tremec speedo drive

[STOMPER]

Just fitted tremec 3550 to my car, The speedo drive gear did not arrive with the
new gear box. Ordered gear from real steel and it came as a genuine Ford part
and with a T5 part number on the invoice. When asking real steel was this wright
I was not convinced by the salesman, He said their the same on both.
is there any one out there who can reassure me this is wright as I dont want to
cause any damage. I also have to check out to see if I need to have the speedo recalibrated, Has any one not needed to have a recalibration after a change.
Regards
Paul.:7

[wilf]

pPaul - I don't think you have a problem. T5 and tremec 3550 both made by same company, use same speedo drives. Make sure you have the circlip and retaining metal thing with bolt/washer.
Not sure if you will need to get your speedo recalibrated - what was it calibrated for before? From memory I think the driving gear inside the tremec is 7 teeth (on 'box output shaft) your driven gear will probably have 18 teeth (count to check). You could work out your speedo calibration needs (in terms of revolutions per mile) from this info, your rear axle ratio, and number of turns per mile of your tyres (probably around 797). Speedy cables will tell you how to go about it in their terms - involves turing wheels, counting speedo cable revs.

Wilf

[mikey]

Just done it this weekend. Speedy cables do the retaining clip etc. I previously had Toyota setup and although close mine needs adjustment. If you had the speedo recalibrated to your previous set up it should have the number of turns per mile written on the side. If this is the case, the formula Speedy use is (1680 x 6.1)/height from hub centre to ground in inches. 6.1 is the figure they use relative to number of revolutions of the wheel. I guess the .1 is to ensure they dont calbrate to read low leading to zero tolerence fines. If the anhswer differs from number of turns given on your speedo, ring speedy up and they will advise you on whether it needs carrying out. There number is 01639 732213 and they are on 4 weeks turnaround at present. However Fit Bit on the other end of the phone will advise you further. A TIP - IF YOU ARE COUNTING NUMBER OF TURNS OF SPEEDO RELATIVE TO NUMBER OF WHEEL TURNS MAKE SURE THE SPEEDO CABLE HAS TAKEN UP SLACK AND STARTED TO REVOLVE IN THE FORWARD DIRECTION BEFORE YOU MARK YOUR TYRE AND START THE COUNTING IF YOU DONT AND START AFTER REVERSING BACK THE WHEEL WILL TURN A GOOD 6" BEFORE THE CABLE STARTS TO REVOLVE LEADING TO AN INACCURATE READING.
Allthe best.
Mike.

[wilf]

More info - my understanding is that speedo's leave the manufacturers calibrated to 1000 turns per mile as standard. To give a better idea of how I calculated mine (an alternate or at least a way of checking the turning wheels method):

Required speedo calibration in revs per mile = Tyre revs/mile times by axle ratio times speedo driving gear number of teeth divided by speedo driven gear number of teeth, so for my own example:

797 x 3.31 x 7 / 18 = 1027

If you can get the tyre manufacturers revs/mile figure, this will incorporate the actual rolling circumference of their tyre, and improve accuracy. Often the "tech questions" department will give you the figure.

WIlf

[paul]

Hi there why not zoom over to Speedy cables as they are now in Hertford so not a million miles from you I'm sure Andy (if he made the move)will sort your speedo out maybe while you wait ??
cheers
Paul

[wilf]

I thought Speedy's Instrument section had moved to Wales?? Am I dreaming here or have they just employed a receptionist with a Welsh accent???

Wilf

[John Tisbury]

Wilf

Still seem to be in London, however searching on the web there is a Speedy Cables in Wales too?????


http://freespace.virgin.net/matt.buc...Speedy_Cables/

John

[dave]

It's kinda both....
Cable manufacture-England
Speedo calibration-Wales

[mikey]

Dave
Instruments section are at Abercave, Swansea SA9 1SQ Tel:01639 732213. Cables are at Unit 14, Merchant Drive, Hertford SG13 7AZ. Tel:01992 581600. 4 days return on cables and 2-3 weeks on recalibration at present.
Regards.
Mike.