Vacuum modulator th400. As you open the throttle and begin to accelerate the engine vacuum drops. Jan 13, 2021 · No vacuum leaks that I can find although the engine vacuum is a little low relative to what I had on the dyno (7 vs 11). Does there exist a conversion that will convert a TH400 from vacuum modulator to a TV cable operation. Problem being very low manifold vacuum at idle ~10" which results in the modulator being inactive -allowing highest possible pressure at idle => hard jerk when May 6, 2014 · May 2002. $14. I bought one today from the local parts store and tested with the following results: TH400 Modulator. Be sure to use an adjustable modulator. I understand that the vacuum modulator only affects part-throttle shifts, and that WOT shifts are determined by the governor. TCI 350001 GM TH350/TH400 Adjustable Vacuum Modulator Valve. Lines are available in OM steel Apr 4, 2010 · Yeah, Wade is correct, the vacuum hose from the vacuum modulator should be hooked up to direct manifold vacuum. #1 · Jan 8, 2010. Adjustable Vacuum Modulator. #5 · Apr 15, 2009. Henry Ford, on the stock market. 109 posts · Joined 2010. Apr 5, 2015 · Low vacuum means W. TCI Auto GM Th350/Th400 Adjustable Vacuum Modulator $ 25 99. Jan 12, 2002 · Location. $3099. this is done to save energy in the power train by reducing the demand on the oil pump Dec 7, 2023 · The typical cost to replace a faulty transmission vacuum modulator ranges between $150 and $390 for parts and labor. The valve fits into the transmission housing and controls vacuum used for shifting and kick-down functions. Nov 30, 2020 · Delayed and harsh shifts, low vacuum at the modulator would be about 95% of what I would be looking for. #3 · Jan 22, 1999. Automatic Transmission Master Repair Kit, Ford, Lincoln, 4R100, Kit. #1 · Jul 19, 2008. . Sep 21, 2009 · 850 posts · Joined 2005. Mar 2, 2013 · Re: Vacuum Modulator Questions. It was in rough shape. Jul 27, 2010 · On a TH400 that should only affect the kickdown for passing gear I think. SHARE POST #2. com Should just be the o-ring. A port that comes directly out of the intake manifold will provide the signal that the modulator needs. Lines are available in OM steel Apr 29, 2004 · 5. We carry transmission vacuum lines for GM Powerglide, TH350, TH400; Ford C-4, C-6, Fordomatic; Chrysler Torqueflite 727, and many others. com/user/BMrac Nov 21, 2009 · TH400 Vacuum Modulator Change. e. patreon. More complex modulators for automatic GM, TH350/TH400 Adjustable Vacuum Modulator. #1 · May 27, 2008. $209. When I am at WOT making a pass it will not shift into third gear. BTW the converter is 4,000 stall. The modulator is connected to the engine by using steel tubing and rubber hosing. i have a th400 tci streetfighter trans with an adjustable shift modulator ,how do you adjust, is it a small flat head screw driver or allen wrench which wat to delay part throttle shifts a bit (1st is to short) how far is fully advanced,i only need to delay 2-4 miles Oct 17, 2011 · The vacuum modulator is plumbed from the intake manifold to the modulator on the trans. The current unit in my '68 has developed a leak in the crimp area and is making a mess on the exhaust (not to mention a trail of smoke behind the car), so I have bought a replacement unit. #1 · Nov 25, 2016. 50. Start your automatic transmission vacuum line replacement now at Summit Racing! Replace your rusted or worn automatic transmission vacuum lines with something better. I adjusted it out two turns and it was a little better. Two questions: First is around torque converters and a recommendation for that: Having a TH400 built to go behind what will be a newly built SBC 383. As a part of the transgo reprogramming kit, you can remove that spring to firm up shifts. A higher stalling toprque converter is akin to slipping the clutch in a dirt bike. Currently, if I sit at a light for more than 20 seconds the truck shifts into neutral. 229 posts · Joined 2006. 