700R4 shifts too early
#1
Instructor
Thread Starter
700R4 shifts too early
So my rebuilt gave out on me after 13 hard years of service. Transmission was damaged past rebuilding so my transmission guy got me another 700R4 from "another vette" Had it rebuilt with a transgo shift kit. I like the feel of the shifts. I don't like when it shifts. Very early for all gears even under wot.
I always manually shifted my car in the past (b&m megashifter). But even holding the car in 1st the transmission will shift at 4800 rpm. That does not seem right. It will hold manual 2nd past 5500 rpm.
TV cable is properly adjusted and I have experimented with the adjustment to see if it affects the shift points. It does not.
I suspect the governor is not out of a vette. Any other ideas?
I always manually shifted my car in the past (b&m megashifter). But even holding the car in 1st the transmission will shift at 4800 rpm. That does not seem right. It will hold manual 2nd past 5500 rpm.
TV cable is properly adjusted and I have experimented with the adjustment to see if it affects the shift points. It does not.
I suspect the governor is not out of a vette. Any other ideas?
#2
Le Mans Master
..... Higher line pressures will affect the governor's shift points ... you need to get a B&M governor recalibration kit and adjust the weights and springs to get the desired shift timing ..... the gov is under a small bowl shaped cover on the drivers side rear of the trans ... some exhaust systems make it a PITA to get at .................
#3
Race Director
Playing with the governor will get you familiar with the underside of your car real quick.
#4
Drifting
I had to re work the governor on my now long gone '88. When it was done, it was shifting at 7200rpm for the motor I built, so there's a ton of play in there. It's not hard to do....the kit gives good directions on the effects of changing the springs and weights. The bad thing is that sometimes it can take a lot of experimenting to get it where you want it. Expect to change it, drive it a few miles, go home, let the car cool, change it and repeat a number of times.
If the motor's a stock L98, I would skip the hassle and just get a correct governor for it. If it's not stock, use the recal kit and get the shifts where you want them. Not much need for manually shifting if you set the governor properly.
Chris
If the motor's a stock L98, I would skip the hassle and just get a correct governor for it. If it's not stock, use the recal kit and get the shifts where you want them. Not much need for manually shifting if you set the governor properly.
Chris
#5
made some visual check on governors coming from an 82 c3 700r4 and an actual c4 governor.while the C4 governor uses light triangle shaped wheights with an heavy blue springs and a light brown one the C3 governor uses heavy quad shaped wheights.total unit weight is:
c3 82 governor= 273 gm
C4 85 governor= 253 gm
a truck governor= 263 gm
c3 82 governor= 273 gm
C4 85 governor= 253 gm
a truck governor= 263 gm
#6
Instructor
Thread Starter
#8
Team Owner
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If this was mine, I'd ask the trans guy for my other governor back. Feel free to explain why. Recalibrating the new governor will not be an easy job. The cover is a bitch to remove and replace. If you have a good friend whom has experienced the process, bring him into the project. OTOH maybe you'll be fortunate and hit the nail on the head first try. For which I hope will be the case.
#10
Race Director
When I was running a 700R4, I spent a lot of time playing with weights and springs. I found it difficult to nail the wot shift points and still have the car shift perfectly on the street. The weights affect mainly wot shifts but also affect part throttle shifts and vice versa for the springs. I mixed and matched springs and weights; actually filing weights or brazing weights to get it as perfect as possible. Finally, I just went with a computer controlled 4L60E which allows me to dial in shift points with a laptop. I am somewhat of a perfectionist and close wasn't good enough for me.
#11
Instructor
Thread Starter
I was very happy with the trans before it blew. It would shift too early as well but with the ratchet shifter, I could hold the gear I was in as long as I wanted. Its bad enough when my kids ignore me, but I draw the line at my trans ignoring me.
#12
Race Director
And more importantly, the wife?
#13
when my trans was rebuild the shop changed the governor and for sure they didn't consider that a Corvette governor is a CORVETTE governor not a mini-van governor...So i'm now using my auto like a stick trans continuously shifting by hand only to hold the gear and let it change when i want...the same issue and solution is only mess with the governor weights to have it tuned
#14
Instructor
Thread Starter
when my trans was rebuild the shop changed the governor and for sure they didn't consider that a Corvette governor is a CORVETTE governor not a mini-van governor...So i'm now using my auto like a stick trans continuously shifting by hand only to hold the gear and let it change when i want...the same issue and solution is only mess with the governor weights to have it tuned
#17
Heel & Toe
Yes I to bought the B M spring kit and had great luck with it. Shifts at 6500 manually and about 5200 in drive. Sucky part is taking out the y pipe to change springs.
#19
Instructor
Thread Starter
Problem resolved! I finally got around to installing my new sonomax blue governor. This did not resolve the issue, in fact I could not feel any difference whatsoever. I installed a Transgo reprograming kit with "Gear Command". Now it holds the gear in whatever I manually select.
#20
Heel & Toe
Problem resolved! I finally got around to installing my new sonomax blue governor. This did not resolve the issue, in fact I could not feel any difference whatsoever. I installed a Transgo reprograming kit with "Gear Command". Now it holds the gear in whatever I manually select.