Triumph Sports Cars

I know that Goodparts sells the mounting hardware for the diff but has anyone tried narrowing the axles and mounting the rear end diff and axles completely as whole? Just wondering. Thanks

I have only seen one instance of where someone took it upon themselves to take a Q45 rearend and do it themselves. It was a TR6 that was done by a hotrod shop and they put in one of those modern Japanese turbo charged straight 6 engines. You can see it in the following link [schradersspeedandstyle.com]
I am sure if you have access to a good machine shop it can be done but I think the cost will be almost the same in the end as if you bought the goods from Richard Good. If you have the diff you can modify it yourself and save a fair amount of money on shipping and buying the modified diff from Richard Good. The biggest cost is buying the hubs along with the axel shafts.

Cheers
Byron

Thanks for the link. Well i'm the proud owner of 91 q45 with traction control so we'll see If I go that route.

If your axels have a 6 bolt pattern then your rear end ratio will be 3.54:1
What engine and transmission are you using in your TR6?
I had a an opportunity to a 3.54:1 R200 diff and I passed on it as the ratio was too high for my engine and transmission combo, a GM 3400 V6 and a Ford T5 (V8) transmission that had a final drive of .63.
I used a gear ratio speed calculator and I found the system would work better with a 3.69:1 ratio. So I will run with the stock TR6 rearend which has a 3.7:1 ratio and when it blows up I will be on the hook for a Richard Good R200 diff and axels.
Use the following link and check out what kind of rpm's you will be running at.
[www.apexgarage.com]

Cheers
Byron

I'm running a 2.3 l ford turbo and t5 out of a 88 mustang. Hmm i better try and run the numbers if they don't work I can probably still sell the diff.. Thanks for the link

If you have the id tag # for your transmission you can get the gear ratios from a list that is here on the British V8 forum it is published in the British V8 news letter, Volume XV Issue 2, Sept 2007
You should be able to find stamped on the transmission case a 4 digit number a hyphen and a 2 digit number.
There is a guy on this forum Dale Knapke that has the same motor in his TR6 and he does a lot of drag racing with his car. You should send him a note and ask him what would be the best rearend ratio to get the optimal performance out of this engine.
You should post some photos for us, we really like pictures on this forum.

Cheers
Byron

looking up the number seems my transmission is different from what the guy said that sold it to me, my transmission is from a 92 mustang final drive is 0.68. the turbo motor redlines at just above 6000 rpm first gear is theoretically with 26 inch tires is 63 km/h. Hmmm.



Edited 1 time(s). Last edit at 11/29/2013 04:31PM by ALV.

My transmission has the following gear ratios:
2.95 1.94 1.34 1.0 .63
The 3.54 diff is too high a ratio for my transmission.
It looks like your transmission has the following gear ratios:
3.15 3.35 1.99 1.33 1.00 .68
You might be able to get by with this combo being that your transmission has a lower gearing in it.
Just the next number down from your number the transmission is for a 92 2.3l Mustang and the gearing is even lower: 3.7 3.97 2.34 1.48 1.00 .79. This is because of the weight of the car. Your TR6 is much lighter than the Mustang so I think it should be okay.

Cheers
Byron

Actually The 2.95 gear is much more desirable I guess with the higher number rear end say 3.69 for the sake of acceleration

Dale Knapke uses a 2.95 first gear with a 3.89 rear end

I'm still somewhat mysified by the relationship between the gearing.of the ransmission and rear end. For some reason my intuition tells me the tr will accelerate poorly off the line.

Another guide you can use in conjunction with the gear speed calculator is to determine the power band of the engine. A rough guide is to take the redline RPM and divide by 2 then take this number and add it to the redline RPM. Now divide this number by 2 and you will get the approx RPM for your power band. Now take this RPM and play with the gear speed calculator and see what speed your car will be at.
The number for my engine is 4650 RPM so with my transmission and a 3.7 rearend I will have the folowing speedo numbers
1 34 mph
2 52 mph
3 75 mph
4 100 mph
5 159 mph Of course this number is theoretical and I doubt a 210 hp V6 engine will push a block shaped TR6 to this speed!!
To me this set of numbers looks quite reasonable, if anything I could possibly go to a slightly lower gear ratio. The 3400 V6 engine has been stuffed into the MGB and it has a 3.9 rearend and the whole package works quite well.
The final thing to consider is the type of driving you will be doing. If you plan on doing a lot of highway cruising you need to consider that the engine will work best and give you the best fuel economy at a certain RPM.

Cheers
Byron

With a 2.95 1st gear T5 I am currently running a 4:11 rear gear. I have even run a 4:56 on the street with very little issue. I run the 2.95 to get the close ratio 1 thru 4 for drag racing. Fifth (.63) then gets me down the Interstate at a very reasonable cruising RPM (28 MPG / 400+ HP). For a street TR6 running a 4 cyl turbo Ford I would run a 4.1 1st gear T5 and a 3.5 rear gear. The 4.1 transmission has a .87 5th gear. This trans gives you more even splits between all the gear changes. The 4.1 first will give you a very good pull away in 1st. The problem with the 2.95 trans is that the split between 4th and 5th is very large and you find yourself wishing you had a 4 1/2 gear (a 6 speed). I have been running the 2.95 trans for over 40,000 miles and do well with it but for a mostly street car I would run the 4.1 T5 trans.

Dale Knapke

Sorry Dale I got the info from the write up in this forum under the fotos of the different conversions. Are you saying them that the 3.35 first gear t5 may well be somewhat streetable with the 3.54 rear end? or it gets close?

I did run a 3.89 rear gear with a 4.1 first gear T5 at one time. That is not a good combination for the street. All the other combinations I mentioned will work on the street but in my opinion for street use the 4.1 first gear T5 with a 3.5 rear gear is the best street combo. Your 3.35 with a 3.54 rear gear will work well but you will at times see that a gear between 4th and 5th would be beneficial. If you already have the 3.35 and 3.54 stuff I would not spend any more money to change it.

Al, Did you know that to run a T5 from a V8 car behind a 2.3 you have to run a special pilot bushing in the crank or have the end of the input shaft turned down. If you search Turboford.org you can find a lot of discussion on this.

Thanks Dale. I will stick with what I have then. Yes I know about the pilot bushing Esslinger and rapido sells one for about 35 bucks. The turbo ford website is great, learning lots. The whole turbo thing with all the acronyms is a bit confusing at times.