Jbreth

I recently purchased a 68 Cutlass Supreme. All original. The floor shift automatic transmission surges 2 to 5 times before going into high gear. If you stand on the gas it shifts smoothly. With more moderate acceleration you get the surging as it shift to top gear.



Any thought?

don71

First off, Welcome to the site.

"Surging" by description can be a couple of different things. Is it for sure, the trans is slipping or is the engine running out of fuel at this certain rpm? A tachometer is helpful in this case. This could be a bad fuel pump, lets don't go there yet.

Have you verified your trans has the proper amount of fluid in it? Is it at the full mark on the dipstick when warmed up? A trans low on fluid will slip like you described.

Another possibility is the shifter dents are worn or the linkage is little out of adjustment. You might think you are in drive when actually the linkage is still somewhat in neutral.

If your shifter will manually go into first gear AND park then your linkage is pretty close to right. If the fluid level is correct also, this might mean a trans rebuild is in your future. Have you manually shifted this trans when driving before? Does it do the same thing? Just be careful if you do and not select reverse.

Let us know any thing else or if you want to describe these symptoms in different words, please do so.

RROLDSX

According to my reference book for 1-2 Shift at Full throttle only:
1. Detent switch defective or energized
2. detent solenoid gasket leaking or bolts not tightened
3. No vacuum to modulator or stuck/sticking modulator or modulator valve.

Obviously as Don said the first things to check are fluid levels and linkages. Burnt fluid could indicate burnt clutch pack requiring a rebuild. Hope this helps.

Randy

Jbreth

Thanks for the info! I did pick up a new Modulator Valve last night. I'll do a little more trouble shooting with the info you guys provided. I did happen to talk to a local good ole boy he said what I was experiencing was referred to as 'Flaring".


I'll let you know what I come up with.


Jim

Jbreth

Heres an update. Turns out the car had a 2 speed tansmission in it and the preasure was dropping off after it warmed up causing the issues. We ended up replacing it with a rebuilt 3 speed tranny out of a 76 Omega.


It was rolled into storeage as it is winter here in Minnesota. A road test in the spring and some final adjustments and we should be good to go!

oldcutlass

A good swap you'll like better than the jetaway.