88 V30 top speed 55 mph!!!

[patches05]

I have a 3 spd with granny gear, running LT265/75r/16 with 4.56 gears, 350 TBI. Any ideas how to improve my speed??? I tow a 30ft 5th wheel from job to job but, still empty i get same speed. I only move from town to town maybe twice a year. Empty i get 13-14 mpgs at the ol'double nickle so i would like to if possible keep or improve that as well.

 

[87scotty]

Sounds pretty decent to me you may be happier with 4:10s but gonna dog her down a lil mpre

 

[patches05]

Would the 4.10 get me up to 75 mph?thats my goal running empty

 

[Georgeb]

Why is your top speed only 55 MPH? Can't get it to go any faster or screaming it's guts out?

 

[patches05]

Its wound up like howling like a tornado

 

[Georgeb]

For what it's worth my 87 R3500 has a 350, SM465 and 3.73:1 gears with the same tires. 70 MPH is doable with that setup. With the gearing in the trans getting stuff moving isn't a problem.

 

[Half Assed]

A 1 ton 4x4 with a SM465 trans and 4.56 gear is a sweet combo. You're doing about 2700rpm @ 55mph and 3600rpm @ 75mph.


I would just deal with it as is and accept that 60-65 its probably as fast as you should push it. That truck wasn't built to cruise at 75mph. 4.10s will be a downgrade and it won't haul as well with it. A 350 needs all the help it can get with a 30ft 5th wheel.

 

[crazy4offroad]

You could take your tire size up a little to gain a few mph out of it. But of course that depends on whether or not you can fit bigger tires. Only other option from re-gearing would be to swap in a 5-speed or overdrive auto trans. Honestly the SM465 is a brute of a transmission, there's a reason it is in everything heavy duty. But you usually don't see older dump trucks going faster than 60 on the highway.

 

[patches05]

What about the gear vendors overdrive or something similar... It sees the hwy everday to get to the rightaway. Thats my main reason for speed

 

[patches05]

I do love the low gears when in 4wd aint got it stuck yet knock on wood... Thats another reason for wanting to keep the smtranny

 

[crazy4offroad]

Gear vendor OD is money but it would help. A 0.70 OD would be around 2300 RPMs at 70 MPH. You may want to get a cheap tach just to see what you're running now. Sometimes it sounds worse than it really is, especially if there's a manifold leak or clattering valves. Your 265s are equal to a 31" tire, going up to a 33 would only save you ~200 RPM the way it stands now.

 

[crazy4offroad]

Gear Vendor overdrive for your truck is over $3000, with an OD ratio of 0.78 which would actually be 2700 RPM at 70 MPH.

 

[patches05]

Is the nv4500 option a bad one. Also i read that there is a 5speed sm465 is that true if so are any of those options more doable than the GV. or am i just pissing in the wind....

 

[Georgeb]

This is another option.... I want one but only for the cool factor. If I had a burb or crew cab I sed for family camping I would have one.
http://m.summitracing.com/parts/add-760002m-27

 

[CSFJ]

Is the nv4500 option a bad one. Also i read that there is a 5speed sm465 is that true if so are any of those options more doable than the GV. or am i just pissing in the wind....

I would guess they were referring to the nv4500 when they spoke of a 465 with overdrive. From what I understand, the 4500 is very similar to the 465, except they added the OD on the back end of it. At least that's what I took away from everything I've read.