Starting to build a XR4ti.

Pieter sent me a message elsewhere asking about some rally car prep advise, and I ended up typing a rather lengthy document with my opinion and advise for building a Merkur. Thought I'd post it here for any additions I may have missed and/or for anyone who may be considering a Merkur rally car.



Alright. Got a little more time now.

Really everything depends upon the level you want to do stuff. Like I said, suspension shouldn't be an option. JVAB stuff is the only thing that makes any sense to spend money on for a rally car and should be done right away.

Brakes. Two levels. Budget and Proper. For Budget, I'd run on stock and try to find a good set of Porterfields or Hawk Blue or similar, (get in touch with Matt Smith or Colin McLeery and find out what they are using). Replace the soft lines at the wheels with braided. Flush all fluid and run good fluid. Check the calipers and rear drum piston things to see if they need rebuilt/replaced (quite likely).

For proper, buy a dual master cylinder setup, big rear brake kit, hydraulic handbrake and complete brake line replacement kit from me. Kit will probably be around $1600-1800+ when finalized.
Buy the front big brake kit from JVAB. Probably around $800.
You will have the braking capability of the Ford WRC cars at around the same price of just the front brake kit for Group A stuff. Budget around $3000 for proper rally big brakes.

I personally wouldn't bother with the Turbo Poop rear disc upgrade. Either do it right, or spend your money elsewhere. The caliper will interfere with coilovers. The proportioning valve will need replaced. You are upgrading 80's drums with 80's small diameter, non-vented discs. I don't call that much of an upgrade personally.

Weld the stock rear diff if you want to do some rallycrosses beforehand and start keeping your eye out for a Supra diff from the 86.5-89 Supras with the LSD and 3.9 or 4.3 final drive ratio at the junkyards. Set aside 300-500ish to buy the JVAB WRC rear beam replica and Supra diff adapters. This will be hands down the best diff option for these cars when he finishes it and starts selling them.

Start compiling parts for the T5 tranny upgrade. The Camaro T5's have the shifter in a more proper location for fitting into the XR. Bellhousing we want is from a pre-86 Turbo Coupe, unless you want to have to deal with converting to hydraulic clutch. I've not yet spent time researching driveshafts or mounts yet. If you want a really nice gearbox, see gearboxman.co.uk or G Force Transmissions, both of which make sweet close ratio straight cut dog or synchro engagement T5 gearboxes.

Fix/replace any suspension bushings you can. JVAB, NACS, or Mc2 should be able to supply bushings. I did nylon ones in the STA in the rear and left the stock beam one in. In front, I haven't touched them as I haven't really done much up front yet and am hoping for a adjustable TCA/compression strut with rosejointed ends someday. Will probably throw some poly ones in when I get around to it.

Figure out a free flowing 3" exhaust. Think about which turbo housing you are going to use. A good upgrade for these is to just use the Cosworth housing (JVAB can source these) which will spool much faster and build better torque. Will require a custom downpipe different from the stock flange.

That's pretty much the best place to start. Search on rallyanarchy and you'll see my shopping list for adding in an oil cooler, many use a RX7 cooler from the Junkyard as a cheap solution. I'm planning to use an SSautochrome radiator with a Cosworth 2WD intercooler. Others use a Saab 900 radiator as it is less expensive. I plan to use stand alone engine management and when the engine needs rebuilt I'll probably port the head, install big valves, port all the intake parts, and rebuild with better internals. Until then, I'm leaving it all mostly alone. I think the fuel system is going to need to be improved upon with dual fuel pumps, FIA FT-3 fuel cell, and relocated lines into the interior of the car. If you are going to rally it, the underhood fuel lines need dealt with as they are plastic and can break relatively easy and I've seen three of these that had underhood fires at some point and I'd not be surprised if that was part of the culprit.

Anyhow, now I'd better get back to work.
Grant

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Grant Hughes

Grant, your car is going to be B-A!

I like what you're doing with the brakes, and I agree that the Thunderbird rear disk isn't a good way to go... BAT makes some stuff. Cossie 280mm front disks with Wilwood calipers, and a 260mm vented disk setup for the rear. Of course, it's no dual master cylinder WRC replica setup, but the cost is 1/2, and it's available now.

So the question is...what's wrong with the BAT stuff?...I've been told I don't want it, but I'm not sure why.

I'm doing the same sort of stuff to the engine. I noticed on here that you (or someone) was replacing the turbo oil lines with some braided stuff. Literally the next day the oil line going to the turbo on my Xratty developed a hairline crack inside the fitting and started leaking oil onto the exhaust housing. I went with the MaxPSI kit because it's available and didn't require engineering on my part. It works as advertised. Stuff like that and the fuel lines needs to be gone through before hitting the stages. That would have been a DNF due to FIRE if it had cracked on stage.

I had my oil line crack 80 miles from home on my last XR and replaced it with the Max PSI kit for the same reason.

As to the BAT kit. From what I saw, it looked expensive for what it was. If you want lower budget, go for John's kit in the front without a doubt. It'll probably be cheaper than the BAT kit and definitely better. Better braking and lighter weight. In the rear you could run the same setup as I have for $1000. Or you could do Turbopoop upgrade, or a stock Euro disc upgrade. I have a set of brackets for the Euro XR4X4 calipers and rotors sitting here. The calipers and rotors should be able to be sourced from John. He is/was planning to do a rear brake upgrade to go with the front eventually too, that will likely be less expensive than the stuff I have. You could always leave the master stock and just rerun the rear lines with a manual proportioning valve.

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Grant Hughes

frumby-You realize the stock t-bird rear disks are 260mm, same as front of XR. Same thing BAT sells. You can get the disks for $30 each from NAPA.

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Scott Manley
Spokane, WA
86' XR4Ti
37

To be honest I'm just trying to build up a base of knowledge on Xratty stuff. I saw the difference being the fact the BAT kit has vented rear rotors, but wasn't sure what kind of calipers and stuff they used.

Anyway...JVL type stuff looks realy nice.

Jason - THE BAT KIT USES STOCK T-BIRD ROTORS , THEY'RE ALL VENTED! Looking at it the whole BAT kit is just the stock t-bird brakes, plus some adapter plate for mounting the caliper.

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Scott Manley
Spokane, WA
86' XR4Ti
37

frumby Wrote:
-------------------------------------------------------
> To be honest I'm just trying to build up a base of
> knowledge on Xratty stuff. I saw the difference
> being the fact the BAT kit has vented rear rotors,
> but wasn't sure what kind of calipers and stuff
> they used.
>
> Anyway...JVL type stuff looks realy nice.

thanks, theyäre just copies of Fords AR based stuff using US sourced equivalents.
The rear shall be as nice and importantly, balanced to the front.

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John Vanlandingham
Sleezattle, WA, USA

Vive le Prole-le-ralliat

www.rallyrace.net/jvab
CALL +1 206 431-9696
Remember! Pacific Standard Time
is 3 hours behind Eastern Standard Time.

Wow, that would be a huge waste of $$ I would say!

frumby Wrote:
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> Wow, that would be a huge waste of $$ I would say!

Hit "quote" so's we's guys have some idear of whats youse talking about, eh?

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John Vanlandingham
Sleezattle, WA, USA

Vive le Prole-le-ralliat

www.rallyrace.net/jvab
CALL +1 206 431-9696
Remember! Pacific Standard Time
is 3 hours behind Eastern Standard Time.