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View Full Version : TR5/TR250 TR250 Highway Speeds



MadRiver
07-13-2009, 01:15 PM
Howdy all:

Got a question about highway speeds in my 250. On Friday, I took part in our local club's escort of John MacCartney's cross-country trip. Most of our run was on the interstate -- 140 mile round trip at highway speeds. I found that my 250 was doing anywhere between 65 and 70 mph for a sustained period of time, and ticking over around 4500 rmps in 4th gear. I could in fact push it further to pass, and take it up to the yellow and even to the red line if I had to. We all compared notes with the modern car that was in our caravan, and confirmed that the speeds noted above are accurate.

Here's my question. I do very little interstate driving, and I just don't know if that's what I should expect, or whether I should be able to go a bit faster in 4th at those rpms. Any wisdom from the collective is most appreciated. I of course long for overdrive, but that's a different story...

As an aside, if John is coming your way, take the opportunity to do so. John is a delightful gentleman, and I was thrilled to experience a small part of his journey. I was hesitant to close our office down for the day, but it was well worth it.

Best,

B.

TR3driver
07-13-2009, 01:25 PM
That's too high. Either someone has changed the gears in the diff; or your tachometer is reading high. You shouldn't be turning more than 3500 @ 70 mph, even without OD and with somewhat shorter tires than original.

I have a similar problem with my project TR3, at 4000 rpm the traffic on the freeway is rushing around me. Turns out the DPO installed 4.10 gears without an OD. I'm going to drop in an overdrive, as soon as I make the tool to check the hydraulic pressure and make sure it's OK.

TR6oldtimer
07-13-2009, 02:25 PM
Randall has it right, either tires, tach, or diff, in that order of ease to check.

MadRiver
07-14-2009, 10:53 AM
Thanks guys. I do need to replace my tach drive since it's been bouncing around. The fact that it was willing to still accelerate relatively easily at those speeds makes me think that it's the tach. I'm pretty sure that the rear end is original but who knows?

I'm also running on Coker 185r15s so my tire size is as original. Lousy tires for modern driving.

Thanks!