1967-1969 Camaro Vacuum Modulator Line, Automatic Transmission, TurboHydra-Matic 400 (TH400), Zinc Plated Re: TH400: Leaking vaccum modulator 03-14-05 11:41 AM - Post# 648640 In response to Broncoholics. However, the total cost can vary depending on the specific vehicle and who does the work. without the kickdown hooked up it is totally reliant on tailshaft speed and the modulater signal to shift. Aug 1, 2014 · A th400 has an internal electric kick down solenoid. Part Number: FTI-F4046. Designation Change: 3L80; 3L80-HD (1991) Matching Turbo Hydra Matic 375s, 400s and 475s with Associated Applications. The Assembly Manual shows this line has a bracket atached and bolts to one of the transmission housing bolts. You will need to leave the modulator unless you have replace the valve body with a manual unit. The second is to convert to a fully manual valve body and shift Dec 26, 2004 · 683 posts · Joined 2002. Hi All, Would like some info from anyone who has expereince changing the vacuum modulator on a TH400. Search this Thread. , so the modulator delays upshift. Jul 15, 2002 · C3 Tech/Performance V8 Technical Info, Internal Engine, External Engine, Basic Tech and Maintenance for the C3 Corvette. #1 · Sep 20, 2009. « Reply #1 on: March 03, 2013, 10:20:47 AM ». 0 out of 5 stars 3 ratings Transmission. if it is not hooked up it will shift somewhat inconsistently. 2 or there abouts, had a Th400 and vacuum modulator. Mar 26, 2020 · SUBSCRIBE to the channel if you haven't already done so. Learn more. Reply Subscribe. I explain what the vacuum modulator is and its primary function and go for a test driveThere are more FTI Performance Automatic Transmission Modulators F4046. Jan 22, 2004 · It takes a special brass fitting that connects to the passenger side upper intake manifold. Apr 11, 2010 · T-400 modulator line. May 17, 2010 · 49855 posts · Joined 2005. Vacuum modulator line replacement. Super easy to replace. Pump it up to 20 inches of vacuum and see how long it holds the vacuum. #1 · Jul 27, 2010. I am not sure which port it should connect to on the intake. Nov 13, 2005 · So my solution was to throw the modulator in the box with the rest of the crap I just dont want to throw away yet, and put the vacuum modulator back in. Georgetown, TX. FTI Dec 29, 2009 · from Metro Hiram. U. All good with the case (lugs, threaded Mar 24, 2017 · Vacuum Modulator Retainer Clip Hold-Down Bracket, compatible with TH400. I also recently readjusted my vacuum advance. Jul 27, 2010 · 7640. The governor pressure is 0 because there is no tailshaft RPM (no road speed). Any issues with that? I am considering moving to a full manual valve body to eliminate this problem. which mine had a plug. Also included is an additional hose and oring to use later. Straight manifold vacuum IS too much. Hoping to get my hands on one this week. You have now fixed the stall issue, and to get your ripping 1-2 shifts back, need a little former shift kit. TH400 modulators are a type of valve that is designed to assist in controlling shift patterns. Apr 24, 2018 · PATREON - https://www. (79 C20) I took the truck for a test drive and everything went fine. O. Compare. That's what is in all the CUCV Military trucks is the 6. "As betting at the race ring adds neither strength nor speed to the horse, so the exchange of shares in the stock market adds no capital to business, no increase in the production and no purchasing Modulator Valve, 1965-77 GM Cars, TH-350/TH-400 Automatic Transmission. All TH400 variants come from the factory with a metal tag riveted in place on the passenger side of the unit. Car is between 3100 - 3200 pounds and street driven only, no track or strip. To decrease or eliminate harsh shifts, turn adjusting screw in modulator in a counter-clockwise direction. Thread Tools. My car is equipped with power disc brakes, cowl induction, and A/T so it has Dec 26, 2004 · 683 posts · Joined 2002. They should have them on the shelf. Details. I put a smoke machine from the transmission and see that the smoke goes all the Jun 12, 2015 · Proposed Troubleshooting: General: Check transmission fluid level warm and in Park. These vacuum lines are an authentic reproduction of original equipment and are necessity for proper transmission operation. Perfect for High-Performance, Heavy-Duty, Racing and Regular-Duty transmissions Fits the following General Motors Transmissions: TH-400 (TH400, THM-400, THM400) 3L80/3L80HD GMC, Chevy, Pontiac, Oldsmobile, Cadillac Years: 1964 and Up Nov 25, 2016 · L. TH400 Adjustable Vacuum Modulator Kit. Posts. the t-400 trans was set up to shift early with the diesel engines that would be the governor and valve body too. TH-400 . Oct 26, 2014 · I have a freshly rebuilt turbo 400 that shift very late under part throttle acceleration. I would hope our resident transmission "builder" would know that. Manifold pressure at idle runs 15 in/hg. Shut off the engine and allow it to cool for 20 minutes. com/OUR WEBSITE - www. Step 5. FTI