Windshield wipers

[Cacti_Ken]

I went for a ride a few days ago. I had to go thru some rain.
Wiper system sucks on my M38.
Two things,
1. new wiper blades do not wipe glass uniformly. Wiper arms are not applying much pressure on the blade. Plus the rubber on new blades is not so good.
2. accelerating engine causes vacuum to decrease.
I was surprised to see the wiper motor slow down on accelerating. I thought this wouldn't happen if there was a vacuum pump involved.

Was curious as to what other members have done to improve the wiper system. Especially the wiper blade quality.

[wesk]

If the system is restored to it's original factory new condition it performs quite admirably.

Korean rubber blades and arms will not help performance. For a driver skip the cheap offshore repop blades and adapt modern US made blades. If arms are weak find stronger springs.

Low vacuum output on pump can degrade performance. You must get 12 to 15" HG at cruise RPMs about 1500 to 2000.

Leaks in the system can degrade performance.

Old slightly reconditioned wiper motors often perform poorly. The internal rubber has to be in excellant shape and the interior surfaces it has to seal against must be flawless and smooth. Case sealing is an absolute necessity.

The use of the 1/4" hose instead of the correct 3/32" hose can promote leaks and takes mor vacuum volume.

Low manifold pressure can also have a degrading affect. Basic at idle engine vacuum must be 18 to 21" HG with the vac side of the fuel pump not playing. The vac side of the fuel pump is a booster for the wipers. If you are 5 or 6" HG short on basic manifold vacuum you will be short 5 or 6" HG on the wipers as well.

Yes they will slow slightly when accelerating but they should still be adequate. As a last resort (before adding electric wipers) add a storage boost tank. Any of the inline plastic vacuum reservoirs found in the salvage yard will work. Look for one that has nipples that match the under hood hose size.

[Cacti_Ken]

Ok, I will do some trouble shooting.