does sound like the upshift valve will help you at least keep it in OD for a bit longer.
SSC
#7
Supreme Member
Join Date: Jan 2001
Location: Someone owes me 10,000 posts
Posts: 7,164
Likes: 0
Received 1 Like
on
1 Post
Car: 99 Formula
Engine: LS1
Transmission: T56
Axle/Gears: 342
What car and motor do you have? If you got an LG4 or LO3, I don't think stock you're going to have enough power in OD to push the car much faster.
Trending Topics
#8
TGO Supporter
Join Date: Jul 1999
Location: The Bone Yard
Posts: 10,907
Likes: 0
Received 3 Likes
on
3 Posts
Car: Death Mobile
Engine: 666 c.i.
Patrick and SSC are correct - certain engines DO have a speed limiter set in the eprom. Generally, if your car did not come out with Z-rated tires, GM gave you a speed limiter set between 120-125 mph.
There is also an "upshift" problem with the stock 700R4/4L60. Where the tranny will not upshift into 4th @ WOT. Check out the Tranny Board for the proper fix.
There is also an "upshift" problem with the stock 700R4/4L60. Where the tranny will not upshift into 4th @ WOT. Check out the Tranny Board for the proper fix.
#9
Supreme Member
iTrader: (2)
Join Date: Apr 2000
Location: South Windsor, CT
Posts: 1,316
Likes: 0
Received 229 Likes
on
193 Posts
Car: '89 GTA
Engine: ZZ6TPI
Transmission: T56
Axle/Gears: Borg Warner 3.70:1
A word about the GM upshift valve kit. After using both the GM and the B&M, the GM is much better. The B&M valve can be installed at home, but I would recommend having a transmission shop or the dealer install the GM part. It comes with the valve, some springs, and spacers, and no instructions. It will allow WOT in 4th at anything above 50mph, where as the B&M only allows it for 3/4 throttle.
#10
Junior Member
Thread Starter
Join Date: Jan 2002
Location: B-Town
Posts: 35
Likes: 0
Received 0 Likes
on
0 Posts
Originally posted by TransamGTA350
A word about the GM upshift valve kit. After using both the GM and the B&M, the GM is much better. The B&M valve can be installed at home, but I would recommend having a transmission shop or the dealer install the GM part. It comes with the valve, some springs, and spacers, and no instructions. It will allow WOT in 4th at anything above 50mph, where as the B&M only allows it for 3/4 throttle.
A word about the GM upshift valve kit. After using both the GM and the B&M, the GM is much better. The B&M valve can be installed at home, but I would recommend having a transmission shop or the dealer install the GM part. It comes with the valve, some springs, and spacers, and no instructions. It will allow WOT in 4th at anything above 50mph, where as the B&M only allows it for 3/4 throttle.
Aight, I got an LB9, do you know an approx. on how much it would be to have a tranny shop put it in? Is it really hard to put it in? Do you got to drop the trans?
#11
Supreme Member
iTrader: (2)
Join Date: Apr 2000
Location: South Windsor, CT
Posts: 1,316
Likes: 0
Received 229 Likes
on
193 Posts
Car: '89 GTA
Engine: ZZ6TPI
Transmission: T56
Axle/Gears: Borg Warner 3.70:1
It is not "really hard" to put in. In fact, it's not hard at all. The problem comes in with knowledge of transmissions. The tranny can stay in the car, but the valve body must be dropped, and a few other things have to be taken apart. Like it said before, the GM kit doesn't come with any instructions, so you're on your own, and it comes with a bunch of peices. If you got a book on the 700R4 and familiarized yourself with it, then you could do it yourself. Mine was done at a transmission shop while it was being rebuilt, so there was no labor charge. I would imagine it would be about 1.5-2 hours of labor at around $60 per hour, and in my opinion well worth it.
#13
Supreme Member
Join Date: Jul 2001
Location: Pueblo Co
Posts: 3,974
Likes: 0
Received 0 Likes
on
0 Posts
Car: 1989 C4
Engine: L98
Transmission: 700r4
Axle/Gears: 307
Originally posted by FoREEL
Im not in to tranny's at all. Damn 120$? You say B&M's is easier but not as good? Whats wrong with the B&M?
Im not in to tranny's at all. Damn 120$? You say B&M's is easier but not as good? Whats wrong with the B&M?
I just installed the B&M upshift valve in my tranny and it was straight forward (good directions) and took 25 min to install but the tranny was out.
SSC
#15
Supreme Member
Join Date: Dec 2000
Location: Springfield, MO, USA
Posts: 1,536
Likes: 0
Received 0 Likes
on
0 Posts
Car: 1986 Trans Am, 1991 Firebird
Engine: 355 TPI, 3.1L V6
Transmission: 700R4 in both
It doesn't matter if you're in 3rd or OD at WOT throttle anyhow (talking EFI here) because in the computer chips there's a TCC unlock prevention threshold that is set to a certain MPH (about 85mph if memory serves) that will automatically lock up the TCC once you hit that speed regardless of what gear you're in. Real world gains with the upshift kits are very minimal and not worth the money IMO.
Thread
Thread Starter
Forum
Replies
Last Post
no green
Organized Drag Racing and Autocross
7
03-03-2016 05:19 PM