Offers a wide variety of TH400 Parts including racing transmisison pumps, valve bodies, gear sets and deep transmission pans. Jumpstart Your Next Project! Find Parts and Accessories th400 vacuum modulator KEYWORD and get Free Shipping on Orders Over $109 at Summit Racing! Vacuum Modulator Line, TH400 Transmission, 1969-70 Bonneville/Catalina, 4BBL. Aug 8, 2017 · Install: B&M Vacuum Modulator for GM TH350 & TH400 Automatic Transmissions 20234. The line comes off the vacuum tee on the intake manifold, and rather than go directly to the modulator, it attaches to one end of cylinder (about 4 inches long and 1 1/2 in tall) and then out the other end of the cylinder to the modulator. Have no fear, it can be done. This is pulling vacuum from the same place as the brake booster. #1 · Apr 11, 2010. First I have well over 200 passes on the transmission and it came with the car when i bought it, so I knew it was going to happen sooner or later. Allows you to Tailor Shift Points. While I had the 400 trans apart, I decided to clean the valve body up and make sure it was assembled correctly. Feb 9, 2011 · th400 modulator Jump to Latest Follow 6K views 3 replies 4 participants last post by jtamulonis Feb 10, 2011 TH400 Adjustable Vacuum Modulator Kit. 107 posts · Joined 2009. Apr 13, 2020 · The engine vacuum at idle causes a very low modulator pressure (nearly 0). However, as I stated above, the modulator valve (in the case) might be sticking when fully inserted into the Jun 1, 2014 · Vacuum modulator? I recently had to put a new shifter cable on my Hurst ratchet shifter on a th400. This causes the modulator pressure to rise. Jump to Latest Follow. anthony Discussion starter. comFOLLOW US ON IN May 20, 2013 · (vac modulator on a TH400). MrQuick ΜΟΛ'ΩΝ ΛΑΒ'Ε. Usually I'm pretty good at find this stuff, but seems like everyone lists the modulator assembly (which mine is fine), but not just a replacement o-ring. Aug 1, 2012 · Other common problems our experts experience in both the TH350 and TH400 is the amount of automatic transmission fluid (ATF) in the vacuum modulator. 13K views 8 replies 3 participants last post by Unstable Apr 12, 2010. This works well for superchargers and on diesel motors without a vacuum regulator. Application: TH350 1969-1986. 0 5. Mar 24, 2023 · Product Description. Fits 1970–1972 Buick Skylark, 1970–1972 Pontiac GTO, 1970–1972 Pontiac LeMans, 1970 Pontiac Tempest, , , , . I bought a B &M adjustable modulator. #1 · Dec 26, 2004. All Turbo 400's use an electrical solenoid to control the kick-down. Remove the vacuum pump from the hose. #1 · Apr 29, 2004. In the process of running new cooler lines today, the steel vacuum line going to the modulator fell apart. It must hold the vacuum for a few minutes without dramatic loss of vacuum or the diaphragm is bad. I am restoring a 1970 SS L34/M40 car and I have a question about the proper routing of the steel vacuum line that goes from the intake to the vacuum modulator. Services. Buy in monthly payments with Affirm on orders over $50. Turning the screw inwards will make the shifts later and firmer. com FREE DELIVERY possible on eligible purchases Amazon. I have surmissed this is due to the lower than stock manifold vacuum; i. No speed, no vac advance & 1,200 RPM – D/N/P=150 Jun 16, 2010 · How is a vacuum modulator going to raise shift points "under power"? It's for part throttle operation, not WOT or near WOT. loafing1 Discussion starter. Feb 23, 2004 · Re: Transmission modulator line on TH400 (73'Vette) 73, The modulater line goes up from the modulator, passenger side, then attaches to the top vacuum port on the manifold just behind the carburetor with a very short vacuum hose ta a "Y" fitting made to attach two vacuum lines. For TH400 only. If vacuum is less at the bottom run a rubber hose from a good vacuum source to the modulator We carry transmission vacuum lines for GM Powerglide, TH350, TH400; Ford C-4, C-6, Fordomatic; Chrysler Torqueflite 727, and many others. I had planned on using an ATI SuperCase for my build, but due to a lengthy backorder wait time (ordered in April), I decided instead to just use a stock TH400 case and use the money elsewhere. Or fastest delivery Feb 23 - 26. All good with the case (lugs, threaded Jan 22, 1999 · 68502. Hard line from manifold to modulator with a short rubber line at each end. Jun 30, 2019 · TH400 Modulator Valve Not Seating Completely. Aug 12, 2023 · A new vacuum modulator for TH350 and TH400 Transmissions, 1965 & up. Check vacuum advance connected, clear and operable. Special Order. TCI. Select Store. 