1ST GEAR START VALVE BODY
#1
Three Wheelin'
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1ST GEAR START VALVE BODY
Tony,Shane,PeteS and any one interested
The first gear start modification of the valve body allows the A28 transmission to start in first gear at a dead stop. It’s done by modifying your existing valve body (changing valves and springs) it is not an electrical modification that others sell which do not work in the A28 transmissions.
Your valve body is completely rebuilt. All seals are changed; the valves are cleaned and checked for wear. The shift valve springs are changed to extend the shift points. The added benefit of the modified valve body fixes in most cases the 3rd to 4th up shift slip and the delay engagement from park to drive, that a lot of the A28 transmission develop over a period of time. They are two valve bodies congruently installed one in my car the other in Greg’s cars. I want to test mine for a lest 200.miles before I offer it for sale, around $400.
As for the 2nd to 1st downshift at a higher speed, off the top of my head I can’t see why it can not be done. I will work on that modification next, as others have expressed an interest.
Others projects that I’m working on are a stall speed torque converter, externally adjusting the full throttle control pressure up shift points. The other project which I think is the best way to improve the A28’s low end torque is a differential kit to change the rear end ratio. It is still on paper only. Beside my self only one other person know, super secret project. <img border="0" alt="[icon107]" title="" src="graemlins/icon107.gif" /> I will keep any one interested informed as I progress.
<img border="0" alt="[cheers]" title="" src="graemlins/beerchug.gif" />
The first gear start modification of the valve body allows the A28 transmission to start in first gear at a dead stop. It’s done by modifying your existing valve body (changing valves and springs) it is not an electrical modification that others sell which do not work in the A28 transmissions.
Your valve body is completely rebuilt. All seals are changed; the valves are cleaned and checked for wear. The shift valve springs are changed to extend the shift points. The added benefit of the modified valve body fixes in most cases the 3rd to 4th up shift slip and the delay engagement from park to drive, that a lot of the A28 transmission develop over a period of time. They are two valve bodies congruently installed one in my car the other in Greg’s cars. I want to test mine for a lest 200.miles before I offer it for sale, around $400.
As for the 2nd to 1st downshift at a higher speed, off the top of my head I can’t see why it can not be done. I will work on that modification next, as others have expressed an interest.
Others projects that I’m working on are a stall speed torque converter, externally adjusting the full throttle control pressure up shift points. The other project which I think is the best way to improve the A28’s low end torque is a differential kit to change the rear end ratio. It is still on paper only. Beside my self only one other person know, super secret project. <img border="0" alt="[icon107]" title="" src="graemlins/icon107.gif" /> I will keep any one interested informed as I progress.
<img border="0" alt="[cheers]" title="" src="graemlins/beerchug.gif" />
#3
Nordschleife Master
Will you please include me in your "list" - Also, Do you have anyone on the West side that you would recommend for tranny work?. Not that I need any right know, but for future reference.
TIA
TIA
#4
Three Wheelin'
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Hi john,
I made a deal with Shawn for the black car, he is going to bring his transmission as well as the two you have to PA when we pick up those two cars, I am always at the shop as I still turn wrenches, are you going to SITM.
I made a deal with Shawn for the black car, he is going to bring his transmission as well as the two you have to PA when we pick up those two cars, I am always at the shop as I still turn wrenches, are you going to SITM.
#5
928 Barrister
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My '86.5 already does that: it starts out in 1st and shifts quickly to 2nd, unless considerable throttle is applied. I like it that way.
In fact, I like the whole range of functions of this transmission, except the delay when it is placed in reverse and the time it takes to actually engage. I reasoned that it is slow to react for safety reasons, but honestly think it is unsafe to have the delay, as it is sometimes tense if I need to reverse out of someone's way quickly.
I would be interested in a lower differential ratio, since I don't live in Nevada or Montana.
In fact, I like the whole range of functions of this transmission, except the delay when it is placed in reverse and the time it takes to actually engage. I reasoned that it is slow to react for safety reasons, but honestly think it is unsafe to have the delay, as it is sometimes tense if I need to reverse out of someone's way quickly.
I would be interested in a lower differential ratio, since I don't live in Nevada or Montana.
#6
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Steve,
Unfortunately I will not be attending SITM this year. I hope everyone has an outstanding time. It sounds like a great adventure. I am moving, and a few other things cooking in the pot as well.
Unfortunately I will not be attending SITM this year. I hope everyone has an outstanding time. It sounds like a great adventure. I am moving, and a few other things cooking in the pot as well.
#7
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Drew,
You are on the list. What is your zip code, so I can locate a reputable shop?
Ron,
Adjust the throttle valve cable and the Trans will shift later. The delay is a problem; change the fluid and filter it may help. If all goes well with the rear, ratios are 3.17 3.73 3.90 and 4.10
John,
I hope all goes well. I will speak with you tomorrow about your transmission.
You are on the list. What is your zip code, so I can locate a reputable shop?
Ron,
Adjust the throttle valve cable and the Trans will shift later. The delay is a problem; change the fluid and filter it may help. If all goes well with the rear, ratios are 3.17 3.73 3.90 and 4.10
John,
I hope all goes well. I will speak with you tomorrow about your transmission.
