I got this truck a while ago and I've worked out a lot of bugs. One of the first things I did was put new tires on it. It is an 87 w/ 225 and 883od. I noticed that the speedo is pessimistic and that it is hard to get off the line and I need to stretch the gears pretty far before shifting. I thought I just had a tired motor or clutch but today my mind started churning about tire size.

I am not sure but it looks like some trucks got 235/75/15 (now on truck) while some got 205/75/15. I know that a slant fullsize pickup is underpowered but I dread stopping at a light uphill. It involves a way slower clutch foot than I like.

The 205/75 is just over 27" tall and the 235/75 is just under 29". That is a big difference, right? Like enough to turn a 3.55 rear into what feels like 2.9?

Any thoughts or experiences would be awesome.

Thanks
Kevin

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madam im adam

Well it changes yer final drive ratio by 7%.......final drive ratio would seem like 3.3.

Hows the timing chain?

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Yeah....Im the one who destroyed this rare, vintage automobile.....

Speedo pessimistic + low power around town makes me wonder if somebody might've swapped the rear axle, perhaps installing one from an automatic truck (2.76s, maybe). Have you actually checked the rear axle ratio?

The 205 vs. 235 tires aren't causing your issue.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Is your ebrake on?

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Its so nice out side, I think I'll go lay under my car..

The e brake is all screwed up. It needs the cables cleaned and lubed it sticks on sometimes. Gonna go up on jackstands this week and Ill count out the rear ratio.

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madam im adam

I put new wheel cylinders in both rear drums, along with new springs. The shoes had plenty of meat on them. So I didn't figure the brakes would stick on with the new springs pulling on them.

I knew the adjustment on my e-brake was frozen, and the extra slack caused it to barely be tight enough at the floor (foot pedal). When disenguaged it actually hung down a little loose. This gave me a false confidence that it was not applied, but I knew it needed attention.

The cable system is way different than my a-bodies. The pedal pulls a cable that terminates in a threaded adjustor, which was frozen and now is broken off. The adjustor pulls an intermediate cable which pulls a lever which pulls a balance linkage which pulls the rear e-brake cables.

With all that pulling it turns out the pivot for the lever part was sticking, keeping some drag on the rears. It seems unlikely because there is lots of leverage on it. I freed and lubed it, then spent a half hour removing the frozen nut from the adjustor and cleaning up the rusty threads.

I finally got it all freed up and back together and tested it out and broke the cable right where it is attached (brazed?) to the threaded rod adjustor.

Rockauto's got the front cable for pretty cheap, but I might just go see the local spot for next day service and to keep my $ local.

Thanks for the replies I needed a push.

Keivn

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madam im adam

My dad used to have a '82 truck with S/6 833OD and 3.23 gears,The OD gear was useless in my opinon.If you intend to buy new tires anyway,the smaller tires will help out some.

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V8?? We don't need no stink'n V8!!

I have 295/50 x 15 (much wider but way shorter) on my d150 with 3.55 gears and am looking for 3.71 or 3.91 gears

I use this...http://vexer.com/68rt/speed.html...to save my brain when doing tire size/gear ratio/rpm type stuff....it is much quicker than a pencil and paper.