2 and Th400. Push in type, black & red stripe, adjustable. a modified governor would help for later shifts and that vacuum modulator as mentioned. Rear Axle. When I removed the 2-3 modulator valve components out, the 2-3 valve spring came out in many pieces (this is what ron sessions book calls it, referring to #20 on page 125). The vacuum modulator position TH400 transmission turbo controls the amount of vacuum applied to the transmission gears. May 26, 2005 · Red Strip Modulator for T-400. 2's with Th400's the Vac Modulator line is connected to the vacuum pump. like 3,500-4'000 rpm. #4 · May 17, 2010. Makes. Problem being very low manifold vacuum at idle ~10" which results in the modulator being inactive -allowing highest possible pressure at idle => hard jerk when The TH400 uses an electronic kick-down mechanism, which means that there will be an electric plug on it. Louis should have plenty May 4, 2016 · To eliminate soft shifts or slippage, turn adjusting screw in modulator in a clockwise direction. com: Vacuum Modulator Retainer Clip Hold-Down Bracket With Bolt, fits GM TH400 Heavy Duty 8627650K : Automotive May 7, 2019 · First to make sure that you have vacuum at the modulator. Disconnect the hose at the modulator with the motor running. This vacuum modulator valve is a must-have for all TH350 and TH400 automatic transmissions. F-350 DRW Diesel w/5th wheel RV. There is a hose from that to the AC/Heat, IP and Correct pre-bent vacuum modulator line for TH-400 automatics in original steel. Since Diesels don't produce vacuum, they put a vacuum pump either on the back of the motor or later models have a belt driven one. Our trio of professionals suggested to check the modulator, pull the vacuum line off and check for signs of ATF in the hose or the the nipple of the modulator. Sponsored by: TH400. You can find all the fittings/line in the Zip catalog :thumbs: This Apr 15, 2009 · 10765 posts · Joined 2002. New O-ring Helps Stop Leaks. TCI Automotive862566. Any thoughts on squishy power-robbing TH400's? TH350 / TH400 Cable Operated Modulator. I'm trying to install my vacuum modulator line for a turbo 400 and 396/325. Please subscribe to our YouTube channel: https://www. When there is more vacuum from the engine, the transmission will have an easier shift feel to it. It is a small, round device that sits on the transmission’s output shaft. One side of the T went to the modulator, and the other side got a vacuum cap with a Sep 8, 2016 · This all tells me that a combo, if running properly, is understalled and perhaps under geared for the engine setup. Sponsored. I just finished a build of a 350 SBC (stroked 383) with HP cam, intake, carb, etc. 73 open rear. Vehicle TCI MOD35820R - Adjustable Vacuum Modulator GM TH350. Th350 has the vacuum modulator in the back, and the TH400 keeps it on the side. What can I do to make it shift earlier under light throttle. ATP Automatic Transmission Master Repair Kits FM-40. onlychevrolets, Dec 29, 2009. Steel line with the correct bends. 78 posts · Joined 2003. Concours quality. May 2, 2019 · Brand: Rostra (Modulator) and Tri Component (Bracket) Modulator is Pre-Tested and Calibrated. Typical: $39. This line goes from the carburetor to the transmission modulator. Fits 1965–1976 Buick Riviera, 1965–1972 Buick Skylark, 1965–1976 Cadillac DeVille, 1965–1976 Cadillac Eldorado, 1965 Aug 13, 2007 · I have a '69 Malibu with a mild 454, TH400, and 2. TV-906 Shown. Check line pressures: Road, variable speed 60psi min to 150 forward gears, steady state 150 and 95-260 in reverse. Heavy Duty. 99 delivery Feb 26 - 28. Sep 9, 2009 · th400 vacuum Modulator. I'd like to replace it with the original style modulator, but all I can find are the newer style ones (smaller, gold color with red band). 