1989 Suburban Transmission Problem?
hey everyone,
i have a 1989 chevy 4-wheel drive suburban that i am in the process of restoring. it has some type of transmission problem…given the fact that im a college student and trying to conserve as much money as possible while still making this a cool ride, i would rather fix it myself.
the problem is: when you accelerate it shifts into first year just fine…when it tries to go in second and and especially third, it bogs down…the more gas you apply the more it bogs until it jerks into gear and kinda “shimmys” for a second…sometimes it will still struggle and slightly fall into a higher gear making it bog again.
supposedly this is a throttle cable issue? ive adjusted it so that it should shift once it reaches higher RPM’s…this also makes it shift harder which in my opinion feels better.
anyone know what causes the slipping? do i need a whole new throttle body? is this a gear problem?
thanks!
daniel mcmahan
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Filed under Gas Conservation FAQ by on Oct 3rd, 2010. Comment. 
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Comments on 1989 Suburban Transmission Problem?
I dont think it is the tranny sound like fuel or spark issues try changing the fuel filter and run some sea foam in the gas this stuff will clean the fuel system up good and works fast put it in and let it sit and run for 15-20 then drive it to see if it helped.
Daniel, that trans should be a 700R4. They are known for problems. What you are describing sounds like a clutch issue. The clutches inside the trans are slipping. The only way to fix it is to rebuild it. If you change the fluid, you chance it getting worse. If you do decide to rebuild it, there are many new upgrades that will make it bullet proof.
The throttle cable issue you are referring to is the detente cable. It is a cable that attaches to the trans and to the throttle linkage at the throttle body. All that cable does is make the transmission down shift when accelerating (passing). It does not control when the transmission shifts into the next gear. To adjust the shift point, look under the burban on the passenger side. There is a black hose going to a solenoid. Unplug the hose and stick a pocket screwdriver in the hole. There is a small screw that you can tighten to increase the rpms before it shifts.
Being an ’89 this may not be a vacuum operated kick down. But if it that type of transmission, look for a vacuum problem to the transmission.
You sound like you are fighting the governor and the throttle cable. The governor kicks the transmission into the next gear, and the throttle cable kicks it down toward first gear.
A lot of that control has been changed to computer control. In this case you want to look toward bad shift solenoids.
I dont suspect this is a rebuild problem, nor do I suspect this is something a transmission shop is needed for. First determine if your transmission is the 700R4 or A4OD (same thing). If so, look toward replacing all the shift solenoids ($25 or so each; one for each upshift).
You adjust the thottle cable this way: 1. with car at idle position and engine off, press to release the throttle cable tab. This is the plastic cable with the teeth on a toothed shaft (best way to explain). You want to press the toothed shaft toward the cable so that the tip bottoms out on the tabbed area. 2. release the adjust lock tab 3. operate the throttle by hand as far open as it will allow. This will pull the plastic toothed shaft across the adjuster. 4. release the throttle and the toothed shaft should stay in place. That is it.
email me if you want to/need to.