TRExp

TR7 & TR8 Forum

Ring Gear and Pinion Swap

Moss Motors
AutoShrine Sponsor
AutoShrine Sponsor
AutoShrine Sponsor
AutoShrine Sponsor

John Houston Winfred John Houston
Hurricane, UT, USA   USA
Is it possible to remove the 3:90 Ring and Pinion from my 5 speed axle, and instal a NEW 3:08 unit from Rimmers. I believe they also have a 3:45, and a 3:68 available as well. Freight from England would'nt be cheap, but I need to get the rpms down. The speed limit here in Utah on Interstate 15 is 80 mph. So pretty much everyone is moving along about 85mph. My little TR7 is running about 4,000 rpm at 80mph, and it's a bit unsettling. But if I cruise along at 75mph, (about 3,500 rpm) every semi on the freeway climbs right up my tailpipe, and it's SCARY! Thanks guys. Really want to keep my axle, and just change the gear ratio

. Hide banner ads & support this website by becoming a > Gold Supporting Member <
Mr. Nuts Peter N
Tucumcari, NM, USA   USA
Yes, it's possible to do that. But, I don't think Rimmers has the 3:08 gear set any longer. If you are interested, I probably have a 3:08 gear set here. I know I have a 3:08 rear end laying around. Probably ship the complete rear end for the cost of shipping a ring set from GB. I also have a 3:45 gear set here. So, at 80 mph, your RPM would be 3160 rpms with the 3:08 gear set and 3540 rpms with the 3:45 gear set. Good luck with your project.



Edited 1 time(s). Last edit at 2018-01-02 09:41 AM by Mr. Nuts.

John Houston Winfred John Houston
Hurricane, UT, USA   USA
You're right, they only have the 3:45 gears available. I am interested in your 3:08 set up. Maybe I need to take my wife "ON VACATION" to New Mexico!

. Hide banner ads & support this website by becoming a > Gold Supporting Member <
Darth V8R Avatar
Darth V8R Vance Navarrette
Beaverton, OR, USA   USA
1980 Triumph TR8 "Wedgie"
In reply to # 1505647 by John Houston You're right, they only have the 3:45 gears available. I am interested in your 3:08 set up. Maybe I need to take my wife "ON VACATION" to New Mexico!

I lived there, years ago. Visit the Very Large Array (VLA) radio-telescope near Magdalena, and White Sands, and there is a way cool space museum at Alamagordo. Make sure you drive through Cloud Croft. Of course there are the Carlsbad Caverns, but avoid the nearby hotels, they are all fleabags.

And, if you happen to pick up some car parts while you are there, who will be the wiser?

Vance



1980 Platinum Metallic TR8, navy blue interior
Bare metal respray, Crower cam, raised compression
ported heads, modified Zenith carbs, 0.060" overbore

sliproc Avatar
sliproc Kevin Quistberg E
Long Beach, CA, USA   USA
John,

I've driven that stretch of I-15 going to and from Colorado, you can flat fly and make great time, I love it. You might also want to consider what effect that gear change is going to have on your city driving.

ozkippy Michael Kip
Emerald, Victoria, Australia   AUS
1976 Triumph Stag "Staglet"
1978 Triumph TR7 "Yellow Wedge"
1979 Triumph TR7
My opinion only but I think its a mistake putting a 3.08 axle made for the V8 in a 4 cylinder.
These engines are made to rev and I'm not sure you'll be able to drive the thing in top gear at normal highway speeds. Just my 2 cents is all. 4 cylinders do sound really buzzy flogging along at 4000 rpm where a modern turbo diesel would be whisper quiet doing maybe half those revs. 40 years of progression I guess.
Michael

nick Avatar
nick nick m
Bend, OR, USA   USA
I have two cars. One with 3.45 and the other with 3.90. The former is quite nice at highway speeds but still goes off the line OK. With the 3.08 you may have trouble keeping up with the school buses when pulling away from the light.



nick

. Hide banner ads & support this website by becoming a > Gold Supporting Member <
John Houston Winfred John Houston
Hurricane, UT, USA   USA
Thanks for your input guys! I believe you're right. The Revington web site says the 3:08 will make the ole 4 banger a real dog!
3:45 it is!!

TR8todd Avatar
TR8todd Todd Kishbach
Mass, USA   USA
1977 Triumph TR7 "Rally Fraud"
1978 Triumph TR8
1979 Triumph TR7
1980 Triumph TR8    & more
The 3.08 would be OK if your not looking for the best 0 to 60 times. The 81 automatic TR7s actually came with a 3.08. The PO of my coupe installed a 3.08 in the car. It was slower, but not terrible. I took it out and installed a 3.45, and it makes for a nice driving car. I am not looking for performance out of a TR7 anyway, so it fits the bill of a nice reliable comfortable cruiser. Excellent commuter car. I suggest you go find a rusty TR7 5 speed convertible and grab the rear end out of that. Just make sure to double check that its a 3.45. If you decide you still want to swap the R&P, I can hook you up with either a 3.45 or a 3.08.

. Hide banner ads & support this website by becoming a > Gold Supporting Member <
TR3barton Avatar
TR3barton John Taylor
Greenfield, MA, USA   USA
FREE !!

I have a complete 3.45 drum to drum axel. I am in Greenfield MA.

John Houston Winfred John Houston
Hurricane, UT, USA   USA
Dang, wish you were nearer!

sliproc Avatar
sliproc Kevin Quistberg E
Long Beach, CA, USA   USA
John,

I'm just curious, how much time do you actually spend at 80mph? If it's most of the time then a swap probably makes sense. Also if the swap doesn't work out for you returning it to stock should be easier. Prepping for a smog check I was out on the freeway yesterday and took it up to 80mph at 4000rpm and while that does feel a bit high for cruise remember you're still running only two-thirds of your redline.

lgray001 Avatar
lgray001 Gold Member Larry Gray
Lexington, VA, USA   USA
1976 Triumph TR7 "POS-2"
1979 Triumph TR7 "The Money Pit"
Rimmer has the reconditioned 3.08:1 listed on the TR8 parts list for $714 plus core charge of $205 and a limited slip for $2K.


Member Services:
A Small Business serving the aviation community with avionics knowledge.
. Hide banner ads & support this website by becoming a > Gold Supporting Member <

To add your reply, or post your own questions




Registration is FREE and takes less than a minute!


Having trouble posting or changing forum settings?
Read the Forum Help (FAQ) or contact the webmaster