2L diesel switch-overs. I have a 1989 Turbo R and have the issue of the transmission shifting late. Brand: Tri Component. In-Store Pickup. I do believe on the 6. NO, the modulator has nothing to do with the "kick down" function of the transmission. I recently changed the transmission in my truck. Shift on the TH400 seems to be too early. Push in type, single red stripe. Order ships free when this item is included and exceeds $149. Dec 17, 2016 · Buy Vacuum Modulator Retainer Clip Hold-Down Bracket With Bolt, fits GM TH400 Heavy Duty 8627650K: Transmissions & Parts - Amazon. #7. I just decided to address it. The first is to replace the TH350 with a trans that uses a throttle valve cable instead of vacuum, like a 700R4 or a 200-4R. I sourced the case from eBay and it appears to be an "HD" case. Northern California. Mar 23, 2016 · Vacuum Modulator TH400 Jump to Latest Follow 875 views 5 replies 5 participants last post by total newb Mar 24, 2016 Apr 21, 2017 · The TH400 needs a vacuum feed from the motor to control shifting (don't ask me how it does this, automatic transmissions are some sort of weird black magic). I ran line from a vacuum source, put in a check valve, then a T on the modulator side of the check valve. Install it with a short piece of hose onto the modulator. A vacuum pump gives you high vacuum (and early upshift) all the time. Using the pan bolt pattern is the easiest way to identify the TH400. Unstable Discussion starter. Modulator and crank it down. Pre-bent to factory specifications, the lines feature the correctly bubbled ends, which keep the rubber lines in place at the modulator and the intake manifold. T. 07-15-2002, 04:31 PM. The fitting is a 90-degree "street elbow" type (has a male end and a female end), that most importantly has a tiny internal orifice to limit the vacuum to the modulator. I checked and the vacuum modulator's line and there is no vacuum produced at the modulator, therefore it is running as if it always has WOT. Under normal driving with lots of vacuum the modulator shifts the trans and can be adjusted like Wade said. been reading stuff online about "boost valve" modifications for full manual shift th400's and how you use a plug for the vac mod spot. I adjusted the vacuum modulator all the way out. Another thing guys will do is use an electronic vac modulator eliminator. try your local transmission shop. , vacuum modulator on trans thinks we are going faster than we really are. #9 · Jan 6, 2006. Adjustable for early or late shift. Jan 4, 2006 · 55 posts · Joined 2005. TH-400. Call a local transmission shop. The trans was rebuilt with a higher-than-stock torque converter (1800-2200) and an adjustable vacuum modulator. If it is adjustable I think you'll need to use an allen wrench down in the fitting where the vacuum hose connects. Modulator is good, no leaks in diaphragm. Overall dimensions 17-32 of 39 results for "th400 vacuum modulator" Results. I checked fluid level, vacuum at modulator is 15 and engine is tuned but problem exists. Jul 28, 2013 · I have had a hard second gear shift on my TH400 since I got the car 5 years ago. Hey guys I am experiencing some issues with my th400. TH400 1965-1998. My new line does not have a bracket attached. 5. Most of us cant keep these as consistent as we think we can when testing. Re-adjust as per step B, if necessary, until proper adjustment is achieved. FTI Performance TH400 AFTERMARKET SHORT OUPUT SHAFT . jake something you may find interesting n a 2/3 ratio change with a th400 governer oil is fed to the vaccuum modulators large land to actually reduce line pressure regardless of the vacuum modulator valves position. Try a vacuum gauge at the engine then try it again at the modulator hose end. When I was taking apart the transmission for my 76, the spring behind the Jun 30, 2019 · TH400 Modulator Valve Not Seating Completely. The tranny shifts itself into 1st, 2nd, and will only shift itself into 3rd (Drive) when i really get on the throttle, and shifts into 3rd (Drive) around 3500-4000 RPMs. Is the kickdown hooked up? 12V getting to the connector on the drivers side above the pan rail at WOT? Jan 20, 2024 · THM400 (1964-1994) THM475 (1971-1990) Predecessor Transmissions: Powerglide, Hydramatic, Jetaway. 20. IIRC, there is a specific port for the Jan 8, 2010 · Mark2Mac Discussion starter. The vacuum modulator is a vital component of automatic transmissions. Vacuum Modulator Line, TH400 Transmission, 1969-70 Bonneville/Catalina, 2BBL. It will stop irritating late shift issues in the TH350 and TH400. . You should have at least 15in of vacuum to make it shift correctly. Part # 350001. Replace vacuum tube. I'm not that familiar with the TH400, but on a TH350, the modulator valve has a spring behind it. Aug 24, 2012 · My last engine only made 12" - 13" on a good day and the TH400 responded well to that connected to the carb - use an adjustable Vac. I hope this trans is designed to shift on its own in the first place. Location. cosmolinedirect. If the modulator itself was leaking, it would leak internally, and allow engine vacuum to suck transmission fluid in and you'd have smoking from the tailpipes over it. The connector is located on the driver's side of the transmission. If I rev the motor up a little it will jump back into drive. After install no difference. The engine rpm should change immediately. youtube. Our selection of steel and stainless Jun 1, 2014 · Vacuum modulator? I recently had to put a new shifter cable on my Hurst ratchet shifter on a th400. $23. Add to Cart. Dec 19, 2020 · TH400 Transmission Vacuum Modulator Vacuum line. Brand. Jan 12, 2002. F4046: TH400 Adjustable Vacuum Modulator. 