Bouncing Speedometer and Fuel Level Indicators

[n/a]

As I mentioned in another post, I am in the process of evaluating a 1964 230SL for purchase. The seller mentioned the bouncing needles and I didn't think much of it until I was reading another post today.
How small or large of an issue can this be?
Thanks!
From a new member with an old itch i'm finally ready to scratch!

[jeffc280sl]

Good Luck Steve!

I've had my 280SL for 10 years now and in the winter the tach used to squeal.  The speedo sometimes gets stuck at zero and I need to tap on the glass to free the needle.  Last time I had the gauges out I cleaned and oiled the cables to see if that would help.  I think it has a little.  I see others from time to time replacing their cables.  Maybe the car you are looking at just has a dirty cable that can be cleaned.  I would not worry too much about it.  I'd listen to the engine and do many other things as part of my evaluation before thinking about the gauges.

Jeff C.
1970 280SL 4-speed

[ja17]

Jeff,
Steve is referring to speedometer  problems caused by a loose drive gear in the transmission.

Jeff does bring up a point. Don't confuse instrument problems with tranmission problems. with the transmission problem, acceleration and de-acceleration will cause a noticable and predictable bounce in the speedometer unrelated to speed. Acceleration will often cause the speedometer to drop. de-accelration will cause it to jump up!

Joe Alexander
Blacklick, Ohio

[ted280sl]

Steve,
  I believe the movement in the fuel gauge is due to the way the sending unit is designed. The jumping speedometer or tach are usually due to either the cables or the instruments need to be rebuilt. The cables can be inspected, cleaned and lubed for free. I believe replacement cables are less than $50 each. Having the instruments serviced is about $100 each. I understand there are two levels of service. Palo Alto in Caloifornia basicall rebuilds the instrumnets. I had mine serviced at a local shop and they basically repaired my instrumnets. Within a few years I have had some problems again. I would suggest using Palo Alto for the rebuild.
  I concur with our experts that the instruments are the least of the systems to make your decision based upon. Have a compression test done on the engine. Also have someone knowledgeable check the ride of the car.
Good luck,
Ted 1969 280SL
Summer evenings are among the best times to take a Pagoda for a ride!

[tonyfern75]

Can rear transmission shaft locking nut/ flange speedometer bounce problem occur in an automatic transmission 230 SL? If so, I have a boucing speedometer and a bit of chatter coming from the center..behind the seats and I'm getting a bit worried. Not excited about having to do the fix described in the forum. If someone knows the answer to that question please respond.

Thanks
Tony

[ja17]

Hello Tony,

The problem is not as common in automatics but if the speedometer bounces up during deceleration and down during acceleration you could have a loose slotted nut also. The speedometer drive geasr in both automatic and standard transmission are not  keyed on the shaft but depend on the rear flange nut to be tight in order for the gear and speedometer  to stay engaged. The good news is that with an automatic, merely re-tightening the nut will cure all the problems.
Ignoring the problem can cause the nut to come all the way off and damage to the flex disc, drive shaft and transmission may occur. 

The key here is to closely study the above symptoms of this particular problem. If your symptoms are different you may have an issue with your speedometer or the speedometer cable.