differentials

[lyledtaylor@gmail.com]

Hi is anyone running a 3.45 diff in a standard 2 litre engine can advise the driveability of the car?

[john 215]

Hi,

[:)] WELCOME TO THE BEST TR7 / 8 FORUM INTO THE WORLD EVER [8D]

Before I stuck a V8 in my DHC, being a late car, it had a 3.45 : 1 rear end in it and never had a problem with driveability of her but I do like a car with higher ratio.

Cheers John


LIVE LIFE A QUARTER OF A MILE AT A TIME!

1976 Speke FHC Beauty Now with an overdrive conversion

1979 3.5 FHC(STATUS PENDING!!)

1982 2.0 DHC NOW A 4.6, BUILT NOT BROUGHT !!!!

[lyledtaylor@gmail.com]

Thanks John the reason I enquired is that a so called expert here told me the 2 litre engine wouldn't have enough power but from what you say your engine handelled it quite well.

[Hasbeen]

There are TR7s, & TR7s, as you perhaps know.

Some US 7s had very little power, even in their younger days. By now many are carrying a few dead horses along for the ride.

The 7, in UK spec, or better is quite a torquey thing. It makes most modern engines, with their very high revs a bit breathless. one of those should be fine. However I once had a US spec 7, in quite good condition, & it really did remind me of 1960 driving.

You may know the story, back to third every time a moderate hill appeared. That was what that car was like, even with a 3.9:1 rear end. Of course it was 4Th gear with the 7, but there were a few times I gad to go back to third.

For example, at the legal 60Km/H speed limit, the thing could not climb up to the top of the Mount Panorama, Bathurst race track in 4Th. & I had to go back to third to get up it.

So I believe, that while it could handle a 3.45 diff, it would require a lot of gearbox stirring to do it. I would not even consider it with a California spec car. If you enjoy a lot of stirring, it should help with fuel economy.

Hasbeen

[Workshop Help]

For my all around uses, the 3.63:1 differential is ideal. The terrain around here is all over the place from flat plains, rolling hills, to steep and curvy inclines.

If you have the 3.45:1 under you, be thankful for the improved gas mileage compared to the folks with the more common 3.90:1. Even with the 8.0/1 compression pistons, you will chug down the road just fine.

Mildred Hargis

[lyledtaylor@gmail.com]

Thanks Mildred the 3.63 seems to be the ideal ratio but I wonder if you could advise me where I might source one.
Regards Lyle.

[FI Spyder]

While the 3.90 is fine for getting up my steep drive way and chugging along in parades, I wish I had a 3.45 for highway cruising. While I get good gas mileage with the 3.9 (see other posts) it would no doubt be better with the 3.45. I wouldn't be able to go up the Malahat in over drive with the 3.45 like I can with the 3.9 it would be a welcome trade off. OF course UK pistons would help. Ron (Orange Rag) had a 3.45 in his 30th Anniversary Edition I don't think he had any problems. Post a word Ron.



- - -TR7 Spider - - - 1978 Spitfire- - - - 1976 Spitfire - - 1988 Tercel 4X4 - Kali on Integra - 1991 Integra - Yellow TCT

[jeffremj]

There is no problem in using the 3.45:1. In fact, it was standard fitment to the 2 litre car from VIN402027. From this VIN, the 3.08:1 was used with the 2 litre auto. Make sure you use the proper speedo gearbox drive (21 tooth) to keep the mph values correct.

[Workshop Help]

Perhaps, if you would tell us what differential ratio you have? If you already have a 3.45, you're already sitting pretty. A 3.90?, then it all depends on how much money and work you wish to spend. But, the 3.63 is found all over the place in the 4-speed and automatic cars until they changed to use the then common late differential housing.

Mildred Hargis

[john 215]

Hi,

From approx. chassis number 402027 manual TR7's in the UK had 3.45 rear ends in them from factory. As far as I can remember never had a problem driving with the 3.45 axle, the gearbox also featured the higher 5th gear as a very late car and it worked fine with that.

Cheers John


LIVE LIFE A QUARTER OF A MILE AT A TIME!

1976 Speke FHC Beauty Now with an overdrive conversion

1979 3.5 FHC(STATUS PENDING!!)

1982 2.0 DHC NOW A 4.6, BUILT NOT BROUGHT !!!!

[lyledtaylor@gmail.com]

Perhaps I should explain a little better. The car is a 1978 Australian delivered 5 speed with a 3.9 diff also has improved fuel induction by way of suhs6 carby's with Ramflo aircleaners also fitted with electric fan so to me the engine seems to be quite responsive. The main reason I'm cosidering going to a 3.45 diff is to reduce the revs on highway driving but I don't want to do this if it is going to affect the drivability of the car for city driving. I do apologise if I haven't been very clear.

Cheers Lyle.

[Hasbeen]

Well Lyle, that should handle it. What part of Oz? Why don't you add your "state of origin" to your profile? Then we wouldn't have to guess.

It might mean doing a lot of your town driving in 4TH, but that is no problem. I rarely get into top gear in my Honda S2000 in town, but that doesn't distract from enjoyment.

I don't mind at all doing 3000 RPM cruising at the speed limit. In fact every sports car I have owned, from my 1962 Morgan +4 on, have all done around that 20 MPH/1000 revs until the Honda that is, so I guess I'm used to it.

One of the things I like about the 7 is it's torquey nature. The fact that will out perform, with both in top, the much younger & much more expensive S2000 to almost our 100Km/H speed limit, gives me great pleasure. But then, I guess I always have been a little strange.

Hasbeen

[Workshop Help]

Yes, you DO need the 3.45:1. The advice you received is wrong for keeping the stump puller rear end, that is, unless you actually want and need to pull stumps out of the ground or pull a trailer with a tractor on it. Trust me, you'll be a happy soul with a good 3.45.

If you can get your hands on a 3.45, do so with our blessings. Your reduced gasoline bill for the first month will enable you to buy ice cream for Hasbeen, Cobber, and UKPhil.

Mildred Hargis

[john 215]

Hi Lyle,

It will be fine mate, my 4 speeder runs a 3.27:1 auto rear end [:(] Some said it would be way to high but I like it, ok wont smoke the tyres at the lights but then I have a TR7 V8 for that [}:)] So a 3.45:1 will not a problem.

The Rover SD1 2.0 auto, 2.3 and 2.6 all ran this ratio and that is a lot bigger and heavier car and was fine.

How about posting some pictures of your car, we all enjoy looking at others car's.

Cheers John


LIVE LIFE A QUARTER OF A MILE AT A TIME!

1976 Speke FHC Beauty Now with an overdrive conversion

1979 3.5 FHC(STATUS PENDING!!)

1982 2.0 DHC NOW A 4.6, BUILT NOT BROUGHT !!!!

[Benzo]

I have a 3.45:1 Crown wheel and pinion I will sell and post to you as you wish, I have no need for it anymore, what part of the world are you in?



Building - TR7 V8 - M62B44.