00. Ships UPS Oversize. Looking for torque converter recommendations. 18 posts · Joined 1999. Apr 29, 2004 · 5. This low vac modulator will give you an earlier (and smoother) shift from first to second, and second to third. I need to replace the vacuum modulator on my TH400 trans. This mechanical modulator is designed to take the place of the vacuum modulator on all 700-R4 to 400 6. Ed OLDED - It's STOCK if it's made by GM and it fits! May 27, 2008 · 355 posts · Joined 1999. for TCI Auto GM Th350/Th400 Adjustable Vacuum Modulator. # 1. May 4, 2016 · To eliminate soft shifts or slippage, turn adjusting screw in modulator in a clockwise direction. #17 · Oct 24, 2012. counter-clockwise and that where it shifts. $11. Both the TH350 and May 6, 2014 · May 2002. B&M 20234 Transmission Vacuum Modulator for GM TH350 and TH400 made by B&M, for as low as $39. You don't want to use ported vacuum from the carb or you'll confuse the heck out of the modulator. Turning out the screw in the modulator will make the shifts earlier and softer. Safety Information. Add To Cart. Mark Vilbert in St. There shouldn’t be any. 49. B&M Adjustable Modulator - GM TH350/TH400 Automatic Transmissions. Our products have been featured on Gas Monkey Garage Oct 21, 2012 · 710 posts · Joined 2011. 2-Pack Vacuum Modulator Retainer Clip Hold-Down Bracket, compatible with TH400. TCI Auto GM Th350/Th400 Adjustable Vacuum Modulator Shop All TCI Automotive. 59vette Discussion starter. 86. SKU # 862566. TH400s used a switch on the throttle linkage instead of a kickdown cable for this function. Jul 19, 2008 · 333 posts · Joined 2004. Turbo 400 Performance Racing Transmission Parts by FTI Performance. 10,716. CT4692 - A new made in USA vacuum modulator for TH350 and TH400 Transmissions, 1965 & up. I did some googling and found your average mid-eighties Chevy Diesel 6. Over time, modulators can develop leaks, suffer ruptured diaphragms, become bent, etc. The TH350 uses a mechanical linkage that attaches to the carburetor. ( 2 ) Estimated Ship Date: Jun 17, 2024 (if ordered today) Drop Ship. Check adjustment of shifter cable detents. The vacuum modulator definitely affects shift timing. 48. When the solenoid is activated (12 volts), the line pressure also increases slightly resulting in a slightly higher rpm shift point. You have four options. The vacuum modulator position TH400 transmission turbo is located at the front of the transmission in the engine compartment. Vacuum Modulator Valve Color Code: White Stripe: VMRS Code: 027-026-002 # Vacuum Modulator Valve Hose Connectors: 1: Buyer's Guide. Popular Brand Pick. Includes vacuum tube and very important oring. Mechanical, Controlled By 700R4 Type Cable. odysseyoverland4x4. 959 posts · Joined 2003. The vacuum line for the truck is still the steel one but Vacuum Modulator Line, TH400, 1970-72 Skylark/Pontiac A-Body, 1/4". TH400 ADJUSTABLE MODULATOR, ADJUST SHIFT POINTS WITH EASE, CALIBRATED FOR HIGH PERFORMANCE USE. Our selection of steel and stainless Apr 15, 2009 · 10765 posts · Joined 2002. May 10, 2017 · These "vacuum modulator-assisted" transmissions will employ a kickdown cable (or an electric switch, in the TH400's case) that serves only to "kick-down" the trans into a lower gear for passing Aug 16, 2015 · It occurred to me that many Diesel engines used the Th400, and the diesel engines don't really make much in the way of vacuum. The spade connector you have a photo of is the "kick-down" switch connection. It tells the transmission what kind of load is being put on it, allowing the transmission to react with the proper line pressures and shift points. Re: TH400 Vacuum source? And the answer is: Manifold vacuum. com/OdysseyOverland4x4RUST PREVENTION - https://www. Parts Cost: The vacuum modulator replacement part itself usually costs between $30 and $150. rv so tc gj lb bx ks pq uv bt