Chewbacca Posted August 16, 2018 Share Posted August 16, 2018 Hi all Looking for some help My 64 Riviera with the 425 engine and ST400 automatic box will not shift up from first gear. It was running fine for 40 miles or so and then refused to shift up. The transmission fluid is the correct level and clean/pink. Certainly not burned. What else could it be? Link to comment Share on other sites More sharing options...
RivNut Posted August 16, 2018 Share Posted August 16, 2018 Lost vacuum to the modulator. Link to comment Share on other sites More sharing options...
Chewbacca Posted August 16, 2018 Author Share Posted August 16, 2018 Thanks Vacuum comes from the carb inlet? Would the fact it is a replacement (Edelbrock) carb make a difference? Link to comment Share on other sites More sharing options...
RivNut Posted August 16, 2018 Share Posted August 16, 2018 Where exactly is the vacuum port on the Edlebrock carb? Link to comment Share on other sites More sharing options...
oneriviera64 Posted August 16, 2018 Share Posted August 16, 2018 My car has Edelbrock 1406 and the correct transmission vacuum port is driver's side port in front side of the carburetor. Previous owner had connected PCV, transmission and power brakes all together to the back side of the carburetor which in result caused very poor power braking effect, high rews for gears to change and rough gear change. I rerouted all vacuum lines like it is stated in Edelbrock manual and car can stop now with 4 wheels blocking and gear shifts really smoothly on low rpms. Here is good video guide for Edelbrock: Link to comment Share on other sites More sharing options...
RivNut Posted August 16, 2018 Share Posted August 16, 2018 The original line from the carb to the vacuum modulator is a steel line. In order to connect the line as Edelbrock states, you'll need to run a flexible line to the steel line or run a flexible line all the way to the transmission. Unless you want to custom bend a solid line. Captain Obvious Link to comment Share on other sites More sharing options...
Seafoam65 Posted August 16, 2018 Share Posted August 16, 2018 You guys are barking up the wrong tree........if you have no vacuum to the modulator the symptom is a very late shift, not no shift at all. The most likely culprit is the governor gear, which is located behind the square metal cover with four bolts, one on each corner that is bolted to the driver's side of the transmission at the rear. Remove the cover and inspect the gear......they are known to to have the center totally break out of them like an apple that has been cored (the gear is made of plastic) The other possibility which is less likely is that the kickdown is stuck. You can diagnose this by unplugging the wire on the side of the transmission for the kickdown and see if it will shift after doing that. 2 Link to comment Share on other sites More sharing options...
RivNut Posted August 16, 2018 Share Posted August 16, 2018 53 minutes ago, Seafoam65 said: You guys are barking up the wrong tree........if you have no vacuum to the modulator the symptom is a very late shift, not no shift at all. The most likely culprit is the governor gear, which is located behind the square metal cover with four bolts, one on each corner that is bolted to the driver's side of the transmission at the rear. Remove the cover and inspect the gear......they are known to to have the center totally break out of them like an apple that has been cored (the gear is made of plastic) The other possibility which is less likely is that the kickdown is stuck. You can diagnose this by unplugging the wire on the side of the transmission for the kickdown and see if it will shift after doing that. 2 Link to comment Share on other sites More sharing options...
telriv Posted August 17, 2018 Share Posted August 17, 2018 With NO vacuum or the hose off the modulator the trans. WILL NOT upshift until the governor lets it shift, like at wide open throttle should automatically shift between 440-4800RPM's. Link to comment Share on other sites More sharing options...
first64riv Posted August 17, 2018 Share Posted August 17, 2018 I'm no guru but I've been doing external maintenance on my transmission lately. I would first start with the easy stuff: check for a good vacuum to the modulator. If it's good, then maybe you're modulator is faulty or stuck. The modulator is fairly cheap and it might be worth purchasing just to rule out a variable. Thank you Chris Link to comment Share on other sites More sharing options...
telriv Posted August 17, 2018 Share Posted August 17, 2018 Another thing could be the downshift switch is stuck in the downshift position. Link to comment Share on other sites More sharing options...
Chewbacca Posted August 17, 2018 Author Share Posted August 17, 2018 Thanks guys. My mechanic is now telling me it may be the actuator on the side of the gearbox (is this what you are calling the modulator?) If so, where would I source one? I'm in the UK but happy to buy from US companies. Link to comment Share on other sites More sharing options...
