86 300E & 300SL SERVICE

I am taking my 1986 300E in for service at 135,000 miles and the 300SL in at 45,000 miles. My mechanic says not to replace the fuel pump relay until it
or the fuel pump goes bad since when the fuel pump goes bad you will need to replace the relay again. Any thoughts on how to get colder A/C on both? The SLs A/C only operates at one speed not matter which speed is pushed-any thoughts. Cruise control on SL is out-$1,000 plus labor? (its not a road car-just around LA-mostly in 1st or 2nd on the 405-usually skipping 4th on both-are there replacement gear ratios for 4th and 5th on both 300E and 300SL and where to get them and what would they cost? And why is the shift pattern on the 300E differerent for the shift pattern on the 300SL) Any suggestions for preventative maintenance on either or both?
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Fuel pump on Mercedes rarely goes bad... they are super reliable. So replace your fuel pump relays. You can buy them cheap online or refurbished one too.
Cooler AC depends on how well the system is charged... stick with R12 for maximum cooling capacity and charged it to about 35 degree evaporator temp... the mechanic can read it at their pressure gauge.
The SL probably need a rebuilt control unit... or a resistor pack... you need to do diagnostic.
Cruise Control can be repaired very cheaply... buy rebuilt amplifier. Go to mbcoupes.com and look under part supplier for the three vendors... Colorado one is the best.
Both of your cars has 4 speed tranny. They both starts off 2nd gear. You can have your tranny serviced to starts off first... but it will cost you money. Best leave it alone and service the tranny fluid and filter.
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Tiger, both cars have a five speed manual transmission.

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Oh! Okay, then to change the gear ratio, you change the rear end differential to a higher gear.
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Tiger, both cars have the five speed manual transmission.

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