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#9
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Steve,
Tomorrow I will talk to you about the rear gears as well. I am interested as well. Might work out to be very good timing for me, seeing I will be dropping my trans. Catch you later, enjoy the night.
Tomorrow I will talk to you about the rear gears as well. I am interested as well. Might work out to be very good timing for me, seeing I will be dropping my trans. Catch you later, enjoy the night.
#10
Steve, You can add me to the list for the Valve body mod. & I would most likely do the 3.17 or 3.73 gears also. Can the valve body mod. be done while the trans. is in the car?
#11
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I don't know about other cars, but with my GTS unless I'm desiring a quick launch, a 1st gear start isn't what I want. I know because early on in the car's life I had a transmission problem where it would only start in 1st gear.
The GTS is low geared enough that 1st gear doesn't provide a smooth launch at low throttle levels. For day to day driving 2nd is really the way to go.
With my GTS, all that I have to do for a 1st gear launch is pull the selector down to position "2" or give the throttle a quick poke (not even down to the downshift detent) and I'll get the growl and go that I want.
BTW, I have a factory rebuilt GTS A/T valvebody for sale. It was used less than one week (long story). I'm offering 50% off a discounted price.
The GTS is low geared enough that 1st gear doesn't provide a smooth launch at low throttle levels. For day to day driving 2nd is really the way to go.
With my GTS, all that I have to do for a 1st gear launch is pull the selector down to position "2" or give the throttle a quick poke (not even down to the downshift detent) and I'll get the growl and go that I want.
BTW, I have a factory rebuilt GTS A/T valvebody for sale. It was used less than one week (long story). I'm offering 50% off a discounted price.
#12
928 Barrister
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Steve:
Thanks for the advice. I have changed the oil/filter when I changed the lines to the cooler which were leaking. I simply live with the "slow into reverse" quirk, because I like all the other aspects of the transmission. I am interested in the lower rear end gears though. According to Kim Crumb, 2.7 was the lowest available, and I could not consider tearing out a great transmission to make that small a change; but the 3.17 or 3.73 sounds good. Please keep us posted. <img border="0" alt="[bigbye]" title="" src="graemlins/xyxwave.gif" />
Thanks for the advice. I have changed the oil/filter when I changed the lines to the cooler which were leaking. I simply live with the "slow into reverse" quirk, because I like all the other aspects of the transmission. I am interested in the lower rear end gears though. According to Kim Crumb, 2.7 was the lowest available, and I could not consider tearing out a great transmission to make that small a change; but the 3.17 or 3.73 sounds good. Please keep us posted. <img border="0" alt="[bigbye]" title="" src="graemlins/xyxwave.gif" />
#13
Steve,
Are you still going to SITM, I was wondering if you could bring your guage set with you. I am still having the no third upshift problem and would like to know if you can show me how to check the pressures in the transmission and adjust them correctly. at this point I think it may be the third gear soloinoid as shifts 1-2 are correct and crisp so I dont think the governer would be the problem. if I have to replace that solinoid how much work is it?
thanks
Are you still going to SITM, I was wondering if you could bring your guage set with you. I am still having the no third upshift problem and would like to know if you can show me how to check the pressures in the transmission and adjust them correctly. at this point I think it may be the third gear soloinoid as shifts 1-2 are correct and crisp so I dont think the governer would be the problem. if I have to replace that solinoid how much work is it?
thanks
#14
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Considering more AT Mods
Hello Steve Cattaneo,
I've been following your posts regarding the 928 automatic transmission discussions. A number of 928 owners in my area are interested in improving the performance of their 4 speed automatics. I am in California.
My car is an 89 S4 which underwent a number of modifications last year.
My transmission was rebuilt in 2001 but it is now leaking from the vent. It will be pulled on the 27th.
I am exploring a series of changes that might improve performance;
1) Raise the stall speed of my torque converter
2) Reprogram the valve body to allow 1st gear starts
3) Add a second to first down shift modification
What are your thoughts on these matters? Are you supplying any of the components required to modify these transmissions?
Thank you
I've been following your posts regarding the 928 automatic transmission discussions. A number of 928 owners in my area are interested in improving the performance of their 4 speed automatics. I am in California.
My car is an 89 S4 which underwent a number of modifications last year.
My transmission was rebuilt in 2001 but it is now leaking from the vent. It will be pulled on the 27th.
I am exploring a series of changes that might improve performance;
1) Raise the stall speed of my torque converter
2) Reprogram the valve body to allow 1st gear starts
3) Add a second to first down shift modification
What are your thoughts on these matters? Are you supplying any of the components required to modify these transmissions?
Thank you
#15
Racer
I've done the 2.72 rear gear ratio change to a a28 and put it into my 79 928...........with the almost 4 to ratio of first gear it is a real screamer and unless you want a really high rpm on the road at cruising speed I don't see the need for a 3.73.I've also been exploring the higher stall speed converters for this trans and its not that hard to find them in the 2200-2400 range as they where factory installed in some cars.