Chewbacca Posted August 17, 2018 Author Share Posted August 17, 2018 OK guys, I've found a few sources. Why are Standard products twice the price of everyone else (eg FRAM)? Are they higher quality or just ambitious marketing of the same Chinese sourced products? Link to comment Share on other sites More sharing options...
first64riv Posted August 17, 2018 Share Posted August 17, 2018 (edited) 4 minutes ago, Chewbacca said: OK guys, I've found a few sources. Why are Standard products twice the price of everyone else (eg FRAM)? Are they higher quality or just ambitious marketing of the same Chinese sourced products? Here is the one I bought https://www.amazon.com/gp/aw/d/B0184BF00G/ref=oh_aui_i_sh_in_o0_img?ie=UTF8&psc=1 It works fine for me but there may be other recommendations. Edited August 17, 2018 by first64riv (see edit history) 1 Link to comment Share on other sites More sharing options...
Chewbacca Posted August 27, 2018 Author Share Posted August 27, 2018 (edited) Unfortunately none of the above seem to be the issue so the box has gone an expert to analyse and possibly rebuild. Very disappointing. I’ve managed to get 40 miles out of it during the best summer the UK had for 40 years☹️ Edited August 27, 2018 by Chewbacca (see edit history) Link to comment Share on other sites More sharing options...
first64riv Posted August 27, 2018 Share Posted August 27, 2018 Keep us posted! Link to comment Share on other sites More sharing options...
Grimy Posted August 28, 2018 Share Posted August 28, 2018 I had the same problem with a 1964 Cadillac Fleetwood 60S with TH400, and the issue was the 4-inch piece of rubber tubing connecting the steel vacuum tube to the modulator at a 90-degree angle and thus subject to a lot of flexing. I had to look closely at the small piece of hose to determine that it was compromised. You say you've checked "all of the above," but did you replace that PIA small piece? I was 10 miles from home when this happened to me, and I found that if I ran the car up to 30 mph in first (no upshift), momentarily placed the selector in neutral, then back to drive, I was in 3rd gear. For those more skilled than I in TH400s, you might want to tell them whether that trick works on yours. Link to comment Share on other sites More sharing options...
lrlforfun Posted August 28, 2018 Share Posted August 28, 2018 OK Riviera People: I have had several with similar symptoms. This is NOT a scientific diagnosis and that's what's needed on your unit. In my cases both cars had stuck valve bodies. Mitch Link to comment Share on other sites More sharing options...
Chewbacca Posted August 29, 2018 Author Share Posted August 29, 2018 On 8/16/2018 at 4:17 PM, Seafoam65 said: You guys are barking up the wrong tree........if you have no vacuum to the modulator the symptom is a very late shift, not no shift at all. The most likely culprit is the governor gear, which is located behind the square metal cover with four bolts, one on each corner that is bolted to the driver's side of the transmission at the rear. Remove the cover and inspect the gear......they are known to to have the center totally break out of them like an apple that has been cored (the gear is made of plastic) The other possibility which is less likely is that the kickdown is stuck. You can diagnose this by unplugging the wire on the side of the transmission for the kickdown and see if it will shift after doing that. Congrats. The gearbox expert says the governor is jammed but not broken. Reckons taking apart, cleaning and reassembly should cure the problem. Hope so! This is a $200 fix compared to a $1000 rebuild. Link to comment Share on other sites More sharing options...
Scott Mckenzie Posted August 29, 2018 Share Posted August 29, 2018 Maybe you`ll get some driving in this Summer after all ! Link to comment Share on other sites More sharing options...
Chewbacca Posted September 11, 2018 Author Share Posted September 11, 2018 OK, so this issue is fixed but what I have noticed now that I am driving it some more is that when I pull up to a junction, if I sit on the brakes with the car in D, there is a knocking noise from the rear of the car. If I shift into neutral, it disappears. It is not there when moving. Any ideas? Link to comment Share on other sites More sharing options...
Seafoam65 Posted September 11, 2018 Share Posted September 11, 2018 You are hearing the "Riviera Rattle" which is caused by the pulsing of fuel through the rear fuel return line to the tank. My car does the same thing sometimes when I'm sitting at a red light. Link to comment Share on other sites More sharing options...
Chewbacca Posted September 11, 2018 Author Share Posted September 11, 2018 Any cure? Link to comment Share on other sites More sharing options...
Seafoam65 Posted September 11, 2018 Share Posted September 11, 2018 Supposedly there is a way to secure the line where it can't ratlle.......there was a long discussion on this in a previous blog that you should be able to find. Link to comment Share on other sites More sharing options...
Riviera63 Posted September 12, 2018 Share Posted September 12, 2018 9 hours ago, Chewbacca said: Any cure? 8 hours ago, Seafoam65 said: Supposedly there is a way to secure the line where it can't ratlle.......there was a long discussion on this in a previous blog that you should be able to find. Here is the link: Link to comment Share on other sites More sharing options...
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