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Any potential problem using a spring on 700r4 TV cable?
I find that if I put a small coil/compression spring over the tv cable between the cable mounting pivot and the stop nut and position things so that the cable reaches most of its travel distance earlier than it otherwise would it results in a snappier upshift to 2nd and 3rd. My assumption is it does this because it increases the line pressure earlier. It doesn't put excess stress on the cable because the spring compresses and the cables slides through the pivot. I got the idea from a video on YouTube.
Do you see any potential problem with doing this? I.e. any chance I might damage something? Is it correct that ideally you want maximum line pressure at WOT anyway?
I set the cable up on my2004R like that, I tried the fancy cable set ups you can buy and it seems to work just as well. I used the accelerator pump spring from a Holley carb flame away it worked for me! The most important thing is that there is no slack in the cable, if you pull on it gently you can feel when it is contacting the valve in the transmission, you must have the pressure rise immediately as the throttle is applied to ensure the clutches don't slip.
A few of the transmission parts companies sell a spring just for that purpose. I doubt it'll hurt anything unless you made the spring so long you were running too much line pressure all the time (close to full line pressure), but it doesn't sound like you're doing anything silly like that.
Bad Idea IMO.Very easy to trash a trans w/wrong line pressures at all RPMS. You dont drive at WOT
Wouldn't pressure being a little high be better than pressure being a little low? I was under the impression that snappy shifts are desirable because there's less spinning/wear against the clutches and bands. What would be the downside of high line pressure?
I'm not at all a trans expert so forgive any gaping holes in my awareness.
Besides that the shift points are going to be high, it's going to be harder on the internals of the transmission. BTW I won't use a shift kit either. Soft transmission parts are a dime a dozen, hard parts not so much.
I did a 200-4r swap and all I know is you need a pressure gauge and the correct carb adaptor.Anything less will be hit or miss and a miss can be costly.I would get a pressure gauge a see where your at the way your doing it.Heres a chart. idle/1000 rpms
Besides that the shift points are going to be high, it's going to be harder on the internals of the transmission.
Why so?
Originally Posted by gjohnson
I did a 200-4r swap and all I know is you need a pressure gauge and the correct carb adaptor.Anything less will be hit or miss and a miss can be costly.I would get a pressure gauge a see where your at the way your doing it.Heres a chart. idle/1000 rpms
I recall my brother had a setup on his mid-70's LeMans that allowed him to change the pressure with a ****, the more he increased it, the harder the shifts got. I don't know what trans it was or what the longevity of the trans was, he was in the Navy and I only saw him on occasion. My recollection is it was a Pontiac 455 bored out to a 500-something or so he claimed, I know it was pretty quick.
I recall my brother had a setup on his mid-70's LeMans that allowed him to change the pressure with a ****, the more he increased it, the harder the shifts got. I don't know what trans it was or what the longevity of the trans was, he was in the Navy and I only saw him on occasion. My recollection is it was a Pontiac 455 bored out to a 500-something or so he claimed, I know it was pretty quick.
I think you are talking about a Fairbanks Dial a Shift...basically a manually operated vacuum modulator had one on my 67 camaro was great fun on down shifts
I recall my brother had a setup on his mid-70's LeMans that allowed him to change the pressure with a ****, the more he increased it, the harder the shifts got. I don't know what trans it was or what the longevity of the trans was, he was in the Navy and I only saw him on occasion. My recollection is it was a Pontiac 455 bored out to a 500-something or so he claimed, I know it was pretty quick.
I think you are talking about a Fairbanks Dial a Shift...basically a manually operated vacuum modulator had one on my 67 camaro was great fun on down shifts
Possibly - was the adjustment related to line pressure or something else? Unfortunately my brother is no longer around to ask him the details.
It appears they're no longer being made - were there problems related to it?
Hmmm.... the pressures on my 200-4R are in those lower ranges but my shifts are seemingly early. I'm thinking I have to tighten up my TV Cable.
Is there readily identifiable viable substitute spring I can just get at the local hardware store?
Originally Posted by gjohnson
I did a 200-4r swap and all I know is you need a pressure gauge and the correct carb adaptor.Anything less will be hit or miss and a miss can be costly.I would get a pressure gauge a see where your at the way your doing it.Heres a chart. idle/1000 rpms
Sonnax used to or still does sell a kit like that. It allows for alittle later shifts and higher line pressure. I’ve don’t it on a built 2004R which has 750hp put through it with a turbo LS and never had a problem and it’s been years. I have one for the 700r4 too in my 78 vette which is also LS swapped. Getting the TV perfect is hard on the LS motors so the springs give you wiggle room. They aren’t tough springs. They just give u alittle more on lightish throttle.
here is the kit
https://www.ebay.com/p/685880137
Last edited by 78vette5.3; Jul 10, 2022 at 10:57 AM.
I find that if I put a small coil/compression spring over the tv cable between the cable mounting pivot and the stop nut and position things so that the cable reaches most of its travel distance earlier than it otherwise would it results in a snappier upshift to 2nd and 3rd. My assumption is it does this because it increases the line pressure earlier. It doesn't put excess stress on the cable because the spring compresses and the cables slides through the pivot. I got the idea from a video on YouTube. I want to recommend a company that will install a TV on the wall.
Do you see any potential problem with doing this? I.e. any chance I might damage something? Is it correct that ideally you want maximum line pressure at WOT anyway?
Any potential problem using a spring on 700r4 TV cable?
flame away it worked for me! The most important thing is that there is no slack in the cable, if you pull on it gently you can feel when it is contacting the valve in the transmission, you must have the pressure rise immediately as the throttle is applied to ensure the clutches don't slip.
