1968 Jetaway downshifting clunk
#1
1968 Jetaway downshifting clunk
Hello all -
As you can gather from my other threads, I'm in the process of returning my dad's '68 F-85 to the road after a 6 year hiatus (with very limited driving 5 years before, after the first time it was resurrected). When it last was on the road, we noticed a small leak of transmission fluid, which was regularly topped off. During the 6 year period it sat, there was a massive leak (something I've gathered the Jetaway is famous for when it sits after use for a while). This weekend, I completed work on the manifold and carb swap, filled the trans to the dipstick level, and backed out with no problems. However, there was a noticeable clunk shifting into drive, but then no issues shifting from 1st to 2nd. However, when downshifting while slowing down, there was a noticeable clunk that would occur - but only when downshifting, not upshifting! Fluid levels are full, I used DEX/MERC as I had in the past.....any ideas what could be causing a clunk when downshifting or shifting into drive from park/neutral when stopped?
Pics of new top end parts included, just because.
As you can gather from my other threads, I'm in the process of returning my dad's '68 F-85 to the road after a 6 year hiatus (with very limited driving 5 years before, after the first time it was resurrected). When it last was on the road, we noticed a small leak of transmission fluid, which was regularly topped off. During the 6 year period it sat, there was a massive leak (something I've gathered the Jetaway is famous for when it sits after use for a while). This weekend, I completed work on the manifold and carb swap, filled the trans to the dipstick level, and backed out with no problems. However, there was a noticeable clunk shifting into drive, but then no issues shifting from 1st to 2nd. However, when downshifting while slowing down, there was a noticeable clunk that would occur - but only when downshifting, not upshifting! Fluid levels are full, I used DEX/MERC as I had in the past.....any ideas what could be causing a clunk when downshifting or shifting into drive from park/neutral when stopped?
Pics of new top end parts included, just because.
#2
Looks like a fun project. You are going to get a lot of people suggesting that you drop that Jetaway and replace it with either a TH350 or 200R4, and I am definitely in that camp. Doing any work to the Jetaway is not worth the trouble nor the money. The car will drive so much better with a TH350 or 200R4, and both of these more or less drop in.
#4
#5
Way back in the '70s (when Dad still owned my Cutlass) it exhibited these same symptoms, most noticeable was the hard clunk when slowing to a stop at the downshift from 2-1. Discovered that Dad had set the idle speed too high. Once that was adjusted back to spec, the clunk went away. I high idle speed would also cause a clunk when shifting into gear. Considering you have a new intake/carb, I wouldn't be surprised if something similar is going on.
#6
Sorry for the very late (necro thread!) reply, but just wanted to say thank you for this - I ended up swapping carbs with a buddy, as we suspected the used carb I got needs a rebuild, and the new idle speed from his carb eliminated the clunk altogether. I've since adjusted the idle with no clunk return, so you were spot on. Thank you again!
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