mthomas3 Posted August 11, 2009 Share Posted August 11, 2009 My R690ST has started hopping at 45 to 50mph. The truck does it worse when you stay at the same speed, you can give it more fuel and it will stop. We have checked ujoints, and tires. Any help ? Quote Link to comment https://www.bigmacktrucks.com/topic/10306-r-model-started-hopping/ Share on other sites More sharing options...
Lmackattack Posted August 11, 2009 Share Posted August 11, 2009 this can be caused by many things. Tires and driveline are first to check. I have also seen the throttle linkage near the fuel pump allowed to "flutter" and cause the truck to seam as it is bouncing. That little lever off of the pump that has the spring was the issue.can you put the truck up on jack stands to see what it does with the drive line and tires spinning? Quote Link to comment https://www.bigmacktrucks.com/topic/10306-r-model-started-hopping/#findComment-38958 Share on other sites More sharing options...
Bollweevil Posted August 12, 2009 Share Posted August 12, 2009 My R690ST has started hopping at 45 to 50mph. The truck does it worse when you stay at the same speed, you can give it more fuel and it will stop. We have checked ujoints, and tires. Any help ? What was the last thing you did with the truck, before it started acting up? Quote Link to comment https://www.bigmacktrucks.com/topic/10306-r-model-started-hopping/#findComment-38973 Share on other sites More sharing options...
TWO DOGS Posted August 12, 2009 Share Posted August 12, 2009 I have had the same problem at that speed with my r model since nov last year.Changed jackshaft, all unis, center bearing, engine mount, gearbox mounts, 2 spider hubs and new tyres medium price.Put truck on blocks and got into high range couldnt fault anything. Took tyres back to shop they say nothing wrong with them so put weight bags in them and rotated still hopping, went back where the diffs were recoed 2 yrs ago he couldnt find anything. i havent pulled the power divider out yet shop said it wouldnt cause the hopping. mine started after doing a job on a steep hill in sand and i used power divider to take off, hopping started sometime after and got worse. maybe i should get driveshafts checked or update truck but couldnt sell it hopping. Also put new rear springs, trunion bushes and elephant feet pads with side blocks in july last year. hope you have better luck than me, any other ideasLyndon Quote Link to comment https://www.bigmacktrucks.com/topic/10306-r-model-started-hopping/#findComment-38990 Share on other sites More sharing options...
MACKS Posted August 12, 2009 Share Posted August 12, 2009 What do you mean by hopping?Are you talking about a vibration or a bouncing movement,I never heard that term used for a problem. Quote Link to comment https://www.bigmacktrucks.com/topic/10306-r-model-started-hopping/#findComment-39005 Share on other sites More sharing options...
TWO DOGS Posted August 13, 2009 Share Posted August 13, 2009 Mine is vibrating and bouncing, can see tipper body moving up and down at 60 to 70 ks. Other drivers freak out when they see it bounce. Power divider seals front and rear are leaking a little, bit of movement up and down on both yokes and there was brass fillings on axle when i done brakesLyndon Quote Link to comment https://www.bigmacktrucks.com/topic/10306-r-model-started-hopping/#findComment-39027 Share on other sites More sharing options...
HK Trucking Posted August 14, 2009 Share Posted August 14, 2009 Mine is vibrating and bouncing, can see tipper body moving up and down at 60 to 70 ks. Other drivers freak out when they see it bounce. Power divider seals front and rear are leaking a little, bit of movement up and down on both yokes and there was brass fillings on axle when i done brakesLyndonBrass filings in the rears means the thrust washers are taking a crap. Quote "If You Can't Shift It Smoothly, You Shouldn't Be Driving It" Link to comment https://www.bigmacktrucks.com/topic/10306-r-model-started-hopping/#findComment-39084 Share on other sites More sharing options...
Rob Posted August 14, 2009 Share Posted August 14, 2009 Brass filings in the rears means the thrust washers are taking a crap.Yup. Time for reman "chunks".Rob Quote Plodding along with no job nor practical application for my existence, but still trying to fix what's broke. Link to comment https://www.bigmacktrucks.com/topic/10306-r-model-started-hopping/#findComment-39085 Share on other sites More sharing options...
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